fix: validate resolved ancestry inside atomic projection dispatch

Resolve one connected lineage and retain its root-to-parent capabilities. Backends validate ancestor identity/membership and refresh all policy metadata inside the same boundary as target validators and typed dispatch; hidden/replaced ancestors reject as NotFound without invocation or effects. Preserve pinned leaf and configured-root capabilities. Covers MR ANCESTOR_VISIBILITY_TOCTOU with HTTP memory and Linux replacement/budget/guard regressions; all T-19 workspace acceptance commands pass (Clippy via Nix shell).

CHANGELOG.md

@@ -0,0 +1,16 @@
+# Changelog
+
+All notable changes to the published WIP Rust crates are documented here.
+
+## 0.1.0
+
+Initial public release of:
+
+- `wip-protocol`: transport-independent WIP logical model and validation.
+- `wip-interface-macros`: procedural-macro implementation for interface and DTO declarations.
+- `wip-interface`: public Rust interface-authoring facade and typed value codecs.
+- `wip-host`: request-scoped publication, precondition validation, and qualified operation dispatch.
+- `wip-http`: framework-independent WIP over HTTP v1 routes, strict JSON codecs, and failure classification.
+- `wip-client`: stateful Known Space, interest-driven acquisition, request ownership, and operation lifecycle.
+
+The repository also contains non-published filesystem server, terminal client, and public-API conformance packages.

Cargo.toml

@@ -1,3 +1,19 @@
 [workspace]
 members = ["crates/*"]
 resolver = "3"
+
+[workspace.package]
+version = "0.1.0"
+edition = "2024"
+rust-version = "1.88"
+license = "MIT OR Apache-2.0"
+repository = "https://gitea.hareworks.net/Hare/wip-rs"
+
+[workspace.dependencies]
+wip-client = { version = "0.1.0", path = "crates/wip-client" }
+wip-fs-server = { version = "0.1.0", path = "crates/wip-fs-server" }
+wip-host = { version = "0.1.0", path = "crates/wip-host" }
+wip-http = { version = "0.1.0", path = "crates/wip-http" }
+wip-interface = { version = "0.1.0", path = "crates/wip-interface" }
+wip-interface-macros = { version = "0.1.0", path = "crates/wip-interface-macros" }
+wip-protocol = { version = "0.1.0", path = "crates/wip-protocol" }

LICENSE-APACHE

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

LICENSE-MIT

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Hare
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -4,37 +4,77 @@ Rust building blocks for the Web Interface Protocol (WIP).
 
 The repository is a resolver-3 virtual Cargo workspace whose packages all live
 under `crates/*`. It provides a transport-independent protocol model, the
-standard framework-independent WIP over HTTPS v1 binding, a Rust
+standard framework-independent WIP over HTTP v1 binding, a stateful
-interface-authoring facade, a request-scoped host runtime, and a private
+presentation-independent client runtime, a Rust interface-authoring facade, a
-public-API conformance consumer. The repository root is not itself a package.
+request-scoped host runtime, a bounded Linux filesystem projection server, an
+interactive terminal client, and a private public-API conformance consumer. The
+repository root is not itself a package.
 
 ## Crate graph and responsibilities
 
 ```text
-wip-public-api-example (workspace-only executable, integration tests, doctest)
+Published libraries
-├── wip-protocol              logical declarations, values, calls, and validation
+
-├── wip-https                 standard HTTPS v1 routes, JSON codecs, envelopes, and batching
+wip-client
+├── wip-http
 │   └── wip-protocol
-├── wip-interface             application DTO codecs and interface authoring facade
+└── wip-protocol
-│   ├── wip-protocol
+
-│   └── wip-interface-macros  proc-macro implementation detail
+wip-host
-└── wip-host                  descriptor registry, publication, and qualified dispatch
+├── wip-interface
-    ├── wip-interface
+│   ├── wip-interface-macros
-    └── wip-protocol
+│   └── wip-protocol
+└── wip-protocol
+
+Workspace-only applications and conformance consumers
+
+wip-tui
+├── wip-client
+├── wip-http
+└── wip-protocol
+
+wip-fs-server
+├── wip-host
+├── wip-http
+├── wip-interface
+└── wip-protocol
+
+wip-public-api-example
+├── wip-host
+├── wip-interface
+└── wip-protocol
 ```
 
 | Crate | Responsibility | Does not own |
 | --- | --- | --- |
 | `wip-protocol` | Transport-independent descriptors, object/call/result types, logical `Value`s, validation, and stable protocol error categories. | Application DTOs, implementations, persistence, or wire encoding. |
-| `wip-https` | Standard HTTPS v1 endpoint/route derivation, UTF-8 JSON codecs, direct success bodies, error/status classification, and retrieval batches. | HTTP I/O, TLS termination, authentication schemes, server frameworks, filesystem projection, or client presentation/cache policy. |
+| `wip-http` | Standard WIP over HTTP v1 endpoint/route derivation, UTF-8 JSON codecs, direct success bodies, and error/status classification. | HTTP I/O, URL scheme or TLS policy, authentication schemes, server frameworks, filesystem projection, or client presentation/cache policy. |
+| `wip-client` | Endpoint/security-context-isolated Known Space, normalized object and interface observations, intent-driven object and descriptor coverage with bounded request deduplication, immutable operation call contexts, stale transitions, and bounded histories. | HTTP I/O, credentials, persistent cache, automatic operation retries, or presentation widgets/events. |
+| `wip-tui` | Keyboard-only interactive Worldspace tree, selected Entry and qualified operation panes, descriptor-driven argument editing, bounded result/diagnostic rendering, terminal lifecycle, and HTTP I/O workers over `wip-client`. | Independent cache/validator semantics, automatic operation retries, Host internals, backend paths, or persistent state. |
 | `wip-interface` | The public `WipType`/`interface` authoring API, Rust-to-protocol codecs, generated descriptors, and typed implementation dispatch. | Object publication, backend lifetime, or transport policy. |
 | `wip-interface-macros` | Procedural-macro expansion used by `wip-interface`. It is not an application dependency. | A supported direct user API. |
-| `wip-host` | Opaque interface registration, explicit object membership, validator checks, and interface-qualified dispatch against one host-owned instance. | Backend atomicity, global object lookup, or network serving. |
+| `wip-host` | Opaque interface registration, explicit object membership, validator checks, interface-qualified dispatch against one host-owned instance, and descriptor-guided argument decoding inside that same resolution boundary. | Backend atomicity, global object lookup, or network serving. |
+| `wip-fs-server` | Linux directory-handle-confined request-time projection, complete depth-bounded observations and bounded file operations, standard `wip-http` dispatch, and a loopback HTTP binary. | A new wire profile, implicit symlink following, non-loopback cleartext, authentication policy, TLS termination, or filesystem-wide preregistration. |
 | `wip-public-api-example` | An independently compiled consumer of the protocol, authoring, and host public crates. Its DTOs and traits are application-owned; its implementation and backend handle remain host-private. | Reusable library API or a production server. |
 
+## Published crates
+
+The `0.1.0` release consists of these six crates:
+
+- `wip-protocol`
+- `wip-interface-macros` — implementation dependency re-exported by `wip-interface`
+- `wip-interface`
+- `wip-host`
+- `wip-http`
+- `wip-client`
+
+The filesystem server, terminal client, and public-API example are workspace-only packages and set `publish = false`. All workspace packages require Rust 1.88 or newer and are licensed under either Apache-2.0 or MIT at your option.
+
+See [RELEASING.md](RELEASING.md) for the dependency-ordered crates.io procedure and [CHANGELOG.md](CHANGELOG.md) for release contents.
+
 The boundary is intentional: protocol types describe what can cross a
 transport; application DTOs opt into that model with `WipType`; a host-private
-implementation owns credentials, handles, and backend state; and `wip-https`
+implementation owns credentials, handles, and backend state; and `wip-http`
 maps standard routes/envelopes to `CallOperationRequest` and
 `CallOperationResponse` without placing transport-specific types in descriptors
 or application traits.
@@ -238,6 +278,33 @@ rolled back. Without that proof, post-invocation failures remain
 comparison and backend commit atomic and return a validator describing the state
 that becomes committed.
 
+## Interactive terminal client
+
+[`crates/wip-tui`](crates/wip-tui) provides the `wip-tui` executable. It starts
+from Worldspace `/`, lazily expands materialized tree nodes, displays current
+object/interface/operation metadata, validates all canonical descriptor types in
+a field editor, and requires a separate confirmation action before every call.
+It uses the stateful `wip-client` runtime for request correlation, observed
+validators, stale transitions, and unknown outcomes. One canonical `http` or
+`https` endpoint is used unchanged for request construction, transport, and
+cache partitioning. Scheme, TLS, certificates, authentication, and proxy policy
+belong to the HTTP implementation and deployment. Full startup, key binding,
+layout, validator, and filesystem-operation examples are in the
+[package README](crates/wip-tui/README.md).
+
+## Filesystem projection server
+
+[`crates/wip-fs-server`](crates/wip-fs-server) contains the practical server
+binary and its full security model, configuration, curl walkthrough, and
+resource/failure semantics. It resolves every object from current filesystem
+state, uses pinned directory-relative handles without following symlinks, omits
+non-UTF-8 backend names, returns complete recursive observations through the
+requested depth or a resource-limit failure, and publishes validator-protected
+replacement only in explicit read-write mode.
+The built-in HTTP listener is loopback-only. Externally visible URL schemes,
+TLS termination, certificates, authentication, and proxy routing are deployment
+concerns rather than separate WIP profiles.
+
 ## Validation
 
 Enter the dev shell and run the acceptance commands exactly:

RELEASING.md

@@ -0,0 +1,75 @@
+# Releasing
+
+The six crates published from this workspace use one version and must be released in dependency order. The filesystem server, terminal client, and public-API example set `publish = false` and are never uploaded.
+
+## Preconditions
+
+1. Work from a clean `master` whose `HEAD` matches `origin/master`.
+2. Confirm the intended version in `[workspace.package]` and every internal requirement in `[workspace.dependencies]`.
+3. Confirm ownership of all six names on crates.io.
+4. Run the complete repository validation suite:
+
+```console
+cargo fmt --all -- --check
+cargo check --workspace --all-targets
+cargo test --workspace --all-targets
+cargo test --workspace --doc
+cargo clippy --workspace --all-targets -- -D warnings
+RUSTDOCFLAGS='-D warnings' cargo doc --workspace --no-deps
+cargo run --package wip-public-api-example
+git diff --check
+```
+
+## Publish order
+
+Before uploading anything, dry-run the exact public package set together. Cargo uses a temporary local registry for unpublished workspace dependencies during this check:
+
+```console
+cargo publish --dry-run --workspace \
+  --exclude wip-fs-server \
+  --exclude wip-public-api-example \
+  --exclude wip-tui
+```
+
+Then dry-run and publish each layer before moving to a crate that depends on it:
+
+```console
+cargo publish --dry-run --package wip-protocol
+cargo publish --package wip-protocol
+
+cargo publish --dry-run --package wip-interface-macros
+cargo publish --package wip-interface-macros
+```
+
+Wait until both versions are available from the crates.io index, then continue:
+
+```console
+cargo publish --dry-run --package wip-interface
+cargo publish --package wip-interface
+
+cargo publish --dry-run --package wip-http
+cargo publish --package wip-http
+```
+
+After those versions are available from the index:
+
+```console
+cargo publish --dry-run --package wip-host
+cargo publish --package wip-host
+
+cargo publish --dry-run --package wip-client
+cargo publish --package wip-client
+```
+
+Registry propagation can take time. A dependent dry-run reporting that a WIP crate is unavailable means the previous publish is not visible in the selected registry yet; do not bypass verification.
+
+## Tag
+
+After all six uploads resolve successfully, tag the exact published commit and push the tag:
+
+```console
+git tag -a v0.1.0 -m "release: 0.1.0"
+git push origin v0.1.0
+```
+
+Do not move or recreate a published version or its tag. Prepare a new version for any subsequent correction.

crates/wip-client/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "wip-client"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+description = "Presentation-independent stateful WIP client runtime"
+license.workspace = true
+repository.workspace = true
+readme = "README.md"
+documentation = "https://docs.rs/wip-client"
+
+[dependencies]
+wip-http.workspace = true
+wip-protocol.workspace = true

crates/wip-client/LICENSE-APACHE

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

crates/wip-client/LICENSE-MIT

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Hare
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

crates/wip-client/README.md

@@ -0,0 +1,16 @@
+# wip-client
+
+Presentation-independent stateful runtime for Web Interface Protocol (WIP) clients.
+
+`wip-client` manages endpoint- and security-context-isolated Known Space, object and Interface Descriptor observations, bounded request ownership, supersession, out-of-order response suppression, validator recovery, and operation call contexts. It produces and consumes framework-neutral `wip-http` messages but performs no network I/O and contains no UI types.
+
+```toml
+[dependencies]
+wip-client = "0.1.0"
+```
+
+Applications provide the HTTP adapter and presentation layer, send each prepared request exactly as owned by the runtime, then return the corresponding response for completion.
+
+See the [API documentation](https://docs.rs/wip-client) for session, acquisition, cache, and call APIs.
+
+Licensed under either of Apache-2.0 or MIT at your option.

crates/wip-client/tests/adapter.rs

@@ -0,0 +1,350 @@
+use std::collections::BTreeMap;
+
+use wip_client::{
+    CallOutcome, Client, ClientErrorKind, ClientLimits, Completion, DiagnosticKind,
+    ObservationState, OutcomeUnknownReason, SecurityContext,
+};
+use wip_http::http::{Response, StatusCode};
+use wip_http::{
+    Limits, encode_fetch_interface_response, encode_observe_response,
+    encode_protocol_error_response,
+};
+use wip_protocol::{
+    FetchInterfaceRequest, FetchInterfaceResponse, INTERFACE_FORMAT_V1, InterfaceDescriptor,
+    Object, ObjectObservation, ObserveRequest, OperationDeclaration, ParameterDeclaration,
+    ProtocolError, ProtocolErrorCode, ProtocolInteraction, ReturnDeclaration, TypeExpr, Value,
+};
+
+fn limits() -> Limits {
+    Limits::new(64 * 1024, 64 * 1024, 64).unwrap()
+}
+
+fn setup() -> (Client, wip_client::SessionId) {
+    let mut client = Client::new(ClientLimits::new(2, 16, 16, 16, 16).unwrap(), limits());
+    let session = client
+        .open_session("https://example.test/wip", SecurityContext::new("subject"))
+        .unwrap();
+    (client, session)
+}
+
+fn response(status: StatusCode, body: &[u8]) -> Response<Vec<u8>> {
+    Response::builder()
+        .status(status)
+        .header("content-type", "application/json; charset=utf-8")
+        .body(body.to_vec())
+        .unwrap()
+}
+
+fn object() -> Object {
+    Object {
+        name: "item".into(),
+        description: None,
+        interfaces: vec!["math".into()],
+        r#ref: None,
+        validator: Some(b"object-v1".to_vec()),
+    }
+}
+
+fn descriptor(format: &str) -> InterfaceDescriptor {
+    InterfaceDescriptor {
+        format: format.into(),
+        documentation: None,
+        types: vec![],
+        operations: vec![OperationDeclaration {
+            name: "calculate".into(),
+            documentation: None,
+            parameters: vec![ParameterDeclaration {
+                name: "value".into(),
+                required: true,
+                documentation: None,
+                r#type: TypeExpr::Integer,
+            }],
+            returns: ReturnDeclaration {
+                documentation: None,
+                r#type: TypeExpr::Integer,
+            },
+        }],
+    }
+}
+
+#[test]
+fn malformed_json_unknown_fields_duplicates_and_invalid_success_are_invalid_response() {
+    let cases: &[&[u8]] = &[
+        b"{not json",
+        br#"{"name":"item","interfaces":[],"unknown":true}"#,
+        br#"{"name":"item","interfaces":["math","math"]}"#,
+        br#"{"name":"wrong","interfaces":[]}"#,
+    ];
+    for body in cases {
+        let (mut client, session) = setup();
+        let request = client.refresh_observed(&session, "/item", 0).unwrap();
+        let error = client
+            .complete(request.id, response(StatusCode::OK, body))
+            .unwrap_err();
+        assert_eq!(error.kind, ClientErrorKind::InvalidResponse);
+        assert!(matches!(
+            client.object(&session, "/item").unwrap().state,
+            ObservationState::Error(_)
+        ));
+    }
+}
+
+#[test]
+fn disallowed_code_and_status_success_contradictions_are_invalid_response() {
+    let cases = [
+        (
+            StatusCode::NOT_FOUND,
+            br#"{"error":{"code":"interface_not_found","message":"wrong"}}"#.as_slice(),
+        ),
+        (
+            StatusCode::OK,
+            br#"{"error":{"code":"not_found","message":"wrong status"}}"#.as_slice(),
+        ),
+        (
+            StatusCode::CREATED,
+            br#"{"name":"item","interfaces":[]}"#.as_slice(),
+        ),
+    ];
+    for (status, body) in cases {
+        let (mut client, session) = setup();
+        let request = client.refresh_observed(&session, "/item", 0).unwrap();
+        assert_eq!(
+            client
+                .complete(request.id, response(status, body))
+                .unwrap_err()
+                .kind,
+            ClientErrorKind::InvalidResponse
+        );
+    }
+}
+
+#[test]
+fn valid_error_envelope_is_authoritative_and_status_mismatch_is_diagnostic() {
+    let (mut client, session) = setup();
+    let request = client.refresh_observed(&session, "/item", 0).unwrap();
+    let error = ProtocolError {
+        code: ProtocolErrorCode::NotFound,
+        message: "missing".into(),
+    };
+    let mut encoded =
+        encode_protocol_error_response(ProtocolInteraction::Observe, &error, limits()).unwrap();
+    *encoded.status_mut() = StatusCode::IM_A_TEAPOT;
+
+    assert_eq!(
+        client.complete(request.id, encoded).unwrap(),
+        Completion::ProtocolFailure(error)
+    );
+    assert_eq!(
+        client.object(&session, "/item").unwrap().state,
+        ObservationState::Stale
+    );
+    assert_eq!(
+        client.diagnostics(&session).unwrap().back().unwrap().kind,
+        DiagnosticKind::HttpStatusMismatch
+    );
+}
+
+#[test]
+fn resource_envelope_on_413_uses_code_and_records_canonical_422_mismatch() {
+    let (mut client, session) = setup();
+    let request = client.refresh_observed(&session, "/item", 0).unwrap();
+    let error = ProtocolError {
+        code: ProtocolErrorCode::ResourceLimitExceeded,
+        message: "logical observation limit exceeded".into(),
+    };
+    let mut encoded =
+        encode_protocol_error_response(ProtocolInteraction::Observe, &error, limits()).unwrap();
+    *encoded.status_mut() = StatusCode::PAYLOAD_TOO_LARGE;
+
+    assert_eq!(
+        client.complete(request.id, encoded).unwrap(),
+        Completion::ProtocolFailure(error)
+    );
+    assert_eq!(
+        client.diagnostics(&session).unwrap().back().unwrap().kind,
+        DiagnosticKind::HttpStatusMismatch
+    );
+}
+
+#[test]
+fn non_success_without_valid_envelope_remains_transport_failure() {
+    for status in [StatusCode::BAD_GATEWAY, StatusCode::PAYLOAD_TOO_LARGE] {
+        let (mut client, session) = setup();
+        let request = client.refresh_observed(&session, "/item", 0).unwrap();
+        let error = client
+            .complete(request.id, response(status, b"infrastructure failure"))
+            .unwrap_err();
+        assert_eq!(error.kind, ClientErrorKind::Transport);
+    }
+}
+
+#[test]
+fn unsupported_descriptor_format_is_distinct_from_invalid_response() {
+    let (mut client, session) = setup();
+    let request = client.prepare_interface(&session, "math").unwrap();
+    let logical = FetchInterfaceRequest {
+        interface: "math".into(),
+    };
+    let value = FetchInterfaceResponse {
+        interface: "math".into(),
+        descriptor: descriptor("future-format/2"),
+        validator: Some(b"v2".to_vec()),
+    };
+    let encoded = encode_fetch_interface_response(&logical, &value, limits()).unwrap();
+    let error = client.complete(request.id, encoded).unwrap_err();
+    assert_eq!(error.kind, ClientErrorKind::UnsupportedDescriptorFormat);
+}
+
+#[test]
+fn malformed_call_success_after_dispatch_is_outcome_unknown_and_stales_object() {
+    let (mut client, session) = setup();
+    let observation = client.refresh_observed(&session, "/item", 0).unwrap();
+    client
+        .complete(
+            observation.id,
+            encode_observe_response(
+                &ObserveRequest {
+                    path: "/item".into(),
+                    depth: 0,
+                },
+                &ObjectObservation {
+                    object: object(),
+                    children: None,
+                },
+                limits(),
+            )
+            .unwrap(),
+        )
+        .unwrap();
+    let interface = client.prepare_interface(&session, "math").unwrap();
+    client
+        .complete(
+            interface.id,
+            encode_fetch_interface_response(
+                &FetchInterfaceRequest {
+                    interface: "math".into(),
+                },
+                &FetchInterfaceResponse {
+                    interface: "math".into(),
+                    descriptor: descriptor(INTERFACE_FORMAT_V1),
+                    validator: None,
+                },
+                limits(),
+            )
+            .unwrap(),
+        )
+        .unwrap();
+    let call = client
+        .prepare_call(
+            &session,
+            "/item",
+            "math",
+            "calculate",
+            BTreeMap::from([("value".into(), Value::Integer(2))]),
+        )
+        .unwrap();
+    client.mark_dispatched(call.id).unwrap();
+
+    let completion = client
+        .complete(
+            call.id,
+            response(
+                StatusCode::OK,
+                br#"{"result":"not an integer","unknown":true}"#,
+            ),
+        )
+        .unwrap();
+    assert!(matches!(
+        completion,
+        Completion::Call(record)
+            if matches!(
+                &record.outcome,
+                CallOutcome::Unknown {
+                    reason: OutcomeUnknownReason::ResponseDecode,
+                    failure: Some(failure),
+                } if failure.kind == ClientErrorKind::InvalidResponse
+            )
+    ));
+    assert_eq!(
+        client.object(&session, "/item").unwrap().state,
+        ObservationState::Stale
+    );
+    assert_eq!(client.in_flight_len(), 0);
+}
+
+#[test]
+fn plain_413_after_call_dispatch_is_unknown_transport_outcome() {
+    let (mut client, session) = setup();
+    let observation = client.refresh_observed(&session, "/item", 0).unwrap();
+    client
+        .complete(
+            observation.id,
+            encode_observe_response(
+                &ObserveRequest {
+                    path: "/item".into(),
+                    depth: 0,
+                },
+                &ObjectObservation {
+                    object: object(),
+                    children: None,
+                },
+                limits(),
+            )
+            .unwrap(),
+        )
+        .unwrap();
+    let interface = client.prepare_interface(&session, "math").unwrap();
+    client
+        .complete(
+            interface.id,
+            encode_fetch_interface_response(
+                &FetchInterfaceRequest {
+                    interface: "math".into(),
+                },
+                &FetchInterfaceResponse {
+                    interface: "math".into(),
+                    descriptor: descriptor(INTERFACE_FORMAT_V1),
+                    validator: None,
+                },
+                limits(),
+            )
+            .unwrap(),
+        )
+        .unwrap();
+    let call = client
+        .prepare_call(
+            &session,
+            "/item",
+            "math",
+            "calculate",
+            BTreeMap::from([("value".into(), Value::Integer(2))]),
+        )
+        .unwrap();
+    client.mark_dispatched(call.id).unwrap();
+
+    let completion = client
+        .complete(
+            call.id,
+            Response::builder()
+                .status(StatusCode::PAYLOAD_TOO_LARGE)
+                .body(Vec::<u8>::new())
+                .unwrap(),
+        )
+        .unwrap();
+    assert!(matches!(
+        completion,
+        Completion::Call(record)
+            if matches!(
+                &record.outcome,
+                CallOutcome::Unknown {
+                    reason: OutcomeUnknownReason::ResponseDecode,
+                    failure: Some(failure),
+                } if failure.kind == ClientErrorKind::Transport
+            )
+    ));
+    assert_eq!(
+        client.object(&session, "/item").unwrap().state,
+        ObservationState::Stale
+    );
+    assert_eq!(client.in_flight_len(), 0);
+}

crates/wip-fs-server/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "wip-fs-server"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+description = "Extensible request-time filesystem projection library and WIP over HTTP server"
+license.workspace = true
+repository.workspace = true
+readme = "README.md"
+publish = false
+
+[dependencies]
+http = "1"
+rustix = { version = "1.1", features = ["fs"] }
+wip-host.workspace = true
+wip-http.workspace = true
+wip-interface.workspace = true
+wip-protocol.workspace = true
+
+[dev-dependencies]
+tempfile = "3"

crates/wip-fs-server/README.md

@@ -0,0 +1,255 @@
+# wip-fs-server
+
+`wip-fs-server` projects one configured Linux filesystem directory onto WIP
+Worldspace `/` at request time. It does not register the filesystem contents or
+keep one object instance per entry. It uses `wip-host` for publication and typed
+operation dispatch and uses the standard `wip-http` routes, JSON codecs,
+envelopes, and HTTP status mapping.
+
+## Library assembly and migration
+
+The existing `ServerConfig`, `WipFsServer::new`, `handle_http`, CLI flags and wire
+representation remain compatible. The formerly private projection has become a
+public, generic library engine. No package version or publication policy changes
+are required.
+
+Use `default_projection(root, access, limits)` to obtain the default Linux engine
+without starting a listener. `projection.view(&principal)` is the effective view;
+it owns canonical `observe` and `fetch_interface` and implements the standard
+`wip_host::ObjectProvider` typed `call_operation` API. `DefaultPolicy` has the unit
+principal `()`; default engines also offer unit-principal convenience methods.
+
+For an external backend/composition:
+
+1. Implement `BackendEntry` on a local, cloneable, root-confined stable capability.
+   Its `WipObject` metadata is public-only; its validator binds identity and the
+   protected state. Implement `FilesystemBackend` to resolve one connected
+   `ResolvedEntry<Entry>` (root-to-parent ancestry plus pinned target), enumerate
+   bounded children, and execute against that already-resolved lineage.
+2. Register generated `#[wip_interface::interface]` definitions using the existing
+   `wip_host::InterfaceRegistry`. `DefaultInterfaces::register` optionally supplies
+   reusable built-in tokens; using those tokens does not force their publication.
+3. Implement `Composition<Entry>` on a local type. Its local Object wraps the entry
+   and implements both `WipObject` and the chosen generated traits, avoiding orphan
+   rules. `PublishedObject::expose` proves each implementation at compile time.
+   Publication can add, replace, reorder or omit built-ins based on entry metadata
+   and actual backend capabilities, not just entry kind. `LinuxEntry` implements
+   bounded `FileRead`, `FileWrite` and `SymlinkInspect` for safe delegation; never
+   advertise write in read-only mode or link operations on a non-link capability.
+4. Assemble `Projection::new(backend, registry, composition, policy, limits)`.
+   `ProjectionPolicy` supplies an opaque associated `Principal`, hides Objects and
+   entire hidden subtrees, selects an ordered subset of implemented interfaces,
+   controls descriptor/operation visibility, and permits or denies execution.
+5. An authenticated deployment chooses the principal and `ExecutionContext`. To
+   use HTTP, construct `HttpAdapter::new(&view, &endpoint, limits)` and invoke
+   `handle_http_with_context`. This uses the standard `wip-http` binding, not a
+   filesystem wire profile. Enforce body collection, header, concurrency and
+   deadline bounds in the deployment's listener; the adapter owns none of these
+   intake resources. The bundled loopback listener remains a thin default user.
+
+A complete external-style memory backend, local Object with multiple custom
+Operations, typed registration, principal policy and HTTP flow is exercised in
+[`tests/extensions.rs`](tests/extensions.rs). It uses no Linux filesystem for its
+backend. The public library APIs do not require private types, a fork, an HTTP
+listener, a global object registry, or dynamic plugin loading.
+
+### Extension security contract
+
+Backend implementations and Operation authors are trusted code, not sandboxed
+plugins. `FilesystemBackend::resolve` returns `ResolvedEntry::new(ancestors, target)`
+from one connected backend traversal/snapshot, not independent path-prefix
+resolutions. A root target has no ancestors; other targets retain the root first,
+then intermediate parent containers. This is backend-private context, never wire
+metadata. Backend `resolve` and `execute` signatures both carry this type;
+compositions still receive only the exact scoped target `Entry`.
+
+`FilesystemBackend::execute` must validate ancestor membership/identity and
+refresh **all** lineage state/validators inside its transaction or lock before
+calling the engine callback, retaining the same target and connected ancestry
+through validation and dispatch. Replaced/detached ancestors must return
+`NotFound` without callback invocation, even when the replacement is visible.
+The engine evaluates Object visibility for every refreshed ancestor and target
+inside that same boundary; a hidden ancestor rejects the entire subtree before
+publication/typed dispatch. Never fix a changed lineage by resolving the raw path
+again and substituting capabilities. Participating policy-relevant backend state
+changes must be serialized by this boundary, not just target-content writes.
+Return the committed post-operation validator. Retained ancestry is subject to
+handle/work ceilings; resource exhaustion is an error, not missing ancestry.
+Confirm rollback only after rollback succeeds. Pre-dispatch failures
+must never commit; failed started operations without a non-commit guarantee remain
+`OperationOutcomeUnknown`. Object implementations must delegate validators to
+that entry and declare requirements per `(InterfaceRef, operation)`, rather than
+classify all operations by a read/write name. Operations use the scoped entry and
+propagated context, not a fresh raw-path resolution; they must check deadlines,
+cancellation and resource budgets throughout backend work and report effects
+truthfully. POSIX symlinks, identity, atomic mutations and locking cannot be assumed
+for other backends.
+
+The default Linux backend acquires advisory exclusive locks in root-to-parent
+order and then on the lockable target (directory or regular file). It compares
+retained ancestor identity to no-follow descriptor-relative lookup results,
+refreshes lineage snapshots after acquiring the locks, and holds the guards
+through post-dispatch state observation. The configured root remains its pinned
+capability even if its textual path is renamed; replaced intermediate ancestors
+are rejected. Leaf path replacement never redirects execution to a new inode.
+This serializes cooperating library calls; it does **not** promise transactional
+isolation from unrelated processes ignoring `flock`. Linux capabilities only
+expose bounded methods, not raw descriptors or backend paths.
+
+A policy must be stable/deterministic within one effective Worldspace view.
+Interface/operation visibility is uniform per registered reference within that
+view, so observation, fetch and dispatch use the identical filtered descriptor.
+For entry-specific operation sets, register distinct interface definitions and
+select them by entry. Different principals may have different effective views.
+Changing a policy must establish a new view/reference lifetime (e.g. rebuild the
+registry/engine); do not keep validator-free references while changing their
+meaning. Execution permission may deny a visible Operation without hiding it.
+A published interface is always fetchable by that principal; hidden operations
+are omitted (along with their unreachable named types and interface-wide docs)
+and guessed calls return `OperationNotFound`, whereas visible denied
+operations return `PermissionDenied`. Hidden Objects and descendants return
+`NotFound` and are absent from parent observations. Work spent scanning hidden
+entries still counts against traversal bounds; resource limits are not a
+constant-time/side-channel guarantee.
+
+Never put absolute paths, hidden metadata, credentials or policy internals in
+public `WipObject` metadata, descriptions, validators or normal logs. Validators
+must be opaque public tokens, not confidential content. Engine/HTTP failures use
+bounded generic diagnostics; arbitrary trusted implementation metadata/logging
+cannot be sanitized automatically. Do not log credentials or sensitive panic
+payloads from extensions.
+
+## Security model
+
+- The effective root is opened once as a directory capability. Root path
+  components must be real directories (symlink components are rejected), and the
+  displayed effective root is read back from that same pinned descriptor. Every
+  request is resolved segment-by-segment with directory-relative, `O_NOFOLLOW`
+  handles.
+- Symlinks are projected as links and are never followed. Their stored target is
+  available only through the `SymlinkInspect.read_link` application operation.
+- Regular files, directories, symlinks, and unsupported entry types have distinct
+  public descriptions and capability sets.
+- WIP names are Unicode. Linux names that are not valid UTF-8 are deliberately
+  not published; valid UTF-8 names map byte-for-byte and therefore cannot collide.
+  Unicode paths containing backend-invalid NUL bytes are likewise treated as
+  unpublished rather than as backend failures.
+- No object `ref` is issued. This avoids claiming representation identity for
+  hard links or path-specific names. Regular files and symlinks receive an opaque
+  validator containing filesystem identity plus protected metadata; replacing a
+  path therefore does not preserve its validator.
+- Protocol metadata and errors never contain the backend absolute path. Startup
+  prints only the explicitly configured effective root and security-sensitive
+  modes.
+- The built-in HTTP listener is loopback-only. TLS termination, certificates,
+  authentication, an externally visible URL scheme, and proxy routing are
+  deployment concerns rather than separate WIP transport profiles.
+
+The implementation currently targets Linux because it uses `O_PATH`,
+directory-relative descriptor traversal, and `/proc/self/fd` to reopen the same
+pinned backend object without resolving the untrusted Worldspace path twice.
+
+## Run
+
+Run the loopback listener in read-only mode:
+
+```console
+cargo run -p wip-fs-server -- \
+  --root /srv/public-files \
+  --listen 127.0.0.1:8080 \
+  --base-path /wip
+```
+
+Run with the write capability deliberately enabled:
+
+```console
+cargo run -p wip-fs-server -- \
+  --root ./example-files \
+  --listen 127.0.0.1:8080 \
+  --base-path /wip \
+  --read-write
+```
+
+The server reports the effective root, `ReadOnly`/`ReadWrite` mode, endpoint,
+and actual listen address. It does not enumerate the root.
+
+## Standard interactions
+
+The following examples use the built-in HTTP listener. The JSON follows the
+standard WIP over HTTP binding; validators and operation `Bytes` are base64 body
+fields, never `ETag` or `If-Match` headers.
+
+Observe only the root Object:
+
+```console
+curl -sS -X POST http://127.0.0.1:8080/wip/v1/observe \
+  -H 'Content-Type: application/json' -H 'Accept: application/json' \
+  --data '{"path":"/","depth":0}'
+```
+
+Observe the root and two levels of indexable children:
+
+```console
+curl -sS -X POST http://127.0.0.1:8080/wip/v1/observe \
+  -H 'Content-Type: application/json' -H 'Accept: application/json' \
+  --data '{"path":"/","depth":2}'
+```
+
+A regular-file observation returns the opaque read interface reference and an object
+validator. Retrieve that descriptor with:
+
+```console
+curl -sS -X POST http://127.0.0.1:8080/wip/v1/fetch_interface \
+  -H 'Content-Type: application/json' -H 'Accept: application/json' \
+  --data '{"interface":"<read-interface-from-observation>"}'
+```
+
+Then call a bounded range read:
+
+```console
+curl -sS -X POST http://127.0.0.1:8080/wip/v1/call_operation \
+  -H 'Content-Type: application/json' -H 'Accept: application/json' \
+  --data '{
+    "target":{"path":"/notes.txt","validator":"<base64-validator>"},
+    "interface":{"reference":"<read-interface>"},
+    "operation":"read",
+    "arguments":{"offset":0,"length":4096}
+  }'
+```
+
+In `--read-write` mode a second regular-file interface declares `replace`.
+Writes require the current object validator and return the post-write validator:
+
+```console
+curl -sS -X POST http://127.0.0.1:8080/wip/v1/call_operation \
+  -H 'Content-Type: application/json' -H 'Accept: application/json' \
+  --data '{
+    "target":{"path":"/notes.txt","validator":"<base64-validator>"},
+    "interface":{"reference":"<write-interface>"},
+    "operation":"replace",
+    "arguments":{"contents":"dXBkYXRlZA=="}
+  }'
+```
+
+## Resource and failure behavior
+
+`ResourceLimits` bounds request/response bytes, HTTP request-head bytes, JSON
+nesting, file read/write bytes, tree depth/node count, pinned handles, and active
+connections/requests. One absolute request deadline covers header and
+body intake, dispatch, cooperative filesystem work, and response transmission;
+stalled clients are closed and cannot occupy a worker beyond that bound. Workers
+accept connections directly, so the listener never moves more than the configured
+concurrency into active userspace service. Advisory file-lock acquisition uses a
+nonblocking loop and checks the same deadline/cancellation rather than allowing a
+contended lock to stall a worker. Object observation recursively opens only the
+requested depth. A successful response is complete through that depth; if the
+configured projected-node budget would be exceeded, the interaction fails with
+`ResourceLimitExceeded` instead of returning a partial observation. I/O failure
+and cancellation remain errors.
+
+Whole-file replacement compares the request validator against the identity and
+state of the same pinned file handle used for the write. Failures before mutation
+carry a `NotCommitted` guarantee and map to `Internal` or
+`ResourceLimitExceeded`; a failure after truncation/write begins maps to
+`OperationOutcomeUnknown`. The server and Clients do not automatically retry
+side-effecting operations.

crates/wip-fs-server/src/defaults.rs

@@ -0,0 +1,146 @@
+//! Reusable default Linux composition; no listener or authentication dependency.
+use crate::engine::{BackendEntry, Composition, DefaultPolicy, EntryKind, Projection};
+use crate::interfaces::{
+    FileRead, FileReadDefinition, FileWrite, FileWriteDefinition, SymlinkInspect,
+    SymlinkInspectDefinition,
+};
+use crate::projection::{LinuxBackend, LinuxEntry};
+use crate::{AccessMode, ResourceLimits};
+use wip_host::{
+    ExecutionContext, HostError, InterfaceRef, InterfaceRegistry, PublishedObject,
+    RegisteredInterface, RegistrationError, Validator, WipObject,
+};
+use wip_interface as wip;
+
+/// Registered built-in interfaces, usable by external compositions and Objects.
+pub struct DefaultInterfaces {
+    /// Bounded regular-file reads.
+    pub read: RegisteredInterface<FileReadDefinition>,
+    /// No-follow link inspection.
+    pub symlink: RegisteredInterface<SymlinkInspectDefinition>,
+    /// Validator-protected replacement.
+    pub write: RegisteredInterface<FileWriteDefinition>,
+}
+impl DefaultInterfaces {
+    /// Register reusable default descriptors without publishing any objects.
+    pub fn register(registry: &mut InterfaceRegistry) -> Result<Self, RegistrationError> {
+        Ok(Self {
+            read: registry.register(FileReadDefinition, None)?,
+            symlink: registry.register(SymlinkInspectDefinition, None)?,
+            write: registry.register(FileWriteDefinition, None)?,
+        })
+    }
+}
+
+/// Default capability-aware Linux publication, independent of HTTP.
+pub struct DefaultComposition {
+    interfaces: DefaultInterfaces,
+}
+impl DefaultComposition {
+    /// Use previously registered built-in interface tokens.
+    pub fn new(interfaces: DefaultInterfaces) -> Self {
+        Self { interfaces }
+    }
+}
+
+/// Request-scoped default Object; external Objects may instead wrap `LinuxEntry`.
+pub struct DefaultObject {
+    entry: LinuxEntry,
+    write: InterfaceRef,
+}
+impl DefaultObject {
+    /// The pinned, bounded capability used by every operation on this Object.
+    pub fn entry(&self) -> &LinuxEntry {
+        &self.entry
+    }
+}
+impl WipObject for DefaultObject {
+    fn name(&self) -> &str {
+        self.entry.name()
+    }
+    fn description(&self) -> Option<&str> {
+        self.entry.description()
+    }
+    fn reference(&self) -> Option<&str> {
+        self.entry.reference()
+    }
+    fn validator(&self) -> Option<&Validator> {
+        self.entry.validator()
+    }
+    fn requires_validator(&self, interface: &InterfaceRef, operation: &str) -> bool {
+        interface == &self.write && operation == "replace"
+    }
+}
+impl FileRead for DefaultObject {
+    fn read(&self, offset: Option<u64>, length: Option<u64>) -> wip::OperationResult<wip::Bytes> {
+        self.entry.read(offset, length)
+    }
+}
+impl SymlinkInspect for DefaultObject {
+    fn read_link(&self) -> wip::OperationResult<wip::Bytes> {
+        self.entry.read_link()
+    }
+}
+impl FileWrite for DefaultObject {
+    fn replace(&self, contents: wip::Bytes) -> wip::OperationResult<()> {
+        self.entry.replace(contents)
+    }
+}
+impl Composition<LinuxEntry> for DefaultComposition {
+    type Object = DefaultObject;
+    fn publish(
+        &self,
+        entry: LinuxEntry,
+        _: &ExecutionContext,
+    ) -> Result<PublishedObject<Self::Object>, HostError> {
+        let kind = entry.kind();
+        let writable = entry.access_mode() == AccessMode::ReadWrite;
+        let mut publication = PublishedObject::new(DefaultObject {
+            entry,
+            write: self.interfaces.write.reference().clone(),
+        });
+        match kind {
+            EntryKind::Regular => {
+                publication = publication
+                    .expose(&self.interfaces.read)
+                    .map_err(publication_error)?;
+                if writable {
+                    publication = publication
+                        .expose(&self.interfaces.write)
+                        .map_err(publication_error)?;
+                }
+            }
+            EntryKind::Symlink => {
+                publication = publication
+                    .expose(&self.interfaces.symlink)
+                    .map_err(publication_error)?;
+            }
+            EntryKind::Directory | EntryKind::Unsupported => {}
+        }
+        Ok(publication)
+    }
+}
+fn publication_error(_: wip_host::PublicationError) -> HostError {
+    HostError::internal(
+        "default publication failed",
+        wip_host::EffectGuarantee::NotCommitted,
+    )
+}
+
+/// Construct the secure-by-default Linux engine without binding a listener.
+pub fn default_projection(
+    root: &std::path::Path,
+    access: AccessMode,
+    limits: ResourceLimits,
+) -> Result<Projection<LinuxBackend, DefaultComposition, DefaultPolicy>, std::io::Error> {
+    let backend = LinuxBackend::open(root, access, limits)?;
+    let mut registry = InterfaceRegistry::new();
+    let interfaces = DefaultInterfaces::register(&mut registry).map_err(std::io::Error::other)?;
+    Ok(Projection::new(
+        backend,
+        registry,
+        DefaultComposition::new(interfaces),
+        DefaultPolicy,
+        limits,
+    ))
+}

crates/wip-fs-server/src/engine.rs

@@ -0,0 +1,661 @@
+//! Transport-independent projection, publication, and principal view boundaries.
+
+use crate::ResourceLimits;
+use wip_host::{
+    EffectGuarantee, ExecutionContext, HostError, InterfaceRef, InterfaceRegistry, ObjectProvider,
+    OperationAttempt, ProviderResult, PublishedObject, WipObject,
+};
+use wip_protocol::{
+    FetchInterfaceRequest, FetchInterfaceResponse, ObjectObservation, ObserveRequest,
+    ObserveResponse, ProtocolError, ProtocolErrorCode,
+};
+
+/// Portable entry classification; capabilities must not be inferred from kind alone.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum EntryKind {
+    /// Container whose children can be enumerated.
+    Directory,
+    /// Regular data entry.
+    Regular,
+    /// Link itself, never implicitly followed.
+    Symlink,
+    /// Metadata-only entry unless the composition supplies a capability.
+    Unsupported,
+}
+
+/// A root-confined, request-time capability, not a path to resolve again.
+///
+/// Metadata must be safe for public exposure. Validators bind both identity and
+/// protected state. Cloning must retain the same target rather than re-resolve it.
+pub trait BackendEntry: WipObject + Clone {
+    /// Classification for observation and publication selection.
+    fn kind(&self) -> EntryKind;
+}
+
+/// A single resolved target together with its retained root-to-parent lineage.
+///
+/// The backend must resolve a connected lineage, never independent raw-path
+/// prefixes. At execution it validates ancestor membership/identity, refreshes
+/// their policy metadata, and pins that snapshot through dispatch. Target
+/// replacement must not redirect the original capability. This value is private
+/// backend context, not protocol metadata.
+#[derive(Clone)]
+pub struct ResolvedEntry<E> {
+    ancestors: Vec<E>,
+    target: E,
+}
+
+impl<E> ResolvedEntry<E> {
+    /// Create backend resolution context. `/` has no ancestors; a non-root target
+    /// has the pinned root first, followed by its intermediate parent containers.
+    pub fn new(ancestors: Vec<E>, target: E) -> Self {
+        Self { ancestors, target }
+    }
+    /// Pinned ancestor capabilities, ordered from the root to the direct parent.
+    pub fn ancestors(&self) -> &[E] {
+        &self.ancestors
+    }
+    /// The original resolved target capability, never a redirected replacement.
+    pub fn target(&self) -> &E {
+        &self.target
+    }
+    /// Consume this snapshot for refresh or request-time publication.
+    pub fn into_parts(self) -> (Vec<E>, E) {
+        (self.ancestors, self.target)
+    }
+}
+
+/// Trusted backend boundary. Implementations need not use POSIX semantics.
+///
+/// Resolve and enumerate pinned capabilities within the configured root. Enforce
+/// context cancellation, deadlines and work budgets during backend work. Do not
+/// advertise capabilities the backend cannot guarantee. Errors must not include
+/// backend paths, credentials or hidden metadata.
+///
+/// `execute` must retain the same target and complete lineage and serialize
+/// ancestor identity/membership checks, policy metadata, validator observation,
+/// publication, validation, typed dispatch and commit/rollback. Changed/detached
+/// ancestors must return `NotFound` before the callback; never substitute a new
+/// ancestor or redirect the target by re-resolving its raw path. Refresh *all*
+/// lineage metadata/validators inside the boundary and retain that snapshot
+/// through dispatch, then return the committed post-operation validator. Never
+/// upgrade an unknown outcome except after confirmed rollback. Locks only protect
+/// actors participating in the protocol; document any external-writer limits.
+pub trait FilesystemBackend {
+    /// Stable capability supplied to the composition.
+    type Entry: BackendEntry;
+    /// Resolve a canonical WIP path and retain its connected ancestry.
+    ///
+    /// Obtain the target and lineage in one backend traversal/snapshot. Enforce
+    /// configured handle/work budgets while retaining ancestors; do not silently
+    /// omit ancestry on resource exhaustion.
+    fn resolve(
+        &self,
+        context: &ExecutionContext,
+        path: &str,
+    ) -> ProviderResult<ResolvedEntry<Self::Entry>>;
+    /// Enumerate direct children, at most `maximum`; excess must fail, not truncate.
+    fn children(
+        &self,
+        context: &ExecutionContext,
+        entry: &Self::Entry,
+        maximum: usize,
+    ) -> Result<Vec<Self::Entry>, HostError>;
+    /// Execute against this already-resolved target within an atomic boundary.
+    fn execute(
+        &self,
+        context: &ExecutionContext,
+        entry: ResolvedEntry<Self::Entry>,
+        operation: impl FnOnce(ResolvedEntry<Self::Entry>) -> OperationAttempt,
+    ) -> ProviderResult<OperationAttempt>;
+}
+
+/// Typed publication extension point, implementable on an external crate's type.
+///
+/// Use `InterfaceRegistry::register` and `PublishedObject::expose` with generated
+/// definitions. An external local Object can wrap the entry and implement any
+/// number of interfaces, avoiding orphan rules. Its `WipObject` implementation
+/// declares validator requirements per qualified operation. Operation failures
+/// declare their own `EffectGuarantee`, not a fixed read/write classification.
+pub trait Composition<E: BackendEntry> {
+    /// Local typed operation implementation and safe public metadata.
+    type Object: WipObject;
+    /// Build a request-scoped publication using this exact capability/context.
+    ///
+    /// Publication and policy hooks must be side-effect-free with respect to the
+    /// backend. A publication failure is a pre-dispatch rejection, never a
+    /// started Operation. Delegate metadata/validators to the boundary snapshot.
+    fn publish(
+        &self,
+        entry: E,
+        context: &ExecutionContext,
+    ) -> Result<PublishedObject<Self::Object>, HostError>;
+}
+
+/// Principal-specific view policy, independent of authentication transport.
+///
+/// Keep decisions deterministic and stable within an effective Worldspace view.
+/// A changed policy requires a new view/reference lifetime (or interface
+/// validators). Operation visibility is interface-wide within a view so every
+/// published reference has exactly the descriptor returned by fetch. Entry-
+/// specific differences should select different registered interfaces. Hooks
+/// cannot add implementations, metadata, or raw paths to a publication.
+pub trait ProjectionPolicy<E: BackendEntry, O: WipObject> {
+    /// Opaque deployment-established principal/request identity.
+    type Principal;
+    /// Whether the entry is visible. Invisible ancestors hide their whole subtree.
+    fn object_visible(&self, principal: &Self::Principal, entry: &E) -> bool;
+    /// Whether an interface descriptor may be fetched in this view.
+    fn interface_visible(&self, _principal: &Self::Principal, _interface: &InterfaceRef) -> bool {
+        true
+    }
+    /// Select/order a subset of implemented interfaces; defaults to all.
+    fn interfaces(
+        &self,
+        _principal: &Self::Principal,
+        _entry: &E,
+        available: &[InterfaceRef],
+    ) -> Vec<InterfaceRef> {
+        available.to_vec()
+    }
+    /// Whether an operation is present in this view's descriptor and dispatch.
+    fn operation_visible(
+        &self,
+        _principal: &Self::Principal,
+        _interface: &InterfaceRef,
+        _operation: &str,
+    ) -> bool {
+        true
+    }
+    /// Execution permission for a visible operation, after canonical preconditions.
+    fn authorize(
+        &self,
+        _principal: &Self::Principal,
+        _object: &O,
+        _interface: &InterfaceRef,
+        _operation: &str,
+    ) -> bool {
+        true
+    }
+}
+
+/// No authentication assumption: all configured objects/operations are visible.
+pub struct DefaultPolicy;
+impl<E: BackendEntry, O: WipObject> ProjectionPolicy<E, O> for DefaultPolicy {
+    type Principal = ();
+    fn object_visible(&self, _: &(), _: &E) -> bool {
+        true
+    }
+}
+
+/// Canonical request-time engine, independent of HTTP and Linux.
+pub struct Projection<B, C, P> {
+    backend: B,
+    registry: InterfaceRegistry,
+    composition: C,
+    policy: P,
+    limits: ResourceLimits,
+}
+
+impl<B, C, P> Projection<B, C, P>
+where
+    B: FilesystemBackend,
+    C: Composition<B::Entry>,
+    P: ProjectionPolicy<B::Entry, C::Object>,
+{
+    /// Assemble trusted components. The registry must contain all exposed tokens.
+    pub fn new(
+        backend: B,
+        registry: InterfaceRegistry,
+        composition: C,
+        policy: P,
+        limits: ResourceLimits,
+    ) -> Self {
+        Self {
+            backend,
+            registry,
+            composition,
+            policy,
+            limits,
+        }
+    }
+    /// Backend access for trusted composition/configuration, never serialized.
+    pub fn backend(&self) -> &B {
+        &self.backend
+    }
+    /// Borrow one effective principal view for observation, fetch and dispatch.
+    pub fn view<'a>(&'a self, principal: &'a P::Principal) -> ProjectionView<'a, B, C, P> {
+        ProjectionView {
+            projection: self,
+            principal,
+        }
+    }
+}
+
+/// A coherent principal view implementing canonical typed host dispatch.
+pub struct ProjectionView<'a, B, C, P>
+where
+    B: FilesystemBackend,
+    C: Composition<B::Entry>,
+    P: ProjectionPolicy<B::Entry, C::Object>,
+{
+    projection: &'a Projection<B, C, P>,
+    principal: &'a P::Principal,
+}
+
+impl<B, C, P> ProjectionView<'_, B, C, P>
+where
+    B: FilesystemBackend,
+    C: Composition<B::Entry>,
+    P: ProjectionPolicy<B::Entry, C::Object>,
+{
+    fn resolve(
+        &self,
+        context: &ExecutionContext,
+        path: &str,
+    ) -> ProviderResult<ResolvedEntry<B::Entry>> {
+        if let Err(error) = preflight(context) {
+            return ProviderResult::Failure(error);
+        }
+        if wip_protocol::validate_path(path).is_err() {
+            return ProviderResult::NotFound;
+        }
+        match self.projection.backend.resolve(context, path) {
+            ProviderResult::Found(resolved) => {
+                if !lineage_matches_path(&resolved, path) {
+                    return ProviderResult::Failure(internal());
+                }
+                if !self.lineage_visible(&resolved) {
+                    return ProviderResult::NotFound;
+                }
+                ProviderResult::Found(resolved)
+            }
+            ProviderResult::NotFound => ProviderResult::NotFound,
+            ProviderResult::Failure(error) => ProviderResult::Failure(error),
+        }
+    }
+
+    fn lineage_visible(&self, resolved: &ResolvedEntry<B::Entry>) -> bool {
+        resolved
+            .ancestors()
+            .iter()
+            .chain(std::iter::once(resolved.target()))
+            .all(|entry| self.projection.policy.object_visible(self.principal, entry))
+    }
+
+    fn publication(
+        &self,
+        entry: B::Entry,
+        context: &ExecutionContext,
+    ) -> Result<PublishedObject<C::Object>, HostError> {
+        let publication = self
+            .projection
+            .composition
+            .publish(entry.clone(), context)?;
+        let available = publication
+            .protocol_object()
+            .interfaces
+            .iter()
+            .map(|reference| {
+                self.projection
+                    .registry
+                    .resolve(reference)
+                    .ok_or_else(internal)
+            })
+            .collect::<Result<Vec<_>, _>>()?;
+        let mut selected = self
+            .projection
+            .policy
+            .interfaces(self.principal, &entry, &available);
+        selected.retain(|reference| {
+            self.projection
+                .policy
+                .interface_visible(self.principal, reference)
+        });
+        publication
+            .project(&selected, |reference, operation| {
+                self.projection
+                    .policy
+                    .operation_visible(self.principal, reference, operation)
+            })
+            .map_err(|_| internal())
+    }
+
+    /// Retrieve the descriptor with precisely this principal's visible operations.
+    pub fn fetch_interface(
+        &self,
+        request: &FetchInterfaceRequest,
+    ) -> Result<FetchInterfaceResponse, ProtocolError> {
+        read_boundary(|| self.fetch_interface_inner(request))
+    }
+
+    fn fetch_interface_inner(
+        &self,
+        request: &FetchInterfaceRequest,
+    ) -> Result<FetchInterfaceResponse, ProtocolError> {
+        let observation = self
+            .projection
+            .registry
+            .fetch_interface(&request.interface)?;
+        if !self
+            .projection
+            .policy
+            .interface_visible(self.principal, &observation.reference)
+        {
+            return Err(protocol(
+                ProtocolErrorCode::InterfaceNotFound,
+                "interface is not published",
+            ));
+        }
+        let reference = observation.reference.clone();
+        observation
+            .project_operations(|operation| {
+                self.projection
+                    .policy
+                    .operation_visible(self.principal, &reference, operation)
+            })
+            .protocol_response()
+    }
+
+    /// Observe a complete bounded tree, omitting invisible children and subtrees.
+    pub fn observe(
+        &self,
+        context: &ExecutionContext,
+        request: &ObserveRequest,
+    ) -> Result<ObserveResponse, ProtocolError> {
+        read_boundary(|| self.observe_inner(context, request))
+    }
+
+    fn observe_inner(
+        &self,
+        context: &ExecutionContext,
+        request: &ObserveRequest,
+    ) -> Result<ObserveResponse, ProtocolError> {
+        request
+            .validate()
+            .map_err(|_| protocol(ProtocolErrorCode::InvalidRequest, "invalid observe request"))?;
+        if request.depth > self.projection.limits.max_observation_depth {
+            return Err(resource_protocol());
+        }
+        let entry = match self.resolve(context, &request.path) {
+            ProviderResult::Found(entry) => entry,
+            ProviderResult::NotFound => {
+                return Err(protocol(
+                    ProtocolErrorCode::NotFound,
+                    "target path is not published",
+                ));
+            }
+            ProviderResult::Failure(error) => return Err(read_error(error)),
+        };
+        let (_ancestors, entry) = entry.into_parts();
+        let mut remaining = u64::from(self.projection.limits.max_observation_nodes)
+            .min(context.resource_budget().unwrap_or(u64::MAX));
+        let response = self.observe_entry(context, entry, request.depth, &mut remaining)?;
+        request.validate_response(&response).map_err(|_| {
+            protocol(
+                ProtocolErrorCode::Internal,
+                "invalid projection observation",
+            )
+        })?;
+        Ok(response)
+    }
+
+    fn observe_entry(
+        &self,
+        context: &ExecutionContext,
+        entry: B::Entry,
+        depth: u32,
+        remaining: &mut u64,
+    ) -> Result<ObjectObservation, ProtocolError> {
+        preflight(context).map_err(read_error)?;
+        if *remaining == 0 {
+            return Err(resource_protocol());
+        }
+        *remaining -= 1;
+        let object = self
+            .publication(entry.clone(), context)
+            .map_err(read_error)?
+            .protocol_object();
+        if depth == 0 {
+            return Ok(ObjectObservation {
+                object,
+                children: None,
+            });
+        }
+        let mut children = Vec::new();
+        if entry.kind() == EntryKind::Directory {
+            let entries = self
+                .projection
+                .backend
+                .children(
+                    context,
+                    &entry,
+                    usize::try_from(*remaining).unwrap_or(usize::MAX),
+                )
+                .map_err(read_error)?;
+            if entries.len() as u64 > *remaining {
+                return Err(resource_protocol());
+            }
+            for child in entries {
+                if self
+                    .projection
+                    .policy
+                    .object_visible(self.principal, &child)
+                {
+                    children.push(self.observe_entry(context, child, depth - 1, remaining)?);
+                } else {
+                    if *remaining == 0 {
+                        return Err(resource_protocol());
+                    }
+                    *remaining -= 1;
+                }
+            }
+        }
+        Ok(ObjectObservation {
+            object,
+            children: Some(children),
+        })
+    }
+}
+
+impl<B, C, P> ObjectProvider for ProjectionView<'_, B, C, P>
+where
+    B: FilesystemBackend,
+    C: Composition<B::Entry>,
+    P: ProjectionPolicy<B::Entry, C::Object>,
+{
+    type Object = C::Object;
+    fn with_object<R>(
+        &self,
+        context: &ExecutionContext,
+        path: &str,
+        operation: impl FnOnce(&PublishedObject<Self::Object>) -> R,
+    ) -> ProviderResult<R> {
+        match self.resolve(context, path) {
+            ProviderResult::Found(resolved) => {
+                let (_ancestors, entry) = resolved.into_parts();
+                match self.publication(entry, context) {
+                    Ok(publication) => ProviderResult::Found(operation(&publication)),
+                    Err(error) => ProviderResult::Failure(error),
+                }
+            }
+            ProviderResult::NotFound => ProviderResult::NotFound,
+            ProviderResult::Failure(error) => ProviderResult::Failure(error),
+        }
+    }
+    fn execute_operation(
+        &self,
+        context: &ExecutionContext,
+        path: &str,
+        operation: impl FnOnce(&PublishedObject<Self::Object>) -> OperationAttempt,
+    ) -> ProviderResult<OperationAttempt> {
+        let entry = match self.resolve(context, path) {
+            ProviderResult::Found(entry) => entry,
+            ProviderResult::NotFound => return ProviderResult::NotFound,
+            ProviderResult::Failure(error) => return ProviderResult::Failure(error),
+        };
+        self.projection.backend.execute(context, entry, |resolved| {
+            // Backend validates retained lineage membership/identity and refreshes
+            // all metadata before this callback under the same boundary as dispatch.
+            if !lineage_matches_path(&resolved, path) {
+                return OperationAttempt::reject(wip_host::CallErrorKind::Internal);
+            }
+            if !self.lineage_visible(&resolved) {
+                return OperationAttempt::reject(wip_host::CallErrorKind::NotFound);
+            }
+            let (_ancestors, entry) = resolved.into_parts();
+            if let Err(error) = preflight(context) {
+                return OperationAttempt::reject(match error.kind() {
+                    wip_host::HostErrorKind::Internal => wip_host::CallErrorKind::Internal,
+                    wip_host::HostErrorKind::ResourceLimitExceeded => {
+                        wip_host::CallErrorKind::ResourceLimitExceeded
+                    }
+                });
+            }
+            match self.publication(entry, context) {
+                Ok(publication) => operation(&publication),
+                Err(error) => OperationAttempt::reject(match error.kind() {
+                    wip_host::HostErrorKind::Internal => wip_host::CallErrorKind::Internal,
+                    wip_host::HostErrorKind::ResourceLimitExceeded => {
+                        wip_host::CallErrorKind::ResourceLimitExceeded
+                    }
+                }),
+            }
+        })
+    }
+    fn authorize(
+        &self,
+        _: &str,
+        object: &Self::Object,
+        interface: &InterfaceRef,
+        operation: &str,
+    ) -> bool {
+        self.projection
+            .policy
+            .authorize(self.principal, object, interface, operation)
+    }
+}
+
+impl<B, C, P> ObjectProvider for Projection<B, C, P>
+where
+    B: FilesystemBackend,
+    C: Composition<B::Entry>,
+    P: ProjectionPolicy<B::Entry, C::Object, Principal = ()>,
+{
+    type Object = C::Object;
+    fn with_object<R>(
+        &self,
+        context: &ExecutionContext,
+        path: &str,
+        operation: impl FnOnce(&PublishedObject<Self::Object>) -> R,
+    ) -> ProviderResult<R> {
+        self.view(&()).with_object(context, path, operation)
+    }
+    fn execute_operation(
+        &self,
+        context: &ExecutionContext,
+        path: &str,
+        operation: impl FnOnce(&PublishedObject<Self::Object>) -> OperationAttempt,
+    ) -> ProviderResult<OperationAttempt> {
+        self.view(&()).execute_operation(context, path, operation)
+    }
+    fn authorize(
+        &self,
+        path: &str,
+        object: &Self::Object,
+        interface: &InterfaceRef,
+        operation: &str,
+    ) -> bool {
+        self.view(&()).authorize(path, object, interface, operation)
+    }
+}
+
+impl<B, C, P> Projection<B, C, P>
+where
+    B: FilesystemBackend,
+    C: Composition<B::Entry>,
+    P: ProjectionPolicy<B::Entry, C::Object, Principal = ()>,
+{
+    /// Observe the default unit-principal view.
+    pub fn observe(
+        &self,
+        context: &ExecutionContext,
+        request: &ObserveRequest,
+    ) -> Result<ObserveResponse, ProtocolError> {
+        self.view(&()).observe(context, request)
+    }
+    /// Fetch in the default unit-principal view.
+    pub fn fetch_interface(
+        &self,
+        request: &FetchInterfaceRequest,
+    ) -> Result<FetchInterfaceResponse, ProtocolError> {
+        self.view(&()).fetch_interface(request)
+    }
+}
+
+fn lineage_matches_path<E: BackendEntry>(resolved: &ResolvedEntry<E>, path: &str) -> bool {
+    let names: Vec<_> = if path == "/" {
+        vec![""]
+    } else {
+        std::iter::once("").chain(path[1..].split('/')).collect()
+    };
+    if resolved.ancestors().len() + 1 != names.len()
+        || resolved.target().name() != names[names.len() - 1]
+    {
+        return false;
+    }
+    resolved
+        .ancestors()
+        .iter()
+        .zip(names)
+        .all(|(entry, name)| entry.kind() == EntryKind::Directory && entry.name() == name)
+}
+
+fn read_boundary<T>(
+    operation: impl FnOnce() -> Result<T, ProtocolError>,
+) -> Result<T, ProtocolError> {
+    std::panic::catch_unwind(std::panic::AssertUnwindSafe(operation))
+        .unwrap_or_else(|_| Err(protocol(ProtocolErrorCode::Internal, "projection failed")))
+}
+
+fn internal() -> HostError {
+    HostError::internal(
+        "projection publication failed",
+        EffectGuarantee::NotCommitted,
+    )
+}
+fn protocol(code: ProtocolErrorCode, message: &str) -> ProtocolError {
+    ProtocolError {
+        code,
+        message: message.into(),
+    }
+}
+fn resource_protocol() -> ProtocolError {
+    protocol(
+        ProtocolErrorCode::ResourceLimitExceeded,
+        "projection resource limit exceeded",
+    )
+}
+fn read_error(error: HostError) -> ProtocolError {
+    match error.kind() {
+        wip_host::HostErrorKind::ResourceLimitExceeded => resource_protocol(),
+        wip_host::HostErrorKind::Internal => {
+            protocol(ProtocolErrorCode::Internal, "projection failed")
+        }
+    }
+}
+fn preflight(context: &ExecutionContext) -> Result<(), HostError> {
+    if context.cancellation().is_cancelled()
+        || context
+            .deadline()
+            .is_some_and(|deadline| std::time::Instant::now() >= deadline)
+        || context.resource_budget() == Some(0)
+    {
+        Err(HostError::resource_limit(
+            "projection work limit exceeded",
+            EffectGuarantee::NotCommitted,
+        ))
+    } else {
+        Ok(())
+    }
+}

crates/wip-fs-server/src/http_adapter.rs

@@ -0,0 +1,435 @@
+//! Framework-neutral standard WIP over HTTP mapping for a projection view.
+
+use std::time::Instant;
+
+use http::header::ALLOW;
+use http::{Request, Response, StatusCode};
+use wip_host::{ExecutionContext, ObjectProvider};
+use wip_http::{
+    CodecError, EncodeHttpError, Endpoint, RequestMetadataError, Route,
+    decode_call_operation_metadata, decode_fetch_interface_request, decode_observe_request,
+    encode_call_operation_response, encode_fetch_interface_response, encode_observe_response,
+    encode_protocol_error_response, validate_http_request,
+};
+use wip_protocol::{ProtocolError, ProtocolErrorCode, ProtocolInteraction};
+
+use crate::engine::ProjectionView;
+use crate::{Composition, FilesystemBackend, ProjectionPolicy, ResourceLimits};
+
+/// Standard HTTP routes and codecs over a caller-scoped projection view.
+///
+/// The adapter borrows the view and endpoint without owning a listener, selecting
+/// a principal, or imposing a new execution context. Integrations must enforce
+/// the request body limit while collecting bytes, before calling this adapter.
+pub struct HttpAdapter<'a, 'view, B, C, P>
+where
+    B: FilesystemBackend,
+    C: Composition<B::Entry>,
+    P: ProjectionPolicy<B::Entry, C::Object>,
+{
+    view: &'a ProjectionView<'view, B, C, P>,
+    endpoint: &'a Endpoint,
+    limits: ResourceLimits,
+}
+
+impl<'a, 'view, B, C, P> HttpAdapter<'a, 'view, B, C, P>
+where
+    B: FilesystemBackend,
+    C: Composition<B::Entry>,
+    P: ProjectionPolicy<B::Entry, C::Object>,
+{
+    /// Creates an adapter for an already-selected principal's projection view.
+    #[must_use]
+    pub fn new(
+        view: &'a ProjectionView<'view, B, C, P>,
+        endpoint: &'a Endpoint,
+        limits: ResourceLimits,
+    ) -> Self {
+        Self {
+            view,
+            endpoint,
+            limits,
+        }
+    }
+
+    /// Handles one buffered request using the supplied execution controls.
+    ///
+    /// Observation and operation dispatch receive the original context, including
+    /// cancellation and resource budget. An elapsed deadline after dispatch keeps
+    /// the listener's existing empty HTTP 504 transport-failure behavior.
+    #[must_use]
+    pub fn handle_http_with_context(
+        &self,
+        request: Request<Vec<u8>>,
+        context: &ExecutionContext,
+    ) -> Response<Vec<u8>> {
+        let Some(route) = self.route(request.uri()) else {
+            return empty_response(StatusCode::NOT_FOUND);
+        };
+        if let Err(error) = validate_http_request(self.endpoint, route, &request) {
+            return self.metadata_error(error);
+        }
+        let response = match route {
+            Route::Observe => self.observe(request.body(), context),
+            Route::FetchInterface => self.fetch_interface(request.body()),
+            Route::CallOperation => self.call_operation(request.body(), context),
+        };
+        if context
+            .deadline()
+            .is_some_and(|deadline| Instant::now() >= deadline)
+        {
+            empty_response(StatusCode::GATEWAY_TIMEOUT)
+        } else {
+            response
+        }
+    }
+
+    fn route(&self, uri: &http::Uri) -> Option<Route> {
+        if uri.query().is_some() {
+            return None;
+        }
+        [Route::Observe, Route::FetchInterface, Route::CallOperation]
+            .into_iter()
+            .find(|route| self.endpoint.route(*route).path() == uri.path())
+    }
+
+    fn observe(&self, body: &[u8], context: &ExecutionContext) -> Response<Vec<u8>> {
+        let request = match decode_observe_request(body, self.limits.wire) {
+            Ok(request) => request,
+            Err(error) => return self.codec_error(ProtocolInteraction::Observe, error),
+        };
+        match self.view.observe(context, &request) {
+            Ok(tree) => {
+                encode_observe_response(&request, &tree, self.limits.wire).unwrap_or_else(|error| {
+                    self.read_encode_error(ProtocolInteraction::Observe, error)
+                })
+            }
+            Err(error) => self.protocol_error(ProtocolInteraction::Observe, &error),
+        }
+    }
+
+    fn fetch_interface(&self, body: &[u8]) -> Response<Vec<u8>> {
+        let request = match decode_fetch_interface_request(body, self.limits.wire) {
+            Ok(request) => request,
+            Err(error) => return self.codec_error(ProtocolInteraction::FetchInterface, error),
+        };
+        match self.view.fetch_interface(&request) {
+            Ok(interface) => {
+                encode_fetch_interface_response(&request, &interface, self.limits.wire)
+                    .unwrap_or_else(|error| {
+                        self.read_encode_error(ProtocolInteraction::FetchInterface, error)
+                    })
+            }
+            Err(error) => self.protocol_error(ProtocolInteraction::FetchInterface, &error),
+        }
+    }
+
+    fn call_operation(&self, body: &[u8], context: &ExecutionContext) -> Response<Vec<u8>> {
+        let metadata = match decode_call_operation_metadata(body, self.limits.wire) {
+            Ok(metadata) => metadata,
+            Err(error) => return self.codec_error(ProtocolInteraction::CallOperation, error),
+        };
+        let decoded = std::sync::Mutex::new(None);
+        let execution = self.view.call_operation_with_context_and_decoder(
+            context,
+            metadata.target.clone(),
+            metadata.interface.clone(),
+            metadata.operation.clone(),
+            |descriptor| {
+                let request = metadata.decode_request(body, descriptor, self.limits.wire)?;
+                let arguments = request.arguments.clone();
+                *decoded.lock().unwrap_or_else(|error| error.into_inner()) =
+                    Some((request, descriptor.clone()));
+                Ok::<_, CodecError>(arguments)
+            },
+        );
+        match execution.map_err(|error| error.protocol_error()) {
+            Ok(result) => {
+                let Some((request, descriptor)) = decoded
+                    .into_inner()
+                    .unwrap_or_else(|error| error.into_inner())
+                else {
+                    return self.protocol_error(
+                        ProtocolInteraction::CallOperation,
+                        &operation_outcome_unknown(),
+                    );
+                };
+                encode_call_operation_response(&request, &descriptor, &result, self.limits.wire)
+                    .unwrap_or_else(|error| self.operation_encode_error(error))
+            }
+            Err(error) => self.protocol_error(ProtocolInteraction::CallOperation, &error),
+        }
+    }
+
+    fn operation_encode_error(&self, error: EncodeHttpError) -> Response<Vec<u8>> {
+        if matches!(&error, EncodeHttpError::Codec(codec) if is_transport_limit(codec)) {
+            return empty_response(StatusCode::INTERNAL_SERVER_ERROR);
+        }
+        // Any successfully executed operation may have committed effects. Its
+        // name cannot establish a non-commit guarantee after response failure.
+        self.protocol_error(
+            ProtocolInteraction::CallOperation,
+            &operation_outcome_unknown(),
+        )
+    }
+
+    fn metadata_error(&self, error: RequestMetadataError) -> Response<Vec<u8>> {
+        match error {
+            RequestMetadataError::NotFound => empty_response(StatusCode::NOT_FOUND),
+            error @ RequestMetadataError::MethodNotAllowed => Response::builder()
+                .status(error.status())
+                .header(
+                    ALLOW,
+                    error
+                        .allow()
+                        .expect("method-not-allowed metadata has an Allow value"),
+                )
+                .body(Vec::new())
+                .expect("static method response is valid"),
+            RequestMetadataError::UnsupportedMediaType => {
+                empty_response(StatusCode::UNSUPPORTED_MEDIA_TYPE)
+            }
+            RequestMetadataError::NotAcceptable => empty_response(StatusCode::NOT_ACCEPTABLE),
+        }
+    }
+
+    fn codec_error(
+        &self,
+        interaction: ProtocolInteraction,
+        error: CodecError,
+    ) -> Response<Vec<u8>> {
+        if is_transport_limit(&error) {
+            empty_response(StatusCode::PAYLOAD_TOO_LARGE)
+        } else {
+            self.protocol_error(
+                interaction,
+                &ProtocolError {
+                    code: ProtocolErrorCode::InvalidRequest,
+                    message: "malformed WIP request".into(),
+                },
+            )
+        }
+    }
+
+    fn read_encode_error(
+        &self,
+        interaction: ProtocolInteraction,
+        error: EncodeHttpError,
+    ) -> Response<Vec<u8>> {
+        match error {
+            EncodeHttpError::Codec(codec) if is_transport_limit(&codec) => {
+                empty_response(StatusCode::INTERNAL_SERVER_ERROR)
+            }
+            _ => self.protocol_error(
+                interaction,
+                &ProtocolError {
+                    code: ProtocolErrorCode::Internal,
+                    message: "HTTP adapter failed".into(),
+                },
+            ),
+        }
+    }
+
+    fn protocol_error(
+        &self,
+        interaction: ProtocolInteraction,
+        error: &ProtocolError,
+    ) -> Response<Vec<u8>> {
+        // Engine and policy diagnostics may contain paths, argument values, or
+        // backend details. Emit only fixed, bounded diagnostics on the wire.
+        let sanitized = ProtocolError {
+            code: error.code,
+            message: sanitized_message(error.code).into(),
+        };
+        encode_protocol_error_response(interaction, &sanitized, self.limits.wire)
+            .unwrap_or_else(|_| empty_response(StatusCode::INTERNAL_SERVER_ERROR))
+    }
+}
+
+fn operation_outcome_unknown() -> ProtocolError {
+    ProtocolError {
+        code: ProtocolErrorCode::OperationOutcomeUnknown,
+        message: "operation completed but its response could not be encoded".into(),
+    }
+}
+
+fn sanitized_message(code: ProtocolErrorCode) -> &'static str {
+    match code {
+        ProtocolErrorCode::InvalidRequest => "malformed WIP request",
+        ProtocolErrorCode::NotFound => "target path is not published",
+        ProtocolErrorCode::InterfaceNotFound => "interface is not published",
+        ProtocolErrorCode::InterfaceMismatch => "interface is not published on the target",
+        ProtocolErrorCode::OperationNotFound => "operation is not published",
+        ProtocolErrorCode::InvalidArguments => "arguments do not match the operation",
+        ProtocolErrorCode::ValidatorRequired => "object validator is required",
+        ProtocolErrorCode::ValidatorMismatch => "object validator does not match",
+        ProtocolErrorCode::InterfaceValidatorRequired => "interface validator is required",
+        ProtocolErrorCode::InterfaceValidatorMismatch => "interface validator does not match",
+        ProtocolErrorCode::PermissionDenied => "operation is not permitted",
+        ProtocolErrorCode::ResourceLimitExceeded => "projection resource limit exceeded",
+        ProtocolErrorCode::Internal => "HTTP adapter failed",
+        ProtocolErrorCode::OperationOutcomeUnknown => "operation outcome is unknown",
+    }
+}
+
+fn is_transport_limit(error: &CodecError) -> bool {
+    matches!(
+        error,
+        CodecError::BodyTooLarge { .. } | CodecError::NestingTooDeep { .. }
+    )
+}
+
+fn empty_response(status: StatusCode) -> Response<Vec<u8>> {
+    Response::builder()
+        .status(status)
+        .body(Vec::new())
+        .expect("static status builds an HTTP response")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::tempdir;
+    use wip_http::{
+        DecodedResponse, Limits, decode_fetch_interface_response, decode_observe_response,
+        encode_fetch_interface_request, encode_observe_request,
+    };
+    use wip_protocol::{FetchInterfaceRequest, ObserveRequest};
+
+    #[test]
+    fn adapter_serves_observation_and_interface_fetch_without_server() {
+        let root = tempdir().unwrap();
+        std::fs::write(root.path().join("file"), b"contents").unwrap();
+        let limits = ResourceLimits::default();
+        let projection =
+            crate::default_projection(root.path(), crate::AccessMode::ReadOnly, limits).unwrap();
+        let view = projection.view(&());
+        let endpoint = Endpoint::parse("http://localhost/custom").unwrap();
+        let adapter = HttpAdapter::new(&view, &endpoint, limits);
+        let context = ExecutionContext::new();
+        let request = ObserveRequest {
+            path: "/file".into(),
+            depth: 0,
+        };
+        let response = adapter.handle_http_with_context(
+            encode_observe_request(&endpoint, &request, limits.wire).unwrap(),
+            &context,
+        );
+        let DecodedResponse::Success(observation) =
+            decode_observe_response(&request, &response, limits.wire).unwrap()
+        else {
+            panic!("expected observation success")
+        };
+        let request = FetchInterfaceRequest {
+            interface: observation.object.interfaces[0].clone(),
+        };
+        let response = adapter.handle_http_with_context(
+            encode_fetch_interface_request(&endpoint, &request, limits.wire).unwrap(),
+            &context,
+        );
+        assert!(matches!(
+            decode_fetch_interface_response(&request, &response, limits.wire).unwrap(),
+            DecodedResponse::Success(_)
+        ));
+    }
+
+    #[test]
+    fn adapter_preserves_transport_boundaries_and_execution_context() {
+        let root = tempdir().unwrap();
+        let limits = ResourceLimits::default();
+        let projection =
+            crate::default_projection(root.path(), crate::AccessMode::ReadOnly, limits).unwrap();
+        let view = projection.view(&());
+        let endpoint = Endpoint::parse("http://localhost/wip").unwrap();
+        let adapter = HttpAdapter::new(&view, &endpoint, limits);
+        let context = ExecutionContext::new();
+        for uri in [
+            "/wip/v1/observe?query=1",
+            "/wip/v1/unknown",
+            "/wip/v1/observe/extra",
+        ] {
+            let response = adapter.handle_http_with_context(
+                Request::builder().uri(uri).body(Vec::new()).unwrap(),
+                &context,
+            );
+            assert_eq!(response.status(), StatusCode::NOT_FOUND);
+            assert!(response.body().is_empty());
+        }
+        let response = adapter.handle_http_with_context(
+            Request::builder()
+                .uri("/wip/v1/observe")
+                .body(Vec::new())
+                .unwrap(),
+            &context,
+        );
+        assert_eq!(response.status(), StatusCode::METHOD_NOT_ALLOWED);
+        assert_eq!(response.headers()[ALLOW], "POST");
+        assert!(response.body().is_empty());
+        let request = ObserveRequest {
+            path: "/".into(),
+            depth: 0,
+        };
+        let response = adapter.handle_http_with_context(
+            encode_observe_request(&endpoint, &request, limits.wire).unwrap(),
+            &ExecutionContext::new().with_resource_budget(0),
+        );
+        let text = std::str::from_utf8(response.body()).unwrap();
+        assert!(text.contains("resource_limit_exceeded"));
+        let response = adapter.handle_http_with_context(
+            encode_observe_request(&endpoint, &request, limits.wire).unwrap(),
+            &ExecutionContext::new().with_deadline(Instant::now()),
+        );
+        assert_eq!(response.status(), StatusCode::GATEWAY_TIMEOUT);
+        assert!(response.body().is_empty());
+    }
+
+    #[test]
+    fn post_success_encoding_is_unknown_except_empty_transport_limit_failure() {
+        let root = tempdir().unwrap();
+        let limits = ResourceLimits::default();
+        let projection =
+            crate::default_projection(root.path(), crate::AccessMode::ReadOnly, limits).unwrap();
+        let view = projection.view(&());
+        let endpoint = Endpoint::parse("http://localhost/wip").unwrap();
+        let adapter = HttpAdapter::new(&view, &endpoint, limits);
+        let error = decode_observe_request(b"{", limits.wire).unwrap_err();
+        let response = adapter.operation_encode_error(EncodeHttpError::Codec(error));
+        assert!(
+            std::str::from_utf8(response.body())
+                .unwrap()
+                .contains("operation_outcome_unknown")
+        );
+        let tiny_limits = Limits::new(1, 1, 1).unwrap();
+        let error = decode_observe_request(b"{}", tiny_limits).unwrap_err();
+        assert!(is_transport_limit(&error));
+        let response = adapter.operation_encode_error(EncodeHttpError::Codec(error));
+        assert_eq!(response.status(), StatusCode::INTERNAL_SERVER_ERROR);
+        assert!(response.body().is_empty());
+        assert!(!response.headers().contains_key(http::header::CONTENT_TYPE));
+    }
+
+    #[test]
+    fn engine_error_diagnostics_are_sanitized_and_bounded() {
+        let root = tempdir().unwrap();
+        let limits = ResourceLimits::default();
+        let projection =
+            crate::default_projection(root.path(), crate::AccessMode::ReadOnly, limits).unwrap();
+        let view = projection.view(&());
+        let endpoint = Endpoint::parse("http://localhost/wip").unwrap();
+        let adapter = HttpAdapter::new(&view, &endpoint, limits);
+        let response = adapter.protocol_error(
+            ProtocolInteraction::Observe,
+            &ProtocolError {
+                code: ProtocolErrorCode::Internal,
+                message: "/private/backend/secret".repeat(1000),
+            },
+        );
+        assert!(response.body().len() < 512);
+        assert!(
+            !std::str::from_utf8(response.body())
+                .unwrap()
+                .contains("secret")
+        );
+        assert_eq!(response.status(), StatusCode::INTERNAL_SERVER_ERROR);
+    }
+}

crates/wip-fs-server/src/interfaces.rs

@@ -0,0 +1,43 @@
+//! Filesystem capability interfaces published by the projection.
+
+use wip_interface as wip;
+
+/// Bounded reads from a regular file.
+#[wip::interface]
+pub trait FileRead {
+    /// Reads bytes from the current regular file.
+    ///
+    /// # Returns
+    /// At most the configured read limit, beginning at `offset`.
+    fn read(
+        &self,
+        /// Byte offset; omitted means zero.
+        offset: Option<u64>,
+        /// Requested byte count; omitted means the rest of the file.
+        length: Option<u64>,
+    ) -> wip::OperationResult<wip::Bytes>;
+}
+
+/// Inspection operations for a symbolic link itself.
+#[wip::interface]
+pub trait SymlinkInspect {
+    /// Reads the link payload without following it.
+    ///
+    /// # Returns
+    /// The platform path bytes stored in the symbolic link.
+    fn read_link(&self) -> wip::OperationResult<wip::Bytes>;
+}
+
+/// Explicitly enabled mutation of a regular file.
+#[wip::interface]
+pub trait FileWrite {
+    /// Replaces the current regular file contents through its pinned handle.
+    ///
+    /// # Returns
+    /// Unit after the new bytes have been written and synchronized.
+    fn replace(
+        &self,
+        /// Complete replacement contents.
+        contents: wip::Bytes,
+    ) -> wip::OperationResult<()>;
+}

crates/wip-fs-server/src/lib.rs

@@ -0,0 +1,222 @@
+//! Request-time filesystem projection served through the standard WIP over HTTP binding.
+//!
+//! This crate deliberately keeps the boundaries visible:
+//!
+//! - [`wip_protocol`] owns logical requests and responses;
+//! - [`wip_host`] owns object publication, validators, and typed dispatch;
+//! - [`wip_http`] owns routes, JSON, envelopes, and status mapping;
+//! - this crate owns the filesystem capability boundary and the real HTTP listener.
+//!
+//! # Extension boundary
+//!
+//! [`Projection`] composes a [`FilesystemBackend`], typed [`Composition`] and
+//! [`ProjectionPolicy`]. External local Objects can wrap a [`BackendEntry`] and
+//! implement generated interfaces without orphan-rule workarounds. The backend
+//! retains a root-confined target and atomic validator/dispatch boundary; the
+//! engine owns recursive observation and standard host typed validation. No
+//! listener is needed to use [`ProjectionView`]. [`HttpAdapter`] applies the
+//! existing standard HTTP binding to a deployment-established principal view.
+//!
+//! Backends and Operations are trusted code, responsible for truthful effects,
+//! public-only metadata and ongoing execution-context bounds. Policies must be
+//! stable within a view; changing descriptor visibility requires new reference
+//! lifetimes. See the crate README for implementer security and migration details.
+//!
+//! ```no_run
+//! use wip_fs_server::{default_projection, AccessMode, ResourceLimits};
+//! use wip_host::{ExecutionContext, ObjectProvider};
+//! use wip_protocol::ObserveRequest;
+//!
+//! let engine = default_projection(std::path::Path::new("./public"),
+//!     AccessMode::ReadOnly, ResourceLimits::default())?;
+//! let view = engine.view(&());
+//! let context = ExecutionContext::new().with_resource_budget(128);
+//! let tree = view.observe(&context, &ObserveRequest { path: "/".into(), depth: 1 })?;
+//! assert_eq!(tree.object.name, "");
+//! let object = view.observe_object_with_context(&context, "/")?;
+//! assert!(object.interfaces.is_empty());
+//! # Ok::<(), Box<dyn std::error::Error>>(())
+//! ```
+//!
+//! The built-in HTTP listener is intentionally loopback-only. TLS termination,
+//! certificates, authentication, and externally visible schemes are independent
+//! deployment concerns rather than WIP transport profiles.
+
+#![deny(missing_docs)]
+
+mod defaults;
+mod engine;
+mod http_adapter;
+mod interfaces;
+mod projection;
+mod server;
+
+use std::net::{IpAddr, Ipv4Addr, SocketAddr};
+use std::path::PathBuf;
+use std::time::Duration;
+
+pub use defaults::{DefaultComposition, DefaultInterfaces, DefaultObject, default_projection};
+pub use engine::{
+    BackendEntry, Composition, DefaultPolicy, EntryKind, FilesystemBackend, Projection,
+    ProjectionPolicy, ProjectionView, ResolvedEntry,
+};
+pub use http_adapter::HttpAdapter;
+pub use interfaces::{
+    FileRead, FileReadDefinition, FileWrite, FileWriteDefinition, SymlinkInspect,
+    SymlinkInspectDefinition,
+};
+pub use projection::{LinuxBackend, LinuxEntry};
+pub use server::{BoundServer, ServerBuildError, WipFsServer};
+
+/// Filesystem capabilities published by regular files.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum AccessMode {
+    /// Publish bounded reads only.
+    ReadOnly,
+    /// Also publish validator-protected whole-file replacement.
+    ReadWrite,
+}
+
+/// Bounded resource policy applied by the HTTP adapter and filesystem provider.
+#[derive(Debug, Clone, Copy)]
+pub struct ResourceLimits {
+    /// Standard JSON, body-size, and nesting limits.
+    pub wire: wip_http::Limits,
+    /// Maximum bytes returned by one file read.
+    pub max_file_read_bytes: usize,
+    /// Maximum bytes accepted by one file replacement.
+    pub max_file_write_bytes: usize,
+    /// Maximum accepted `observe` depth.
+    pub max_observation_depth: u32,
+    /// Maximum accepted `observe` node count, including its root.
+    pub max_observation_nodes: u32,
+    /// Maximum simultaneously pinned projected filesystem handles.
+    pub max_open_handles: usize,
+    /// Maximum bytes accepted for one HTTP request head, including its terminator.
+    pub max_http_header_bytes: usize,
+    /// Maximum requests executing concurrently.
+    pub max_concurrent_requests: usize,
+    /// End-to-end deadline for HTTP intake, dispatch, and response transmission.
+    pub request_timeout: Duration,
+}
+
+impl Default for ResourceLimits {
+    fn default() -> Self {
+        Self {
+            wire: wip_http::Limits::new(256 * 1024, 2 * 1024 * 1024, 64)
+                .expect("default wire limits are nonzero"),
+            max_file_read_bytes: 1024 * 1024,
+            max_file_write_bytes: 1024 * 1024,
+            max_observation_depth: 32,
+            max_observation_nodes: 1024,
+            max_open_handles: 2048,
+            max_http_header_bytes: 16 * 1024,
+            max_concurrent_requests: 32,
+            request_timeout: Duration::from_secs(30),
+        }
+    }
+}
+
+/// Complete listener and projection configuration.
+#[derive(Debug, Clone)]
+pub struct ServerConfig {
+    /// Filesystem directory projected as Worldspace `/`.
+    pub root: PathBuf,
+    /// Loopback socket used by the built-in cleartext listener.
+    pub listen: SocketAddr,
+    /// URL path prefix below which standard `v1/*` routes are mounted.
+    pub endpoint_base_path: String,
+    /// Read-only or explicit read-write publication mode.
+    pub access: AccessMode,
+    /// Request, operation, traversal, and concurrency bounds.
+    pub limits: ResourceLimits,
+}
+
+impl ServerConfig {
+    /// Builds a secure-by-default configuration for `root`.
+    ///
+    /// The listener defaults to an ephemeral loopback port and read-only access.
+    #[must_use]
+    pub fn for_root(root: impl Into<PathBuf>) -> Self {
+        Self {
+            root: root.into(),
+            listen: SocketAddr::new(IpAddr::V4(Ipv4Addr::LOCALHOST), 0),
+            endpoint_base_path: "/wip".into(),
+            access: AccessMode::ReadOnly,
+            limits: ResourceLimits::default(),
+        }
+    }
+
+    pub(crate) fn validate(&self) -> Result<(), ConfigError> {
+        if !self.listen.ip().is_loopback() {
+            return Err(ConfigError::NonLoopbackCleartext);
+        }
+        if !valid_base_path(&self.endpoint_base_path) {
+            return Err(ConfigError::InvalidBasePath);
+        }
+        if self.limits.max_file_read_bytes == 0
+            || self.limits.max_file_write_bytes == 0
+            || self.limits.max_observation_nodes == 0
+            || self.limits.max_open_handles == 0
+            || self.limits.max_http_header_bytes == 0
+            || self.limits.max_concurrent_requests == 0
+            || self.limits.request_timeout.is_zero()
+        {
+            return Err(ConfigError::ZeroLimit);
+        }
+        if self.limits.max_open_handles < self.limits.max_observation_nodes as usize {
+            return Err(ConfigError::InsufficientHandles);
+        }
+        if self.limits.wire.max_response_bytes() < 512 {
+            return Err(ConfigError::ResponseLimitTooSmall);
+        }
+        Ok(())
+    }
+
+    pub(crate) fn endpoint(&self) -> Result<wip_http::Endpoint, ConfigError> {
+        let endpoint = format!("http://localhost{}", self.endpoint_base_path);
+        wip_http::Endpoint::parse(&endpoint).map_err(|_| ConfigError::InvalidBasePath)
+    }
+}
+
+/// Invalid server configuration.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ConfigError {
+    /// The cleartext built-in listener was exposed beyond loopback.
+    NonLoopbackCleartext,
+    /// The endpoint prefix is not an absolute canonical URL path.
+    InvalidBasePath,
+    /// A resource limit is zero.
+    ZeroLimit,
+    /// Tree nodes could exhaust the configured handle ceiling by construction.
+    InsufficientHandles,
+    /// The response limit cannot reliably carry a bounded protocol error envelope.
+    ResponseLimitTooSmall,
+}
+
+impl std::fmt::Display for ConfigError {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        formatter.write_str(match self {
+            Self::NonLoopbackCleartext => "the built-in cleartext listener must bind to loopback",
+            Self::InvalidBasePath => {
+                "endpoint base path must be absolute, canonical, and query-free"
+            }
+            Self::ZeroLimit => "all resource limits and the request timeout must be nonzero",
+            Self::InsufficientHandles => "max_open_handles must cover max_observation_nodes",
+            Self::ResponseLimitTooSmall => "max_response_bytes must be at least 512",
+        })
+    }
+}
+
+impl std::error::Error for ConfigError {}
+
+fn valid_base_path(path: &str) -> bool {
+    path.starts_with('/')
+        && !path.contains('?')
+        && !path.contains('#')
+        && !path.contains("//")
+        && !path
+            .split('/')
+            .any(|segment| segment == "." || segment == "..")
+        && (path == "/" || !path.ends_with('/'))
+}

crates/wip-fs-server/src/main.rs

@@ -0,0 +1,62 @@
+use std::error::Error;
+use std::net::SocketAddr;
+use std::path::PathBuf;
+
+use wip_fs_server::{AccessMode, ServerConfig, WipFsServer};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let mut root: Option<PathBuf> = None;
+    let mut listen: SocketAddr = "127.0.0.1:8080".parse()?;
+    let mut base_path = "/wip".to_owned();
+    let mut access = AccessMode::ReadOnly;
+    let mut arguments = std::env::args().skip(1);
+    while let Some(argument) = arguments.next() {
+        match argument.as_str() {
+            "--root" => root = Some(PathBuf::from(required_value(&mut arguments, "--root")?)),
+            "--listen" => listen = required_value(&mut arguments, "--listen")?.parse()?,
+            "--base-path" => base_path = required_value(&mut arguments, "--base-path")?,
+            "--read-write" => access = AccessMode::ReadWrite,
+            "--help" | "-h" => {
+                print_help();
+                return Ok(());
+            }
+            unknown => return Err(format!("unknown argument `{unknown}`; use --help").into()),
+        }
+    }
+
+    let root = root.ok_or("--root is required")?;
+    let mut config = ServerConfig::for_root(root);
+    config.listen = listen;
+    config.endpoint_base_path = base_path;
+    config.access = access;
+
+    let server = WipFsServer::new(config)?;
+    let effective_root = server.effective_root().to_owned();
+    let endpoint = server.endpoint().clone();
+    let bound = server.bind()?;
+    eprintln!(
+        "wip-fs-server root={} access={access:?} endpoint={} listen={}",
+        effective_root.display(),
+        endpoint,
+        bound.local_addr()
+    );
+    bound.serve()?;
+    Ok(())
+}
+
+fn required_value(
+    arguments: &mut impl Iterator<Item = String>,
+    option: &str,
+) -> Result<String, Box<dyn Error>> {
+    arguments
+        .next()
+        .ok_or_else(|| format!("{option} requires a value").into())
+}
+
+fn print_help() {
+    println!(
+        "Usage: wip-fs-server --root PATH [--listen 127.0.0.1:8080] \\\n         [--base-path /wip] [--read-write]\n\n\
+         The built-in HTTP listener is loopback-only. TLS termination, authentication, \
+         and external routing are deployment concerns."
+    );
+}

crates/wip-fs-server/src/server.rs

@@ -0,0 +1,427 @@
+use std::io::{Read, Write};
+use std::net::{SocketAddr, TcpListener, TcpStream};
+use std::sync::Arc;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::thread;
+use std::time::{Duration, Instant};
+
+use http::{Request, Response, StatusCode};
+use wip_host::ExecutionContext;
+use wip_http::Endpoint;
+
+use crate::engine::Projection;
+use crate::http_adapter::HttpAdapter;
+use crate::{ConfigError, DefaultComposition, DefaultPolicy, LinuxBackend, ServerConfig};
+
+/// Default Linux filesystem projection and bounded loopback HTTP listener.
+pub struct WipFsServer {
+    config: ServerConfig,
+    endpoint: Endpoint,
+    effective_root: std::path::PathBuf,
+    projection: Arc<Projection<LinuxBackend, DefaultComposition, DefaultPolicy>>,
+}
+
+impl WipFsServer {
+    /// Validates configuration and opens the configured directory capability.
+    pub fn new(config: ServerConfig) -> Result<Self, ServerBuildError> {
+        config.validate()?;
+        let endpoint = config.endpoint()?;
+        let projection = crate::default_projection(&config.root, config.access, config.limits)?;
+        let effective_root = projection.backend().effective_root()?;
+        Ok(Self {
+            config,
+            endpoint,
+            effective_root,
+            projection: Arc::new(projection),
+        })
+    }
+
+    /// Returns the canonical effective filesystem root opened by the server.
+    #[must_use]
+    pub fn effective_root(&self) -> &std::path::Path {
+        &self.effective_root
+    }
+
+    /// Returns the configured transport endpoint prefix.
+    #[must_use]
+    pub fn endpoint(&self) -> &Endpoint {
+        &self.endpoint
+    }
+
+    /// Handles one already-buffered HTTP request with the standard `wip-http` codecs.
+    ///
+    /// Listener integrations must enforce the same body limit while collecting bytes.
+    #[must_use]
+    pub fn handle_http(&self, request: Request<Vec<u8>>) -> Response<Vec<u8>> {
+        self.handle_http_with_deadline(request, Instant::now() + self.config.limits.request_timeout)
+    }
+
+    fn handle_http_with_deadline(
+        &self,
+        request: Request<Vec<u8>>,
+        deadline: Instant,
+    ) -> Response<Vec<u8>> {
+        let context = ExecutionContext::new()
+            .with_deadline(deadline)
+            .with_resource_budget(u64::from(self.config.limits.max_observation_nodes));
+        let view = self.projection.view(&());
+        HttpAdapter::new(&view, &self.endpoint, self.config.limits)
+            .handle_http_with_context(request, &context)
+    }
+
+    /// Binds the built-in bounded loopback HTTP listener.
+    ///
+    /// The built-in listener is cleartext and loopback-only. Externally visible
+    /// schemes, TLS termination, authentication, and proxy routing are deployment
+    /// concerns rather than WIP transport profiles.
+    pub fn bind(self) -> Result<BoundServer, ServerBuildError> {
+        let listener = TcpListener::bind(self.config.listen)
+            .map_err(|error| ServerBuildError::Listener(error.to_string()))?;
+        listener
+            .set_nonblocking(true)
+            .map_err(|error| ServerBuildError::Listener(error.to_string()))?;
+        let local_addr = listener
+            .local_addr()
+            .map_err(|error| ServerBuildError::Listener(error.to_string()))?;
+        Ok(BoundServer {
+            local_addr,
+            service: Arc::new(self),
+            listener: Arc::new(listener),
+        })
+    }
+}
+
+/// Bound real HTTP listener for a [`WipFsServer`].
+pub struct BoundServer {
+    local_addr: SocketAddr,
+    service: Arc<WipFsServer>,
+    listener: Arc<TcpListener>,
+}
+
+impl BoundServer {
+    /// Returns the actual bound loopback address, including an assigned port.
+    #[must_use]
+    pub fn local_addr(&self) -> SocketAddr {
+        self.local_addr
+    }
+
+    /// Serves requests with a fixed worker count until `shutdown` becomes true.
+    ///
+    /// Workers accept connections directly, so at most
+    /// `max_concurrent_requests` sockets are active in userspace. Each connection
+    /// is closed after one request and shares one absolute deadline across HTTP
+    /// intake, dispatch, and response transmission.
+    pub fn serve_until(&self, shutdown: Arc<AtomicBool>) -> Result<(), std::io::Error> {
+        let mut workers = Vec::with_capacity(self.service.config.limits.max_concurrent_requests);
+        for _ in 0..self.service.config.limits.max_concurrent_requests {
+            let listener = Arc::clone(&self.listener);
+            let service = Arc::clone(&self.service);
+            let shutdown = Arc::clone(&shutdown);
+            workers.push(thread::spawn(move || {
+                while !shutdown.load(Ordering::Acquire) {
+                    match listener.accept() {
+                        Ok((stream, _)) => serve_connection(&service, stream),
+                        Err(error) if error.kind() == std::io::ErrorKind::WouldBlock => {
+                            thread::sleep(Duration::from_millis(5));
+                        }
+                        Err(error) if error.kind() == std::io::ErrorKind::Interrupted => {}
+                        Err(error) => return Err(error),
+                    }
+                }
+                Ok(())
+            }));
+        }
+        for worker in workers {
+            worker
+                .join()
+                .map_err(|_| std::io::Error::other("HTTP worker panicked"))??;
+        }
+        Ok(())
+    }
+
+    /// Serves until the process is terminated.
+    pub fn serve(&self) -> Result<(), std::io::Error> {
+        self.serve_until(Arc::new(AtomicBool::new(false)))
+    }
+}
+
+#[derive(Debug)]
+struct ParsedRequestHead {
+    method: http::Method,
+    target: String,
+    headers: Vec<(http::header::HeaderName, http::HeaderValue)>,
+    content_length: usize,
+}
+
+#[derive(Debug)]
+enum IntakeError {
+    Timeout,
+    HeaderTooLarge,
+    PayloadTooLarge,
+    BadRequest,
+    Socket,
+}
+
+fn serve_connection(service: &WipFsServer, mut stream: TcpStream) {
+    let _ = stream.set_nonblocking(false);
+    let started = Instant::now();
+    let deadline = started
+        .checked_add(service.config.limits.request_timeout)
+        .unwrap_or(started);
+    let response = match read_http_request(
+        &mut stream,
+        service.config.limits.max_http_header_bytes,
+        service.config.limits.wire.max_request_bytes(),
+        deadline,
+    ) {
+        Ok(request) => Some(service.handle_http_with_deadline(request, deadline)),
+        Err(IntakeError::HeaderTooLarge) => {
+            Some(empty_response(StatusCode::REQUEST_HEADER_FIELDS_TOO_LARGE))
+        }
+        Err(IntakeError::PayloadTooLarge) => Some(empty_response(StatusCode::PAYLOAD_TOO_LARGE)),
+        Err(IntakeError::BadRequest) => Some(empty_response(StatusCode::BAD_REQUEST)),
+        Err(IntakeError::Timeout | IntakeError::Socket) => None,
+    };
+    if let Some(response) = response {
+        let _ = write_http_response(&mut stream, &response, deadline);
+    }
+    let _ = stream.shutdown(std::net::Shutdown::Both);
+}
+
+fn read_http_request(
+    stream: &mut TcpStream,
+    maximum_header: usize,
+    maximum_body: usize,
+    deadline: Instant,
+) -> Result<Request<Vec<u8>>, IntakeError> {
+    let mut received = Vec::with_capacity(maximum_header.min(8 * 1024));
+    let header_end = loop {
+        if let Some(position) = received.windows(4).position(|window| window == b"\r\n\r\n") {
+            let end = position + 4;
+            if end > maximum_header {
+                return Err(IntakeError::HeaderTooLarge);
+            }
+            break end;
+        }
+        if received.len() >= maximum_header {
+            return Err(IntakeError::HeaderTooLarge);
+        }
+        let mut chunk = [0_u8; 4 * 1024];
+        let available = (maximum_header - received.len()).min(chunk.len());
+        let count = read_with_deadline(stream, &mut chunk[..available], deadline)?;
+        if count == 0 {
+            return Err(IntakeError::BadRequest);
+        }
+        received.extend_from_slice(&chunk[..count]);
+    };
+
+    let parsed = parse_request_head(&received[..header_end])?;
+    if parsed.content_length > maximum_body {
+        return Err(IntakeError::PayloadTooLarge);
+    }
+    let mut body = Vec::with_capacity(parsed.content_length);
+    let buffered = &received[header_end..];
+    body.extend_from_slice(&buffered[..buffered.len().min(parsed.content_length)]);
+    while body.len() < parsed.content_length {
+        let mut chunk = [0_u8; 8 * 1024];
+        let wanted = (parsed.content_length - body.len()).min(chunk.len());
+        let count = read_with_deadline(stream, &mut chunk[..wanted], deadline)?;
+        if count == 0 {
+            return Err(IntakeError::BadRequest);
+        }
+        body.extend_from_slice(&chunk[..count]);
+    }
+
+    let mut builder = Request::builder().method(parsed.method).uri(parsed.target);
+    for (name, value) in parsed.headers {
+        builder = builder.header(name, value);
+    }
+    builder.body(body).map_err(|_| IntakeError::BadRequest)
+}
+
+fn parse_request_head(bytes: &[u8]) -> Result<ParsedRequestHead, IntakeError> {
+    let text = std::str::from_utf8(bytes).map_err(|_| IntakeError::BadRequest)?;
+    let mut lines = text
+        .strip_suffix("\r\n\r\n")
+        .ok_or(IntakeError::BadRequest)?
+        .split("\r\n");
+    let mut request_line = lines
+        .next()
+        .ok_or(IntakeError::BadRequest)?
+        .split_ascii_whitespace();
+    let method = request_line.next().ok_or(IntakeError::BadRequest)?;
+    let target = request_line.next().ok_or(IntakeError::BadRequest)?;
+    let version = request_line.next().ok_or(IntakeError::BadRequest)?;
+    if request_line.next().is_some()
+        || !matches!(version, "HTTP/1.0" | "HTTP/1.1")
+        || !target.starts_with('/')
+    {
+        return Err(IntakeError::BadRequest);
+    }
+    let method =
+        http::Method::from_bytes(method.as_bytes()).map_err(|_| IntakeError::BadRequest)?;
+    let _: http::Uri = target.parse().map_err(|_| IntakeError::BadRequest)?;
+
+    let mut headers = Vec::new();
+    let mut content_length = None;
+    for line in lines {
+        if line.is_empty() || line.starts_with([' ', '\t']) {
+            return Err(IntakeError::BadRequest);
+        }
+        let (name, value) = line.split_once(':').ok_or(IntakeError::BadRequest)?;
+        let name = http::header::HeaderName::from_bytes(name.as_bytes())
+            .map_err(|_| IntakeError::BadRequest)?;
+        let value =
+            http::HeaderValue::from_str(value.trim()).map_err(|_| IntakeError::BadRequest)?;
+        if name == http::header::CONTENT_LENGTH {
+            if content_length.is_some() {
+                return Err(IntakeError::BadRequest);
+            }
+            content_length = Some(
+                value
+                    .to_str()
+                    .ok()
+                    .and_then(|value| value.parse::<usize>().ok())
+                    .ok_or(IntakeError::BadRequest)?,
+            );
+        }
+        if name == http::header::TRANSFER_ENCODING {
+            return Err(IntakeError::BadRequest);
+        }
+        headers.push((name, value));
+    }
+
+    Ok(ParsedRequestHead {
+        method,
+        target: target.to_owned(),
+        headers,
+        content_length: content_length.unwrap_or(0),
+    })
+}
+
+fn read_with_deadline(
+    stream: &mut TcpStream,
+    buffer: &mut [u8],
+    deadline: Instant,
+) -> Result<usize, IntakeError> {
+    let remaining = deadline
+        .checked_duration_since(Instant::now())
+        .ok_or(IntakeError::Timeout)?;
+    stream
+        .set_read_timeout(Some(remaining.max(Duration::from_millis(1))))
+        .map_err(|_| IntakeError::Socket)?;
+    stream.read(buffer).map_err(|error| match error.kind() {
+        std::io::ErrorKind::TimedOut | std::io::ErrorKind::WouldBlock => IntakeError::Timeout,
+        _ => IntakeError::Socket,
+    })
+}
+
+fn write_http_response(
+    stream: &mut TcpStream,
+    response: &Response<Vec<u8>>,
+    deadline: Instant,
+) -> Result<(), std::io::Error> {
+    let mut encoded = Vec::new();
+    write!(
+        encoded,
+        "HTTP/1.1 {} {}\r\n",
+        response.status().as_u16(),
+        response.status().canonical_reason().unwrap_or("")
+    )?;
+    for (name, value) in response.headers() {
+        if name == http::header::CONTENT_LENGTH
+            || name == http::header::CONNECTION
+            || name == http::header::TRANSFER_ENCODING
+        {
+            continue;
+        }
+        encoded.extend_from_slice(name.as_str().as_bytes());
+        encoded.extend_from_slice(b": ");
+        encoded.extend_from_slice(value.as_bytes());
+        encoded.extend_from_slice(b"\r\n");
+    }
+    write!(
+        encoded,
+        "Content-Length: {}\r\nConnection: close\r\n\r\n",
+        response.body().len()
+    )?;
+    encoded.extend_from_slice(response.body());
+    write_all_with_deadline(stream, &encoded, deadline)
+}
+
+fn write_all_with_deadline(
+    stream: &mut TcpStream,
+    mut bytes: &[u8],
+    deadline: Instant,
+) -> Result<(), std::io::Error> {
+    while !bytes.is_empty() {
+        let remaining = deadline
+            .checked_duration_since(Instant::now())
+            .ok_or_else(|| {
+                std::io::Error::new(std::io::ErrorKind::TimedOut, "request timed out")
+            })?;
+        stream.set_write_timeout(Some(remaining.max(Duration::from_millis(1))))?;
+        match stream.write(bytes) {
+            Ok(0) => {
+                return Err(std::io::Error::new(
+                    std::io::ErrorKind::WriteZero,
+                    "socket closed",
+                ));
+            }
+            Ok(count) => bytes = &bytes[count..],
+            Err(error) if error.kind() == std::io::ErrorKind::Interrupted => {}
+            Err(error) => return Err(error),
+        }
+    }
+    stream.flush()
+}
+
+fn empty_response(status: StatusCode) -> Response<Vec<u8>> {
+    Response::builder()
+        .status(status)
+        .body(Vec::new())
+        .expect("static status builds an HTTP response")
+}
+
+/// Failure while validating, opening, or binding the server.
+#[derive(Debug)]
+pub enum ServerBuildError {
+    /// Configuration is unsafe or unbounded.
+    Config(ConfigError),
+    /// The root capability could not be opened.
+    Io(std::io::Error),
+    /// The listener could not be bound.
+    Listener(String),
+}
+
+impl std::fmt::Display for ServerBuildError {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Config(error) => write!(formatter, "invalid server configuration: {error}"),
+            Self::Io(error) => write!(formatter, "filesystem root could not be opened: {error}"),
+            Self::Listener(error) => write!(formatter, "HTTP listener could not be bound: {error}"),
+        }
+    }
+}
+
+impl std::error::Error for ServerBuildError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::Config(error) => Some(error),
+            Self::Io(error) => Some(error),
+            Self::Listener(_) => None,
+        }
+    }
+}
+
+impl From<ConfigError> for ServerBuildError {
+    fn from(value: ConfigError) -> Self {
+        Self::Config(value)
+    }
+}
+
+impl From<std::io::Error> for ServerBuildError {
+    fn from(value: std::io::Error) -> Self {
+        Self::Io(value)
+    }
+}

crates/wip-fs-server/tests/end_to_end.rs

@@ -0,0 +1,583 @@
+use std::collections::BTreeMap;
+use std::io::{Read, Write};
+use std::net::{SocketAddr, TcpStream};
+use std::sync::Arc;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::thread;
+use std::time::{Duration, Instant};
+
+use tempfile::tempdir;
+use wip_fs_server::{AccessMode, ServerConfig, WipFsServer};
+use wip_http::{
+    ClientResponseError, DecodedResponse, Endpoint, JSON_CONTENT_TYPE, Limits, Route,
+    TransportFailureKind, decode_call_operation_response, decode_fetch_interface_response,
+    decode_observe_response, encode_call_operation_request, encode_fetch_interface_request,
+    encode_observe_request,
+};
+use wip_protocol::{
+    CallOperationRequest, FetchInterfaceRequest, InterfaceTarget, ObserveRequest,
+    ProtocolErrorCode, Target, Value,
+};
+
+#[test]
+fn real_listener_serves_three_core_interactions_and_write() {
+    let temporary = tempdir().expect("temporary root");
+    std::fs::write(temporary.path().join("hello.txt"), b"hello world").expect("write file");
+    std::fs::create_dir(temporary.path().join("nested")).expect("create directory");
+
+    let mut config = ServerConfig::for_root(temporary.path());
+    config.access = AccessMode::ReadWrite;
+    let limits = config.limits.wire;
+    let bound = Arc::new(
+        WipFsServer::new(config)
+            .expect("build server")
+            .bind()
+            .expect("bind"),
+    );
+    let address = bound.local_addr();
+    let shutdown = Arc::new(AtomicBool::new(false));
+    let worker = {
+        let bound = Arc::clone(&bound);
+        let shutdown = Arc::clone(&shutdown);
+        thread::spawn(move || bound.serve_until(shutdown))
+    };
+    let endpoint = Endpoint::parse(&format!("http://localhost:{}/wip", address.port()))
+        .expect("client endpoint");
+
+    let file_request = ObserveRequest {
+        path: "/hello.txt".into(),
+        depth: 0,
+    };
+    let response = exchange(
+        address,
+        encode_observe_request(&endpoint, &file_request, limits).expect("encode observation"),
+    );
+    let file = success(
+        decode_observe_response(&file_request, &response, limits).expect("decode observation"),
+    )
+    .object;
+    assert_eq!(file.name, "hello.txt");
+    assert_eq!(file.interfaces.len(), 2);
+    assert!(file.validator.is_some());
+
+    let tree_request = ObserveRequest {
+        path: "/".into(),
+        depth: 1,
+    };
+    let response = exchange(
+        address,
+        encode_observe_request(&endpoint, &tree_request, limits).expect("encode tree"),
+    );
+    let tree =
+        success(decode_observe_response(&tree_request, &response, limits).expect("decode tree"));
+    assert_eq!(
+        tree.children
+            .as_ref()
+            .expect("root children observed")
+            .len(),
+        2
+    );
+
+    let read_interface_request = FetchInterfaceRequest {
+        interface: file.interfaces[0].clone(),
+    };
+    let response = exchange(
+        address,
+        encode_fetch_interface_request(&endpoint, &read_interface_request, limits)
+            .expect("encode interface fetch"),
+    );
+    let read_interface = success(
+        decode_fetch_interface_response(&read_interface_request, &response, limits)
+            .expect("decode interface"),
+    );
+    assert_eq!(read_interface.descriptor.operations[0].name, "read");
+
+    let read_request = CallOperationRequest {
+        target: Target {
+            path: "/hello.txt".into(),
+            validator: file.validator.clone(),
+        },
+        interface: InterfaceTarget {
+            reference: file.interfaces[0].clone(),
+            validator: None,
+        },
+        operation: "read".into(),
+        arguments: BTreeMap::from([
+            ("offset".into(), Value::Integer(6)),
+            ("length".into(), Value::Integer(5)),
+        ]),
+    };
+    let response = exchange(
+        address,
+        encode_call_operation_request(&endpoint, &read_request, &read_interface.descriptor, limits)
+            .expect("encode read call"),
+    );
+    let read = success(
+        decode_call_operation_response(
+            &read_request,
+            &read_interface.descriptor,
+            &response,
+            limits,
+        )
+        .expect("decode read call"),
+    );
+    assert_eq!(read.result, Value::Bytes(b"world".to_vec()));
+
+    let write_interface_request = FetchInterfaceRequest {
+        interface: file.interfaces[1].clone(),
+    };
+    let response = exchange(
+        address,
+        encode_fetch_interface_request(&endpoint, &write_interface_request, limits)
+            .expect("encode write interface fetch"),
+    );
+    let write_interface = success(
+        decode_fetch_interface_response(&write_interface_request, &response, limits)
+            .expect("decode write interface"),
+    );
+    let write_request = CallOperationRequest {
+        target: Target {
+            path: "/hello.txt".into(),
+            validator: file.validator,
+        },
+        interface: InterfaceTarget {
+            reference: file.interfaces[1].clone(),
+            validator: None,
+        },
+        operation: "replace".into(),
+        arguments: BTreeMap::from([("contents".into(), Value::Bytes(b"updated".to_vec()))]),
+    };
+    let response = exchange(
+        address,
+        encode_call_operation_request(
+            &endpoint,
+            &write_request,
+            &write_interface.descriptor,
+            limits,
+        )
+        .expect("encode write call"),
+    );
+    let write = success(
+        decode_call_operation_response(
+            &write_request,
+            &write_interface.descriptor,
+            &response,
+            limits,
+        )
+        .expect("decode write call"),
+    );
+    assert!(write.validator.is_some());
+    assert_eq!(
+        std::fs::read(temporary.path().join("hello.txt")).expect("read updated file"),
+        b"updated"
+    );
+
+    shutdown.store(true, Ordering::Release);
+    worker
+        .join()
+        .expect("join listener")
+        .expect("listener exits cleanly");
+}
+
+#[test]
+fn real_listener_keeps_route_method_and_malformed_body_boundaries_distinct() {
+    let temporary = tempdir().expect("temporary root");
+    let mut config = ServerConfig::for_root(temporary.path());
+    config.limits.wire = Limits::new(64, 4_096, 64).expect("wire limits");
+    let bound = Arc::new(
+        WipFsServer::new(config)
+            .expect("build server")
+            .bind()
+            .expect("bind"),
+    );
+    let address = bound.local_addr();
+    let shutdown = Arc::new(AtomicBool::new(false));
+    let worker = {
+        let bound = Arc::clone(&bound);
+        let shutdown = Arc::clone(&shutdown);
+        thread::spawn(move || bound.serve_until(shutdown))
+    };
+
+    for uri in [
+        "/wip/v1/unknown",
+        "/wip/v1/batch",
+        "/wip/v1/observe?unexpected=true",
+        "/wip/v1/observe/extra",
+    ] {
+        let response = exchange(address, json_request(http::Method::POST, uri, b"{}"));
+        assert_eq!(response.status(), http::StatusCode::NOT_FOUND);
+        assert!(response.body().is_empty());
+        assert!(!response.headers().contains_key(http::header::CONTENT_TYPE));
+        assert!(!response.headers().contains_key(http::header::ALLOW));
+    }
+
+    let wrong_method = exchange(
+        address,
+        json_request(http::Method::GET, "/wip/v1/observe", b""),
+    );
+    assert_eq!(wrong_method.status(), http::StatusCode::METHOD_NOT_ALLOWED);
+    assert_eq!(wrong_method.headers()[http::header::ALLOW], "POST");
+    assert!(wrong_method.body().is_empty());
+    assert!(
+        !wrong_method
+            .headers()
+            .contains_key(http::header::CONTENT_TYPE)
+    );
+
+    let mut unsupported_coding = json_request(
+        http::Method::POST,
+        "/wip/v1/observe",
+        br#"{"path":"/","depth":0}"#,
+    );
+    unsupported_coding
+        .headers_mut()
+        .insert(http::header::CONTENT_ENCODING, "gzip".parse().unwrap());
+    let unsupported_coding = exchange(address, unsupported_coding);
+    assert_eq!(
+        unsupported_coding.status(),
+        http::StatusCode::UNSUPPORTED_MEDIA_TYPE
+    );
+    assert!(unsupported_coding.body().is_empty());
+    assert!(
+        !unsupported_coding
+            .headers()
+            .contains_key(http::header::CONTENT_TYPE)
+    );
+
+    let malformed = exchange(
+        address,
+        json_request(http::Method::POST, "/wip/v1/observe", b"{"),
+    );
+    assert_eq!(malformed.status(), http::StatusCode::BAD_REQUEST);
+    assert_eq!(
+        malformed.headers()[http::header::CONTENT_TYPE],
+        JSON_CONTENT_TYPE
+    );
+    assert!(
+        std::str::from_utf8(malformed.body())
+            .expect("UTF-8 error envelope")
+            .contains("\"invalid_request\"")
+    );
+
+    let oversized = exchange(
+        address,
+        json_request(http::Method::POST, "/wip/v1/observe", &[b'x'; 65]),
+    );
+    assert_eq!(oversized.status(), http::StatusCode::PAYLOAD_TOO_LARGE);
+    assert!(oversized.body().is_empty());
+    assert!(!oversized.headers().contains_key(http::header::CONTENT_TYPE));
+
+    let mut header_only = TcpStream::connect(address).expect("connect header-only client");
+    header_only
+        .set_read_timeout(Some(Duration::from_secs(1)))
+        .expect("set header-only timeout");
+    write!(
+        header_only,
+        "POST /wip/v1/observe HTTP/1.1\r\nHost: localhost\r\nContent-Type: application/json\r\nContent-Length: 65\r\n\r\n"
+    )
+    .expect("write oversized request head");
+    header_only.flush().expect("flush oversized request head");
+    let mut raw = Vec::new();
+    header_only
+        .read_to_end(&mut raw)
+        .expect("read immediate limit response");
+    assert!(raw.starts_with(b"HTTP/1.1 413 "));
+    assert!(raw.ends_with(b"\r\n\r\n"));
+    assert!(
+        !raw.windows(b"resource_limit_exceeded".len())
+            .any(|window| { window == b"resource_limit_exceeded" })
+    );
+
+    shutdown.store(true, Ordering::Release);
+    worker
+        .join()
+        .expect("join listener")
+        .expect("listener exits cleanly");
+}
+
+#[test]
+fn raw_decoder_limits_are_transport_failures() {
+    let temporary = tempdir().expect("temporary root");
+    let mut config = ServerConfig::for_root(temporary.path());
+    config.limits.wire = Limits::new(4_096, 4_096, 8).expect("wire limits");
+    let server = WipFsServer::new(config).expect("build server");
+
+    let nested = br#"{"path":[[[[[[[[["/"]]]]]]]]],"depth":0}"#;
+    let response = server.handle_http(json_request(http::Method::POST, "/wip/v1/observe", nested));
+    assert_eq!(response.status(), http::StatusCode::PAYLOAD_TOO_LARGE);
+    assert!(response.body().is_empty());
+    assert!(!response.headers().contains_key(http::header::CONTENT_TYPE));
+}
+
+#[test]
+fn logical_observation_limit_remains_protocol_resource_failure() {
+    let temporary = tempdir().expect("temporary root");
+    let mut config = ServerConfig::for_root(temporary.path());
+    config.limits.max_observation_depth = 0;
+    let limits = config.limits.wire;
+    let server = WipFsServer::new(config).expect("build server");
+    let endpoint = Endpoint::parse("http://localhost/wip").expect("endpoint");
+    let request = ObserveRequest {
+        path: "/".into(),
+        depth: 1,
+    };
+
+    let response = server.handle_http(
+        encode_observe_request(&endpoint, &request, limits).expect("encode observation"),
+    );
+    assert_eq!(response.status(), http::StatusCode::UNPROCESSABLE_ENTITY);
+    assert!(matches!(
+        decode_observe_response(&request, &response, limits).expect("decode logical limit"),
+        DecodedResponse::ProtocolFailure {
+            error,
+            status_mismatch: None,
+        } if error.code == ProtocolErrorCode::ResourceLimitExceeded
+    ));
+}
+
+#[test]
+fn stalled_request_body_times_out_and_releases_the_only_worker() {
+    let temporary = tempdir().expect("temporary root");
+    let mut config = ServerConfig::for_root(temporary.path());
+    config.limits.max_concurrent_requests = 1;
+    config.limits.request_timeout = Duration::from_millis(200);
+    let limits = config.limits.wire;
+    let bound = Arc::new(
+        WipFsServer::new(config)
+            .expect("build server")
+            .bind()
+            .expect("bind"),
+    );
+    let address = bound.local_addr();
+    let shutdown = Arc::new(AtomicBool::new(false));
+    let worker = {
+        let bound = Arc::clone(&bound);
+        let shutdown = Arc::clone(&shutdown);
+        thread::spawn(move || bound.serve_until(shutdown))
+    };
+
+    let mut stalled = TcpStream::connect(address).expect("connect stalled client");
+    stalled
+        .set_read_timeout(Some(Duration::from_secs(1)))
+        .expect("set stalled read timeout");
+    write!(
+        stalled,
+        "POST /wip/v1/observe HTTP/1.1\r\nHost: localhost\r\nContent-Type: application/json\r\nAccept: application/json\r\nContent-Length: 100\r\n\r\n{{"
+    )
+    .expect("write partial request");
+    stalled.flush().expect("flush partial request");
+    thread::sleep(Duration::from_millis(25));
+
+    let endpoint = Endpoint::parse(&format!("http://localhost:{}/wip", address.port()))
+        .expect("client endpoint");
+    let observe = ObserveRequest {
+        path: "/".into(),
+        depth: 0,
+    };
+    let started = Instant::now();
+    let response = exchange(
+        address,
+        encode_observe_request(&endpoint, &observe, limits).expect("encode observation"),
+    );
+    let _root =
+        success(decode_observe_response(&observe, &response, limits).expect("decode observation"));
+    assert!(
+        started.elapsed() < Duration::from_secs(1),
+        "the valid request remained starved after the intake deadline"
+    );
+
+    let mut byte = [0_u8; 1];
+    match stalled.read(&mut byte) {
+        Ok(0) => {}
+        Err(error)
+            if matches!(
+                error.kind(),
+                std::io::ErrorKind::ConnectionReset
+                    | std::io::ErrorKind::ConnectionAborted
+                    | std::io::ErrorKind::BrokenPipe
+            ) => {}
+        outcome => panic!("stalled connection was not closed after its deadline: {outcome:?}"),
+    }
+
+    shutdown.store(true, Ordering::Release);
+    worker
+        .join()
+        .expect("join listener")
+        .expect("listener exits cleanly");
+}
+
+#[test]
+fn call_argument_decoding_does_not_mask_missing_target() {
+    let temporary = tempdir().expect("temporary root");
+    let config = ServerConfig::for_root(temporary.path());
+    let server = WipFsServer::new(config).expect("build server");
+    let endpoint = Endpoint::parse("http://localhost/wip").expect("endpoint");
+    let body = br#"{"target":{"path":"/missing"},"interface":{"reference":"unknown"},"operation":"missing","arguments":{"bytes":"not-base64"}}"#;
+    let request = http::Request::builder()
+        .method(http::Method::POST)
+        .uri(endpoint.route(Route::CallOperation).as_str())
+        .header(http::header::CONTENT_TYPE, JSON_CONTENT_TYPE)
+        .header(http::header::ACCEPT, "application/json")
+        .body(body.to_vec())
+        .expect("build request");
+    let response = server.handle_http(request);
+    assert_eq!(response.status(), http::StatusCode::NOT_FOUND);
+    assert!(
+        std::str::from_utf8(response.body())
+            .expect("UTF-8 error")
+            .contains("\"not_found\"")
+    );
+}
+
+#[test]
+fn backend_invalid_unicode_path_is_not_found_not_internal() {
+    let temporary = tempdir().expect("temporary root");
+    let config = ServerConfig::for_root(temporary.path());
+    let limits = config.limits.wire;
+    let server = WipFsServer::new(config).expect("build server");
+    let endpoint = Endpoint::parse("http://localhost/wip").expect("endpoint");
+    let request = ObserveRequest {
+        path: "/bad\0name".into(),
+        depth: 0,
+    };
+    let response = server.handle_http(
+        encode_observe_request(&endpoint, &request, limits).expect("encode observation"),
+    );
+    assert_eq!(response.status(), http::StatusCode::NOT_FOUND);
+    match decode_observe_response(&request, &response, limits).expect("decode missing response") {
+        DecodedResponse::ProtocolFailure { error, .. } => {
+            assert_eq!(error.code, ProtocolErrorCode::NotFound);
+        }
+        DecodedResponse::Success(_) => panic!("backend-invalid path must not resolve"),
+    }
+}
+
+#[test]
+fn read_response_size_failure_is_transport_local() {
+    let temporary = tempdir().expect("temporary root");
+    std::fs::write(temporary.path().join("large"), vec![b'x'; 2_000]).expect("write file");
+    let mut config = ServerConfig::for_root(temporary.path());
+    config.limits.wire = Limits::new(4_096, 1_024, 64).expect("wire limits");
+    let limits = config.limits.wire;
+    let server = WipFsServer::new(config).expect("build server");
+    let endpoint = Endpoint::parse("http://localhost/wip").expect("endpoint");
+
+    let observe_request = ObserveRequest {
+        path: "/large".into(),
+        depth: 0,
+    };
+    let response = server.handle_http(
+        encode_observe_request(&endpoint, &observe_request, limits).expect("encode observation"),
+    );
+    let file = success(
+        decode_observe_response(&observe_request, &response, limits).expect("decode observation"),
+    )
+    .object;
+    let interface_request = FetchInterfaceRequest {
+        interface: file.interfaces[0].clone(),
+    };
+    let response = server.handle_http(
+        encode_fetch_interface_request(&endpoint, &interface_request, limits)
+            .expect("encode interface fetch"),
+    );
+    let interface = success(
+        decode_fetch_interface_response(&interface_request, &response, limits)
+            .expect("decode interface"),
+    );
+    let call = CallOperationRequest {
+        target: Target {
+            path: "/large".into(),
+            validator: file.validator,
+        },
+        interface: InterfaceTarget {
+            reference: file.interfaces[0].clone(),
+            validator: None,
+        },
+        operation: "read".into(),
+        arguments: BTreeMap::from([("length".into(), Value::Integer(1_500))]),
+    };
+    let response = server.handle_http(
+        encode_call_operation_request(&endpoint, &call, &interface.descriptor, limits)
+            .expect("encode read call"),
+    );
+    assert_eq!(response.status(), http::StatusCode::INTERNAL_SERVER_ERROR);
+    assert!(response.body().is_empty());
+    assert!(!response.headers().contains_key(http::header::CONTENT_TYPE));
+    assert!(matches!(
+        decode_call_operation_response(&call, &interface.descriptor, &response, limits)
+            .expect_err("oversized representation is not a protocol failure"),
+        ClientResponseError::TransportBinding(failure)
+            if failure.status == http::StatusCode::INTERNAL_SERVER_ERROR
+                && failure.kind == TransportFailureKind::HttpStatus
+    ));
+}
+
+fn success<T>(response: DecodedResponse<T>) -> T {
+    match response {
+        DecodedResponse::Success(value) => value,
+        DecodedResponse::ProtocolFailure { error, .. } => panic!("protocol failure: {error}"),
+    }
+}
+
+fn json_request(method: http::Method, uri: &str, body: &[u8]) -> http::Request<Vec<u8>> {
+    http::Request::builder()
+        .method(method)
+        .uri(uri)
+        .header(http::header::CONTENT_TYPE, JSON_CONTENT_TYPE)
+        .header(http::header::ACCEPT, "application/json")
+        .body(body.to_vec())
+        .expect("build JSON request")
+}
+
+fn exchange(address: SocketAddr, request: http::Request<Vec<u8>>) -> http::Response<Vec<u8>> {
+    let mut stream = TcpStream::connect(address).expect("connect listener");
+    stream
+        .set_read_timeout(Some(Duration::from_secs(5)))
+        .expect("set read timeout");
+    let path = request
+        .uri()
+        .path_and_query()
+        .map_or("/", |value| value.as_str());
+    write!(
+        stream,
+        "{} {} HTTP/1.1\r\nHost: localhost\r\nConnection: close\r\n",
+        request.method(),
+        path
+    )
+    .expect("write request line");
+    for (name, value) in request.headers() {
+        write!(
+            stream,
+            "{}: {}\r\n",
+            name,
+            value.to_str().expect("ASCII request header")
+        )
+        .expect("write header");
+    }
+    write!(stream, "Content-Length: {}\r\n\r\n", request.body().len())
+        .expect("write content length");
+    stream.write_all(request.body()).expect("write body");
+    stream.flush().expect("flush request");
+
+    let mut raw = Vec::new();
+    stream.read_to_end(&mut raw).expect("read response");
+    let split = raw
+        .windows(4)
+        .position(|window| window == b"\r\n\r\n")
+        .expect("HTTP response header");
+    let head = std::str::from_utf8(&raw[..split]).expect("UTF-8 response head");
+    let mut lines = head.split("\r\n");
+    let status = lines
+        .next()
+        .and_then(|line| line.split_whitespace().nth(1))
+        .and_then(|status| status.parse::<u16>().ok())
+        .expect("response status");
+    let mut builder = http::Response::builder().status(status);
+    for line in lines {
+        let (name, value) = line.split_once(':').expect("response header");
+        builder = builder.header(name, value.trim());
+    }
+    builder
+        .body(raw[split + 4..].to_vec())
+        .expect("build response")
+}

crates/wip-host/Cargo.toml

@@ -1,13 +1,17 @@
 [package]
 name = "wip-host"
-version = "0.1.0"
+version.workspace = true
-edition = "2024"
+edition.workspace = true
+rust-version.workspace = true
 description = "Host-side object publication and operation dispatch for WIP"
-license = "MIT OR Apache-2.0"
+license.workspace = true
+repository.workspace = true
+readme = "README.md"
+documentation = "https://docs.rs/wip-host"
 
 [dependencies]
-wip-interface = { path = "../wip-interface" }
+wip-interface.workspace = true
-wip-protocol = { path = "../wip-protocol" }
+wip-protocol.workspace = true
 
 [dev-dependencies]
 trybuild = "1"

crates/wip-host/LICENSE-APACHE

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

crates/wip-host/LICENSE-MIT

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Hare
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

crates/wip-host/README.md

@@ -0,0 +1,15 @@
+# wip-host
+
+Framework-independent Host publication and operation dispatch for the Web Interface Protocol (WIP).
+
+`wip-host` registers generated interfaces, explicitly publishes them on request-scoped objects, validates object and interface preconditions, and performs interface-qualified operation dispatch against one host-owned instance. Backend transactions, persistence, and network serving remain application responsibilities.
+
+```toml
+[dependencies]
+wip-host = "0.1.0"
+wip-interface = "0.1.0"
+```
+
+See the [API documentation](https://docs.rs/wip-host) for publication, provider, execution-context, and effect-guarantee boundaries.
+
+Licensed under either of Apache-2.0 or MIT at your option.

crates/wip-host/src/lib.rs

@@ -211,6 +211,17 @@ pub struct InterfaceObservation {
 }
 
 impl InterfaceObservation {
+    /// Restricts this effective view to visible operations and reachable types.
+    ///
+    /// Registry artifacts are unchanged. When operations are removed, interface-
+    /// wide documentation is omitted because it may describe hidden operations.
+    /// Providers must use the same predicate for publication and fetch.
+    #[must_use]
+    pub fn project_operations(mut self, visible: impl Fn(&str) -> bool) -> Self {
+        restrict_descriptor(&mut self.descriptor, visible);
+        self
+    }
+
     /// Converts this host observation to a validated canonical protocol response.
     ///
     /// A Host-side response construction failure is returned as `Internal`; it is
@@ -352,7 +363,7 @@ impl InterfaceRegistry {
 
     /// Observes a registered interface by its host-side reference.
     #[must_use]
-    pub fn observe(&self, reference: &InterfaceRef) -> Option<InterfaceObservation> {
+    pub fn observe_object(&self, reference: &InterfaceRef) -> Option<InterfaceObservation> {
         self.artifacts.get(reference).map(Self::observation)
     }
 
@@ -449,6 +460,60 @@ pub trait WipObject {
     }
 }
 
+fn restrict_descriptor(descriptor: &mut InterfaceDescriptor, visible: impl Fn(&str) -> bool) {
+    let count = descriptor.operations.len();
+    descriptor
+        .operations
+        .retain(|operation| visible(&operation.name));
+    if descriptor.operations.len() == count {
+        return;
+    }
+    descriptor.documentation = None;
+    let mut used = HashSet::new();
+    fn references(expression: &wip_protocol::TypeExpr, used: &mut HashSet<String>) {
+        use wip_protocol::TypeExpr;
+        match expression {
+            TypeExpr::Named { name } => {
+                used.insert(name.clone());
+            }
+            TypeExpr::Record { fields } => {
+                for field in fields {
+                    references(&field.r#type, used);
+                }
+            }
+            TypeExpr::List { items } => references(items, used),
+            TypeExpr::Union { cases } => {
+                for case in cases {
+                    if let Some(payload) = &case.payload {
+                        references(payload, used);
+                    }
+                }
+            }
+            _ => {}
+        }
+    }
+    for operation in &descriptor.operations {
+        for parameter in &operation.parameters {
+            references(&parameter.r#type, &mut used);
+        }
+        references(&operation.returns.r#type, &mut used);
+    }
+    loop {
+        let before = used.len();
+        for declaration in &descriptor.types {
+            if used.contains(&declaration.name) {
+                references(&declaration.definition, &mut used);
+            }
+        }
+        if before == used.len() {
+            break;
+        }
+    }
+    descriptor
+        .types
+        .retain(|declaration| used.contains(&declaration.name));
+}
+
 type DispatchFn<T> = fn(&T, &str, BTreeMap<String, Value>) -> Result<Value, DispatchError>;
 
 struct BoundInterface<T> {
@@ -502,6 +567,46 @@ impl<T: WipObject> PublishedObject<T> {
         Ok(self)
     }
 
+    /// Restricts a publication to an ordered interface/operation view.
+    ///
+    /// This never adds implementations or changes codecs. The provider must use
+    /// the identical operation predicate for `fetch_interface`, and keep the
+    /// effective view stable for the lifetime of its references. Filtered
+    /// descriptors are scoped to that view, not mutations of registry artifacts.
+    pub fn project(
+        mut self,
+        interfaces: &[InterfaceRef],
+        visible: impl Fn(&InterfaceRef, &str) -> bool,
+    ) -> Result<Self, PublicationError> {
+        let mut projected = Vec::with_capacity(interfaces.len());
+        for reference in interfaces {
+            if projected
+                .iter()
+                .any(|bound: &BoundInterface<T>| &bound.artifact.reference == reference)
+            {
+                return Err(PublicationError::DuplicateInterface(reference.clone()));
+            }
+            let Some(index) = self
+                .interfaces
+                .iter()
+                .position(|bound| &bound.artifact.reference == reference)
+            else {
+                return Err(PublicationError::UnexposedInterface(reference.clone()));
+            };
+            let mut bound = self.interfaces.remove(index);
+            let mut descriptor = bound.artifact.descriptor.clone();
+            restrict_descriptor(&mut descriptor, |operation| visible(reference, operation));
+            bound.artifact = Arc::new(InterfaceArtifact {
+                reference: reference.clone(),
+                descriptor,
+                validator: bound.artifact.validator.clone(),
+            });
+            projected.push(bound);
+        }
+        self.interfaces = projected;
+        Ok(self)
+    }
+
     /// Returns the host-private implementation without projecting its fields.
     #[must_use]
     pub fn implementation(&self) -> &T {
@@ -535,11 +640,36 @@ impl<T: WipObject> PublishedObject<T> {
         context: &ExecutionContext,
         request: CallRequest,
         authorize: impl FnOnce(&T, &InterfaceRef, &str) -> bool,
+    ) -> OperationAttempt {
+        let CallRequest {
+            target,
+            interface,
+            operation,
+            arguments,
+        } = request;
+        self.dispatch_resolved_with_decoder(
+            context,
+            target,
+            interface,
+            operation,
+            |_| Ok::<_, std::convert::Infallible>(arguments),
+            authorize,
+        )
+    }
+
+    fn dispatch_resolved_with_decoder<E>(
+        &self,
+        context: &ExecutionContext,
+        target: Target,
+        interface: InterfaceTarget,
+        operation: String,
+        decode_arguments: impl FnOnce(&InterfaceDescriptor) -> Result<BTreeMap<String, Value>, E>,
+        authorize: impl FnOnce(&T, &InterfaceRef, &str) -> bool,
     ) -> OperationAttempt {
         let pre_dispatch_failure =
             |kind, message: &str| OperationAttempt::NotStarted(CallError::new(kind, message));
         let current_object_validator = self.implementation.validator();
-        if let Some(supplied) = request.target.validator.as_deref()
+        if let Some(supplied) = target.validator.as_deref()
             && current_object_validator.map(Validator::as_bytes) != Some(supplied)
         {
             return pre_dispatch_failure(
@@ -548,9 +678,11 @@ impl<T: WipObject> PublishedObject<T> {
             );
         }
 
-        let Some(bound) = self.interfaces.iter().find(|bound| {
+        let Some(bound) = self
-            bound.artifact.reference.as_str() == request.interface.reference.as_str()
+            .interfaces
-        }) else {
+            .iter()
+            .find(|bound| bound.artifact.reference.as_str() == interface.reference.as_str())
+        else {
             return pre_dispatch_failure(
                 CallErrorKind::InterfaceMismatch,
                 "interface is not a member of the current object publication",
@@ -559,7 +691,7 @@ impl<T: WipObject> PublishedObject<T> {
 
         match (
             bound.artifact.validator.as_ref(),
-            request.interface.validator.as_deref(),
+            interface.validator.as_deref(),
         ) {
             (Some(_), None) => {
                 return pre_dispatch_failure(
@@ -581,18 +713,18 @@ impl<T: WipObject> PublishedObject<T> {
             .descriptor
             .operations
             .iter()
-            .any(|operation| operation.name == request.operation)
+            .any(|declared| declared.name == operation)
         {
             return pre_dispatch_failure(
                 CallErrorKind::OperationNotFound,
-                &format!("operation `{}` is not declared", request.operation),
+                &format!("operation `{operation}` is not declared"),
             );
         }
 
-        if request.target.validator.is_none()
+        if target.validator.is_none()
             && self
                 .implementation
-                .requires_validator(&bound.artifact.reference, &request.operation)
+                .requires_validator(&bound.artifact.reference, &operation)
         {
             return pre_dispatch_failure(
                 CallErrorKind::ValidatorRequired,
@@ -600,19 +732,24 @@ impl<T: WipObject> PublishedObject<T> {
             );
         }
 
+        let arguments = match decode_arguments(&bound.artifact.descriptor) {
+            Ok(arguments) => arguments,
+            Err(_) => {
+                return pre_dispatch_failure(
+                    CallErrorKind::InvalidArguments,
+                    "operation arguments could not be decoded",
+                );
+            }
+        };
         if let Err(error) = bound
             .artifact
             .descriptor
-            .validate_arguments(&request.operation, &request.arguments)
+            .validate_arguments(&operation, &arguments)
         {
             return pre_dispatch_failure(CallErrorKind::InvalidArguments, &error.to_string());
         }
 
-        if !authorize(
+        if !authorize(&self.implementation, &bound.artifact.reference, &operation) {
-            &self.implementation,
-            &bound.artifact.reference,
-            &request.operation,
-        ) {
             return pre_dispatch_failure(
                 CallErrorKind::PermissionDenied,
                 "operation is not permitted for this caller",
@@ -623,23 +760,22 @@ impl<T: WipObject> PublishedObject<T> {
             return OperationAttempt::NotStarted(error);
         }
 
-        let value =
+        let value = match (bound.dispatch)(&self.implementation, &operation, arguments) {
-            match (bound.dispatch)(&self.implementation, &request.operation, request.arguments) {
+            Ok(value) => value,
-                Ok(value) => value,
+            Err(
-                Err(
+                error @ (DispatchError::UnknownOperation(_)
-                    error @ (DispatchError::UnknownOperation(_)
+                | DispatchError::InvalidArguments(_)
-                    | DispatchError::InvalidArguments(_)
+                | DispatchError::Decode(_)),
-                    | DispatchError::Decode(_)),
+            ) => return OperationAttempt::NotStarted(CallError::from_pre_dispatch(error)),
-                ) => return OperationAttempt::NotStarted(CallError::from_pre_dispatch(error)),
+            Err(error) => {
-                Err(error) => {
+                return OperationAttempt::Started(Err(OperationFailure::from_dispatch(error)));
-                    return OperationAttempt::Started(Err(OperationFailure::from_dispatch(error)));
+            }
-                }
+        };
-            };
 
         if bound
             .artifact
             .descriptor
-            .validate_result(&request.operation, &value)
+            .validate_result(&operation, &value)
             .is_err()
         {
             return OperationAttempt::Started(Err(OperationFailure::internal(
@@ -751,6 +887,15 @@ pub enum OperationAttempt {
 }
 
 impl OperationAttempt {
+    /// Rejects a provider precondition before typed implementation invocation.
+    ///
+    /// Only use this before dispatch starts; post-invocation failures require
+    /// an explicit effect disposition. The diagnostic is intentionally generic.
+    #[must_use]
+    pub fn reject(kind: CallErrorKind) -> Self {
+        Self::NotStarted(CallError::new(kind, "provider precondition failed"))
+    }
+
     /// Marks a post-invocation failure as fully rolled back.
     ///
     /// Successful attempts and pre-dispatch failures are returned unchanged.
@@ -832,13 +977,13 @@ pub trait ObjectProvider {
         true
     }
 
-    /// Fetches the canonical object projection currently published at `path`.
+    /// Observes the canonical object projection currently published at `path`.
-    fn fetch(&self, path: &str) -> Result<Object, CallError> {
+    fn observe_object(&self, path: &str) -> Result<Object, CallError> {
-        self.fetch_with_context(&ExecutionContext::default(), path)
+        self.observe_object_with_context(&ExecutionContext::default(), path)
     }
 
-    /// Fetches an object while propagating runtime execution controls.
+    /// Observes an object while propagating runtime execution controls.
-    fn fetch_with_context(
+    fn observe_object_with_context(
         &self,
         context: &ExecutionContext,
         path: &str,
@@ -851,7 +996,7 @@ pub trait ObjectProvider {
         .map_err(|_| {
             CallError::new(
                 CallErrorKind::Internal,
-                "provider panicked while fetching an object",
+                "provider panicked while observing an object",
             )
         })?;
         let object = match resolved {
@@ -922,6 +1067,62 @@ pub trait ObjectProvider {
             ProviderResult::Failure(error) => Err(CallError::from_host_failure(error)),
         }
     }
+
+    /// Resolves one operation target and decodes its arguments only after all
+    /// descriptor-independent canonical preconditions have succeeded.
+    ///
+    /// Transport bindings whose value representation depends on the selected
+    /// interface descriptor should use this method instead of resolving a
+    /// descriptor before [`ObjectProvider::call_operation_with_context`]. The
+    /// callback executes inside the same exact-once provider boundary after
+    /// object/interface validators, membership, operation lookup, and required
+    /// object-validator checks. A callback error becomes `InvalidArguments` and
+    /// typed implementation code is not invoked.
+    fn call_operation_with_context_and_decoder<E>(
+        &self,
+        context: &ExecutionContext,
+        target: Target,
+        interface: InterfaceTarget,
+        operation: String,
+        decode_arguments: impl FnOnce(&InterfaceDescriptor) -> Result<BTreeMap<String, Value>, E>,
+    ) -> Result<CallResult, CallError> {
+        wip_protocol::validate_path(&target.path)
+            .map_err(|error| CallError::new(CallErrorKind::InvalidRequest, error.to_string()))?;
+        let path = target.path.clone();
+        let execution = catch_unwind(AssertUnwindSafe(|| {
+            self.execute_operation(context, &path, |publication| {
+                publication.dispatch_resolved_with_decoder(
+                    context,
+                    target,
+                    interface,
+                    operation,
+                    decode_arguments,
+                    |object, interface, operation| {
+                        self.authorize(&path, object, interface, operation)
+                    },
+                )
+            })
+        }));
+
+        let execution = execution.map_err(|_| {
+            CallError::from_operation_failure(OperationFailure::internal(
+                EffectGuarantee::Unknown,
+                "provider execution panicked",
+            ))
+        })?;
+        match execution {
+            ProviderResult::Found(OperationAttempt::NotStarted(error)) => Err(error),
+            ProviderResult::Found(OperationAttempt::Started(Ok(result))) => Ok(result),
+            ProviderResult::Found(OperationAttempt::Started(Err(error))) => {
+                Err(CallError::from_operation_failure(error))
+            }
+            ProviderResult::NotFound => Err(CallError::new(
+                CallErrorKind::NotFound,
+                "target path is not published",
+            )),
+            ProviderResult::Failure(error) => Err(CallError::from_host_failure(error)),
+        }
+    }
 }
 
 /// Failure to construct an explicit object publication.
@@ -929,11 +1130,18 @@ pub trait ObjectProvider {
 pub enum PublicationError {
     /// The same opaque interface reference was exposed more than once.
     DuplicateInterface(InterfaceRef),
+    /// Projection attempted to add an interface without an implementation.
+    UnexposedInterface(InterfaceRef),
 }
 
 impl Display for PublicationError {
     fn fmt(&self, formatter: &mut Formatter<'_>) -> fmt::Result {
         match self {
+            Self::UnexposedInterface(reference) => write!(
+                formatter,
+                "interface `{}` has no implementation",
+                reference.as_str()
+            ),
             Self::DuplicateInterface(reference) => write!(
                 formatter,
                 "interface `{}` is already exposed by this object",
@@ -945,6 +1153,70 @@ impl Display for PublicationError {
 
 impl Error for PublicationError {}
 
+#[cfg(test)]
+mod projection_tests {
+    use super::*;
+    use wip_protocol::{
+        Documentation, OperationDeclaration, ReturnDeclaration, TypeDeclaration, TypeExpr,
+    };
+
+    #[test]
+    fn operation_views_prune_hidden_types_and_documentation_without_mutating_registry() {
+        let named = |name: &str| TypeExpr::Named { name: name.into() };
+        let operation = |name: &str, returns| OperationDeclaration {
+            name: name.into(),
+            documentation: None,
+            parameters: Vec::new(),
+            returns: ReturnDeclaration {
+                documentation: None,
+                r#type: returns,
+            },
+        };
+        let declaration = |name: &str, definition| TypeDeclaration {
+            name: name.into(),
+            documentation: None,
+            definition,
+        };
+        let descriptor = InterfaceDescriptor {
+            format: "wip/1".into(),
+            documentation: Some(Documentation {
+                summary: "contains hidden operation details".into(),
+                details: None,
+            }),
+            operations: vec![
+                operation("visible", named("Public")),
+                operation("secret", named("Secret")),
+            ],
+            types: vec![
+                declaration(
+                    "Public",
+                    TypeExpr::List {
+                        items: Box::new(named("Shared")),
+                    },
+                ),
+                declaration("Shared", TypeExpr::String),
+                declaration("Secret", TypeExpr::Bytes),
+            ],
+        };
+        let mut projected = descriptor.clone();
+        restrict_descriptor(&mut projected, |operation| operation == "visible");
+        assert_eq!(projected.operations.len(), 1);
+        assert!(projected.documentation.is_none());
+        assert_eq!(
+            projected
+                .types
+                .iter()
+                .map(|declaration| declaration.name.as_str())
+                .collect::<Vec<_>>(),
+            vec!["Public", "Shared"]
+        );
+        assert_eq!(descriptor.types.len(), 3);
+        restrict_descriptor(&mut projected, |_| false);
+        assert!(projected.types.is_empty());
+        assert!(projected.operations.is_empty());
+    }
+}
+
 /// Stable Host dispatch failure kind.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum CallErrorKind {

crates/wip-host/tests/host.rs

@@ -14,6 +14,62 @@ use wip_interface::{
 };
 use wip_protocol::ProtocolErrorCode;
 
+#[test]
+fn principal_projection_orders_subsets_and_rejects_unimplemented_or_duplicate_tokens() {
+    let mut registry = InterfaceRegistry::new();
+    let read = registry.register(ReaderDefinition, None).unwrap();
+    let write = registry.register(WriterDefinition, None).unwrap();
+    let hidden = registry.register(HiddenDefinition, None).unwrap();
+    let publication = || {
+        PublishedObject::new(Document::open("document", None, Rc::new(Cell::new(0))))
+            .expose(&read)
+            .unwrap()
+            .expose(&write)
+            .unwrap()
+    };
+    let projected = publication()
+        .project(
+            &[write.reference().clone(), read.reference().clone()],
+            |_, operation| operation == "label",
+        )
+        .unwrap();
+    assert_eq!(
+        projected.protocol_object().interfaces,
+        vec![write.reference().as_str(), read.reference().as_str()]
+    );
+    assert!(
+        publication()
+            .project(&[hidden.reference().clone()], |_, _| true)
+            .is_err()
+    );
+    assert!(
+        publication()
+            .project(
+                &[read.reference().clone(), read.reference().clone()],
+                |_, _| true
+            )
+            .is_err()
+    );
+    assert!(
+        publication()
+            .project(&[], |_, _| true)
+            .unwrap()
+            .protocol_object()
+            .interfaces
+            .is_empty()
+    );
+    let full = registry.fetch_interface(read.reference().as_str()).unwrap();
+    let filtered = full
+        .clone()
+        .project_operations(|operation| operation == "label");
+    assert_eq!(filtered.descriptor.operations.len(), 1);
+    assert_eq!(full.descriptor.operations.len(), 3);
+    assert_eq!(
+        registry.fetch_interface(read.reference().as_str()).unwrap(),
+        full
+    );
+}
+
 #[interface]
 pub trait Reader {
     /// Returns the reader-qualified label.
@@ -467,7 +523,7 @@ fn registry_returns_atomic_canonical_observation_without_rewriting_descriptor()
 #[test]
 fn canonical_object_projection_supports_optional_metadata_and_ordered_sets() {
     let (_, provider, _) = registry_and_provider();
-    let object = provider.fetch("/document").unwrap();
+    let object = provider.observe_object("/document").unwrap();
 
     assert_eq!(object.name, "document");
     assert_eq!(object.description.as_deref(), Some("public document"));
@@ -483,7 +539,7 @@ fn canonical_object_projection_supports_optional_metadata_and_ordered_sets() {
     assert!(!format!("{object:?}").contains("secret-handle"));
     assert!(!format!("{object:?}").contains("/document"));
 
-    let empty = provider.fetch("/empty").unwrap();
+    let empty = provider.observe_object("/empty").unwrap();
     assert!(empty.interfaces.is_empty());
     assert_eq!(empty.r#ref, None);
     assert_eq!(empty.validator, None);
@@ -518,13 +574,13 @@ fn duplicate_exposure_is_rejected_and_private_state_is_not_projected() {
 fn paths_are_resolution_context_not_object_identity() {
     let (_, provider, _) = registry_and_provider();
 
-    let left = provider.fetch("/left/document").unwrap();
+    let left = provider.observe_object("/left/document").unwrap();
-    let right = provider.fetch("/right/document").unwrap();
+    let right = provider.observe_object("/right/document").unwrap();
     assert_eq!(left, right);
     assert_eq!(left.r#ref.as_deref(), Some("shared-ref"));
 
-    let first = provider.fetch("/switch").unwrap();
+    let first = provider.observe_object("/switch").unwrap();
-    let second = provider.fetch("/switch").unwrap();
+    let second = provider.observe_object("/switch").unwrap();
     assert_ne!(first.r#ref, second.r#ref);
     assert_ne!(first.validator, second.validator);
 }
@@ -603,7 +659,7 @@ fn call_failures_follow_canonical_precedence_without_execution() {
     }
     assert_eq!(provider.resolutions.get(), resolutions);
     assert_failure(
-        provider.fetch("/invalid/").unwrap_err(),
+        provider.observe_object("/invalid/").unwrap_err(),
         CallErrorKind::InvalidRequest,
         ProtocolErrorCode::InvalidRequest,
     );
@@ -741,6 +797,89 @@ fn call_failures_follow_canonical_precedence_without_execution() {
     assert_eq!(provider.calls.get(), 0);
 }
 
+#[test]
+fn descriptor_guided_decoder_runs_inside_canonical_resolution_boundary() {
+    let (_, provider, hidden) = registry_and_provider();
+    let decodes = Cell::new(0_u32);
+    let decode_failure = || {
+        decodes.set(decodes.get() + 1);
+        Err::<BTreeMap<String, Value>, _>(())
+    };
+
+    let missing = provider
+        .call_operation_with_context_and_decoder(
+            &ExecutionContext::new(),
+            Target {
+                path: "/missing".into(),
+                validator: Some(b"stale".to_vec()),
+            },
+            InterfaceTarget {
+                reference: hidden.reference().as_str().into(),
+                validator: None,
+            },
+            "missing".into(),
+            |_| decode_failure(),
+        )
+        .unwrap_err();
+    assert_eq!(missing.kind(), CallErrorKind::NotFound);
+    assert_eq!(decodes.get(), 0);
+
+    let stale = provider
+        .call_operation_with_context_and_decoder(
+            &ExecutionContext::new(),
+            Target {
+                path: "/document".into(),
+                validator: Some(b"stale".to_vec()),
+            },
+            InterfaceTarget {
+                reference: hidden.reference().as_str().into(),
+                validator: None,
+            },
+            "hidden".into(),
+            |_| decode_failure(),
+        )
+        .unwrap_err();
+    assert_eq!(stale.kind(), CallErrorKind::ValidatorMismatch);
+    assert_eq!(decodes.get(), 0);
+
+    let mismatch = provider
+        .call_operation_with_context_and_decoder(
+            &ExecutionContext::new(),
+            Target {
+                path: "/document".into(),
+                validator: Some(b"object-v1".to_vec()),
+            },
+            InterfaceTarget {
+                reference: hidden.reference().as_str().into(),
+                validator: None,
+            },
+            "hidden".into(),
+            |_| decode_failure(),
+        )
+        .unwrap_err();
+    assert_eq!(mismatch.kind(), CallErrorKind::InterfaceMismatch);
+    assert_eq!(decodes.get(), 0);
+
+    let invalid_arguments = provider
+        .call_operation_with_context_and_decoder(
+            &ExecutionContext::new(),
+            Target {
+                path: "/document".into(),
+                validator: Some(b"object-v1".to_vec()),
+            },
+            InterfaceTarget {
+                reference: provider.reader.reference().as_str().into(),
+                validator: Some(b"schema-v1".to_vec()),
+            },
+            "add".into(),
+            |_| decode_failure(),
+        )
+        .unwrap_err();
+    assert_eq!(invalid_arguments.kind(), CallErrorKind::InvalidArguments);
+    assert_eq!(decodes.get(), 1);
+    assert_eq!(provider.calls.get(), 0);
+}
+
 #[test]
 fn immutable_interface_rejects_a_supplied_validator() {
     let (_, provider, _) = registry_and_provider();
@@ -766,7 +905,7 @@ fn invalid_host_responses_and_uncertain_operation_failures_use_canonical_codes()
     let (_, provider, _) = registry_and_provider();
 
     assert_failure(
-        provider.fetch("/invalid-object").unwrap_err(),
+        provider.observe_object("/invalid-object").unwrap_err(),
         CallErrorKind::Internal,
         ProtocolErrorCode::Internal,
     );

crates/wip-http/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "wip-http"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+description = "Framework-independent standard WIP over HTTP v1 binding"
+license.workspace = true
+repository.workspace = true
+readme = "README.md"
+documentation = "https://docs.rs/wip-http"
+
+[dependencies]
+base64 = "0.22"
+http = "1"
+serde = "1"
+serde_json = "1"
+url = "2"
+wip-protocol.workspace = true

crates/wip-http/LICENSE-APACHE

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

crates/wip-http/LICENSE-MIT

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Hare
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

crates/wip-http/README.md

@@ -0,0 +1,31 @@
+# wip-http
+
+Framework-independent WIP over HTTP v1 endpoint, route, JSON codec, and response-classification support.
+
+The crate maps the three WIP Core interactions to fixed HTTP routes and strict UTF-8 JSON representations. It constructs and validates `http` request and response values but deliberately performs no network I/O and does not define TLS, authentication, proxy, or connection policy.
+
+```toml
+[dependencies]
+wip-http = "0.1.0"
+```
+
+```rust
+use wip_http::wip_protocol::ObserveRequest;
+use wip_http::{Endpoint, Limits, encode_observe_request};
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let endpoint = Endpoint::parse("https://example.test/wip")?;
+    let limits = Limits::new(64 * 1024, 1024 * 1024, 64)?;
+    let request = encode_observe_request(
+        &endpoint,
+        &ObserveRequest { path: "/".into(), depth: 0 },
+        limits,
+    )?;
+    assert_eq!(request.uri(), "https://example.test/wip/v1/observe");
+    Ok(())
+}
+```
+
+See the [API documentation](https://docs.rs/wip-http) for codec and failure-boundary details.
+
+Licensed under either of Apache-2.0 or MIT at your option.

crates/wip-http/src/codec.rs

@@ -1,9 +1,12 @@
-use http::header::CONTENT_TYPE;
+use std::error::Error;
-use http::{Method, Request, Response, StatusCode};
+use std::fmt::{self, Display, Formatter};
+
+use http::header::{ACCEPT, CONTENT_ENCODING, CONTENT_TYPE};
+use http::{HeaderMap, Method, Request, Response, StatusCode};
 use wip_protocol::{
     CallOperationRequest, CallOperationResponse, FetchInterfaceRequest, FetchInterfaceResponse,
-    FetchRequest, FetchResponse, FetchTreeRequest, FetchTreeResponse, INTERFACE_FORMAT_V1,
+    INTERFACE_FORMAT_V1, InterfaceDescriptor, InterfaceTarget, ObserveRequest, ObserveResponse,
-    InterfaceDescriptor, InterfaceTarget, ProtocolError, ProtocolInteraction, Target,
+    ProtocolError, ProtocolInteraction, Target,
 };
 
 use crate::response::{self, DecodedResponse};
@@ -21,6 +24,7 @@ fn request(
         .method(Method::POST)
         .uri(endpoint.route(route).as_str())
         .header(CONTENT_TYPE, JSON_CONTENT_TYPE)
+        .header(ACCEPT, "application/json")
         .body(body)
 }
 
@@ -32,6 +36,9 @@ fn response(status: StatusCode, body: Vec<u8>) -> Result<Response<Vec<u8>>, http
 }
 
 fn require_response_content_type<B>(response: &Response<B>) -> Result<(), ClientResponseError> {
+    if !has_supported_content_coding(response.headers()) {
+        return Err(response::unsupported_content_coding(response.status()));
+    }
     let valid = response
         .headers()
         .get(CONTENT_TYPE)
@@ -49,6 +56,15 @@ fn require_response_content_type<B>(response: &Response<B>) -> Result<(), Client
     }
 }
 
+fn is_utf8_charset(value: &str) -> bool {
+    let value = value.trim();
+    value.eq_ignore_ascii_case("utf-8")
+        || value
+            .strip_prefix('"')
+            .and_then(|value| value.strip_suffix('"'))
+            .is_some_and(|value| value.eq_ignore_ascii_case("utf-8"))
+}
+
 /// Returns whether a Content-Type value denotes UTF-8 `application/json`.
 ///
 /// The charset parameter is optional because JSON exchanged by this binding is
@@ -68,13 +84,7 @@ pub fn is_json_content_type(value: &str) -> bool {
         let Some((name, value)) = parameter.trim().split_once('=') else {
             return false;
         };
-        let charset = value.trim();
+        if !name.trim().eq_ignore_ascii_case("charset") || !is_utf8_charset(value) || saw_charset {
-        let charset_is_utf8 = charset.eq_ignore_ascii_case("utf-8")
-            || charset
-                .strip_prefix('"')
-                .and_then(|value| value.strip_suffix('"'))
-                .is_some_and(|value| value.eq_ignore_ascii_case("utf-8"));
-        if !name.trim().eq_ignore_ascii_case("charset") || !charset_is_utf8 || saw_charset {
             return false;
         }
         saw_charset = true;
@@ -82,85 +92,207 @@ pub fn is_json_content_type(value: &str) -> bool {
     true
 }
 
+fn accepts_json(headers: &HeaderMap) -> bool {
+    let mut present = false;
+    let mut best_match: Option<((u8, u8), f32)> = None;
+    for value in headers.get_all(ACCEPT) {
+        present = true;
+        let Ok(value) = value.to_str() else {
+            continue;
+        };
+        for range in value.split(',') {
+            let mut parts = range.split(';');
+            let media_range = parts.next().unwrap_or_default().trim();
+            let mut quality = 1.0_f32;
+            let mut saw_quality = false;
+            let mut saw_charset = false;
+            let mut media_parameter_count = 0;
+            let mut valid = true;
+            for parameter in parts {
+                let parameter = parameter.trim();
+                let (name, value) = parameter
+                    .split_once('=')
+                    .map_or((parameter, None), |(name, value)| {
+                        (name.trim(), Some(value))
+                    });
+                if name.is_empty() {
+                    valid = false;
+                    break;
+                }
+                if saw_quality {
+                    // Parameters after q are Accept extensions and do not
+                    // constrain the selected representation.
+                    continue;
+                }
+                if name.eq_ignore_ascii_case("q") {
+                    let Some(value) = value else {
+                        valid = false;
+                        break;
+                    };
+                    saw_quality = true;
+                    match value.trim().parse::<f32>() {
+                        Ok(value) if (0.0..=1.0).contains(&value) => quality = value,
+                        _ => {
+                            valid = false;
+                            break;
+                        }
+                    }
+                } else {
+                    let Some(value) = value else {
+                        valid = false;
+                        break;
+                    };
+                    if !name.eq_ignore_ascii_case("charset")
+                        || !is_utf8_charset(value)
+                        || saw_charset
+                    {
+                        valid = false;
+                        break;
+                    }
+                    saw_charset = true;
+                    media_parameter_count += 1;
+                }
+            }
+            let media_specificity = if media_range.eq_ignore_ascii_case("application/json") {
+                Some(2)
+            } else if media_range.eq_ignore_ascii_case("application/*") {
+                Some(1)
+            } else if media_range == "*/*" {
+                Some(0)
+            } else {
+                None
+            };
+            if valid && let Some(media_specificity) = media_specificity {
+                let specificity = (media_specificity, media_parameter_count);
+                match best_match {
+                    Some((best_specificity, _)) if best_specificity > specificity => {}
+                    Some((best_specificity, best_quality)) if best_specificity == specificity => {
+                        best_match = Some((specificity, best_quality.max(quality)));
+                    }
+                    _ => best_match = Some((specificity, quality)),
+                }
+            }
+        }
+    }
+    if present {
+        best_match.is_some_and(|(_, quality)| quality > 0.0)
+    } else {
+        true
+    }
+}
+
+/// A failure while validating inbound HTTP request metadata.
+#[derive(Debug)]
+pub enum RequestMetadataError {
+    /// The request URI does not exactly identify the selected standard route.
+    NotFound,
+    /// A known standard route was requested with a method other than `POST`.
+    MethodNotAllowed,
+    /// The request body does not use UTF-8 `application/json` or identity coding.
+    UnsupportedMediaType,
+    /// The request's `Accept` metadata excludes `application/json`.
+    NotAcceptable,
+}
+
+impl RequestMetadataError {
+    /// Returns the HTTP status for this metadata failure.
+    #[must_use]
+    pub const fn status(&self) -> StatusCode {
+        match self {
+            Self::NotFound => StatusCode::NOT_FOUND,
+            Self::MethodNotAllowed => StatusCode::METHOD_NOT_ALLOWED,
+            Self::UnsupportedMediaType => StatusCode::UNSUPPORTED_MEDIA_TYPE,
+            Self::NotAcceptable => StatusCode::NOT_ACCEPTABLE,
+        }
+    }
+
+    /// Returns the value for an `Allow` response header, when required.
+    #[must_use]
+    pub const fn allow(&self) -> Option<&'static str> {
+        match self {
+            Self::MethodNotAllowed => Some("POST"),
+            Self::NotFound | Self::UnsupportedMediaType | Self::NotAcceptable => None,
+        }
+    }
+}
+
+impl Display for RequestMetadataError {
+    fn fmt(&self, formatter: &mut Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::NotFound => formatter.write_str("request URI is not a standard WIP route"),
+            Self::MethodNotAllowed => formatter.write_str("standard WIP routes require POST"),
+            Self::UnsupportedMediaType => {
+                formatter.write_str("expected identity-coded UTF-8 application/json Content-Type")
+            }
+            Self::NotAcceptable => formatter.write_str("request does not accept application/json"),
+        }
+    }
+}
+
+impl Error for RequestMetadataError {}
+
+pub(crate) fn has_supported_content_coding(headers: &HeaderMap) -> bool {
+    headers.get_all(CONTENT_ENCODING).iter().all(|value| {
+        value.to_str().is_ok_and(|value| {
+            let mut codings = value.split(',').map(str::trim);
+            let first = codings.next();
+            first.is_some_and(|coding| coding.eq_ignore_ascii_case("identity"))
+                && codings.all(|coding| coding.eq_ignore_ascii_case("identity"))
+        })
+    })
+}
+
 /// Validates mandatory HTTP metadata for an inbound WIP request.
 ///
 /// Both absolute-form and origin-form request URIs are accepted, but the path
 /// must exactly equal the selected endpoint route and a query is forbidden.
+/// Unsupported content negotiation is reported as a Transport Binding metadata
+/// failure rather than a Core `invalid_request`.
 pub fn validate_http_request<B>(
     endpoint: &Endpoint,
     route: Route,
     value: &Request<B>,
-) -> Result<(), CodecError> {
+) -> Result<(), RequestMetadataError> {
-    if value.method() != Method::POST {
-        return Err(CodecError::InvalidField {
-            field: "method".into(),
-            reason: "standard WIP routes require POST".into(),
-        });
-    }
     let expected = endpoint.route(route);
     if value.uri().path() != expected.path() || value.uri().query().is_some() {
-        return Err(CodecError::InvalidField {
+        return Err(RequestMetadataError::NotFound);
-            field: "route".into(),
+    }
-            reason: "request URI does not match the selected standard route".into(),
+    if value.method() != Method::POST {
-        });
+        return Err(RequestMetadataError::MethodNotAllowed);
     }
     let valid_content_type = value
         .headers()
         .get(CONTENT_TYPE)
         .and_then(|value| value.to_str().ok())
         .is_some_and(is_json_content_type);
-    if !valid_content_type {
+    if !valid_content_type || !has_supported_content_coding(value.headers()) {
-        return Err(CodecError::InvalidField {
+        return Err(RequestMetadataError::UnsupportedMediaType);
-            field: "content-type".into(),
+    }
-            reason: "expected UTF-8 application/json".into(),
+    if !accepts_json(value.headers()) {
-        });
+        return Err(RequestMetadataError::NotAcceptable);
     }
     Ok(())
 }
 
-/// Encodes a `fetch` HTTP request.
+/// Encodes an `observe` HTTP request.
-pub fn encode_fetch_request(
+pub fn encode_observe_request(
     endpoint: &Endpoint,
-    value: &FetchRequest,
+    value: &ObserveRequest,
     limits: Limits,
 ) -> Result<Request<Vec<u8>>, EncodeHttpError> {
     value.validate().map_err(CodecError::from)?;
     let body = json::serialize(
-        &json::fetch_request_to_json(value),
+        &json::observe_request_to_json(value),
         BodyKind::Request,
         limits,
     )?;
-    Ok(request(endpoint, Route::Fetch, body)?)
+    Ok(request(endpoint, Route::Observe, body)?)
 }
 
-/// Decodes a `fetch` request body.
+/// Decodes an `observe` request body.
-pub fn decode_fetch_request(body: &[u8], limits: Limits) -> Result<FetchRequest, CodecError> {
+pub fn decode_observe_request(body: &[u8], limits: Limits) -> Result<ObserveRequest, CodecError> {
     let value = json::parse(body, BodyKind::Request, limits)?;
-    json::fetch_request_from_json(&value)
+    json::observe_request_from_json(&value)
-}
-
-/// Encodes a `fetch_tree` HTTP request.
-pub fn encode_fetch_tree_request(
-    endpoint: &Endpoint,
-    value: &FetchTreeRequest,
-    limits: Limits,
-) -> Result<Request<Vec<u8>>, EncodeHttpError> {
-    value.validate().map_err(CodecError::from)?;
-    let body = json::serialize(
-        &json::fetch_tree_request_to_json(value),
-        BodyKind::Request,
-        limits,
-    )?;
-    Ok(request(endpoint, Route::FetchTree, body)?)
-}
-
-/// Decodes a `fetch_tree` request body.
-pub fn decode_fetch_tree_request(
-    body: &[u8],
-    limits: Limits,
-) -> Result<FetchTreeRequest, CodecError> {
-    let value = json::parse(body, BodyKind::Request, limits)?;
-    json::fetch_tree_request_from_json(&value)
 }
 
 /// Encodes a `fetch_interface` HTTP request.
@@ -261,72 +393,39 @@ pub fn decode_call_operation_request(
     json::call_request_from_json(&value, descriptor)
 }
 
-/// Encodes a successful `fetch` response as a direct body with HTTP 200.
+/// Encodes a successful `observe` response as a direct body with HTTP 200.
-pub fn encode_fetch_response(
+pub fn encode_observe_response(
-    request_value: &FetchRequest,
+    request_value: &ObserveRequest,
-    value: &FetchResponse,
+    value: &ObserveResponse,
     limits: Limits,
 ) -> Result<Response<Vec<u8>>, EncodeHttpError> {
     request_value
         .validate_response(value)
         .map_err(CodecError::from)?;
-    let body = json::serialize(&json::object_to_json(value), BodyKind::Response, limits)?;
-    Ok(response(StatusCode::OK, body)?)
-}
-
-/// Decodes and classifies a `fetch` client response.
-pub fn decode_fetch_response<B: AsRef<[u8]>>(
-    request_value: &FetchRequest,
-    value: &Response<B>,
-    limits: Limits,
-) -> Result<DecodedResponse<FetchResponse>, ClientResponseError> {
-    require_response_content_type(value)?;
-    response::decode(
-        value.status(),
-        value.body().as_ref(),
-        ProtocolInteraction::Fetch,
-        limits,
-        |json| {
-            let object = json::object_from_json(json, "response")?;
-            request_value.validate_response(&object)?;
-            Ok(object)
-        },
-    )
-}
-
-/// Encodes a successful `fetch_tree` response as a direct body with HTTP 200.
-pub fn encode_fetch_tree_response(
-    request_value: &FetchTreeRequest,
-    value: &FetchTreeResponse,
-    limits: Limits,
-) -> Result<Response<Vec<u8>>, EncodeHttpError> {
-    value
-        .validate_for(request_value)
-        .map_err(CodecError::from)?;
     let body = json::serialize(
-        &json::fetch_tree_response_to_json(value),
+        &json::observe_response_to_json(value),
         BodyKind::Response,
         limits,
     )?;
     Ok(response(StatusCode::OK, body)?)
 }
 
-/// Decodes and classifies a `fetch_tree` client response.
+/// Decodes and classifies an `observe` client response.
-pub fn decode_fetch_tree_response<B: AsRef<[u8]>>(
+pub fn decode_observe_response<B: AsRef<[u8]>>(
-    request_value: &FetchTreeRequest,
+    request_value: &ObserveRequest,
     value: &Response<B>,
     limits: Limits,
-) -> Result<DecodedResponse<FetchTreeResponse>, ClientResponseError> {
+) -> Result<DecodedResponse<ObserveResponse>, ClientResponseError> {
     require_response_content_type(value)?;
     response::decode(
         value.status(),
         value.body().as_ref(),
-        ProtocolInteraction::FetchTree,
+        ProtocolInteraction::Observe,
         limits,
         |json| {
-            let tree = json::fetch_tree_response_from_json(json)?;
+            let observation = json::observe_response_from_json(json)?;
-            tree.validate_for(request_value)?;
+            request_value.validate_response(&observation)?;
-            Ok(tree)
+            Ok(observation)
         },
     )
 }
@@ -405,17 +504,10 @@ pub fn decode_call_operation_response<B: AsRef<[u8]>>(
     )
 }
 
-/// Encodes a canonical Host error envelope using its standard HTTP status.
+fn validate_protocol_error(
-///
-/// The code must be allowed for `interaction`. This API accepts only
-/// [`ProtocolError`], so client-local `InvalidResponse` and
-/// `UnsupportedDescriptorFormat` classifications cannot be emitted as Host
-/// error envelopes.
-pub fn encode_protocol_error_response(
     interaction: ProtocolInteraction,
     error: &ProtocolError,
-    limits: Limits,
+) -> Result<(), CodecError> {
-) -> Result<Response<Vec<u8>>, EncodeHttpError> {
     if !error.code.is_allowed_for(interaction) {
         return Err(CodecError::InvalidField {
             field: "error.code".into(),
@@ -423,11 +515,40 @@ pub fn encode_protocol_error_response(
                 "code `{}` is not allowed for {interaction:?}",
                 response::error_code_name(error.code)
             ),
-        }
+        });
-        .into());
     }
+    Ok(())
+}
+
+fn encode_protocol_error_with_status(
+    interaction: ProtocolInteraction,
+    error: &ProtocolError,
+    status: StatusCode,
+    limits: Limits,
+) -> Result<Response<Vec<u8>>, EncodeHttpError> {
+    validate_protocol_error(interaction, error)?;
     let body = json::serialize(&response::error_to_json(error), BodyKind::Response, limits)?;
-    Ok(response(response::status_for_error(error.code), body)?)
+    Ok(response(status, body)?)
+}
+
+/// Encodes a canonical Host error envelope using its standard HTTP status.
+///
+/// The code must be allowed for `interaction`. This API accepts only
+/// [`ProtocolError`], so client-local `InvalidResponse` and
+/// `UnsupportedDescriptorFormat` classifications cannot be emitted as Host
+/// error envelopes. Logical `resource_limit_exceeded` failures use HTTP 422;
+/// representation and deployment limits are not protocol errors.
+pub fn encode_protocol_error_response(
+    interaction: ProtocolInteraction,
+    error: &ProtocolError,
+    limits: Limits,
+) -> Result<Response<Vec<u8>>, EncodeHttpError> {
+    encode_protocol_error_with_status(
+        interaction,
+        error,
+        response::status_for_error(error.code),
+        limits,
+    )
 }
 
 /// Failure while building an outbound framework-neutral HTTP message.

crates/wip-http/src/endpoint.rs

@@ -6,19 +6,15 @@ use url::Url;
 /// The media type emitted for every WIP request and every response with a body.
 pub const JSON_CONTENT_TYPE: &str = "application/json; charset=utf-8";
 
-/// A fixed standard WIP over HTTPS v1 route.
+/// A fixed standard WIP over HTTP v1 route.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum Route {
-    /// Fetch one object.
+    /// Observe one object and its indexable descendants.
-    Fetch,
+    Observe,
-    /// Fetch a bounded object tree.
-    FetchTree,
     /// Fetch an interface descriptor.
     FetchInterface,
     /// Call one operation.
     CallOperation,
-    /// Package independent retrieval interactions.
-    Batch,
 }
 
 impl Route {
@@ -26,31 +22,27 @@ impl Route {
     #[must_use]
     pub const fn relative_reference(self) -> &'static str {
         match self {
-            Self::Fetch => "v1/fetch",
+            Self::Observe => "v1/observe",
-            Self::FetchTree => "v1/fetch_tree",
             Self::FetchInterface => "v1/fetch_interface",
             Self::CallOperation => "v1/call_operation",
-            Self::Batch => "v1/batch",
         }
     }
 }
 
-/// A canonical absolute HTTPS base URL whose path always ends in `/`.
+/// A canonical absolute hierarchical base URL whose path always ends in `/`.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Endpoint(Url);
 
 impl Endpoint {
     /// Parses and canonicalizes an endpoint.
     ///
-    /// The input must be an absolute HTTPS URL without a query or fragment. Its
+    /// The input must be an absolute hierarchical URL with a host and without a
-    /// path is an endpoint prefix, not a Worldspace path. A trailing slash is
+    /// query or fragment. Its path is an endpoint prefix, not a Worldspace path.
-    /// appended when absent so RFC 3986 relative-reference resolution preserves
+    /// A trailing slash is appended when absent so RFC 3986 relative-reference
-    /// the final prefix segment.
+    /// resolution preserves the final prefix segment. The supplied scheme is
+    /// preserved; scheme and transport security are deployment concerns.
     pub fn parse(input: &str) -> Result<Self, EndpointError> {
         let mut url = Url::parse(input).map_err(EndpointError::InvalidUrl)?;
-        if url.scheme() != "https" {
-            return Err(EndpointError::NotHttps);
-        }
         if url.cannot_be_a_base() || url.host_str().is_none() {
             return Err(EndpointError::NotAbsoluteBase);
         }
@@ -87,13 +79,7 @@ impl Endpoint {
     /// are not route components and therefore never match.
     #[must_use]
     pub fn recognize(&self, candidate: &Url) -> Option<Route> {
-        const ROUTES: [Route; 5] = [
+        const ROUTES: [Route; 3] = [Route::Observe, Route::FetchInterface, Route::CallOperation];
-            Route::Fetch,
-            Route::FetchTree,
-            Route::FetchInterface,
-            Route::CallOperation,
-            Route::Batch,
-        ];
         if candidate.query().is_some() || candidate.fragment().is_some() {
             return None;
         }
@@ -117,13 +103,11 @@ impl TryFrom<&str> for Endpoint {
     }
 }
 
-/// Why an endpoint is not a valid standard WIP HTTPS base.
+/// Why an endpoint is not a valid standard WIP over HTTP base.
 #[derive(Debug)]
 pub enum EndpointError {
     /// URL parsing failed.
     InvalidUrl(url::ParseError),
-    /// The URL scheme is not `https`.
-    NotHttps,
     /// The URL is not a hierarchical absolute URL with an authority.
     NotAbsoluteBase,
     /// A query component was supplied.
@@ -136,7 +120,6 @@ impl Display for EndpointError {
     fn fmt(&self, formatter: &mut Formatter<'_>) -> fmt::Result {
         match self {
             Self::InvalidUrl(error) => write!(formatter, "invalid endpoint URL: {error}"),
-            Self::NotHttps => formatter.write_str("WIP endpoint must use HTTPS"),
             Self::NotAbsoluteBase => {
                 formatter.write_str("WIP endpoint must be an absolute base URL")
             }

crates/wip-http/src/error.rs

@@ -10,8 +10,6 @@ pub struct Limits {
     pub(crate) max_response_bytes: usize,
     /// Largest accepted JSON container nesting depth.
     pub(crate) max_nesting: usize,
-    /// Largest accepted number of batch items.
-    pub(crate) max_batch_items: usize,
 }
 
 impl Limits {
@@ -20,7 +18,6 @@ impl Limits {
         max_request_bytes: usize,
         max_response_bytes: usize,
         max_nesting: usize,
-        max_batch_items: usize,
     ) -> Result<Self, LimitConfigurationError> {
         if max_request_bytes == 0 {
             return Err(LimitConfigurationError::ZeroRequestBytes);
@@ -31,14 +28,10 @@ impl Limits {
         if max_nesting == 0 {
             return Err(LimitConfigurationError::ZeroNesting);
         }
-        if max_batch_items == 0 {
-            return Err(LimitConfigurationError::ZeroBatchItems);
-        }
         Ok(Self {
             max_request_bytes,
             max_response_bytes,
             max_nesting,
-            max_batch_items,
         })
     }
 
@@ -59,12 +52,6 @@ impl Limits {
     pub const fn max_nesting(self) -> usize {
         self.max_nesting
     }
-
-    /// Returns the batch item count limit.
-    #[must_use]
-    pub const fn max_batch_items(self) -> usize {
-        self.max_batch_items
-    }
 }
 
 /// Why a [`Limits`] configuration is not bounded.
@@ -76,8 +63,6 @@ pub enum LimitConfigurationError {
     ZeroResponseBytes,
     /// Nesting limit was zero.
     ZeroNesting,
-    /// Batch-item limit was zero.
-    ZeroBatchItems,
 }
 
 impl Display for LimitConfigurationError {
@@ -86,7 +71,6 @@ impl Display for LimitConfigurationError {
             Self::ZeroRequestBytes => "request byte limit must be nonzero",
             Self::ZeroResponseBytes => "response byte limit must be nonzero",
             Self::ZeroNesting => "nesting limit must be nonzero",
-            Self::ZeroBatchItems => "batch item limit must be nonzero",
         })
     }
 }
@@ -148,33 +132,6 @@ pub enum CodecError {
     },
     /// Logical protocol validation rejected the decoded representation.
     ProtocolValidation(wip_protocol::ValidationError),
-    /// The batch exceeds its configured item count.
-    TooManyBatchItems {
-        /// Actual item count.
-        actual: usize,
-        /// Configured maximum.
-        maximum: usize,
-    },
-    /// Batch item identifiers are not unique.
-    DuplicateBatchId {
-        /// Repeated identifier.
-        id: String,
-    },
-    /// A response contains a batch identifier that was not requested.
-    UnexpectedBatchId {
-        /// Unexpected identifier.
-        id: String,
-    },
-    /// A response omitted a requested batch identifier.
-    MissingBatchId {
-        /// Missing identifier.
-        id: String,
-    },
-    /// A batch item result does not match its requested interaction.
-    BatchInteractionMismatch {
-        /// Item identifier.
-        id: String,
-    },
 }
 
 impl Display for CodecError {
@@ -202,15 +159,6 @@ impl Display for CodecError {
                 write!(formatter, "field `{field}` is not canonical base64")
             }
             Self::ProtocolValidation(error) => error.fmt(formatter),
-            Self::TooManyBatchItems { actual, maximum } => {
-                write!(formatter, "batch has {actual} items; maximum is {maximum}")
-            }
-            Self::DuplicateBatchId { id } => write!(formatter, "duplicate batch id `{id}`"),
-            Self::UnexpectedBatchId { id } => write!(formatter, "unexpected batch id `{id}`"),
-            Self::MissingBatchId { id } => write!(formatter, "missing batch id `{id}`"),
-            Self::BatchInteractionMismatch { id } => {
-                write!(formatter, "batch result does not match request `{id}`")
-            }
         }
     }
 }

crates/wip-http/src/json.rs

@@ -7,9 +7,9 @@ use serde::de::{self, Deserialize, Deserializer, MapAccess, SeqAccess, Visitor};
 use serde_json::{Map, Number, Value as Json};
 use wip_protocol::{
     CallOperationRequest, CallOperationResponse, Documentation, EnumCase, FetchInterfaceRequest,
-    FetchInterfaceResponse, FetchRequest, FetchTreeRequest, FetchTreeResponse, FieldDeclaration,
+    FetchInterfaceResponse, FieldDeclaration, INTERFACE_FORMAT_V1, InterfaceDescriptor,
-    INTERFACE_FORMAT_V1, InterfaceDescriptor, InterfaceTarget, MAX_SAFE_INTEGER, MIN_SAFE_INTEGER,
+    InterfaceTarget, MAX_SAFE_INTEGER, MIN_SAFE_INTEGER, Object, ObjectObservation, ObserveRequest,
-    Object, ObjectTreeNode, OperationDeclaration, ParameterDeclaration, ReturnDeclaration, Target,
+    ObserveResponse, OperationDeclaration, ParameterDeclaration, ReturnDeclaration, Target,
     TypeDeclaration, TypeExpr, UnionCase, Value,
 };
 
@@ -271,29 +271,15 @@ fn insert_optional_bytes(map: &mut Map<String, Json>, name: &str, value: &Option
     }
 }
 
-pub(crate) fn fetch_request_to_json(request: &FetchRequest) -> Json {
+pub(crate) fn observe_request_to_json(request: &ObserveRequest) -> Json {
-    serde_json::json!({"path": request.path})
+    serde_json::json!({"path": request.path, "depth": request.depth})
 }
 
-pub(crate) fn fetch_request_from_json(value: &Json) -> Result<FetchRequest, CodecError> {
+pub(crate) fn observe_request_from_json(value: &Json) -> Result<ObserveRequest, CodecError> {
-    let fields = exact_object(value, "request", &["path"])?;
+    let fields = exact_object(value, "request", &["path", "depth"])?;
-    let request = FetchRequest {
+    let request = ObserveRequest {
-        path: string(required(fields, "path")?, "path")?,
-    };
-    request.validate()?;
-    Ok(request)
-}
-
-pub(crate) fn fetch_tree_request_to_json(request: &FetchTreeRequest) -> Json {
-    serde_json::json!({"path": request.path, "depth": request.depth, "limit": request.limit})
-}
-
-pub(crate) fn fetch_tree_request_from_json(value: &Json) -> Result<FetchTreeRequest, CodecError> {
-    let fields = exact_object(value, "request", &["path", "depth", "limit"])?;
-    let request = FetchTreeRequest {
         path: string(required(fields, "path")?, "path")?,
         depth: u32_number(required(fields, "depth")?, "depth")?,
-        limit: u32_number(required(fields, "limit")?, "limit")?,
     };
     request.validate()?;
     Ok(request)
@@ -360,35 +346,43 @@ pub(crate) fn object_from_json(value: &Json, field: &str) -> Result<Object, Code
     Ok(object)
 }
 
-fn tree_node_to_json(node: &ObjectTreeNode) -> Json {
+fn observation_to_json(node: &ObjectObservation) -> Json {
-    serde_json::json!({
+    let mut fields = Map::new();
-        "object": object_to_json(&node.object),
+    fields.insert("object".into(), object_to_json(&node.object));
-        "children": node.children.iter().map(tree_node_to_json).collect::<Vec<_>>()
+    if let Some(children) = &node.children {
-    })
+        fields.insert(
+            "children".into(),
+            Json::Array(children.iter().map(observation_to_json).collect()),
+        );
+    }
+    Json::Object(fields)
 }
 
-fn tree_node_from_json(value: &Json, field: &str) -> Result<ObjectTreeNode, CodecError> {
+fn observation_from_json(value: &Json, field: &str) -> Result<ObjectObservation, CodecError> {
     let fields = exact_object(value, field, &["object", "children"])?;
-    Ok(ObjectTreeNode {
+    let children = optional(fields, "children")?
+        .map(|value| {
+            array(value, &qualified(field, "children"))?
+                .iter()
+                .enumerate()
+                .map(|(index, child)| {
+                    observation_from_json(child, &format!("{field}.children[{index}]"))
+                })
+                .collect::<Result<Vec<_>, _>>()
+        })
+        .transpose()?;
+    Ok(ObjectObservation {
         object: object_from_json(required(fields, "object")?, &qualified(field, "object"))?,
-        children: array(required(fields, "children")?, &qualified(field, "children"))?
+        children,
-            .iter()
-            .enumerate()
-            .map(|(index, child)| tree_node_from_json(child, &format!("{field}.children[{index}]")))
-            .collect::<Result<Vec<_>, _>>()?,
     })
 }
 
-pub(crate) fn fetch_tree_response_to_json(response: &FetchTreeResponse) -> Json {
+pub(crate) fn observe_response_to_json(response: &ObserveResponse) -> Json {
-    serde_json::json!({"root": tree_node_to_json(&response.root), "truncated": response.truncated})
+    observation_to_json(response)
 }
 
-pub(crate) fn fetch_tree_response_from_json(value: &Json) -> Result<FetchTreeResponse, CodecError> {
+pub(crate) fn observe_response_from_json(value: &Json) -> Result<ObserveResponse, CodecError> {
-    let fields = exact_object(value, "response", &["root", "truncated"])?;
+    observation_from_json(value, "response")
-    Ok(FetchTreeResponse {
-        root: tree_node_from_json(required(fields, "root")?, "root")?,
-        truncated: boolean(required(fields, "truncated")?, "truncated")?,
-    })
 }
 
 fn documentation_to_json(documentation: &Documentation) -> Json {

crates/wip-http/src/lib.rs

@@ -0,0 +1,59 @@
+//! Framework-independent standard WIP over HTTP v1 binding.
+//!
+//! This crate owns endpoint and route derivation, UTF-8 JSON encoding, canonical
+//! success and error response handling, HTTP status mapping, descriptor-guided
+//! operation-value conversion. It deliberately performs no I/O and depends on no
+//! server framework, TLS implementation, filesystem projection, client cache, or
+//! presentation layer. URL schemes, TLS, certificates, authentication mechanisms,
+//! proxies, and caches are selected by the HTTP implementation and deployment
+//! rather than by WIP conformance.
+//!
+//! Logical values remain owned by [`wip_protocol`]. Validators and `Bytes` are
+//! encoded in JSON bodies using canonical RFC 4648 Section 4 base64; this crate
+//! does not infer WIP validator semantics from `ETag` or `If-Match`.
+//!
+//! ```
+//! use wip_http::{Endpoint, Limits, encode_observe_request};
+//! use wip_protocol::ObserveRequest;
+//!
+//! let endpoint = Endpoint::parse("http://example.test/api/wip")?;
+//! let limits = Limits::new(64 * 1024, 1024 * 1024, 64)?;
+//! let request = encode_observe_request(
+//!     &endpoint,
+//!     &ObserveRequest { path: "/items/123".into(), depth: 0 },
+//!     limits,
+//! )?;
+//! assert_eq!(request.uri(), "http://example.test/api/wip/v1/observe");
+//! assert_eq!(request.method(), http::Method::POST);
+//! # Ok::<(), Box<dyn std::error::Error>>(())
+//! ```
+
+#![deny(missing_docs)]
+
+mod codec;
+mod endpoint;
+mod error;
+mod json;
+mod response;
+
+pub use codec::{
+    CallOperationMetadata, EncodeHttpError, RequestMetadataError, decode_call_operation_metadata,
+    decode_call_operation_request, decode_call_operation_response, decode_fetch_interface_request,
+    decode_fetch_interface_response, decode_observe_request, decode_observe_response,
+    encode_call_operation_request, encode_call_operation_response, encode_fetch_interface_request,
+    encode_fetch_interface_response, encode_observe_request, encode_observe_response,
+    encode_protocol_error_response, is_json_content_type, validate_http_request,
+};
+pub use endpoint::{Endpoint, EndpointError, JSON_CONTENT_TYPE, Route};
+pub use error::{BodyKind, CodecError, LimitConfigurationError, Limits};
+pub use response::{
+    ClientResponseError, DecodedResponse, InvalidResponseKind, StatusMismatch,
+    TransportBindingFailure, TransportFailureKind, error_code_name, status_for_error,
+};
+
+/// Framework-neutral HTTP types used by this binding's public API.
+pub use http;
+/// URL type used by [`Endpoint`].
+pub use url;
+/// Transport-independent logical protocol model used by this binding.
+pub use wip_protocol;

crates/wip-http/src/response.rs

@@ -37,6 +37,8 @@ pub enum TransportFailureKind {
     AuthenticationRequired,
     /// HTTP 403, commonly emitted by endpoint policy or infrastructure.
     EndpointForbidden,
+    /// The response uses a content coding the client does not support.
+    UnsupportedContentCoding,
     /// Another non-success HTTP response without a WIP error envelope.
     HttpStatus,
 }
@@ -59,10 +61,10 @@ pub enum InvalidResponseKind {
     SuccessBodyOnErrorStatus,
     /// A valid error envelope used a code forbidden for the interaction.
     DisallowedProtocolCode,
+    /// A valid success body used a 2xx status other than canonical HTTP 200.
+    NonCanonicalSuccessStatus,
     /// A 2xx body was malformed or semantically invalid.
     InvalidSuccessBody,
-    /// A batch response did not correlate exactly with its request.
-    InvalidBatch,
 }
 
 /// A local failure while classifying or validating a peer response.
@@ -132,13 +134,17 @@ pub const fn status_for_error(code: ProtocolErrorCode) -> StatusCode {
             StatusCode::PRECONDITION_FAILED
         }
         ProtocolErrorCode::PermissionDenied => StatusCode::FORBIDDEN,
-        ProtocolErrorCode::ResourceLimitExceeded => StatusCode::TOO_MANY_REQUESTS,
+        ProtocolErrorCode::ResourceLimitExceeded => StatusCode::UNPROCESSABLE_ENTITY,
         ProtocolErrorCode::Internal | ProtocolErrorCode::OperationOutcomeUnknown => {
             StatusCode::INTERNAL_SERVER_ERROR
         }
     }
 }
 
+fn status_matches_error(status: StatusCode, code: ProtocolErrorCode) -> bool {
+    status == status_for_error(code)
+}
+
 /// Returns the stable snake-case wire spelling of a protocol code.
 #[must_use]
 pub const fn error_code_name(code: ProtocolErrorCode) -> &'static str {
@@ -189,14 +195,7 @@ pub(crate) fn error_to_json(error: &ProtocolError) -> Json {
     })
 }
 
-pub(crate) fn item_error_to_json(error: &ProtocolError) -> Json {
+fn protocol_error_from_json(value: &Json) -> Result<ProtocolError, CodecError> {
-    serde_json::json!({
-        "code": error_code_name(error.code),
-        "message": error.message,
-    })
-}
-
-pub(crate) fn item_error_from_json(value: &Json) -> Result<ProtocolError, CodecError> {
     let fields = value
         .as_object()
         .ok_or_else(|| invalid_field("error", "expected object"))?;
@@ -215,7 +214,7 @@ fn envelope_error_from_json(value: &Json) -> Result<Option<ProtocolError>, Codec
     if fields.len() != 1 || !fields.contains_key("error") {
         return Ok(None);
     }
-    item_error_from_json(&fields["error"]).map(Some)
+    protocol_error_from_json(&fields["error"]).map(Some)
 }
 
 fn exact(fields: &Map<String, Json>, allowed: &[&str], parent: &str) -> Result<(), CodecError> {
@@ -288,12 +287,14 @@ pub(crate) fn decode<T>(
                 ));
             }
             let expected = status_for_error(error.code);
-            Ok(DecodedResponse::ProtocolFailure {
+            let status_mismatch =
-                error,
+                (!status_matches_error(status, error.code)).then_some(StatusMismatch {
-                status_mismatch: (status != expected).then_some(StatusMismatch {
                     actual: status,
                     expected,
-                }),
+                });
+            Ok(DecodedResponse::ProtocolFailure {
+                error,
+                status_mismatch,
             })
         }
         Err(_) if !status.is_success() => Err(transport_failure(status)),
@@ -301,16 +302,24 @@ pub(crate) fn decode<T>(
             InvalidResponseKind::InvalidSuccessBody,
             error.to_string(),
         )),
-        Ok(None) if status.is_success() => {
+        Ok(None) if status == StatusCode::OK => success(&value)
-            success(&value)
+            .map(DecodedResponse::Success)
-                .map(DecodedResponse::Success)
+            .map_err(|error| {
-                .map_err(|error| {
+                ClientResponseError::invalid(
-                    ClientResponseError::invalid(
+                    InvalidResponseKind::InvalidSuccessBody,
-                        InvalidResponseKind::InvalidSuccessBody,
+                    error.to_string(),
-                        error.to_string(),
+                )
-                    )
+            }),
-                })
+        Ok(None) if status.is_success() => match success(&value) {
-        }
+            Ok(_) => Err(ClientResponseError::invalid(
+                InvalidResponseKind::NonCanonicalSuccessStatus,
+                format!("success body carried by non-canonical HTTP {status}"),
+            )),
+            Err(error) => Err(ClientResponseError::invalid(
+                InvalidResponseKind::InvalidSuccessBody,
+                error.to_string(),
+            )),
+        },
         Ok(None) => match success(&value) {
             Ok(_) => Err(ClientResponseError::invalid(
                 InvalidResponseKind::SuccessBodyOnErrorStatus,
@@ -321,6 +330,13 @@ pub(crate) fn decode<T>(
     }
 }
 
+pub(crate) fn unsupported_content_coding(status: StatusCode) -> ClientResponseError {
+    ClientResponseError::TransportBinding(TransportBindingFailure {
+        status,
+        kind: TransportFailureKind::UnsupportedContentCoding,
+    })
+}
+
 pub(crate) fn transport_failure(status: StatusCode) -> ClientResponseError {
     let kind = match status {
         StatusCode::UNAUTHORIZED => TransportFailureKind::AuthenticationRequired,

crates/wip-http/tests/codecs.rs

@@ -1,25 +1,24 @@
 use std::collections::BTreeMap;
 
-use wip_https::http::StatusCode;
+use wip_http::http::StatusCode;
-use wip_https::wip_protocol::{
+use wip_http::wip_protocol::{
     CallOperationRequest, CallOperationResponse, Documentation, EnumCase, FetchInterfaceRequest,
-    FetchInterfaceResponse, FetchRequest, FetchTreeRequest, FetchTreeResponse, FieldDeclaration,
+    FetchInterfaceResponse, FieldDeclaration, INTERFACE_FORMAT_V1, InterfaceDescriptor,
-    INTERFACE_FORMAT_V1, InterfaceDescriptor, InterfaceTarget, MAX_SAFE_INTEGER, Object,
+    InterfaceTarget, MAX_SAFE_INTEGER, Object, ObjectObservation, ObserveRequest,
-    ObjectTreeNode, OperationDeclaration, ParameterDeclaration, ReturnDeclaration, Target,
+    OperationDeclaration, ParameterDeclaration, ReturnDeclaration, Target, TypeDeclaration,
-    TypeDeclaration, TypeExpr, UnionCase, Value,
+    TypeExpr, UnionCase, Value,
 };
-use wip_https::{
+use wip_http::{
-    ClientResponseError, DecodedResponse, Endpoint, InvalidResponseKind, Limits,
+    ClientResponseError, CodecError, DecodedResponse, Endpoint, InvalidResponseKind, Limits,
     decode_call_operation_metadata, decode_call_operation_request, decode_call_operation_response,
-    decode_fetch_interface_request, decode_fetch_interface_response, decode_fetch_request,
+    decode_fetch_interface_request, decode_fetch_interface_response, decode_observe_request,
-    decode_fetch_response, decode_fetch_tree_request, decode_fetch_tree_response,
+    decode_observe_response, encode_call_operation_request, encode_call_operation_response,
-    encode_call_operation_request, encode_call_operation_response, encode_fetch_interface_request,
+    encode_fetch_interface_request, encode_fetch_interface_response, encode_observe_request,
-    encode_fetch_interface_response, encode_fetch_request, encode_fetch_response,
+    encode_observe_response,
-    encode_fetch_tree_request, encode_fetch_tree_response,
 };
 
 fn limits() -> Limits {
-    Limits::new(1_000_000, 1_000_000, 100, 100).unwrap()
+    Limits::new(1_000_000, 1_000_000, 100).unwrap()
 }
 
 fn endpoint() -> Endpoint {
@@ -194,53 +193,96 @@ fn call_request() -> CallOperationRequest {
 }
 
 #[test]
-fn fetch_round_trips_direct_body_and_body_validator() {
+fn every_single_interaction_request_accepts_json() {
-    let request = FetchRequest {
+    let observe = encode_observe_request(
+        &endpoint(),
+        &ObserveRequest {
+            path: "/".into(),
+            depth: 0,
+        },
+        limits(),
+    )
+    .unwrap();
+    let fetch_interface = encode_fetch_interface_request(
+        &endpoint(),
+        &FetchInterfaceRequest {
+            interface: "interface-v1".into(),
+        },
+        limits(),
+    )
+    .unwrap();
+    let call = encode_call_operation_request(&endpoint(), &call_request(), &descriptor(), limits())
+        .unwrap();
+
+    for request in [observe, fetch_interface, call] {
+        assert_eq!(request.headers()["accept"], "application/json");
+    }
+}
+
+#[test]
+fn depth_zero_observe_round_trips_direct_body_and_validator() {
+    let request = ObserveRequest {
         path: "/items/123".into(),
+        depth: 0,
     };
-    let encoded_request = encode_fetch_request(&endpoint(), &request, limits()).unwrap();
+    let encoded_request = encode_observe_request(&endpoint(), &request, limits()).unwrap();
-    assert_eq!(encoded_request.uri().path(), "/wip/v1/fetch");
+    assert_eq!(encoded_request.uri().path(), "/wip/v1/observe");
     assert_eq!(
-        decode_fetch_request(encoded_request.body(), limits()).unwrap(),
+        decode_observe_request(encoded_request.body(), limits()).unwrap(),
         request
     );
 
-    let expected = object("123", &[0, 1, 2, 255]);
+    let expected = ObjectObservation {
-    let encoded = encode_fetch_response(&request, &expected, limits()).unwrap();
+        object: object("123", &[0, 1, 2, 255]),
+        children: None,
+    };
+    let encoded = encode_observe_response(&request, &expected, limits()).unwrap();
     assert_eq!(encoded.status(), StatusCode::OK);
+    assert!(
+        !std::str::from_utf8(encoded.body())
+            .unwrap()
+            .contains("children")
+    );
     assert_eq!(
-        decode_fetch_response(&request, &encoded, limits()).unwrap(),
+        decode_observe_response(&request, &encoded, limits()).unwrap(),
         DecodedResponse::Success(expected)
     );
     assert!(encoded.headers().get("etag").is_none());
 }
 
 #[test]
-fn tree_and_interface_round_trip_nested_logical_models() {
+fn observe_and_interface_round_trip_nested_logical_models() {
-    let tree_request = FetchTreeRequest {
+    let observe_request = ObserveRequest {
         path: "/items".into(),
         depth: 1,
-        limit: 2,
     };
-    let encoded_request = encode_fetch_tree_request(&endpoint(), &tree_request, limits()).unwrap();
+    let encoded_request = encode_observe_request(&endpoint(), &observe_request, limits()).unwrap();
     assert_eq!(
-        decode_fetch_tree_request(encoded_request.body(), limits()).unwrap(),
+        decode_observe_request(encoded_request.body(), limits()).unwrap(),
-        tree_request
+        observe_request
     );
-    let tree = FetchTreeResponse {
+    let observation = ObjectObservation {
-        root: ObjectTreeNode {
+        object: object("items", b"root-validator"),
-            object: object("items", b"root-validator"),
+        children: Some(vec![ObjectObservation {
-            children: vec![ObjectTreeNode {
+            object: object("123", b"child-validator"),
-                object: object("123", b"child-validator"),
+            children: None,
-                children: vec![],
+        }]),
-            }],
-        },
-        truncated: false,
     };
-    let encoded = encode_fetch_tree_response(&tree_request, &tree, limits()).unwrap();
+    let encoded = encode_observe_response(&observe_request, &observation, limits()).unwrap();
     assert_eq!(
-        decode_fetch_tree_response(&tree_request, &encoded, limits()).unwrap(),
+        decode_observe_response(&observe_request, &encoded, limits()).unwrap(),
-        DecodedResponse::Success(tree)
+        DecodedResponse::Success(observation)
+    );
+
+    let empty = ObjectObservation {
+        object: object("items", b"root-validator"),
+        children: Some(vec![]),
+    };
+    let encoded_empty = encode_observe_response(&observe_request, &empty, limits()).unwrap();
+    assert!(
+        std::str::from_utf8(encoded_empty.body())
+            .unwrap()
+            .contains("\"children\":[]")
     );
 
     let interface_request = FetchInterfaceRequest {
@@ -332,8 +374,10 @@ fn descriptor_guided_values_and_validators_round_trip_both_directions() {
 #[test]
 fn malformed_unknown_null_and_noncanonical_base64_are_rejected() {
     let limits = limits();
-    assert!(decode_fetch_request(br#"{"path":"/","extra":true}"#, limits).is_err());
+    assert!(decode_observe_request(br#"{"path":"/","depth":0,"extra":true}"#, limits).is_err());
-    assert!(decode_fetch_request(br#"{"path":"relative","path":"/"}"#, limits).is_err());
+    assert!(
+        decode_observe_request(br#"{"path":"relative","path":"/","depth":0}"#, limits).is_err()
+    );
 
     let request = call_request();
     let descriptor = descriptor();
@@ -360,15 +404,17 @@ fn malformed_unknown_null_and_noncanonical_base64_are_rejected() {
 }
 
 #[test]
-fn caller_limits_bound_bytes_and_nesting() {
+fn caller_limits_remain_local_codec_failures() {
-    let tiny = Limits::new(8, 8, 2, 1).unwrap();
+    let tiny = Limits::new(8, 8, 2).unwrap();
-    assert!(decode_fetch_request(br#"{"path":"/long"}"#, tiny).is_err());
+    let too_large = decode_observe_request(br#"{"path":"/long","depth":0}"#, tiny).unwrap_err();
+    assert!(matches!(&too_large, CodecError::BodyTooLarge { .. }));
 
-    let nested = br#"{"path":[[["/"]]]}"#;
+    let nested = br#"{"path":[[["/"]]],"depth":0}"#;
-    let nesting_limited = Limits::new(1024, 1024, 2, 1).unwrap();
+    let nesting_limited = Limits::new(1024, 1024, 2).unwrap();
-    assert!(decode_fetch_request(nested, nesting_limited).is_err());
+    let too_deep = decode_observe_request(nested, nesting_limited).unwrap_err();
+    assert!(matches!(&too_deep, CodecError::NestingTooDeep { .. }));
 
-    let outbound_limited = Limits::new(1_000_000, 1_000_000, 1, 10).unwrap();
+    let outbound_limited = Limits::new(1_000_000, 1_000_000, 1).unwrap();
     assert!(
         encode_call_operation_request(
             &endpoint(),
@@ -379,11 +425,15 @@ fn caller_limits_bound_bytes_and_nesting() {
         .is_err()
     );
     assert!(
-        encode_fetch_response(
+        encode_observe_response(
-            &FetchRequest {
+            &ObserveRequest {
                 path: "/item".into(),
+                depth: 0,
+            },
+            &ObjectObservation {
+                object: object("item", b"validator"),
+                children: None,
             },
-            &object("item", b"validator"),
             outbound_limited,
         )
         .is_err()
@@ -408,7 +458,7 @@ fn unsupported_descriptor_format_is_client_local() {
         ClientResponseError::UnsupportedDescriptorFormat { .. }
     ));
 
-    let future_shape = wip_https::http::Response::builder()
+    let future_shape = wip_http::http::Response::builder()
         .status(StatusCode::OK)
         .header("content-type", "application/json; charset=utf-8")
         .body(
@@ -427,7 +477,7 @@ fn unsupported_descriptor_format_is_client_local() {
         br#"{"interface":"interface-v1","descriptor":{"format":"wip-interface/2"},"validator":null}"#
             .as_slice(),
     ] {
-        let response = wip_https::http::Response::builder()
+        let response = wip_http::http::Response::builder()
             .status(StatusCode::OK)
             .header("content-type", "application/json; charset=utf-8")
             .body(malformed.to_vec())
@@ -444,14 +494,15 @@ fn unsupported_descriptor_format_is_client_local() {
 
 #[test]
 fn invalid_success_is_classified_as_invalid_response() {
-    let response = wip_https::http::Response::builder()
+    let response = wip_http::http::Response::builder()
         .status(StatusCode::OK)
         .header("content-type", "application/json; charset=utf-8")
-        .body(br#"{"name":"wrong","interfaces":[]}"#.to_vec())
+        .body(br#"{"object":{"name":"wrong","interfaces":[]}}"#.to_vec())
         .unwrap();
-    let error = decode_fetch_response(
+    let error = decode_observe_response(
-        &FetchRequest {
+        &ObserveRequest {
             path: "/expected".into(),
+            depth: 0,
         },
         &response,
         limits(),

crates/wip-http/tests/responses.rs

@@ -1,19 +1,22 @@
-use wip_https::http::{Response, StatusCode};
+use wip_http::http::{Response, StatusCode};
-use wip_https::wip_protocol::{
+use wip_http::wip_protocol::{
-    FetchRequest, ProtocolError, ProtocolErrorCode, ProtocolInteraction,
+    ObserveRequest, ProtocolError, ProtocolErrorCode, ProtocolInteraction,
 };
-use wip_https::{
+use wip_http::{
     ClientResponseError, DecodedResponse, InvalidResponseKind, Limits, TransportFailureKind,
-    decode_fetch_response, encode_protocol_error_response, error_code_name, is_json_content_type,
+    decode_observe_response, encode_protocol_error_response, error_code_name, is_json_content_type,
     status_for_error,
 };
 
 fn limits() -> Limits {
-    Limits::new(64 * 1024, 64 * 1024, 32, 16).unwrap()
+    Limits::new(64 * 1024, 64 * 1024, 32).unwrap()
 }
 
-fn request() -> FetchRequest {
+fn request() -> ObserveRequest {
-    FetchRequest { path: "/".into() }
+    ObserveRequest {
+        path: "/".into(),
+        depth: 0,
+    }
 }
 
 fn response(status: StatusCode, body: impl Into<Vec<u8>>) -> Response<Vec<u8>> {
@@ -95,7 +98,7 @@ fn every_protocol_code_has_stable_name_and_status() {
         (
             ProtocolErrorCode::ResourceLimitExceeded,
             "resource_limit_exceeded",
-            StatusCode::TOO_MANY_REQUESTS,
+            StatusCode::UNPROCESSABLE_ENTITY,
         ),
         (
             ProtocolErrorCode::Internal,
@@ -115,13 +118,129 @@ fn every_protocol_code_has_stable_name_and_status() {
     }
 }
 
+#[test]
+fn logical_resource_limit_uses_only_422_and_bare_413_is_transport_failure() {
+    let error = ProtocolError {
+        code: ProtocolErrorCode::ResourceLimitExceeded,
+        message: "logical observation limit exceeded".into(),
+    };
+    let encoded =
+        encode_protocol_error_response(ProtocolInteraction::Observe, &error, limits()).unwrap();
+    assert_eq!(encoded.status(), StatusCode::UNPROCESSABLE_ENTITY);
+    assert_eq!(
+        decode_observe_response(&request(), &encoded, limits()).unwrap(),
+        DecodedResponse::ProtocolFailure {
+            error: error.clone(),
+            status_mismatch: None,
+        }
+    );
+
+    let mut noncanonical = encoded;
+    *noncanonical.status_mut() = StatusCode::PAYLOAD_TOO_LARGE;
+    assert_eq!(
+        decode_observe_response(&request(), &noncanonical, limits()).unwrap(),
+        DecodedResponse::ProtocolFailure {
+            error,
+            status_mismatch: Some(wip_http::StatusMismatch {
+                actual: StatusCode::PAYLOAD_TOO_LARGE,
+                expected: StatusCode::UNPROCESSABLE_ENTITY,
+            }),
+        }
+    );
+
+    let bare_413 = Response::builder()
+        .status(StatusCode::PAYLOAD_TOO_LARGE)
+        .body(Vec::<u8>::new())
+        .unwrap();
+    assert!(matches!(
+        decode_observe_response(&request(), &bare_413, limits()).unwrap_err(),
+        ClientResponseError::TransportBinding(failure)
+            if failure.status == StatusCode::PAYLOAD_TOO_LARGE
+                && failure.kind == TransportFailureKind::HttpStatus
+    ));
+}
+
+#[test]
+fn rate_limit_status_without_protocol_envelope_stays_transport_failure() {
+    let response = Response::builder()
+        .status(StatusCode::TOO_MANY_REQUESTS)
+        .body(b"rate limited".to_vec())
+        .unwrap();
+    assert!(matches!(
+        decode_observe_response(&request(), &response, limits()).unwrap_err(),
+        ClientResponseError::TransportBinding(failure)
+            if failure.status == StatusCode::TOO_MANY_REQUESTS
+                && failure.kind == TransportFailureKind::HttpStatus
+    ));
+}
+
+#[test]
+fn unsupported_response_content_coding_is_transport_failure() {
+    let mut encoded = encode_protocol_error_response(
+        ProtocolInteraction::Observe,
+        &ProtocolError {
+            code: ProtocolErrorCode::NotFound,
+            message: "missing".into(),
+        },
+        limits(),
+    )
+    .unwrap();
+    encoded
+        .headers_mut()
+        .insert("content-encoding", "gzip".parse().unwrap());
+    assert!(matches!(
+        decode_observe_response(&request(), &encoded, limits()).unwrap_err(),
+        ClientResponseError::TransportBinding(failure)
+            if failure.status == StatusCode::NOT_FOUND
+                && failure.kind == TransportFailureKind::UnsupportedContentCoding
+    ));
+
+    let success = response(StatusCode::OK, br#"{"object":{"name":"","interfaces":[]}}"#);
+    let mut identity = success.clone();
+    identity
+        .headers_mut()
+        .insert("content-encoding", "identity".parse().unwrap());
+    assert!(matches!(
+        decode_observe_response(&request(), &identity, limits()).unwrap(),
+        DecodedResponse::Success(_)
+    ));
+
+    let mut unsupported = success;
+    unsupported
+        .headers_mut()
+        .insert("content-encoding", "br".parse().unwrap());
+    assert!(matches!(
+        decode_observe_response(&request(), &unsupported, limits()).unwrap_err(),
+        ClientResponseError::TransportBinding(failure)
+            if failure.status == StatusCode::OK
+                && failure.kind == TransportFailureKind::UnsupportedContentCoding
+    ));
+}
+
+#[test]
+fn valid_success_body_requires_exactly_http_200() {
+    let success_body = br#"{"object":{"name":"","interfaces":[]}}"#;
+    for status in [StatusCode::CREATED, StatusCode::ACCEPTED] {
+        assert!(matches!(
+            decode_observe_response(&request(), &response(status, success_body), limits())
+                .unwrap_err(),
+            ClientResponseError::InvalidResponse {
+                kind: InvalidResponseKind::NonCanonicalSuccessStatus,
+                ..
+            }
+        ));
+    }
+}
+
 #[test]
 fn server_encoder_rejects_codes_disallowed_for_the_interaction() {
     let error = ProtocolError {
         code: ProtocolErrorCode::InterfaceNotFound,
-        message: "not valid for fetch".into(),
+        message: "not valid for observe".into(),
     };
-    assert!(encode_protocol_error_response(ProtocolInteraction::Fetch, &error, limits()).is_err());
+    assert!(
+        encode_protocol_error_response(ProtocolInteraction::Observe, &error, limits()).is_err()
+    );
 }
 
 #[test]
@@ -131,14 +250,14 @@ fn valid_envelope_code_is_authoritative_when_status_mismatches() {
         message: "missing".into(),
     };
     let mut encoded =
-        encode_protocol_error_response(ProtocolInteraction::Fetch, &error, limits()).unwrap();
+        encode_protocol_error_response(ProtocolInteraction::Observe, &error, limits()).unwrap();
     *encoded.status_mut() = StatusCode::IM_A_TEAPOT;
 
     assert_eq!(
-        decode_fetch_response(&request(), &encoded, limits()).unwrap(),
+        decode_observe_response(&request(), &encoded, limits()).unwrap(),
         DecodedResponse::ProtocolFailure {
             error,
-            status_mismatch: Some(wip_https::StatusMismatch {
+            status_mismatch: Some(wip_http::StatusMismatch {
                 actual: StatusCode::IM_A_TEAPOT,
                 expected: StatusCode::NOT_FOUND,
             }),
@@ -150,7 +269,7 @@ fn valid_envelope_code_is_authoritative_when_status_mismatches() {
 fn envelope_and_status_contradictions_are_invalid_responses() {
     let error_body = br#"{"error":{"code":"not_found","message":"missing"}}"#;
     let on_success =
-        decode_fetch_response(&request(), &response(StatusCode::OK, error_body), limits())
+        decode_observe_response(&request(), &response(StatusCode::OK, error_body), limits())
             .unwrap_err();
     assert!(matches!(
         on_success,
@@ -160,8 +279,8 @@ fn envelope_and_status_contradictions_are_invalid_responses() {
         }
     ));
 
-    let success_body = br#"{"name":"","interfaces":[]}"#;
+    let success_body = br#"{"object":{"name":"","interfaces":[]}}"#;
-    let on_error = decode_fetch_response(
+    let on_error = decode_observe_response(
         &request(),
         &response(StatusCode::BAD_GATEWAY, success_body),
         limits(),
@@ -179,8 +298,9 @@ fn envelope_and_status_contradictions_are_invalid_responses() {
 #[test]
 fn disallowed_protocol_code_is_invalid_instead_of_reclassified() {
     let body = br#"{"error":{"code":"interface_not_found","message":"wrong interaction"}}"#;
-    let error = decode_fetch_response(&request(), &response(StatusCode::NOT_FOUND, body), limits())
+    let error =
-        .unwrap_err();
+        decode_observe_response(&request(), &response(StatusCode::NOT_FOUND, body), limits())
+            .unwrap_err();
     assert!(matches!(
         error,
         ClientResponseError::InvalidResponse {
@@ -214,7 +334,7 @@ fn proxy_authentication_and_endpoint_failures_stay_transport_failures() {
             .status(status)
             .body(body.to_vec())
             .unwrap();
-        let error = decode_fetch_response(&request(), &response, limits()).unwrap_err();
+        let error = decode_observe_response(&request(), &response, limits()).unwrap_err();
         assert!(matches!(
             error,
             ClientResponseError::TransportBinding(failure)
@@ -230,7 +350,7 @@ fn malformed_non_success_envelope_is_transport_binding_failure() {
         br#"{"error":{"code":"not_found","message":null}}"#,
     );
     assert!(matches!(
-        decode_fetch_response(&request(), &malformed, limits()).unwrap_err(),
+        decode_observe_response(&request(), &malformed, limits()).unwrap_err(),
         ClientResponseError::TransportBinding(_)
     ));
 }

crates/wip-http/tests/routes.rs

@@ -0,0 +1,182 @@
+use wip_http::http::{Method, Request, StatusCode};
+use wip_http::{Endpoint, RequestMetadataError, Route, validate_http_request};
+
+#[test]
+fn endpoint_preserves_http_and_https_when_resolving_canonical_routes() {
+    for scheme in ["http", "https"] {
+        let endpoint = Endpoint::parse(&format!("{scheme}://example.test/root/prefix")).unwrap();
+        assert_eq!(
+            endpoint.to_string(),
+            format!("{scheme}://example.test/root/prefix/")
+        );
+
+        let expected = [
+            (Route::Observe, "v1/observe"),
+            (Route::FetchInterface, "v1/fetch_interface"),
+            (Route::CallOperation, "v1/call_operation"),
+        ];
+        for (route, suffix) in expected {
+            let url = format!("{scheme}://example.test/root/prefix/{suffix}");
+            assert_eq!(endpoint.route(route).as_str(), url);
+            assert_eq!(
+                endpoint.recognize(&wip_http::url::Url::parse(&url).unwrap()),
+                Some(route)
+            );
+        }
+        assert_eq!(
+            endpoint.recognize(
+                &wip_http::url::Url::parse(&format!(
+                    "{scheme}://example.test/root/prefix/v1/observe?path=/items"
+                ))
+                .unwrap()
+            ),
+            None
+        );
+    }
+}
+
+#[test]
+fn routes_never_mix_worldspace_paths_into_endpoint_prefixes() {
+    let endpoint = Endpoint::parse("https://example.test/wip/%E4%B8%96%E7%95%8C/").unwrap();
+    let route = endpoint.route(Route::Observe);
+    assert_eq!(route.path(), "/wip/%E4%B8%96%E7%95%8C/v1/observe");
+    assert!(!route.as_str().contains("items"));
+}
+
+#[test]
+fn inbound_http_metadata_enforces_post_route_and_json() {
+    let endpoint = Endpoint::parse("https://example.test/wip").unwrap();
+    let valid = Request::builder()
+        .method(Method::POST)
+        .uri("/wip/v1/observe")
+        .header("content-type", "application/json; charset=utf-8")
+        .body(Vec::<u8>::new())
+        .unwrap();
+    assert!(validate_http_request(&endpoint, Route::Observe, &valid).is_ok());
+
+    let wrong_method = Request::builder()
+        .method(Method::GET)
+        .uri("/wip/v1/observe")
+        .header("content-type", "application/json")
+        .body(Vec::<u8>::new())
+        .unwrap();
+    let error = validate_http_request(&endpoint, Route::Observe, &wrong_method).unwrap_err();
+    assert!(matches!(&error, RequestMetadataError::MethodNotAllowed));
+    assert_eq!(error.status(), StatusCode::METHOD_NOT_ALLOWED);
+    assert_eq!(error.allow(), Some("POST"));
+
+    let wrong_route = Request::builder()
+        .method(Method::POST)
+        .uri("/wip/v1/fetch_interface")
+        .header("content-type", "application/json")
+        .body(Vec::<u8>::new())
+        .unwrap();
+    let error = validate_http_request(&endpoint, Route::Observe, &wrong_route).unwrap_err();
+    assert!(matches!(&error, RequestMetadataError::NotFound));
+    assert_eq!(error.status(), StatusCode::NOT_FOUND);
+    assert_eq!(error.allow(), None);
+
+    let query_and_wrong_method = Request::builder()
+        .method(Method::GET)
+        .uri("/wip/v1/observe?unexpected=true")
+        .header("content-type", "application/json")
+        .body(Vec::<u8>::new())
+        .unwrap();
+    assert!(matches!(
+        validate_http_request(&endpoint, Route::Observe, &query_and_wrong_method).unwrap_err(),
+        RequestMetadataError::NotFound
+    ));
+
+    for accept in [
+        "text/plain, */*;q=1, application/json;q=0",
+        "application/json; charset=utf-16",
+        "application/json; profile=future",
+    ] {
+        let incompatible_accept = Request::builder()
+            .method(Method::POST)
+            .uri("/wip/v1/observe")
+            .header("content-type", "application/json")
+            .header("accept", accept)
+            .body(Vec::<u8>::new())
+            .unwrap();
+        let error =
+            validate_http_request(&endpoint, Route::Observe, &incompatible_accept).unwrap_err();
+        assert!(matches!(&error, RequestMetadataError::NotAcceptable));
+        assert_eq!(error.status(), StatusCode::NOT_ACCEPTABLE);
+    }
+
+    for accept in [
+        "application/json; charset=UTF-8",
+        "application/json; q=1; profile=accept-extension",
+    ] {
+        let compatible_accept = Request::builder()
+            .method(Method::POST)
+            .uri("/wip/v1/observe")
+            .header("content-type", "application/json")
+            .header("accept", accept)
+            .body(Vec::<u8>::new())
+            .unwrap();
+        assert!(validate_http_request(&endpoint, Route::Observe, &compatible_accept).is_ok());
+    }
+
+    let unsupported_media_type = Request::builder()
+        .method(Method::POST)
+        .uri("/wip/v1/observe")
+        .header("content-type", "text/plain")
+        .header("accept", "application/json")
+        .body(Vec::<u8>::new())
+        .unwrap();
+    let error =
+        validate_http_request(&endpoint, Route::Observe, &unsupported_media_type).unwrap_err();
+    assert!(matches!(&error, RequestMetadataError::UnsupportedMediaType));
+    assert_eq!(error.status(), StatusCode::UNSUPPORTED_MEDIA_TYPE);
+
+    for coding in ["gzip", "identity, gzip"] {
+        let unsupported_coding = Request::builder()
+            .method(Method::POST)
+            .uri("/wip/v1/observe")
+            .header("content-type", "application/json")
+            .header("content-encoding", coding)
+            .body(Vec::<u8>::new())
+            .unwrap();
+        let error =
+            validate_http_request(&endpoint, Route::Observe, &unsupported_coding).unwrap_err();
+        assert!(matches!(&error, RequestMetadataError::UnsupportedMediaType));
+        assert_eq!(error.status(), StatusCode::UNSUPPORTED_MEDIA_TYPE);
+    }
+
+    let identity_coding = Request::builder()
+        .method(Method::POST)
+        .uri("/wip/v1/observe")
+        .header("content-type", "application/json")
+        .header("content-encoding", "identity")
+        .body(Vec::<u8>::new())
+        .unwrap();
+    assert!(validate_http_request(&endpoint, Route::Observe, &identity_coding).is_ok());
+}
+
+#[test]
+fn invalid_endpoint_components_and_non_routes_are_rejected() {
+    assert!(Endpoint::parse("/relative").is_err());
+    assert!(Endpoint::parse("file:///wip").is_err());
+    assert!(Endpoint::parse("https://example.test/wip?q=1").is_err());
+    assert!(Endpoint::parse("https://example.test/wip#fragment").is_err());
+
+    let deployment_endpoint = Endpoint::parse("http://user:secret@example.test/wip").unwrap();
+    assert_eq!(deployment_endpoint.as_url().scheme(), "http");
+    assert_eq!(deployment_endpoint.as_url().username(), "user");
+
+    let endpoint = Endpoint::parse("http://example.test/wip").unwrap();
+    for outside in [
+        "http://example.test/wip/v1/unknown",
+        "http://example.test/wip/v1/batch",
+        "http://example.test/wip/v1/observe/extra",
+        "https://example.test/wip/v1/observe",
+        "http://other.test/wip/v1/observe",
+    ] {
+        assert_eq!(
+            endpoint.recognize(&wip_http::url::Url::parse(outside).unwrap()),
+            None
+        );
+    }
+}

crates/wip-https/Cargo.toml

@@ -1,14 +0,0 @@
-[package]
-name = "wip-https"
-version = "0.1.0"
-edition = "2024"
-description = "Framework-independent standard WIP over HTTPS v1 binding"
-license = "MIT OR Apache-2.0"
-
-[dependencies]
-base64 = "0.22"
-http = "1"
-serde = "1"
-serde_json = "1"
-url = "2"
-wip-protocol = { path = "../wip-protocol" }

crates/wip-https/src/batch.rs

@@ -1,507 +0,0 @@
-use std::collections::{BTreeMap, BTreeSet};
-
-use http::header::CONTENT_TYPE;
-use http::{Method, Request, Response, StatusCode};
-use serde_json::{Map, Value as Json};
-use wip_protocol::{
-    FetchInterfaceRequest, FetchInterfaceResponse, FetchRequest, FetchResponse, FetchTreeRequest,
-    FetchTreeResponse, INTERFACE_FORMAT_V1, ProtocolError, ProtocolErrorCode, ProtocolInteraction,
-};
-
-use crate::response::{self, DecodedResponse};
-use crate::{
-    BodyKind, ClientResponseError, CodecError, EncodeHttpError, Endpoint, InvalidResponseKind,
-    JSON_CONTENT_TYPE, Limits, Route, is_json_content_type, json,
-};
-
-/// One retrieval interaction accepted by the standard v1 batch endpoint.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum BatchRequestKind {
-    /// Fetch one object.
-    Fetch(FetchRequest),
-    /// Fetch one bounded tree.
-    FetchTree(FetchTreeRequest),
-    /// Fetch one interface descriptor.
-    FetchInterface(FetchInterfaceRequest),
-}
-
-impl BatchRequestKind {
-    fn interaction(&self) -> ProtocolInteraction {
-        match self {
-            Self::Fetch(_) => ProtocolInteraction::Fetch,
-            Self::FetchTree(_) => ProtocolInteraction::FetchTree,
-            Self::FetchInterface(_) => ProtocolInteraction::FetchInterface,
-        }
-    }
-}
-
-/// One uniquely identified batch subrequest.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct BatchRequestItem {
-    /// Identifier used only to correlate the corresponding subresponse.
-    pub id: String,
-    /// Retrieval interaction and arguments.
-    pub request: BatchRequestKind,
-}
-
-/// A standard v1 batch request.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct BatchRequest {
-    /// Independent subrequests. Identifiers must be unique.
-    pub requests: Vec<BatchRequestItem>,
-}
-
-/// Successful result of one batch item.
-#[derive(Debug, Clone, PartialEq)]
-pub enum BatchSuccess {
-    /// Successful `fetch` result.
-    Fetch(FetchResponse),
-    /// Successful `fetch_tree` result.
-    FetchTree(FetchTreeResponse),
-    /// Successful `fetch_interface` result.
-    FetchInterface(FetchInterfaceResponse),
-}
-
-/// One batch subresponse, correlated by `id` rather than array position.
-#[derive(Debug, Clone, PartialEq)]
-pub struct BatchResponseItem {
-    /// Identifier copied from its subrequest.
-    pub id: String,
-    /// Direct interaction result or canonical item-local protocol failure.
-    pub outcome: Result<BatchSuccess, ProtocolError>,
-}
-
-/// A valid standard v1 batch response.
-#[derive(Debug, Clone, PartialEq)]
-pub struct BatchResponse {
-    /// Exactly one response for each requested identifier, in any order.
-    pub responses: Vec<BatchResponseItem>,
-}
-
-fn validate_ids<'a>(ids: impl Iterator<Item = &'a str>, maximum: usize) -> Result<(), CodecError> {
-    let mut seen = BTreeSet::new();
-    let mut count = 0;
-    for id in ids {
-        count += 1;
-        if !seen.insert(id) {
-            return Err(CodecError::DuplicateBatchId { id: id.into() });
-        }
-    }
-    if count > maximum {
-        return Err(CodecError::TooManyBatchItems {
-            actual: count,
-            maximum,
-        });
-    }
-    Ok(())
-}
-
-fn request_item_to_json(item: &BatchRequestItem) -> Json {
-    let (method, arguments) = match &item.request {
-        BatchRequestKind::Fetch(value) => ("fetch", json::fetch_request_to_json(value)),
-        BatchRequestKind::FetchTree(value) => {
-            ("fetch_tree", json::fetch_tree_request_to_json(value))
-        }
-        BatchRequestKind::FetchInterface(value) => (
-            "fetch_interface",
-            json::fetch_interface_request_to_json(value),
-        ),
-    };
-    serde_json::json!({"id": item.id, "method": method, "arguments": arguments})
-}
-
-fn request_to_json(request: &BatchRequest, limits: Limits) -> Result<Json, CodecError> {
-    validate_ids(
-        request.requests.iter().map(|item| item.id.as_str()),
-        limits.max_batch_items,
-    )?;
-    for item in &request.requests {
-        match &item.request {
-            BatchRequestKind::Fetch(value) => value.validate()?,
-            BatchRequestKind::FetchTree(value) => value.validate()?,
-            BatchRequestKind::FetchInterface(_) => {}
-        }
-    }
-    Ok(serde_json::json!({
-        "requests": request.requests.iter().map(request_item_to_json).collect::<Vec<_>>()
-    }))
-}
-
-fn request_from_json(value: &Json, limits: Limits) -> Result<BatchRequest, CodecError> {
-    let fields = exact_object(value, "batch", &["requests"])?;
-    let values = array(required(fields, "requests")?, "requests")?;
-    if values.len() > limits.max_batch_items {
-        return Err(CodecError::TooManyBatchItems {
-            actual: values.len(),
-            maximum: limits.max_batch_items,
-        });
-    }
-    let mut requests = Vec::with_capacity(values.len());
-    for (index, value) in values.iter().enumerate() {
-        let field = format!("requests[{index}]");
-        let fields = exact_object(value, &field, &["id", "method", "arguments"])?;
-        let id = string(required(fields, "id")?, &format!("{field}.id"))?;
-        let method = string(required(fields, "method")?, &format!("{field}.method"))?;
-        let arguments = required(fields, "arguments")?;
-        let request = match method.as_str() {
-            "fetch" => BatchRequestKind::Fetch(json::fetch_request_from_json(arguments)?),
-            "fetch_tree" => {
-                BatchRequestKind::FetchTree(json::fetch_tree_request_from_json(arguments)?)
-            }
-            "fetch_interface" => BatchRequestKind::FetchInterface(
-                json::fetch_interface_request_from_json(arguments)?,
-            ),
-            _ => {
-                return Err(CodecError::InvalidField {
-                    field: format!("{field}.method"),
-                    reason: "batch supports only fetch, fetch_tree, and fetch_interface".into(),
-                });
-            }
-        };
-        requests.push(BatchRequestItem { id, request });
-    }
-    validate_ids(
-        requests.iter().map(|item| item.id.as_str()),
-        limits.max_batch_items,
-    )?;
-    Ok(BatchRequest { requests })
-}
-
-/// Encodes a batch request using `POST v1/batch`.
-pub fn encode_batch_request(
-    endpoint: &Endpoint,
-    value: &BatchRequest,
-    limits: Limits,
-) -> Result<Request<Vec<u8>>, EncodeHttpError> {
-    let body = json::serialize(&request_to_json(value, limits)?, BodyKind::Request, limits)?;
-    Ok(Request::builder()
-        .method(Method::POST)
-        .uri(endpoint.route(Route::Batch).as_str())
-        .header(CONTENT_TYPE, JSON_CONTENT_TYPE)
-        .body(body)?)
-}
-
-/// Decodes and validates a batch request body.
-pub fn decode_batch_request(body: &[u8], limits: Limits) -> Result<BatchRequest, CodecError> {
-    let value = json::parse(body, BodyKind::Request, limits)?;
-    request_from_json(&value, limits)
-}
-
-fn success_to_json(success: &BatchSuccess) -> Json {
-    match success {
-        BatchSuccess::Fetch(value) => json::object_to_json(value),
-        BatchSuccess::FetchTree(value) => json::fetch_tree_response_to_json(value),
-        BatchSuccess::FetchInterface(value) => json::fetch_interface_response_to_json(value),
-    }
-}
-
-fn response_to_json(
-    request: &BatchRequest,
-    response: &BatchResponse,
-    limits: Limits,
-) -> Result<Json, CodecError> {
-    correlate(request, response, limits)?;
-    Ok(serde_json::json!({
-        "responses": response.responses.iter().map(|item| {
-            let mut fields = Map::new();
-            fields.insert("id".into(), Json::String(item.id.clone()));
-            match &item.outcome {
-                Ok(success) => { fields.insert("result".into(), success_to_json(success)); }
-                Err(error) => { fields.insert("error".into(), response::item_error_to_json(error)); }
-            }
-            Json::Object(fields)
-        }).collect::<Vec<_>>()
-    }))
-}
-
-fn correlate(
-    request: &BatchRequest,
-    response: &BatchResponse,
-    limits: Limits,
-) -> Result<(), CodecError> {
-    validate_ids(
-        request.requests.iter().map(|item| item.id.as_str()),
-        limits.max_batch_items,
-    )?;
-    validate_ids(
-        response.responses.iter().map(|item| item.id.as_str()),
-        limits.max_batch_items,
-    )?;
-    let requested: BTreeMap<&str, &BatchRequestKind> = request
-        .requests
-        .iter()
-        .map(|item| (item.id.as_str(), &item.request))
-        .collect();
-    for item in &response.responses {
-        let Some(kind) = requested.get(item.id.as_str()) else {
-            return Err(CodecError::UnexpectedBatchId {
-                id: item.id.clone(),
-            });
-        };
-        match &item.outcome {
-            Ok(BatchSuccess::Fetch(value)) if matches!(kind, BatchRequestKind::Fetch(_)) => {
-                if let BatchRequestKind::Fetch(request) = kind {
-                    request.validate_response(value)?;
-                }
-            }
-            Ok(BatchSuccess::FetchTree(value))
-                if matches!(kind, BatchRequestKind::FetchTree(_)) =>
-            {
-                if let BatchRequestKind::FetchTree(request) = kind {
-                    value.validate_for(request)?;
-                }
-            }
-            Ok(BatchSuccess::FetchInterface(value))
-                if matches!(kind, BatchRequestKind::FetchInterface(_)) =>
-            {
-                if let BatchRequestKind::FetchInterface(request) = kind {
-                    value.validate_for(request)?;
-                }
-            }
-            Ok(_) => {
-                return Err(CodecError::BatchInteractionMismatch {
-                    id: item.id.clone(),
-                });
-            }
-            Err(error) if error.code.is_allowed_for(kind.interaction()) => {}
-            Err(_) => {
-                return Err(CodecError::BatchInteractionMismatch {
-                    id: item.id.clone(),
-                });
-            }
-        }
-    }
-    for item in &request.requests {
-        if !response.responses.iter().any(|other| other.id == item.id) {
-            return Err(CodecError::MissingBatchId {
-                id: item.id.clone(),
-            });
-        }
-    }
-    Ok(())
-}
-
-/// Encodes a valid batch response. Item failures remain inside HTTP 200.
-pub fn encode_batch_response(
-    request: &BatchRequest,
-    value: &BatchResponse,
-    limits: Limits,
-) -> Result<Response<Vec<u8>>, EncodeHttpError> {
-    let body = json::serialize(
-        &response_to_json(request, value, limits)?,
-        BodyKind::Response,
-        limits,
-    )?;
-    Ok(Response::builder()
-        .status(StatusCode::OK)
-        .header(CONTENT_TYPE, JSON_CONTENT_TYPE)
-        .body(body)?)
-}
-
-/// Encodes a top-level batch-envelope failure.
-///
-/// Item-local failures belong in [`BatchResponseItem`]. Only failures that can
-/// reject the batch envelope before item execution are accepted here.
-pub fn encode_batch_error_response(
-    error: &ProtocolError,
-    limits: Limits,
-) -> Result<Response<Vec<u8>>, EncodeHttpError> {
-    if !matches!(
-        error.code,
-        ProtocolErrorCode::InvalidRequest
-            | ProtocolErrorCode::ResourceLimitExceeded
-            | ProtocolErrorCode::Internal
-    ) {
-        return Err(CodecError::InvalidField {
-            field: "error.code".into(),
-            reason: "code is not valid for a top-level batch failure".into(),
-        }
-        .into());
-    }
-    let body = json::serialize(&response::error_to_json(error), BodyKind::Response, limits)?;
-    Ok(Response::builder()
-        .status(response::status_for_error(error.code))
-        .header(CONTENT_TYPE, JSON_CONTENT_TYPE)
-        .body(body)?)
-}
-
-fn response_from_json(
-    value: &Json,
-    request: &BatchRequest,
-    limits: Limits,
-) -> Result<BatchResponse, CodecError> {
-    let fields = exact_object(value, "batch", &["responses"])?;
-    let values = array(required(fields, "responses")?, "responses")?;
-    if values.len() > limits.max_batch_items {
-        return Err(CodecError::TooManyBatchItems {
-            actual: values.len(),
-            maximum: limits.max_batch_items,
-        });
-    }
-    let requested: BTreeMap<&str, &BatchRequestKind> = request
-        .requests
-        .iter()
-        .map(|item| (item.id.as_str(), &item.request))
-        .collect();
-    let mut responses = Vec::with_capacity(values.len());
-    for (index, value) in values.iter().enumerate() {
-        let field = format!("responses[{index}]");
-        let fields = object(value, &field)?;
-        for name in fields.keys() {
-            if !["id", "result", "error"].contains(&name.as_str()) {
-                return Err(CodecError::UnknownField {
-                    field: format!("{field}.{name}"),
-                });
-            }
-        }
-        let id = string(required(fields, "id")?, &format!("{field}.id"))?;
-        let Some(kind) = requested.get(id.as_str()) else {
-            return Err(CodecError::UnexpectedBatchId { id });
-        };
-        let outcome = match (fields.get("result"), fields.get("error")) {
-            (Some(_), Some(_)) | (None, None) => {
-                return Err(CodecError::InvalidField {
-                    field,
-                    reason: "batch item must contain exactly one of result or error".into(),
-                });
-            }
-            (None, Some(error)) => {
-                let error = response::item_error_from_json(error)?;
-                if !error.code.is_allowed_for(kind.interaction()) {
-                    return Err(CodecError::BatchInteractionMismatch { id });
-                }
-                Err(error)
-            }
-            (Some(result), None) => Ok(match kind {
-                BatchRequestKind::Fetch(request) => {
-                    let value = json::object_from_json(result, "result")?;
-                    request.validate_response(&value)?;
-                    BatchSuccess::Fetch(value)
-                }
-                BatchRequestKind::FetchTree(request) => {
-                    let value = json::fetch_tree_response_from_json(result)?;
-                    value.validate_for(request)?;
-                    BatchSuccess::FetchTree(value)
-                }
-                BatchRequestKind::FetchInterface(request) => {
-                    let value = json::fetch_interface_response_from_json(result)?;
-                    value.validate_for(request)?;
-                    BatchSuccess::FetchInterface(value)
-                }
-            }),
-        };
-        responses.push(BatchResponseItem { id, outcome });
-    }
-    let response = BatchResponse { responses };
-    correlate(request, &response, limits)?;
-    Ok(response)
-}
-
-/// Decodes a batch response, including item-local failures within HTTP 200.
-pub fn decode_batch_response<B: AsRef<[u8]>>(
-    request: &BatchRequest,
-    value: &Response<B>,
-    limits: Limits,
-) -> Result<DecodedResponse<BatchResponse>, ClientResponseError> {
-    let valid_content_type = value
-        .headers()
-        .get(CONTENT_TYPE)
-        .and_then(|value| value.to_str().ok())
-        .is_some_and(is_json_content_type);
-    if !valid_content_type {
-        if value.status().is_success() {
-            return Err(ClientResponseError::invalid(
-                InvalidResponseKind::InvalidBatch,
-                "missing or non-UTF-8 application/json Content-Type",
-            ));
-        }
-        return Err(response::transport_failure(value.status()));
-    }
-    let decoded = response::decode(
-        value.status(),
-        value.body().as_ref(),
-        ProtocolInteraction::Fetch,
-        limits,
-        |json| response_from_json(json, request, limits),
-    )
-    .map_err(|error| match error {
-        ClientResponseError::InvalidResponse { detail, .. } => {
-            ClientResponseError::invalid(InvalidResponseKind::InvalidBatch, detail)
-        }
-        other => other,
-    })?;
-    if let DecodedResponse::ProtocolFailure { error, .. } = &decoded
-        && !matches!(
-            error.code,
-            ProtocolErrorCode::InvalidRequest
-                | ProtocolErrorCode::ResourceLimitExceeded
-                | ProtocolErrorCode::Internal
-        )
-    {
-        return Err(ClientResponseError::invalid(
-            InvalidResponseKind::InvalidBatch,
-            "protocol code is not valid for a top-level batch failure",
-        ));
-    }
-    if let DecodedResponse::Success(success) = &decoded {
-        for item in &success.responses {
-            if let Ok(BatchSuccess::FetchInterface(interface)) = &item.outcome
-                && interface.descriptor.format != INTERFACE_FORMAT_V1
-            {
-                return Err(ClientResponseError::UnsupportedDescriptorFormat {
-                    format: interface.descriptor.format.clone(),
-                });
-            }
-        }
-    }
-    Ok(decoded)
-}
-
-fn object<'a>(value: &'a Json, field: &str) -> Result<&'a Map<String, Json>, CodecError> {
-    value.as_object().ok_or_else(|| CodecError::InvalidField {
-        field: field.into(),
-        reason: "expected object".into(),
-    })
-}
-
-fn exact_object<'a>(
-    value: &'a Json,
-    field: &str,
-    allowed: &[&str],
-) -> Result<&'a Map<String, Json>, CodecError> {
-    let fields = object(value, field)?;
-    for name in fields.keys() {
-        if !allowed.contains(&name.as_str()) {
-            return Err(CodecError::UnknownField {
-                field: format!("{field}.{name}"),
-            });
-        }
-    }
-    Ok(fields)
-}
-
-fn required<'a>(fields: &'a Map<String, Json>, name: &str) -> Result<&'a Json, CodecError> {
-    fields
-        .get(name)
-        .ok_or_else(|| CodecError::MissingField { field: name.into() })
-}
-
-fn string(value: &Json, field: &str) -> Result<String, CodecError> {
-    value
-        .as_str()
-        .map(str::to_owned)
-        .ok_or_else(|| CodecError::InvalidField {
-            field: field.into(),
-            reason: "expected string".into(),
-        })
-}
-
-fn array<'a>(value: &'a Json, field: &str) -> Result<&'a [Json], CodecError> {
-    value
-        .as_array()
-        .map(Vec::as_slice)
-        .ok_or_else(|| CodecError::InvalidField {
-            field: field.into(),
-            reason: "expected array".into(),
-        })
-}

crates/wip-https/src/lib.rs

@@ -1,65 +0,0 @@
-//! Framework-independent standard WIP over HTTPS v1 binding.
-//!
-//! This crate owns endpoint and route derivation, UTF-8 JSON encoding, canonical
-//! success and error response handling, HTTP status mapping, descriptor-guided
-//! operation-value conversion, and retrieval batching. It deliberately performs
-//! no I/O and depends on no server framework, TLS implementation, filesystem
-//! projection, client cache, or presentation layer.
-//!
-//! Logical values remain owned by [`wip_protocol`]. Validators and `Bytes` are
-//! encoded in JSON bodies using canonical RFC 4648 Section 4 base64; this crate
-//! does not infer WIP validator semantics from `ETag` or `If-Match`.
-//!
-//! ```
-//! use wip_https::{Endpoint, Limits, encode_fetch_request};
-//! use wip_protocol::FetchRequest;
-//!
-//! let endpoint = Endpoint::parse("https://example.test/api/wip")?;
-//! let limits = Limits::new(64 * 1024, 1024 * 1024, 64, 100)?;
-//! let request = encode_fetch_request(
-//!     &endpoint,
-//!     &FetchRequest { path: "/items/123".into() },
-//!     limits,
-//! )?;
-//! assert_eq!(request.uri(), "https://example.test/api/wip/v1/fetch");
-//! assert_eq!(request.method(), http::Method::POST);
-//! # Ok::<(), Box<dyn std::error::Error>>(())
-//! ```
-
-#![deny(missing_docs)]
-
-mod batch;
-mod codec;
-mod endpoint;
-mod error;
-mod json;
-mod response;
-
-pub use batch::{
-    BatchRequest, BatchRequestItem, BatchRequestKind, BatchResponse, BatchResponseItem,
-    BatchSuccess, decode_batch_request, decode_batch_response, encode_batch_error_response,
-    encode_batch_request, encode_batch_response,
-};
-pub use codec::{
-    CallOperationMetadata, EncodeHttpError, decode_call_operation_metadata,
-    decode_call_operation_request, decode_call_operation_response, decode_fetch_interface_request,
-    decode_fetch_interface_response, decode_fetch_request, decode_fetch_response,
-    decode_fetch_tree_request, decode_fetch_tree_response, encode_call_operation_request,
-    encode_call_operation_response, encode_fetch_interface_request,
-    encode_fetch_interface_response, encode_fetch_request, encode_fetch_response,
-    encode_fetch_tree_request, encode_fetch_tree_response, encode_protocol_error_response,
-    is_json_content_type, validate_http_request,
-};
-pub use endpoint::{Endpoint, EndpointError, JSON_CONTENT_TYPE, Route};
-pub use error::{BodyKind, CodecError, LimitConfigurationError, Limits};
-pub use response::{
-    ClientResponseError, DecodedResponse, InvalidResponseKind, StatusMismatch,
-    TransportBindingFailure, TransportFailureKind, error_code_name, status_for_error,
-};
-
-/// Framework-neutral HTTP types used by this binding's public API.
-pub use http;
-/// URL type used by [`Endpoint`].
-pub use url;
-/// Transport-independent logical protocol model used by this binding.
-pub use wip_protocol;

crates/wip-https/tests/batch.rs

@@ -1,233 +0,0 @@
-use wip_https::http::StatusCode;
-use wip_https::wip_protocol::{
-    FetchInterfaceRequest, FetchInterfaceResponse, FetchRequest, INTERFACE_FORMAT_V1,
-    InterfaceDescriptor, Object, ProtocolError, ProtocolErrorCode,
-};
-use wip_https::{
-    BatchRequest, BatchRequestItem, BatchRequestKind, BatchResponse, BatchResponseItem,
-    BatchSuccess, ClientResponseError, DecodedResponse, Endpoint, InvalidResponseKind, Limits,
-    decode_batch_request, decode_batch_response, encode_batch_error_response, encode_batch_request,
-    encode_batch_response,
-};
-
-fn limits() -> Limits {
-    Limits::new(100_000, 100_000, 64, 4).unwrap()
-}
-
-fn request() -> BatchRequest {
-    BatchRequest {
-        requests: vec![
-            BatchRequestItem {
-                id: "object".into(),
-                request: BatchRequestKind::Fetch(FetchRequest {
-                    path: "/item".into(),
-                }),
-            },
-            BatchRequestItem {
-                id: "interface".into(),
-                request: BatchRequestKind::FetchInterface(FetchInterfaceRequest {
-                    interface: "interface-v1".into(),
-                }),
-            },
-        ],
-    }
-}
-
-#[test]
-fn batch_round_trips_by_unique_id_with_item_failures_and_validators() {
-    let request = request();
-    let endpoint = Endpoint::parse("https://example.test/wip").unwrap();
-    let encoded_request = encode_batch_request(&endpoint, &request, limits()).unwrap();
-    assert_eq!(encoded_request.uri().path(), "/wip/v1/batch");
-    assert_eq!(
-        decode_batch_request(encoded_request.body(), limits()).unwrap(),
-        request
-    );
-
-    let response = BatchResponse {
-        responses: vec![
-            BatchResponseItem {
-                id: "interface".into(),
-                outcome: Err(ProtocolError {
-                    code: ProtocolErrorCode::InterfaceNotFound,
-                    message: "gone".into(),
-                }),
-            },
-            BatchResponseItem {
-                id: "object".into(),
-                outcome: Ok(BatchSuccess::Fetch(Object {
-                    name: "item".into(),
-                    description: None,
-                    interfaces: vec![],
-                    r#ref: None,
-                    validator: Some(vec![0, 1, 2, 255]),
-                })),
-            },
-        ],
-    };
-    let encoded = encode_batch_response(&request, &response, limits()).unwrap();
-    assert_eq!(encoded.status(), StatusCode::OK);
-    assert!(
-        std::str::from_utf8(encoded.body())
-            .unwrap()
-            .contains("AAEC/w==")
-    );
-    assert_eq!(
-        decode_batch_response(&request, &encoded, limits()).unwrap(),
-        DecodedResponse::Success(response)
-    );
-}
-
-#[test]
-fn batch_interface_validator_round_trips_in_item_body() {
-    let request = BatchRequest {
-        requests: vec![BatchRequestItem {
-            id: "interface".into(),
-            request: BatchRequestKind::FetchInterface(FetchInterfaceRequest {
-                interface: "interface-v1".into(),
-            }),
-        }],
-    };
-    let response = BatchResponse {
-        responses: vec![BatchResponseItem {
-            id: "interface".into(),
-            outcome: Ok(BatchSuccess::FetchInterface(FetchInterfaceResponse {
-                interface: "interface-v1".into(),
-                descriptor: InterfaceDescriptor {
-                    format: INTERFACE_FORMAT_V1.into(),
-                    documentation: None,
-                    types: vec![],
-                    operations: vec![],
-                },
-                validator: Some(vec![255, 254, 253]),
-            })),
-        }],
-    };
-    let encoded = encode_batch_response(&request, &response, limits()).unwrap();
-    assert!(
-        std::str::from_utf8(encoded.body())
-            .unwrap()
-            .contains("//79")
-    );
-    assert_eq!(
-        decode_batch_response(&request, &encoded, limits()).unwrap(),
-        DecodedResponse::Success(response)
-    );
-}
-
-#[test]
-fn invalid_batch_envelopes_are_rejected_at_top_level() {
-    let duplicate = br#"{
-        "requests": [
-            {"id":"same","method":"fetch","arguments":{"path":"/a"}},
-            {"id":"same","method":"fetch","arguments":{"path":"/b"}}
-        ]
-    }"#;
-    assert!(decode_batch_request(duplicate, limits()).is_err());
-
-    let operation = br#"{
-        "requests": [
-            {"id":"call","method":"call_operation","arguments":{}}
-        ]
-    }"#;
-    assert!(decode_batch_request(operation, limits()).is_err());
-
-    let too_many = Limits::new(100_000, 100_000, 64, 1).unwrap();
-    assert!(decode_batch_request(duplicate, too_many).is_err());
-}
-
-#[test]
-fn top_level_batch_errors_use_the_batch_allowed_code_set() {
-    let invalid = ProtocolError {
-        code: ProtocolErrorCode::InvalidRequest,
-        message: "bad envelope".into(),
-    };
-    let encoded = encode_batch_error_response(&invalid, limits()).unwrap();
-    assert_eq!(
-        decode_batch_response(&request(), &encoded, limits()).unwrap(),
-        DecodedResponse::ProtocolFailure {
-            error: invalid,
-            status_mismatch: None,
-        }
-    );
-
-    let not_found = wip_https::http::Response::builder()
-        .status(StatusCode::NOT_FOUND)
-        .header("content-type", "application/json; charset=utf-8")
-        .body(br#"{"error":{"code":"not_found","message":"not a batch failure"}}"#.to_vec())
-        .unwrap();
-    assert!(matches!(
-        decode_batch_response(&request(), &not_found, limits()).unwrap_err(),
-        ClientResponseError::InvalidResponse {
-            kind: InvalidResponseKind::InvalidBatch,
-            ..
-        }
-    ));
-}
-
-#[test]
-fn unsupported_batch_descriptor_waits_for_envelope_correlation() {
-    let duplicate = wip_https::http::Response::builder()
-        .status(StatusCode::OK)
-        .header("content-type", "application/json; charset=utf-8")
-        .body(
-            br#"{"responses":[{"id":"interface","result":{"interface":"interface-v1","descriptor":{"format":"wip-interface/2","future":true}}},{"id":"interface","result":{"interface":"interface-v1","descriptor":{"format":"wip-interface/2"}}}]}"#
-                .to_vec(),
-        )
-        .unwrap();
-    assert!(matches!(
-        decode_batch_response(&request(), &duplicate, limits()).unwrap_err(),
-        ClientResponseError::InvalidResponse {
-            kind: InvalidResponseKind::InvalidBatch,
-            ..
-        }
-    ));
-
-    let missing = wip_https::http::Response::builder()
-        .status(StatusCode::OK)
-        .header("content-type", "application/json; charset=utf-8")
-        .body(
-            br#"{"responses":[{"id":"interface","result":{"interface":"interface-v1","descriptor":{"format":"wip-interface/2"}}}]}"#
-                .to_vec(),
-        )
-        .unwrap();
-    assert!(matches!(
-        decode_batch_response(&request(), &missing, limits()).unwrap_err(),
-        ClientResponseError::InvalidResponse {
-            kind: InvalidResponseKind::InvalidBatch,
-            ..
-        }
-    ));
-
-    let request = BatchRequest {
-        requests: vec![BatchRequestItem {
-            id: "interface".into(),
-            request: BatchRequestKind::FetchInterface(FetchInterfaceRequest {
-                interface: "interface-v1".into(),
-            }),
-        }],
-    };
-    assert!(matches!(
-        decode_batch_response(&request, &missing, limits()).unwrap_err(),
-        ClientResponseError::UnsupportedDescriptorFormat { format }
-            if format == "wip-interface/2"
-    ));
-}
-
-#[test]
-fn batch_response_must_have_exactly_the_requested_ids() {
-    let request = request();
-    let missing = BatchResponse {
-        responses: vec![BatchResponseItem {
-            id: "object".into(),
-            outcome: Ok(BatchSuccess::Fetch(Object {
-                name: "item".into(),
-                description: None,
-                interfaces: vec![],
-                r#ref: None,
-                validator: None,
-            })),
-        }],
-    };
-    assert!(encode_batch_response(&request, &missing, limits()).is_err());
-}

crates/wip-https/tests/routes.rs

@@ -1,83 +0,0 @@
-use wip_https::http::{Method, Request};
-use wip_https::{Endpoint, Route, validate_http_request};
-
-#[test]
-fn endpoint_is_https_absolute_queryless_and_canonical() {
-    let endpoint = Endpoint::parse("https://example.test/root/prefix").unwrap();
-    assert_eq!(endpoint.to_string(), "https://example.test/root/prefix/");
-
-    let expected = [
-        (Route::Fetch, "https://example.test/root/prefix/v1/fetch"),
-        (
-            Route::FetchTree,
-            "https://example.test/root/prefix/v1/fetch_tree",
-        ),
-        (
-            Route::FetchInterface,
-            "https://example.test/root/prefix/v1/fetch_interface",
-        ),
-        (
-            Route::CallOperation,
-            "https://example.test/root/prefix/v1/call_operation",
-        ),
-        (Route::Batch, "https://example.test/root/prefix/v1/batch"),
-    ];
-    for (route, url) in expected {
-        assert_eq!(endpoint.route(route).as_str(), url);
-        assert_eq!(
-            endpoint.recognize(&wip_https::url::Url::parse(url).unwrap()),
-            Some(route)
-        );
-    }
-    assert_eq!(
-        endpoint.recognize(
-            &wip_https::url::Url::parse("https://example.test/root/prefix/v1/fetch?path=/items")
-                .unwrap()
-        ),
-        None
-    );
-}
-
-#[test]
-fn routes_never_mix_worldspace_paths_into_endpoint_prefixes() {
-    let endpoint = Endpoint::parse("https://example.test/wip/%E4%B8%96%E7%95%8C/").unwrap();
-    let route = endpoint.route(Route::Fetch);
-    assert_eq!(route.path(), "/wip/%E4%B8%96%E7%95%8C/v1/fetch");
-    assert!(!route.as_str().contains("items"));
-}
-
-#[test]
-fn inbound_http_metadata_enforces_post_route_and_json() {
-    let endpoint = Endpoint::parse("https://example.test/wip").unwrap();
-    let valid = Request::builder()
-        .method(Method::POST)
-        .uri("/wip/v1/fetch")
-        .header("content-type", "application/json; charset=utf-8")
-        .body(Vec::<u8>::new())
-        .unwrap();
-    assert!(validate_http_request(&endpoint, Route::Fetch, &valid).is_ok());
-
-    let wrong_method = Request::builder()
-        .method(Method::GET)
-        .uri("/wip/v1/fetch")
-        .header("content-type", "application/json")
-        .body(Vec::<u8>::new())
-        .unwrap();
-    assert!(validate_http_request(&endpoint, Route::Fetch, &wrong_method).is_err());
-
-    let wrong_route = Request::builder()
-        .method(Method::POST)
-        .uri("/wip/v1/fetch_tree")
-        .header("content-type", "application/json")
-        .body(Vec::<u8>::new())
-        .unwrap();
-    assert!(validate_http_request(&endpoint, Route::Fetch, &wrong_route).is_err());
-}
-
-#[test]
-fn invalid_endpoint_components_are_rejected() {
-    assert!(Endpoint::parse("http://example.test/wip").is_err());
-    assert!(Endpoint::parse("/relative").is_err());
-    assert!(Endpoint::parse("https://example.test/wip?q=1").is_err());
-    assert!(Endpoint::parse("https://example.test/wip#fragment").is_err());
-}

crates/wip-interface-macros/Cargo.toml

@@ -1,9 +1,13 @@
 [package]
 name = "wip-interface-macros"
-version = "0.1.0"
+version.workspace = true
-edition = "2024"
+edition.workspace = true
+rust-version.workspace = true
 description = "Procedural macros for WIP interface declarations and DTO codecs"
-license = "MIT OR Apache-2.0"
+license.workspace = true
+repository.workspace = true
+readme = "README.md"
+documentation = "https://docs.rs/wip-interface-macros"
 
 [lib]
 proc-macro = true

crates/wip-interface-macros/LICENSE-APACHE

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

crates/wip-interface-macros/LICENSE-MIT

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Hare
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

crates/wip-interface-macros/README.md

@@ -0,0 +1,9 @@
+# wip-interface-macros
+
+Procedural-macro implementation used by [`wip-interface`](https://crates.io/crates/wip-interface).
+
+Applications should depend on `wip-interface`, which re-exports `#[interface]` and `#[derive(WipType)]` together with the traits and types required by generated code. Direct use of this implementation crate is not a supported application API.
+
+See the [API documentation](https://docs.rs/wip-interface-macros) for the exported macro entry points.
+
+Licensed under either of Apache-2.0 or MIT at your option.

crates/wip-interface/Cargo.toml

@@ -1,13 +1,17 @@
 [package]
 name = "wip-interface"
-version = "0.1.0"
+version.workspace = true
-edition = "2024"
+edition.workspace = true
+rust-version.workspace = true
 description = "Public Rust authoring API for WIP interfaces and operation value codecs"
-license = "MIT OR Apache-2.0"
+license.workspace = true
+repository.workspace = true
+readme = "README.md"
+documentation = "https://docs.rs/wip-interface"
 
 [dependencies]
-wip-interface-macros = { path = "../wip-interface-macros" }
+wip-interface-macros.workspace = true
-wip-protocol = { path = "../wip-protocol" }
+wip-protocol.workspace = true
 
 [dev-dependencies]
 trybuild = "1"

crates/wip-interface/LICENSE-APACHE

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

crates/wip-interface/LICENSE-MIT

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Hare
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

crates/wip-interface/README.md

@@ -0,0 +1,32 @@
+# wip-interface
+
+Public Rust authoring API for Web Interface Protocol (WIP) interfaces and application DTO codecs.
+
+The crate re-exports `#[interface]` and `#[derive(WipType)]`, generates Interface Descriptors and typed dispatch companions, and converts application-owned Rust values to and from the transport-independent value model.
+
+```toml
+[dependencies]
+wip-interface = "0.1.0"
+```
+
+```rust
+use wip_interface as wip;
+
+#[derive(wip::WipType)]
+struct Greeting {
+    message: String,
+}
+
+#[wip::interface]
+pub trait Greeter {
+    /// Builds a greeting.
+    ///
+    /// # Returns
+    /// The generated greeting.
+    fn greet(&self, name: String) -> wip::OperationResult<Greeting>;
+}
+```
+
+See the [API documentation](https://docs.rs/wip-interface) for supported interface syntax, DTO shapes, and failure semantics.
+
+Licensed under either of Apache-2.0 or MIT at your option.

crates/wip-protocol/Cargo.toml

@@ -1,8 +1,12 @@
 [package]
 name = "wip-protocol"
-version = "0.1.0"
+version.workspace = true
-edition = "2024"
+edition.workspace = true
+rust-version.workspace = true
 description = "Transport-independent logical model and validation for WIP"
-license = "MIT OR Apache-2.0"
+license.workspace = true
+repository.workspace = true
+readme = "README.md"
+documentation = "https://docs.rs/wip-protocol"
 
 [dependencies]

crates/wip-protocol/LICENSE-APACHE

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

crates/wip-protocol/LICENSE-MIT

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Hare
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

crates/wip-protocol/README.md

@@ -0,0 +1,14 @@
+# wip-protocol
+
+Transport-independent logical types and validation for the Web Interface Protocol (WIP).
+
+This crate defines the canonical Object and Interface Descriptor models, the three Core interaction request and response types, schema-neutral operation `Value`s, validators, protocol errors, and structural validation. It does not define an HTTP mapping, application DTOs, persistence, or network I/O.
+
+```toml
+[dependencies]
+wip-protocol = "0.1.0"
+```
+
+See the [API documentation](https://docs.rs/wip-protocol) for the complete model and validation rules.
+
+Licensed under either of Apache-2.0 or MIT at your option.

crates/wip-protocol/src/error.rs

@@ -62,7 +62,7 @@ pub enum PathSegment {
     Return,
     /// Object at a Worldspace path.
     Object(String),
-    /// Child object in a tree response.
+    /// Child object in an observation response.
     Child(String),
 }
 
@@ -163,17 +163,15 @@ pub enum ValidationErrorKind {
         /// Shared opaque object reference.
         reference: String,
     },
-    /// A `fetch_tree` request used a zero limit.
+    /// An observation omitted children before reaching the requested depth.
-    ZeroTreeLimit,
+    ChildrenMissingBeforeDepth {
-    /// A tree response exceeds the requested maximum depth.
+        /// Node depth where children were required.
-    TreeDepthExceeded {
+        depth: u32,
-        /// Requested maximum depth.
-        maximum: u32,
     },
-    /// A tree response exceeds the requested maximum node count.
+    /// An observation included children at the requested depth boundary.
-    TreeLimitExceeded {
+    ChildrenAtDepthBoundary {
-        /// Requested maximum node count.
+        /// Boundary depth where children must be unobserved.
-        limit: u32,
+        depth: u32,
     },
     /// A response refers to a different interface than its request.
     InterfaceResponseMismatch {
@@ -226,10 +224,8 @@ impl Error for ValidationError {}
 /// One core interaction whose failure codes form a closed set.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum ProtocolInteraction {
-    /// Fetch one object by its Worldspace path.
+    /// Observe one object and its indexable descendants to a requested depth.
-    Fetch,
+    Observe,
-    /// Fetch a bounded tree of objects.
-    FetchTree,
     /// Fetch one interface descriptor by its opaque reference.
     FetchInterface,
     /// Invoke one operation on a path-targeted object.
@@ -315,11 +311,11 @@ impl ProtocolErrorCode {
             OperationNotFound, OperationOutcomeUnknown, PermissionDenied, ResourceLimitExceeded,
             ValidatorMismatch, ValidatorRequired,
         };
-        use ProtocolInteraction::{CallOperation, Fetch, FetchInterface, FetchTree};
+        use ProtocolInteraction::{CallOperation, FetchInterface, Observe};
 
         match (interaction, self) {
             (_, InvalidRequest | ResourceLimitExceeded | Internal) => true,
-            (Fetch | FetchTree, NotFound) => true,
+            (Observe, NotFound) => true,
             (FetchInterface, InterfaceNotFound) => true,
             (
                 CallOperation,

crates/wip-protocol/src/lib.rs

@@ -11,8 +11,7 @@
 //! | Interface Descriptor | [`InterfaceDescriptor`] |
 //! | Named declaration and all schema expressions | [`TypeDeclaration`] / [`TypeExpr`] |
 //! | Schema-neutral primitive/composite value | [`Value`] |
-//! | `fetch` | [`FetchRequest`] / [`FetchResponse`] |
+//! | `observe` | [`ObserveRequest`] / [`ObserveResponse`] |
-//! | `fetch_tree` | [`FetchTreeRequest`] / [`FetchTreeResponse`] |
 //! | `fetch_interface` | [`FetchInterfaceRequest`] / [`FetchInterfaceResponse`] |
 //! | Object and interface call preconditions | [`Target`] / [`InterfaceTarget`] |
 //! | `call_operation` | [`CallOperationRequest`] / [`CallOperationResponse`] |
@@ -53,10 +52,9 @@ pub use error::{
 };
 pub use model::{
     CallOperationRequest, CallOperationResponse, Documentation, EnumCase, FetchInterfaceRequest,
-    FetchInterfaceResponse, FetchRequest, FetchResponse, FetchTreeRequest, FetchTreeResponse,
+    FetchInterfaceResponse, FieldDeclaration, InterfaceDescriptor, InterfaceTarget, Object,
-    FieldDeclaration, InterfaceDescriptor, InterfaceTarget, Object, ObjectTreeNode,
+    ObjectObservation, ObserveRequest, ObserveResponse, OperationDeclaration, ParameterDeclaration,
-    OperationDeclaration, ParameterDeclaration, ProtocolResult, ReturnDeclaration, Target,
+    ProtocolResult, ReturnDeclaration, Target, TypeDeclaration, TypeExpr, UnionCase, Value,
-    TypeDeclaration, TypeExpr, UnionCase, Value,
 };
 
 /// Validates a canonical absolute Worldspace path.

crates/wip-protocol/src/model.rs

@@ -218,44 +218,26 @@ impl Value {
     }
 }
 
-/// Request for the object currently published at one path.
+/// Request for the object currently published at one path and its indexable descendants.
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct FetchRequest {
+pub struct ObserveRequest {
-    /// Canonical absolute Worldspace path.
+    /// Canonical absolute path of the observation root.
     pub path: String,
-}
+    /// Maximum observed depth, where the requested object has depth zero.
-
-/// Successful `fetch` response.
-pub type FetchResponse = Object;
-
-/// Request for a bounded breadth-first object-tree observation.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct FetchTreeRequest {
-    /// Canonical absolute path of the tree root.
-    pub path: String,
-    /// Maximum depth, where the requested object has depth zero.
     pub depth: u32,
-    /// Maximum total node count, including the root. Must be nonzero.
-    pub limit: u32,
 }
 
-/// One node in a tree observation.
+/// One node in an object observation.
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct ObjectTreeNode {
+pub struct ObjectObservation {
-    /// Object observed at this tree position.
+    /// Object observed at this Worldspace position.
     pub object: Object,
-    /// Direct children in host-defined traversal order.
+    /// Complete direct children when observed, or `None` at the requested depth boundary.
-    pub children: Vec<ObjectTreeNode>,
+    pub children: Option<Vec<ObjectObservation>>,
 }
 
-/// Successful `fetch_tree` response.
+/// Successful `observe` response.
-#[derive(Debug, Clone, PartialEq, Eq)]
+pub type ObserveResponse = ObjectObservation;
-pub struct FetchTreeResponse {
-    /// Observed tree rooted at the requested path.
-    pub root: ObjectTreeNode,
-    /// Whether public indexable children were omitted by depth or limit.
-    pub truncated: bool,
-}
 
 /// Request for the current descriptor of one opaque interface reference.
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -372,35 +354,18 @@ impl InterfaceDescriptor {
     }
 }
 
-impl FetchRequest {
+impl ObserveRequest {
     /// Validates the request path.
     pub fn validate(&self) -> Result<(), ValidationError> {
         crate::validation::validate_path(&self.path)
     }
 
-    /// Validates an object returned for this request.
+    /// Validates observation shape, names, and requested depth.
     ///
     /// Failure means the Client received an invalid success response; it is not a
     /// Host-returned [`crate::ProtocolErrorCode`].
-    pub fn validate_response(&self, response: &FetchResponse) -> Result<(), ValidationError> {
+    pub fn validate_response(&self, response: &ObserveResponse) -> Result<(), ValidationError> {
-        response.validate_at_path(&self.path)
+        crate::validation::validate_observe_response(response, self)
-    }
-}
-
-impl FetchTreeRequest {
-    /// Validates the request path and nonzero node limit.
-    pub fn validate(&self) -> Result<(), ValidationError> {
-        crate::validation::validate_fetch_tree_request(self)
-    }
-}
-
-impl FetchTreeResponse {
-    /// Validates tree shape, names, depth, and node limit for `request`.
-    ///
-    /// Failure means the Client received an invalid success response; it is not a
-    /// Host-returned [`crate::ProtocolErrorCode`].
-    pub fn validate_for(&self, request: &FetchTreeRequest) -> Result<(), ValidationError> {
-        crate::validation::validate_fetch_tree_response(self, request)
     }
 }
 

crates/wip-protocol/src/validation.rs

@@ -1,10 +1,10 @@
 use std::collections::{BTreeMap, HashMap, HashSet};
 
 use crate::{
-    CallOperationRequest, FetchInterfaceRequest, FetchInterfaceResponse, FetchTreeRequest,
+    CallOperationRequest, FetchInterfaceRequest, FetchInterfaceResponse, InterfaceDescriptor,
-    FetchTreeResponse, InterfaceDescriptor, MAX_SAFE_INTEGER, MIN_SAFE_INTEGER, NameNamespace,
+    MAX_SAFE_INTEGER, MIN_SAFE_INTEGER, NameNamespace, Object, ObjectObservation, ObserveRequest,
-    Object, ObjectTreeNode, PathSegment, TypeDeclaration, TypeExpr, UNION_CASE_FIELD,
+    PathSegment, TypeDeclaration, TypeExpr, UNION_CASE_FIELD, UNION_VALUE_FIELD, ValidationError,
-    UNION_VALUE_FIELD, ValidationError, ValidationErrorKind, Value, ValueKind,
+    ValidationErrorKind, Value, ValueKind,
 };
 
 pub(crate) fn validate_object(object: &Object) -> Result<(), ValidationError> {
@@ -604,60 +604,38 @@ fn find_operation<'a>(
         })
 }
 
-pub(crate) fn validate_fetch_tree_request(
+pub(crate) fn validate_observe_response(
-    request: &FetchTreeRequest,
+    response: &ObjectObservation,
-) -> Result<(), ValidationError> {
+    request: &ObserveRequest,
-    validate_path(&request.path)?;
-    if request.limit == 0 {
-        Err(ValidationError::new(ValidationErrorKind::ZeroTreeLimit))
-    } else {
-        Ok(())
-    }
-}
-
-pub(crate) fn validate_fetch_tree_response(
-    response: &FetchTreeResponse,
-    request: &FetchTreeRequest,
 ) -> Result<(), ValidationError> {
     request.validate()?;
-    let mut node_count = 0_u32;
+    validate_observation_node(response, &request.path, 0, request.depth)
-    validate_tree_node(
-        &response.root,
-        &request.path,
-        0,
-        request.depth,
-        request.limit,
-        &mut node_count,
-    )
 }
 
-fn validate_tree_node(
+fn validate_observation_node(
-    node: &ObjectTreeNode,
+    node: &ObjectObservation,
     path: &str,
     depth: u32,
     maximum_depth: u32,
-    limit: u32,
-    node_count: &mut u32,
 ) -> Result<(), ValidationError> {
-    if depth > maximum_depth {
+    node.object.validate_at_path(path)?;
-        return Err(
+
-            ValidationError::new(ValidationErrorKind::TreeDepthExceeded {
+    if depth == maximum_depth {
-                maximum: maximum_depth,
+        if node.children.is_some() {
-            })
+            return Err(
-            .prepend(PathSegment::Object(path.to_owned())),
+                ValidationError::new(ValidationErrorKind::ChildrenAtDepthBoundary { depth })
-        );
+                    .prepend(PathSegment::Object(path.to_owned())),
-    }
+            );
-    *node_count = node_count.saturating_add(1);
+        }
-    if *node_count > limit {
+        return Ok(());
-        return Err(
-            ValidationError::new(ValidationErrorKind::TreeLimitExceeded { limit })
-                .prepend(PathSegment::Object(path.to_owned())),
-        );
     }
 
-    node.object.validate_at_path(path)?;
+    let children = node.children.as_ref().ok_or_else(|| {
+        ValidationError::new(ValidationErrorKind::ChildrenMissingBeforeDepth { depth })
+            .prepend(PathSegment::Object(path.to_owned()))
+    })?;
     let mut names = HashSet::new();
-    for child in &node.children {
+    for child in children {
         validate_object_name(&child.object.name, false)
             .map_err(|error| error.prepend(PathSegment::Child(child.object.name.clone())))?;
         if !names.insert(child.object.name.as_str()) {
@@ -673,14 +651,7 @@ fn validate_tree_node(
         } else {
             format!("{path}/{}", child.object.name)
         };
-        validate_tree_node(
+        validate_observation_node(child, &child_path, depth + 1, maximum_depth)?;
-            child,
-            &child_path,
-            depth.saturating_add(1),
-            maximum_depth,
-            limit,
-            node_count,
-        )?;
     }
     Ok(())
 }

crates/wip-protocol/tests/validation.rs

@@ -2,11 +2,11 @@ use std::collections::BTreeMap;
 
 use wip_protocol::{
     CallOperationRequest, CallOperationResponse, EnumCase, FetchInterfaceRequest,
-    FetchInterfaceResponse, FetchRequest, FetchTreeRequest, FetchTreeResponse, FieldDeclaration,
+    FetchInterfaceResponse, FieldDeclaration, INTERFACE_FORMAT_V1, InterfaceDescriptor,
-    INTERFACE_FORMAT_V1, InterfaceDescriptor, InterfaceTarget, MAX_SAFE_INTEGER, NameNamespace,
+    InterfaceTarget, MAX_SAFE_INTEGER, NameNamespace, Object, ObjectObservation, ObserveRequest,
-    Object, ObjectTreeNode, OperationDeclaration, ParameterDeclaration, PathSegment, ProtocolError,
+    OperationDeclaration, ParameterDeclaration, PathSegment, ProtocolError, ProtocolErrorCode,
-    ProtocolErrorCode, ProtocolInteraction, ProtocolResult, ReturnDeclaration, Target,
+    ProtocolInteraction, ProtocolResult, ReturnDeclaration, Target, TypeDeclaration, TypeExpr,
-    TypeDeclaration, TypeExpr, UnionCase, ValidationErrorKind, Value, ValueKind,
+    UnionCase, ValidationErrorKind, Value, ValueKind,
 };
 
 fn record(entries: impl IntoIterator<Item = (&'static str, Value)>) -> Value {
@@ -617,13 +617,26 @@ fn calls_validate_canonical_paths_named_arguments_and_unit_results() {
 }
 
 #[test]
-fn fetch_and_fetch_interface_dtos_validate_request_response_correspondence() {
+fn observe_and_fetch_interface_dtos_validate_request_response_correspondence() {
-    let fetch = FetchRequest {
+    let observe = ObserveRequest {
         path: "/articles/one".into(),
+        depth: 0,
     };
-    fetch.validate().unwrap();
+    observe.validate().unwrap();
-    fetch.validate_response(&object("one")).unwrap();
+    observe
-    assert!(fetch.validate_response(&object("two")).is_err());
+        .validate_response(&ObjectObservation {
+            object: object("one"),
+            children: None,
+        })
+        .unwrap();
+    assert!(
+        observe
+            .validate_response(&ObjectObservation {
+                object: object("two"),
+                children: None,
+            })
+            .is_err()
+    );
 
     for invalid in [
         "",
@@ -634,8 +647,9 @@ fn fetch_and_fetch_interface_dtos_validate_request_response_correspondence() {
         "/a/../b",
     ] {
         assert!(matches!(
-            FetchRequest {
+            ObserveRequest {
-                path: invalid.into()
+                path: invalid.into(),
+                depth: 0,
             }
             .validate()
             .unwrap_err()
@@ -666,61 +680,51 @@ fn fetch_and_fetch_interface_dtos_validate_request_response_correspondence() {
 }
 
 #[test]
-fn fetch_tree_dtos_validate_names_depth_limit_and_siblings() {
+fn observe_response_validates_complete_children_and_depth_boundary() {
-    let request = FetchTreeRequest {
+    let request = ObserveRequest {
         path: "/articles".into(),
         depth: 1,
-        limit: 3,
     };
-    let leaf = |name: &str| ObjectTreeNode {
+    let leaf = |name: &str| ObjectObservation {
         object: object(name),
-        children: vec![],
+        children: None,
     };
-    let response = FetchTreeResponse {
+    let response = ObjectObservation {
-        root: ObjectTreeNode {
+        object: object("articles"),
-            object: object("articles"),
+        children: Some(vec![leaf("one"), leaf("two")]),
-            children: vec![leaf("one"), leaf("two")],
-        },
-        truncated: false,
     };
-    response.validate_for(&request).unwrap();
+    request.validate_response(&response).unwrap();
 
-    let zero = FetchTreeRequest {
+    let empty = ObjectObservation {
-        limit: 0,
+        object: object("articles"),
-        ..request.clone()
+        children: Some(vec![]),
     };
-    assert_eq!(
+    request.validate_response(&empty).unwrap();
-        zero.validate().unwrap_err().kind,
-        ValidationErrorKind::ZeroTreeLimit
-    );
 
-    let shallow = FetchTreeRequest {
+    let missing = ObjectObservation {
+        object: object("articles"),
+        children: None,
+    };
+    assert!(matches!(
+        request.validate_response(&missing).unwrap_err().kind,
+        ValidationErrorKind::ChildrenMissingBeforeDepth { depth: 0 }
+    ));
+
+    let boundary = ObserveRequest {
         depth: 0,
         ..request.clone()
     };
     assert!(matches!(
-        response.validate_for(&shallow).unwrap_err().kind,
+        boundary.validate_response(&response).unwrap_err().kind,
-        ValidationErrorKind::TreeDepthExceeded { .. }
+        ValidationErrorKind::ChildrenAtDepthBoundary { depth: 0 }
     ));
 
-    let small = FetchTreeRequest {
+    let duplicate = ObjectObservation {
-        limit: 2,
+        object: object("articles"),
-        ..request.clone()
+        children: Some(vec![leaf("one"), leaf("one")]),
     };
     assert!(matches!(
-        response.validate_for(&small).unwrap_err().kind,
+        request.validate_response(&duplicate).unwrap_err().kind,
-        ValidationErrorKind::TreeLimitExceeded { .. }
-    ));
-
-    let duplicate = FetchTreeResponse {
-        root: ObjectTreeNode {
-            object: object("articles"),
-            children: vec![leaf("one"), leaf("one")],
-        },
-        truncated: false,
-    };
-    assert!(matches!(
-        duplicate.validate_for(&request).unwrap_err().kind,
         ValidationErrorKind::DuplicateName {
             namespace: NameNamespace::ChildObject,
             ..
@@ -778,22 +782,9 @@ fn assert_allowed_codes(interaction: ProtocolInteraction, expected: &[ProtocolEr
 }
 
 #[test]
-fn fetch_error_codes_are_exhaustive() {
+fn observe_error_codes_are_exhaustive() {
     assert_allowed_codes(
-        ProtocolInteraction::Fetch,
+        ProtocolInteraction::Observe,
-        &[
-            ProtocolErrorCode::InvalidRequest,
-            ProtocolErrorCode::NotFound,
-            ProtocolErrorCode::ResourceLimitExceeded,
-            ProtocolErrorCode::Internal,
-        ],
-    );
-}
-
-#[test]
-fn fetch_tree_error_codes_are_exhaustive() {
-    assert_allowed_codes(
-        ProtocolInteraction::FetchTree,
         &[
             ProtocolErrorCode::InvalidRequest,
             ProtocolErrorCode::NotFound,
@@ -840,11 +831,18 @@ fn call_operation_error_codes_are_exhaustive() {
 
 #[test]
 fn invalid_success_payloads_remain_client_local_validation_failures() {
-    let fetch = FetchRequest {
+    let observe = ObserveRequest {
         path: "/articles/one".into(),
+        depth: 0,
     };
     assert!(matches!(
-        fetch.validate_response(&object("other")).unwrap_err().kind,
+        observe
+            .validate_response(&ObjectObservation {
+                object: object("other"),
+                children: None,
+            })
+            .unwrap_err()
+            .kind,
         ValidationErrorKind::ObjectNameMismatch { .. }
     ));
 

crates/wip-public-api-example/Cargo.toml

@@ -1,12 +1,14 @@
 [package]
 name = "wip-public-api-example"
-version = "0.1.0"
+version.workspace = true
-edition = "2024"
+edition.workspace = true
+rust-version.workspace = true
 description = "Public-only end-to-end conformance consumer for the WIP Rust APIs"
-license = "MIT OR Apache-2.0"
+license.workspace = true
+repository.workspace = true
 publish = false
 
 [dependencies]
-wip-host = { path = "../wip-host" }
+wip-host.workspace = true
-wip-interface = { path = "../wip-interface" }
+wip-interface.workspace = true
-wip-protocol = { path = "../wip-protocol" }
+wip-protocol.workspace = true

crates/wip-public-api-example/src/lib.rs

@@ -190,7 +190,7 @@ pub fn run() -> Result<DemoReport, Box<dyn Error>> {
         audit: audit.clone(),
     };
 
-    let object = provider.fetch(OBJECT_PATH)?;
+    let object = provider.observe_object(OBJECT_PATH)?;
     let catalog_response = registry
         .fetch_interface(
             object

crates/wip-tui/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "wip-tui"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+description = "Interactive terminal client for exploring and operating WIP Worldspaces"
+license.workspace = true
+repository.workspace = true
+readme = "README.md"
+publish = false
+
+[dependencies]
+base64 = "0.22"
+crossterm = "0.28.1"
+ratatui = "0.29.0"
+serde_json = "1"
+ureq = "3.1.2"
+wip-client.workspace = true
+wip-http.workspace = true
+wip-protocol.workspace = true
+
+[dev-dependencies]
+tempfile = "3"
+wip-fs-server.workspace = true

crates/wip-tui/README.md

@@ -0,0 +1,148 @@
+# wip-tui
+
+`wip-tui` is an interactive terminal client for exploring and operating a WIP
+Worldspace. It is a presentation and terminal-interaction layer over
+`wip-client`: Known Space, request identity, validators, immutable operation call
+contexts, stale transitions, response classification, and bounded histories remain
+owned by the client runtime.
+
+## Start
+
+Supply one `http` or `https` endpoint:
+
+```console
+cargo run -p wip-tui -- --endpoint https://wip.example.test/api/wip
+```
+
+The same canonical endpoint is used unchanged to construct requests, perform
+HTTP I/O, and partition the client cache. WIP over HTTP does not define separate
+HTTPS and development-HTTP profiles; URL scheme, TLS, certificate, authentication,
+and proxy policy belong to the HTTP implementation and deployment.
+
+The endpoint may instead be supplied as `WIP_ENDPOINT`. A non-secret cache
+partition identity may be supplied with `--security-context NAME` or
+`WIP_SECURITY_CONTEXT`. The default request timeout is 30 seconds and can be
+changed with `--timeout SECONDS`.
+
+An Authorization header can be read from an environment variable without placing
+its value in arguments, application state, errors, snapshots, or debug output:
+
+```console
+export WIP_AUTHORIZATION='Bearer …'
+cargo run -p wip-tui -- https://wip.example.test/wip
+```
+
+Use `--authorization-env OTHER_VARIABLE` to select another variable. The value is
+redacted from `Debug` and is never rendered. Shell and process environment security
+remain the operator's responsibility.
+
+### Filesystem server example
+
+In one terminal:
+
+```console
+mkdir -p /tmp/wip-example
+printf 'hello world' >/tmp/wip-example/notes.txt
+cargo run -p wip-fs-server -- \
+  --root /tmp/wip-example \
+  --listen 127.0.0.1:8080 \
+  --base-path /wip \
+  --read-write
+```
+
+In another:
+
+```console
+cargo run -p wip-tui -- http://127.0.0.1:8080/wip
+```
+
+Expand `/`, select `notes.txt`, focus the Interface/Operation pane, and choose
+`read`; descriptors advertised by visible Objects are normally prefetched already.
+The editor labels `offset` and `length` as optional; leave both blank to read the
+bounded file. `Bytes` results are shown as a bounded hex preview. For `replace`,
+enter `contents` as RFC 4648 base64—for example, `dXBkYXRlZA==` for
+`updated`—then review the target Entry, interface reference, operation, and value
+on the confirmation screen before pressing Enter again.
+
+## Keyboard bindings
+
+All required actions are keyboard-accessible.
+
+| Key | Action |
+| --- | --- |
+| `↑`/`k`, `↓`/`j` | Move within the focused tree, operation list, history, or editor |
+| `→`/`l`, `Enter` | Expand a tree node lazily; load/select an interface or operation |
+| `←`/`h` | Collapse a node or move to its parent |
+| `Tab` | Cycle Tree → Selected Entry → Operations → History |
+| `r` | Reobserve the selected Entry and its direct subtree |
+| `c` | Cancel the newest retrieval; a dispatched operation is never presented as canceled |
+| `R` | Reconnect after connection failure |
+| `?` | Open help |
+| `Esc` | Close a modal or return to the tree |
+| `q`, `Ctrl-C` | Exit and restore the terminal |
+
+Inside an argument editor, printable keys are field input, arrows move fields,
+Backspace edits, Enter validates, and Esc cancels. The confirmation screen requires
+a second explicit Enter (or `e`) to execute once. There is no operation auto-retry.
+
+## Screen model
+
+- **Worldspace tree** starts at `/`, lazily materializes expanded nodes, and
+  prefetches children for each visible Object so emptiness and the next expansion
+  frontier are known without selecting that Object first. Text labels distinguish
+  unloaded, loading, empty, stale, and failed state; color is supplemental. Every
+  successful expansion is complete for its requested depth.
+- **Selected Entry** shows only public WIP path, object name, description, ordered
+  interfaces, and freshness. Validators, credentials, Host internals, and backend
+  paths are deliberately hidden. If current metadata disappears, old text is not
+  presented as current.
+- **Interfaces / Operations** identifies every operation by `(interface reference,
+  operation name)`. Descriptor lookahead follows fresh visible Objects, shares the
+  client's in-flight/cache bounds, and never retries retained failures implicitly.
+  The pane shows descriptor documentation, ordered parameters, required/optional
+  status, and result types.
+- **Argument editor** supports Unit, Boolean, Integer, Number, String, base64 Bytes,
+  Record, List, Entry, Enum, Union, Json, and descriptor-local named types. Record,
+  List, Union, and Json values use JSON syntax. Union input is
+  `{"$case":"name","value":…}` when the selected case has a payload. Diagnostics
+  remain attached to the failing field.
+- **Recent results / diagnostics** explicitly distinguishes success, Host failure,
+  invalid protocol response, transport failure, client-local failure, and unknown
+  operation outcome. Large values, bytes, nesting, and control characters are
+  bounded before rendering. Only descriptor-declared `Entry` results become
+  navigation targets; path-looking String or Json values do not.
+
+Terminals below 48×14 show a minimum-size screen instead of attempting the full
+layout.
+
+## Validator and failure behavior
+
+Object and interface validators are observed and attached automatically by
+`wip-client`; users neither copy nor edit them. A successful operation may update the
+cached Object validator but does not by itself make the Object observation stale.
+Validator mismatch, interface mismatch, `OperationOutcomeUnknown`, undecodable
+post-dispatch responses, and post-dispatch timeout/disconnect are displayed using
+the runtime's authoritative transition.
+
+For an unknown outcome, the UI states that execution or side effects may have
+occurred, marks the related Entry stale, and tells the user to refresh. Refreshing
+does not recreate the call: the user must select the operation, review fresh input,
+and explicitly execute again. The same no-auto-retry rule applies after validator
+or interface mismatch.
+
+Retrieval work runs on I/O workers while the input/render loop continues. Responses
+return with the original `RequestId`, so an old completion cannot populate another
+Entry's details. Canceling a retrieval records a local cancellation and drops its
+late response. Once an operation crosses dispatch, cancellation is never described
+as undoing execution.
+
+## Tests
+
+The library form keeps reducers and rendering independent of a real terminal.
+`ratatui::TestBackend` snapshots cover tree/detail/result states and the minimum-size
+fallback. Unit tests cover reducer focus, selection, modal confirmation, key
+translation, descriptor inputs, bounded values, and descriptor-directed Entry
+results. The real HTTP integration test launches `wip-fs-server` on a temporary
+root and covers tree selection, reads, validator-protected replacement, external
+stale-validator rejection without retry, explicit refresh/re-execution, and
+symlink confinement.

crates/wip-tui/src/app.rs

@@ -0,0 +1,952 @@
+//! Pure application state, selection, modal, focus, and key reducer.
+
+use std::collections::{BTreeMap, BTreeSet};
+
+use wip_client::{InterfaceObservation, ObjectObservation, ObservationState, TreeObservation};
+use wip_protocol::{InterfaceDescriptor, Object, Value};
+
+use crate::editor::ArgumentEditor;
+
+const MAX_PRESENTATION_ENTRIES: usize = 2048;
+const MAX_PRESENTATION_INTERFACES: usize = 256;
+
+/// A terminal-independent key understood by the reducer.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum InputKey {
+    /// Up arrow or `k`.
+    Up,
+    /// Down arrow or `j`.
+    Down,
+    /// Left arrow or `h`.
+    Left,
+    /// Right arrow or `l`.
+    Right,
+    /// Focus the next pane.
+    Tab,
+    /// Activate the selected item.
+    Enter,
+    /// Close the current modal or return to the tree.
+    Escape,
+    /// Delete one editor character.
+    Backspace,
+    /// Refresh the selected Entry.
+    Refresh,
+    /// Cancel the newest cancel-safe retrieval.
+    CancelRead,
+    /// Show key help.
+    Help,
+    /// Quit the application.
+    Quit,
+    /// Reconnect after startup or transport failure.
+    Reconnect,
+    /// A printable editor character.
+    Character(char),
+}
+
+/// Pane receiving navigation keys.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Focus {
+    /// Worldspace tree.
+    Tree,
+    /// Selected Entry metadata.
+    Entry,
+    /// Interfaces and operations.
+    Operations,
+    /// Recent result and diagnostic history.
+    History,
+}
+
+impl Focus {
+    fn next(self) -> Self {
+        match self {
+            Self::Tree => Self::Entry,
+            Self::Entry => Self::Operations,
+            Self::Operations => Self::History,
+            Self::History => Self::Tree,
+        }
+    }
+}
+
+/// Connection lifecycle shown without relying on color.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ConnectionState {
+    /// No request has been attempted.
+    Disconnected,
+    /// Initial root request or reconnect is in progress.
+    Connecting,
+    /// The root was observed successfully.
+    Connected,
+    /// Connection failed; reconnect and exit remain available.
+    Failed(String),
+}
+
+/// Presentation-safe observation state.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ViewState {
+    /// No observation has been requested.
+    Unloaded,
+    /// One request is in flight.
+    Loading(u64),
+    /// The observation is current.
+    Fresh,
+    /// The retained value needs reobservation.
+    Stale,
+    /// The latest attempt failed.
+    Error(String),
+}
+
+impl From<&ObservationState> for ViewState {
+    fn from(value: &ObservationState) -> Self {
+        match value {
+            ObservationState::Loading(id) => Self::Loading(id.get()),
+            ObservationState::Fresh => Self::Fresh,
+            ObservationState::Stale => Self::Stale,
+            ObservationState::Error(error) => Self::Error(error.to_string()),
+        }
+    }
+}
+
+/// One materialized tree Entry.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct EntryView {
+    /// Canonical WIP path.
+    pub path: String,
+    /// Latest object when retained by the client runtime.
+    pub object: Option<Object>,
+    /// Object observation state.
+    pub state: ViewState,
+    /// Direct child paths in Host order.
+    pub children: Vec<String>,
+    /// Expansion observation state.
+    pub tree_state: ViewState,
+    /// Whether the user expanded this row.
+    pub expanded: bool,
+}
+
+impl EntryView {
+    fn placeholder(path: impl Into<String>) -> Self {
+        Self {
+            path: path.into(),
+            object: None,
+            state: ViewState::Unloaded,
+            children: Vec::new(),
+            tree_state: ViewState::Unloaded,
+            expanded: false,
+        }
+    }
+}
+
+/// Cached interface descriptor state used by presentation.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct InterfaceView {
+    /// Opaque interface reference.
+    pub reference: String,
+    /// Descriptor when accepted by the client runtime.
+    pub descriptor: Option<InterfaceDescriptor>,
+    /// Descriptor observation state.
+    pub state: ViewState,
+}
+
+/// Stable result/diagnostic category.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum HistoryKind {
+    /// A descriptor-validated operation result.
+    Success,
+    /// A valid Host-declared failure.
+    DomainFailure,
+    /// An invalid protocol response.
+    ProtocolError,
+    /// Network or TLS failure.
+    TransportFailure,
+    /// Client-local validation or capacity failure.
+    ClientFailure,
+    /// Dispatch occurred but execution or commit is uncertain.
+    OutcomeUnknown,
+    /// Informational request state.
+    Information,
+}
+
+/// One bounded recent result or diagnostic.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct HistoryItem {
+    /// Explicit outcome category.
+    pub kind: HistoryKind,
+    /// Short bounded heading.
+    pub title: String,
+    /// Bounded, terminal-safe detail.
+    pub detail: String,
+    /// Navigation target only when declared as descriptor `Entry`.
+    pub entry_target: Option<String>,
+}
+
+/// Kind of request currently in flight.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum InFlightKind {
+    /// Object refresh.
+    Object(String),
+    /// Tree expansion or refresh.
+    Tree(String),
+    /// Descriptor fetch.
+    Interface(String),
+    /// Explicit operation call.
+    Operation {
+        /// Target path.
+        path: String,
+        /// Interface reference.
+        interface: String,
+        /// Operation name.
+        operation: String,
+        /// Whether the transport dispatch boundary was crossed.
+        dispatched: bool,
+    },
+}
+
+impl InFlightKind {
+    /// Whether dropping the response is a safe cancellation operation.
+    #[must_use]
+    pub fn cancel_safe(&self) -> bool {
+        !matches!(self, Self::Operation { .. })
+    }
+}
+
+/// Active overlay.
+#[derive(Debug, Clone, PartialEq)]
+pub enum Modal {
+    /// No overlay.
+    None,
+    /// Keyboard help.
+    Help,
+    /// Descriptor-driven field editor.
+    Editor(ArgumentEditor),
+    /// Explicit pre-execution confirmation.
+    Confirm {
+        /// Editor retained when confirmation is cancelled.
+        editor: ArgumentEditor,
+        /// Validated arguments that will be sent.
+        arguments: BTreeMap<String, Value>,
+    },
+}
+
+/// Side effect requested by the pure reducer.
+#[derive(Debug, Clone, PartialEq)]
+pub enum Action {
+    /// Expand one node lazily.
+    Expand {
+        /// Tree root path.
+        path: String,
+    },
+    /// Reobserve an Entry and its direct children.
+    Refresh {
+        /// Selected path.
+        path: String,
+    },
+    /// Retrieve one interface descriptor.
+    FetchInterface(String),
+    /// Execute only after explicit confirmation.
+    Execute {
+        /// Entry target.
+        path: String,
+        /// Interface reference.
+        interface: String,
+        /// Operation name.
+        operation: String,
+        /// Descriptor-validated arguments.
+        arguments: BTreeMap<String, Value>,
+    },
+    /// Cancel the newest safe retrieval.
+    CancelRead,
+    /// Reconnect and observe the root.
+    Reconnect,
+    /// Navigate to a descriptor-declared Entry result.
+    NavigateEntry(String),
+    /// Exit normally.
+    Quit,
+}
+
+/// Complete presentation model.
+#[derive(Debug, Clone, PartialEq)]
+pub struct App {
+    /// Effective endpoint label (never credential material).
+    pub endpoint: String,
+    /// Connection lifecycle.
+    pub connection: ConnectionState,
+    /// Materialized tree nodes by path.
+    pub entries: BTreeMap<String, EntryView>,
+    /// Selected Entry path.
+    pub selected_path: String,
+    /// Focused pane.
+    pub focus: Focus,
+    /// Interface descriptor views by opaque reference.
+    pub interfaces: BTreeMap<String, InterfaceView>,
+    /// Selected row in the flattened interface/operation view.
+    pub operation_cursor: usize,
+    /// Selected recent-history row.
+    pub history_cursor: usize,
+    /// Active overlay.
+    pub modal: Modal,
+    /// In-flight requests keyed by client request identity.
+    pub in_flight: BTreeMap<u64, InFlightKind>,
+    /// Recent result and diagnostic history, newest first.
+    pub history: Vec<HistoryItem>,
+    /// Maximum retained presentation history.
+    pub history_limit: usize,
+    /// One-line status for local action feedback.
+    pub status: String,
+}
+
+impl App {
+    /// Creates a disconnected model with `/` selected.
+    #[must_use]
+    pub fn new(endpoint: impl Into<String>) -> Self {
+        let mut entries = BTreeMap::new();
+        let mut root = EntryView::placeholder("/");
+        root.expanded = true;
+        entries.insert("/".into(), root);
+        Self {
+            endpoint: endpoint.into(),
+            connection: ConnectionState::Disconnected,
+            entries,
+            selected_path: "/".into(),
+            focus: Focus::Tree,
+            interfaces: BTreeMap::new(),
+            operation_cursor: 0,
+            history_cursor: 0,
+            modal: Modal::None,
+            in_flight: BTreeMap::new(),
+            history: Vec::new(),
+            history_limit: 64,
+            status: "press ? for help".into(),
+        }
+    }
+
+    /// Applies one key and returns requested effects without performing I/O.
+    pub fn reduce(&mut self, key: InputKey) -> Vec<Action> {
+        match std::mem::replace(&mut self.modal, Modal::None) {
+            Modal::Help => {
+                if !matches!(key, InputKey::Escape | InputKey::Help) {
+                    self.modal = Modal::Help;
+                }
+                return Vec::new();
+            }
+            Modal::Editor(mut editor) => {
+                match key {
+                    InputKey::Escape => {}
+                    InputKey::Up => {
+                        editor.previous_field();
+                        self.modal = Modal::Editor(editor);
+                    }
+                    InputKey::Down | InputKey::Tab => {
+                        editor.next_field();
+                        self.modal = Modal::Editor(editor);
+                    }
+                    InputKey::Backspace => {
+                        editor.backspace();
+                        self.modal = Modal::Editor(editor);
+                    }
+                    InputKey::Character(character) => {
+                        editor.insert(character);
+                        self.modal = Modal::Editor(editor);
+                    }
+                    InputKey::Enter => match editor.validate() {
+                        Ok(arguments) => self.modal = Modal::Confirm { editor, arguments },
+                        Err(_) => self.modal = Modal::Editor(editor),
+                    },
+                    _ => self.modal = Modal::Editor(editor),
+                }
+                return Vec::new();
+            }
+            Modal::Confirm { editor, arguments } => match key {
+                InputKey::Escape => {
+                    self.modal = Modal::Editor(editor);
+                    return Vec::new();
+                }
+                InputKey::Enter | InputKey::Character('e') => {
+                    let action = Action::Execute {
+                        path: self.selected_path.clone(),
+                        interface: editor.interface.clone(),
+                        operation: editor.operation.name.clone(),
+                        arguments,
+                    };
+                    self.status =
+                        "operation confirmed; preparing request (not yet dispatched)".into();
+                    return vec![action];
+                }
+                _ => {
+                    self.modal = Modal::Confirm { editor, arguments };
+                    return Vec::new();
+                }
+            },
+            Modal::None => {}
+        }
+
+        if key == InputKey::Help {
+            self.modal = Modal::Help;
+            return Vec::new();
+        }
+        if key == InputKey::Quit {
+            return vec![Action::Quit];
+        }
+        if key == InputKey::Reconnect {
+            return vec![Action::Reconnect];
+        }
+        if key == InputKey::CancelRead {
+            return vec![Action::CancelRead];
+        }
+        if key == InputKey::Tab {
+            self.focus = self.focus.next();
+            return Vec::new();
+        }
+
+        match self.focus {
+            Focus::Tree => self.reduce_tree(key),
+            Focus::Operations => self.reduce_operations(key),
+            Focus::History => self.reduce_history(key),
+            Focus::Entry => {
+                if key == InputKey::Escape {
+                    self.focus = Focus::Tree;
+                } else if key == InputKey::Refresh {
+                    return vec![self.refresh_action()];
+                }
+                Vec::new()
+            }
+        }
+    }
+
+    fn reduce_tree(&mut self, key: InputKey) -> Vec<Action> {
+        let visible = self.visible_paths();
+        let position = visible
+            .iter()
+            .position(|path| path == &self.selected_path)
+            .unwrap_or(0);
+        match key {
+            InputKey::Up if position > 0 => self.selected_path = visible[position - 1].clone(),
+            InputKey::Down if position + 1 < visible.len() => {
+                self.selected_path = visible[position + 1].clone();
+            }
+            InputKey::Right | InputKey::Enter => {
+                let node = self
+                    .entries
+                    .entry(self.selected_path.clone())
+                    .or_insert_with(|| EntryView::placeholder(&self.selected_path));
+                node.expanded = true;
+                if !matches!(node.tree_state, ViewState::Fresh) {
+                    return vec![Action::Expand {
+                        path: node.path.clone(),
+                    }];
+                }
+            }
+            InputKey::Left => {
+                let node = self
+                    .entries
+                    .get_mut(&self.selected_path)
+                    .expect("selected Entry exists");
+                if node.expanded {
+                    node.expanded = false;
+                } else if self.selected_path != "/" {
+                    self.selected_path = parent_path(&self.selected_path);
+                }
+            }
+            InputKey::Refresh => return vec![self.refresh_action()],
+            _ => {}
+        }
+        self.operation_cursor = 0;
+        Vec::new()
+    }
+
+    fn reduce_operations(&mut self, key: InputKey) -> Vec<Action> {
+        let rows = self.operation_rows();
+        match key {
+            InputKey::Up => self.operation_cursor = self.operation_cursor.saturating_sub(1),
+            InputKey::Down if self.operation_cursor + 1 < rows.len() => self.operation_cursor += 1,
+            InputKey::Refresh => return vec![self.refresh_action()],
+            InputKey::Escape => self.focus = Focus::Tree,
+            InputKey::Enter => {
+                if let Some(row) = rows.get(self.operation_cursor) {
+                    if let Some(operation_name) = &row.operation {
+                        if let Some(interface) = self.interfaces.get(&row.interface)
+                            && let Some(descriptor) = &interface.descriptor
+                            && let Some(operation) = descriptor
+                                .operations
+                                .iter()
+                                .find(|operation| operation.name == *operation_name)
+                        {
+                            self.modal = Modal::Editor(ArgumentEditor::new(
+                                row.interface.clone(),
+                                descriptor.clone(),
+                                operation.clone(),
+                            ));
+                        }
+                    } else {
+                        return vec![Action::FetchInterface(row.interface.clone())];
+                    }
+                }
+            }
+            _ => {}
+        }
+        Vec::new()
+    }
+
+    fn reduce_history(&mut self, key: InputKey) -> Vec<Action> {
+        match key {
+            InputKey::Up => self.history_cursor = self.history_cursor.saturating_sub(1),
+            InputKey::Down if self.history_cursor + 1 < self.history.len() => {
+                self.history_cursor += 1;
+            }
+            InputKey::Enter => {
+                if let Some(path) = self
+                    .history
+                    .get(self.history_cursor)
+                    .and_then(|item| item.entry_target.clone())
+                {
+                    return vec![Action::NavigateEntry(path)];
+                }
+            }
+            InputKey::Escape => self.focus = Focus::Tree,
+            _ => {}
+        }
+        Vec::new()
+    }
+
+    fn refresh_action(&self) -> Action {
+        Action::Refresh {
+            path: self.selected_path.clone(),
+        }
+    }
+
+    /// Records a pending request separately by interaction type.
+    pub fn request_started(&mut self, id: u64, kind: InFlightKind) {
+        match &kind {
+            InFlightKind::Object(path) => {
+                self.ensure_entry(path).state = ViewState::Loading(id);
+            }
+            InFlightKind::Tree(path) => {
+                let entry = self.ensure_entry(path);
+                entry.state = ViewState::Loading(id);
+                entry.tree_state = ViewState::Loading(id);
+            }
+            InFlightKind::Interface(reference) => {
+                self.ensure_interface(reference).state = ViewState::Loading(id);
+            }
+            InFlightKind::Operation { .. } => {}
+        }
+        self.in_flight.insert(id, kind);
+    }
+
+    /// Marks an operation as handed to the transport.
+    pub fn request_dispatched(&mut self, id: u64) {
+        if let Some(InFlightKind::Operation { dispatched, .. }) = self.in_flight.get_mut(&id) {
+            *dispatched = true;
+            self.status = "operation dispatched once; automatic retry is disabled".into();
+        }
+    }
+
+    /// Removes a completed request identity.
+    pub fn request_finished(&mut self, id: u64) -> Option<InFlightKind> {
+        self.in_flight.remove(&id)
+    }
+
+    /// Applies an object observation from `wip-client`.
+    pub fn apply_object(&mut self, observation: ObjectObservation) {
+        let entry = self.ensure_entry(&observation.path);
+        entry.object = observation.object;
+        entry.state = ViewState::from(&observation.state);
+    }
+
+    /// Applies a lazy tree observation and ensures child placeholders exist.
+    pub fn apply_tree(&mut self, observation: TreeObservation) {
+        let children = observation.children.clone();
+        let entry = self.ensure_entry(&observation.path);
+        entry.children = children.clone();
+        entry.tree_state = ViewState::from(&observation.state);
+        for path in children {
+            self.ensure_entry(&path);
+        }
+    }
+
+    /// Applies one interface observation from `wip-client`.
+    pub fn apply_interface(&mut self, observation: InterfaceObservation) {
+        let view = self.ensure_interface(&observation.reference);
+        *view = InterfaceView {
+            reference: observation.reference,
+            descriptor: observation.descriptor,
+            state: ViewState::from(&observation.state),
+        };
+    }
+
+    /// Replaces current Entry details from the client's current snapshot.
+    pub fn sync_object(&mut self, path: &str, observation: Option<ObjectObservation>) {
+        match observation {
+            Some(observation) => self.apply_object(observation),
+            None => {
+                let entry = self.ensure_entry(path);
+                entry.object = None;
+                entry.state = ViewState::Stale;
+            }
+        }
+    }
+
+    /// Selects a known or newly discovered descriptor-declared Entry path.
+    pub fn navigate_entry(&mut self, path: impl Into<String>) {
+        let path = path.into();
+        self.ensure_entry(&path);
+        self.selected_path = path;
+        self.focus = Focus::Tree;
+    }
+
+    /// Adds one bounded recent item.
+    pub fn push_history(&mut self, item: HistoryItem) {
+        self.history.insert(0, item);
+        self.history.truncate(self.history_limit);
+        self.history_cursor = 0;
+    }
+
+    /// Returns visible tree paths in display order.
+    #[must_use]
+    pub fn visible_paths(&self) -> Vec<String> {
+        let mut visible = Vec::new();
+        let mut seen = BTreeSet::new();
+        self.collect_visible("/", &mut seen, &mut visible);
+        if !seen.contains(&self.selected_path) && self.entries.contains_key(&self.selected_path) {
+            visible.push(self.selected_path.clone());
+        }
+        visible
+    }
+
+    /// Returns interface references advertised by fresh visible Objects in display
+    /// and per-Object declaration order, with duplicates removed.
+    #[must_use]
+    pub fn visible_interface_references(&self) -> Vec<String> {
+        let mut references = Vec::new();
+        let mut seen = BTreeSet::new();
+        for path in self.visible_paths() {
+            let Some(object) = self
+                .entries
+                .get(&path)
+                .filter(|entry| entry.state == ViewState::Fresh)
+                .and_then(|entry| entry.object.as_ref())
+            else {
+                continue;
+            };
+            for reference in &object.interfaces {
+                if seen.insert(reference.clone()) {
+                    references.push(reference.clone());
+                }
+            }
+        }
+        references
+    }
+
+    fn collect_visible(&self, path: &str, seen: &mut BTreeSet<String>, visible: &mut Vec<String>) {
+        if !seen.insert(path.to_owned()) {
+            return;
+        }
+        visible.push(path.to_owned());
+        let Some(entry) = self.entries.get(path) else {
+            return;
+        };
+        if entry.expanded {
+            for child in &entry.children {
+                self.collect_visible(child, seen, visible);
+            }
+        }
+    }
+
+    /// Returns flattened interface headers and operations for the selected Entry.
+    #[must_use]
+    pub fn operation_rows(&self) -> Vec<OperationRow> {
+        let Some(object) = self
+            .entries
+            .get(&self.selected_path)
+            .filter(|entry| entry.state == ViewState::Fresh)
+            .and_then(|entry| entry.object.as_ref())
+        else {
+            return Vec::new();
+        };
+        let mut rows = Vec::new();
+        for reference in &object.interfaces {
+            rows.push(OperationRow {
+                interface: reference.clone(),
+                operation: None,
+            });
+            if let Some(descriptor) = self
+                .interfaces
+                .get(reference)
+                .filter(|view| view.state == ViewState::Fresh)
+                .and_then(|view| view.descriptor.as_ref())
+            {
+                rows.extend(descriptor.operations.iter().map(|operation| OperationRow {
+                    interface: reference.clone(),
+                    operation: Some(operation.name.clone()),
+                }));
+            }
+        }
+        rows
+    }
+
+    fn ensure_entry(&mut self, path: &str) -> &mut EntryView {
+        if !self.entries.contains_key(path) && self.entries.len() >= MAX_PRESENTATION_ENTRIES {
+            let candidate = self
+                .entries
+                .iter()
+                .find(|(candidate, entry)| {
+                    candidate.as_str() != "/"
+                        && candidate.as_str() != self.selected_path
+                        && matches!(
+                            entry.state,
+                            ViewState::Unloaded | ViewState::Stale | ViewState::Error(_)
+                        )
+                })
+                .or_else(|| {
+                    self.entries.iter().find(|(candidate, entry)| {
+                        candidate.as_str() != "/"
+                            && candidate.as_str() != self.selected_path
+                            && !matches!(entry.state, ViewState::Loading(_))
+                    })
+                })
+                .map(|(candidate, _)| candidate.clone());
+            if let Some(candidate) = candidate {
+                self.entries.remove(&candidate);
+                for entry in self.entries.values_mut() {
+                    entry.children.retain(|child| child != &candidate);
+                }
+            }
+        }
+        self.entries
+            .entry(path.to_owned())
+            .or_insert_with(|| EntryView::placeholder(path))
+    }
+
+    fn ensure_interface(&mut self, reference: &str) -> &mut InterfaceView {
+        if !self.interfaces.contains_key(reference)
+            && self.interfaces.len() >= MAX_PRESENTATION_INTERFACES
+        {
+            let protected = self
+                .entries
+                .get(&self.selected_path)
+                .and_then(|entry| entry.object.as_ref())
+                .map(|object| object.interfaces.iter().cloned().collect::<BTreeSet<_>>())
+                .unwrap_or_default();
+            let candidate = self
+                .interfaces
+                .iter()
+                .find(|(candidate, interface)| {
+                    !protected.contains(*candidate)
+                        && !matches!(interface.state, ViewState::Loading(_))
+                })
+                .or_else(|| {
+                    self.interfaces
+                        .iter()
+                        .find(|(_, interface)| !matches!(interface.state, ViewState::Loading(_)))
+                })
+                .map(|(candidate, _)| candidate.clone());
+            if let Some(candidate) = candidate {
+                self.interfaces.remove(&candidate);
+            }
+        }
+        self.interfaces
+            .entry(reference.to_owned())
+            .or_insert_with(|| InterfaceView {
+                reference: reference.to_owned(),
+                descriptor: None,
+                state: ViewState::Unloaded,
+            })
+    }
+}
+
+/// One row in the combined Interface and Operation pane.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct OperationRow {
+    /// Interface reference, which participates in operation identity.
+    pub interface: String,
+    /// Operation name, or `None` for the interface heading.
+    pub operation: Option<String>,
+}
+
+/// Returns the canonical parent of a non-root path.
+#[must_use]
+pub fn parent_path(path: &str) -> String {
+    match path.rsplit_once('/') {
+        Some(("", _)) | None => "/".into(),
+        Some((parent, _)) => parent.into(),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use wip_protocol::{INTERFACE_FORMAT_V1, OperationDeclaration, ReturnDeclaration, TypeExpr};
+
+    fn object(name: &str, interfaces: &[&str]) -> Object {
+        Object {
+            name: name.into(),
+            description: Some(format!("{name} description")),
+            interfaces: interfaces.iter().map(|value| (*value).into()).collect(),
+            r#ref: None,
+            validator: None,
+        }
+    }
+
+    #[test]
+    fn tree_navigation_and_lazy_expansion_are_pure() {
+        let mut app = App::new("https://example.test/wip");
+        app.apply_tree(TreeObservation {
+            path: "/".into(),
+            children: vec!["/a".into(), "/b".into()],
+            revision: request_id(),
+            state: ObservationState::Fresh,
+        });
+        assert_eq!(app.visible_paths(), ["/", "/a", "/b"]);
+        app.reduce(InputKey::Down);
+        assert_eq!(app.selected_path, "/a");
+        assert!(matches!(
+            app.reduce(InputKey::Right).as_slice(),
+            [Action::Expand { path }] if path == "/a"
+        ));
+    }
+
+    #[test]
+    fn visible_interface_references_are_ordered_deduplicated_and_fresh() {
+        let mut app = App::new("https://example.test/wip");
+        app.apply_tree(TreeObservation {
+            path: "/".into(),
+            children: vec!["/a".into(), "/stale".into()],
+            revision: request_id(),
+            state: ObservationState::Fresh,
+        });
+        app.apply_object(ObjectObservation {
+            path: "/".into(),
+            object: Some(object("", &["root", "shared"])),
+            validator: None,
+            state: ObservationState::Fresh,
+        });
+        app.apply_object(ObjectObservation {
+            path: "/a".into(),
+            object: Some(object("a", &["shared", "child"])),
+            validator: None,
+            state: ObservationState::Fresh,
+        });
+        app.apply_object(ObjectObservation {
+            path: "/stale".into(),
+            object: Some(object("stale", &["ignored"])),
+            validator: None,
+            state: ObservationState::Stale,
+        });
+        app.apply_tree(TreeObservation {
+            path: "/a".into(),
+            children: vec!["/a/hidden".into()],
+            revision: request_id(),
+            state: ObservationState::Fresh,
+        });
+        app.apply_object(ObjectObservation {
+            path: "/a/hidden".into(),
+            object: Some(object("hidden", &["hidden"])),
+            validator: None,
+            state: ObservationState::Fresh,
+        });
+
+        assert_eq!(
+            app.visible_interface_references(),
+            ["root", "shared", "child"]
+        );
+    }
+
+    #[test]
+    fn focus_modal_and_explicit_confirmation_gate_execution() {
+        let mut app = App::new("https://example.test/wip");
+        app.apply_object(ObjectObservation {
+            path: "/".into(),
+            object: Some(object("", &["iface"])),
+            validator: None,
+            state: ObservationState::Fresh,
+        });
+        let descriptor = InterfaceDescriptor {
+            format: INTERFACE_FORMAT_V1.into(),
+            documentation: None,
+            types: vec![],
+            operations: vec![OperationDeclaration {
+                name: "ping".into(),
+                documentation: None,
+                parameters: vec![],
+                returns: ReturnDeclaration {
+                    documentation: None,
+                    r#type: TypeExpr::Unit,
+                },
+            }],
+        };
+        app.apply_interface(InterfaceObservation {
+            reference: "iface".into(),
+            descriptor: Some(descriptor),
+            validator: None,
+            state: ObservationState::Fresh,
+        });
+        app.focus = Focus::Operations;
+        app.operation_cursor = 1;
+        assert!(app.reduce(InputKey::Enter).is_empty());
+        assert!(matches!(app.modal, Modal::Editor(_)));
+        assert!(app.reduce(InputKey::Enter).is_empty());
+        assert!(matches!(app.modal, Modal::Confirm { .. }));
+        assert!(matches!(
+            app.reduce(InputKey::Enter).as_slice(),
+            [Action::Execute { operation, .. }] if operation == "ping"
+        ));
+    }
+
+    #[test]
+    fn presentation_maps_enforce_client_sized_hard_bounds() {
+        let mut app = App::new("https://example.test/wip");
+        for index in 0..(MAX_PRESENTATION_ENTRIES + 100) {
+            app.navigate_entry(format!("/discovered-{index}"));
+            app.selected_path = "/".into();
+        }
+        assert!(app.entries.len() <= MAX_PRESENTATION_ENTRIES);
+        assert!(app.entries.contains_key("/"));
+
+        for index in 0..(MAX_PRESENTATION_INTERFACES + 50) {
+            app.apply_interface(InterfaceObservation {
+                reference: format!("interface-{index}"),
+                descriptor: None,
+                validator: None,
+                state: ObservationState::Fresh,
+            });
+        }
+        assert!(app.interfaces.len() <= MAX_PRESENTATION_INTERFACES);
+    }
+
+    #[test]
+    fn result_navigation_only_uses_explicit_entry_target() {
+        let mut app = App::new("https://example.test/wip");
+        app.push_history(HistoryItem {
+            kind: HistoryKind::Success,
+            title: "string".into(),
+            detail: "/looks/like/a/path".into(),
+            entry_target: None,
+        });
+        app.focus = Focus::History;
+        assert!(app.reduce(InputKey::Enter).is_empty());
+        app.push_history(HistoryItem {
+            kind: HistoryKind::Success,
+            title: "Entry".into(),
+            detail: "/actual".into(),
+            entry_target: Some("/actual".into()),
+        });
+        assert_eq!(
+            app.reduce(InputKey::Enter),
+            vec![Action::NavigateEntry("/actual".into())]
+        );
+    }
+
+    fn request_id() -> wip_client::RequestId {
+        // A request identity has no public constructor; derive one through the runtime.
+        let mut client = wip_client::Client::new(
+            wip_client::ClientLimits::new(1, 4, 4, 4, 4).unwrap(),
+            wip_http::Limits::new(1024, 1024, 8).unwrap(),
+        );
+        let session = client
+            .open_session(
+                "https://example.test/wip",
+                wip_client::SecurityContext::new("test"),
+            )
+            .unwrap();
+        client.refresh_object(&session, "/").unwrap().id
+    }
+}

crates/wip-tui/src/config.rs

@@ -0,0 +1,239 @@
+//! Command-line and environment configuration for the HTTP client.
+
+use std::error::Error;
+use std::fmt::{self, Debug, Display, Formatter};
+use std::time::Duration;
+
+use wip_http::Endpoint;
+
+/// Credential wrapper whose debug output is always redacted.
+#[derive(Clone)]
+pub struct Secret(String);
+
+impl Secret {
+    pub(crate) fn expose(&self) -> &str {
+        &self.0
+    }
+}
+
+impl Debug for Secret {
+    fn fmt(&self, formatter: &mut Formatter<'_>) -> fmt::Result {
+        formatter.write_str("Secret([REDACTED])")
+    }
+}
+
+/// Validated runtime configuration.
+#[derive(Clone)]
+pub struct Config {
+    /// Canonical endpoint used for request construction, transport, and cache partitioning.
+    endpoint: String,
+    /// Non-secret cache partition identity.
+    security_context: String,
+    /// Bounded network timeout.
+    timeout: Duration,
+    /// Optional complete Authorization header value, never rendered or logged.
+    authorization: Option<Secret>,
+}
+
+impl Debug for Config {
+    fn fmt(&self, formatter: &mut Formatter<'_>) -> fmt::Result {
+        formatter
+            .debug_struct("Config")
+            .field("endpoint", &self.endpoint)
+            .field("security_context", &self.security_context)
+            .field("timeout", &self.timeout)
+            .field("authorization", &self.authorization)
+            .finish()
+    }
+}
+
+impl Config {
+    /// Returns the canonical endpoint used by the client and HTTP transport.
+    #[must_use]
+    pub fn endpoint(&self) -> &str {
+        &self.endpoint
+    }
+
+    /// Returns the non-secret session cache partition identity.
+    #[must_use]
+    pub fn security_context(&self) -> &str {
+        &self.security_context
+    }
+
+    /// Returns the end-to-end request timeout.
+    #[must_use]
+    pub const fn timeout(&self) -> Duration {
+        self.timeout
+    }
+
+    pub(crate) fn authorization(&self) -> Option<&Secret> {
+        self.authorization.as_ref()
+    }
+
+    /// Parses process arguments and supported environment variables.
+    ///
+    /// Endpoint precedence is `--endpoint`, a positional endpoint, then
+    /// `WIP_ENDPOINT`. Authorization is read only from the variable named by
+    /// `--authorization-env` (default `WIP_AUTHORIZATION`).
+    pub fn from_env() -> Result<Self, ConfigError> {
+        let arguments = std::env::args().skip(1).collect::<Vec<_>>();
+        let endpoint_env = std::env::var("WIP_ENDPOINT").ok();
+        let security_context = std::env::var("WIP_SECURITY_CONTEXT").ok();
+        Self::parse(arguments, endpoint_env, security_context, |name| {
+            std::env::var(name).ok()
+        })
+    }
+
+    /// Parses supplied values; exposed to make startup policy independently testable.
+    pub fn parse<I, S, F>(
+        arguments: I,
+        endpoint_env: Option<String>,
+        security_context_env: Option<String>,
+        mut read_secret: F,
+    ) -> Result<Self, ConfigError>
+    where
+        I: IntoIterator<Item = S>,
+        S: Into<String>,
+        F: FnMut(&str) -> Option<String>,
+    {
+        let mut endpoint = None;
+        let mut timeout = Duration::from_secs(30);
+        let mut security_context = security_context_env.unwrap_or_else(|| "anonymous".into());
+        let mut authorization_env = "WIP_AUTHORIZATION".to_owned();
+        let mut iter = arguments.into_iter().map(Into::into);
+        while let Some(argument) = iter.next() {
+            match argument.as_str() {
+                "--endpoint" => endpoint = Some(next_value(&mut iter, "--endpoint")?),
+                "--security-context" => {
+                    security_context = next_value(&mut iter, "--security-context")?;
+                }
+                "--authorization-env" => {
+                    authorization_env = next_value(&mut iter, "--authorization-env")?;
+                }
+                "--timeout" => {
+                    let raw = next_value(&mut iter, "--timeout")?;
+                    let seconds = raw
+                        .parse::<u64>()
+                        .ok()
+                        .filter(|seconds| *seconds > 0)
+                        .ok_or_else(|| {
+                            ConfigError::Invalid("--timeout must be a positive integer".into())
+                        })?;
+                    timeout = Duration::from_secs(seconds);
+                }
+                "--help" | "-h" => return Err(ConfigError::Help),
+                value if value.starts_with('-') => {
+                    return Err(ConfigError::Invalid(format!("unknown option {value}")));
+                }
+                value if endpoint.is_none() => endpoint = Some(value.to_owned()),
+                _ => return Err(ConfigError::Invalid("multiple endpoints supplied".into())),
+            }
+        }
+        let supplied = endpoint
+            .or(endpoint_env)
+            .ok_or_else(|| ConfigError::Invalid("endpoint is required".into()))?;
+        let endpoint =
+            Endpoint::parse(&supplied).map_err(|error| ConfigError::Invalid(error.to_string()))?;
+        if !endpoint.as_url().username().is_empty() || endpoint.as_url().password().is_some() {
+            return Err(ConfigError::Invalid(
+                "endpoint userinfo is not accepted; supply credentials through the configured environment variable"
+                    .into(),
+            ));
+        }
+        if !matches!(endpoint.as_url().scheme(), "http" | "https") {
+            return Err(ConfigError::Invalid(
+                "this HTTP client supports http and https endpoint schemes".into(),
+            ));
+        }
+        if security_context.is_empty() {
+            return Err(ConfigError::Invalid(
+                "security context must not be empty".into(),
+            ));
+        }
+        let authorization = read_secret(&authorization_env)
+            .filter(|value| !value.is_empty())
+            .map(Secret);
+        Ok(Self {
+            endpoint: endpoint.to_string(),
+            security_context,
+            timeout,
+            authorization,
+        })
+    }
+
+    /// Returns concise command usage without mentioning credential values.
+    #[must_use]
+    pub const fn usage() -> &'static str {
+        "usage: wip-tui [--endpoint] URL [--security-context NAME] [--authorization-env VAR] [--timeout SECONDS]\n\
+         URL may also be supplied as WIP_ENDPOINT; the HTTP adapter supports http and https."
+    }
+}
+
+fn next_value(
+    iter: &mut impl Iterator<Item = String>,
+    option: &str,
+) -> Result<String, ConfigError> {
+    iter.next()
+        .ok_or_else(|| ConfigError::Invalid(format!("{option} requires a value")))
+}
+
+/// Startup configuration failure.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ConfigError {
+    /// Help was requested.
+    Help,
+    /// A safe, non-secret configuration diagnostic.
+    Invalid(String),
+}
+
+impl Display for ConfigError {
+    fn fmt(&self, formatter: &mut Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Help => formatter.write_str(Config::usage()),
+            Self::Invalid(detail) => write!(formatter, "{detail}\n{}", Config::usage()),
+        }
+    }
+}
+
+impl Error for ConfigError {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn endpoint_is_canonical_and_secrets_are_redacted() {
+        let config = Config::parse(
+            ["https://example.test/wip", "--authorization-env", "TOKEN"],
+            None,
+            None,
+            |name| (name == "TOKEN").then(|| "Bearer secret-value".into()),
+        )
+        .unwrap();
+        assert_eq!(config.endpoint(), "https://example.test/wip/");
+        let debug = format!("{config:?}");
+        assert!(debug.contains("[REDACTED]"));
+        assert!(!debug.contains("secret-value"));
+    }
+
+    #[test]
+    fn endpoint_userinfo_is_rejected_before_it_can_reach_debug_or_render_state() {
+        for endpoint in [
+            "https://user:password@example.test/wip",
+            "http://user:password@localhost:3000/wip",
+        ] {
+            let error = Config::parse([endpoint], None, None, |_| None).unwrap_err();
+            assert!(error.to_string().contains("userinfo"));
+            assert!(!error.to_string().contains("password"));
+        }
+    }
+
+    #[test]
+    fn http_and_https_are_preserved_as_the_single_endpoint() {
+        for expected in ["http://example.test:3000/wip/", "https://example.test/wip/"] {
+            let supplied = expected.trim_end_matches('/');
+            let config = Config::parse([supplied], None, None, |_| None).unwrap();
+            assert_eq!(config.endpoint(), expected);
+        }
+    }
+}

crates/wip-tui/src/editor.rs

@@ -0,0 +1,628 @@
+//! Descriptor-driven operation argument editing and validation.
+
+use std::collections::BTreeMap;
+
+use base64::Engine as _;
+use base64::engine::general_purpose::STANDARD;
+use wip_protocol::{InterfaceDescriptor, OperationDeclaration, TypeExpr, Value};
+
+const MAX_FIELD_INPUT_BYTES: usize = 256 * 1024;
+
+/// One editable top-level operation parameter.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ArgumentField {
+    /// Parameter name.
+    pub name: String,
+    /// Whether the parameter must be supplied.
+    pub required: bool,
+    /// Canonical descriptor type.
+    pub r#type: TypeExpr,
+    /// User-entered text.
+    pub input: String,
+    /// Field-local validation diagnostic.
+    pub diagnostic: Option<String>,
+}
+
+/// Marker returned when one or more field diagnostics prevent submission.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct InvalidArguments;
+
+/// Pure, terminal-independent editor built from an operation descriptor.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ArgumentEditor {
+    /// Opaque interface reference selected for the call.
+    pub interface: String,
+    /// Selected operation declaration.
+    pub operation: OperationDeclaration,
+    /// Complete descriptor used to resolve named types.
+    pub descriptor: InterfaceDescriptor,
+    /// Top-level parameter fields in declaration order.
+    pub fields: Vec<ArgumentField>,
+    /// Index of the active field.
+    pub cursor: usize,
+}
+
+impl ArgumentEditor {
+    /// Builds an editor whose fields preserve descriptor order.
+    #[must_use]
+    pub fn new(
+        interface: impl Into<String>,
+        descriptor: InterfaceDescriptor,
+        operation: OperationDeclaration,
+    ) -> Self {
+        let fields = operation
+            .parameters
+            .iter()
+            .map(|parameter| ArgumentField {
+                name: parameter.name.clone(),
+                required: parameter.required,
+                r#type: parameter.r#type.clone(),
+                input: if parameter.required && parameter.r#type == TypeExpr::Unit {
+                    "null".into()
+                } else {
+                    String::new()
+                },
+                diagnostic: None,
+            })
+            .collect();
+        Self {
+            interface: interface.into(),
+            operation,
+            descriptor,
+            fields,
+            cursor: 0,
+        }
+    }
+
+    /// Moves to the preceding field without wrapping.
+    pub fn previous_field(&mut self) {
+        self.cursor = self.cursor.saturating_sub(1);
+    }
+
+    /// Moves to the following field without wrapping.
+    pub fn next_field(&mut self) {
+        if self.cursor + 1 < self.fields.len() {
+            self.cursor += 1;
+        }
+    }
+
+    /// Appends one printable character to the active field.
+    pub fn insert(&mut self, character: char) {
+        if !character.is_control()
+            && let Some(field) = self.fields.get_mut(self.cursor)
+        {
+            if field.input.len().saturating_add(character.len_utf8()) <= MAX_FIELD_INPUT_BYTES {
+                field.input.push(character);
+                field.diagnostic = None;
+            } else {
+                field.diagnostic = Some("field input reached the 256 KiB limit".into());
+            }
+        }
+    }
+
+    /// Removes one scalar value from the active field.
+    pub fn backspace(&mut self) {
+        if let Some(field) = self.fields.get_mut(self.cursor) {
+            field.input.pop();
+            field.diagnostic = None;
+        }
+    }
+
+    /// Validates all fields and returns protocol values when every field is valid.
+    ///
+    /// Invalid or missing values are retained as field-local diagnostics. Optional
+    /// blank fields are omitted from the resulting argument map.
+    pub fn validate(&mut self) -> Result<BTreeMap<String, Value>, InvalidArguments> {
+        let mut arguments = BTreeMap::new();
+        let mut invalid = false;
+        for field in &mut self.fields {
+            field.diagnostic = None;
+            if field.input.len() > MAX_FIELD_INPUT_BYTES {
+                field.diagnostic = Some("field input exceeds the 256 KiB limit".into());
+                invalid = true;
+                continue;
+            }
+            if field.input.trim().is_empty() {
+                if field.required {
+                    field.diagnostic = Some("required value is missing".into());
+                    invalid = true;
+                }
+                continue;
+            }
+            match parse_value(
+                &self.descriptor,
+                &field.r#type,
+                field.input.trim(),
+                &field.name,
+            ) {
+                Ok(value) => {
+                    arguments.insert(field.name.clone(), value);
+                }
+                Err(error) => {
+                    field.diagnostic = Some(error);
+                    invalid = true;
+                }
+            }
+        }
+        if invalid {
+            return Err(InvalidArguments);
+        }
+        if let Err(error) = self
+            .descriptor
+            .validate_arguments(&self.operation.name, &arguments)
+        {
+            if let Some(field) = self.fields.get_mut(self.cursor) {
+                field.diagnostic = Some(error.to_string());
+            }
+            return Err(InvalidArguments);
+        }
+        Ok(arguments)
+    }
+}
+
+/// Returns a compact canonical spelling for a type expression.
+#[must_use]
+pub fn type_name(r#type: &TypeExpr) -> String {
+    match r#type {
+        TypeExpr::Unit => "Unit".into(),
+        TypeExpr::Boolean => "Boolean".into(),
+        TypeExpr::Integer => "Integer".into(),
+        TypeExpr::Number => "Number".into(),
+        TypeExpr::String => "String".into(),
+        TypeExpr::Bytes => "Bytes(base64)".into(),
+        TypeExpr::Json => "Json".into(),
+        TypeExpr::Entry => "Entry".into(),
+        TypeExpr::Named { name } => name.clone(),
+        TypeExpr::Record { fields } => format!(
+            "Record{{{}}}",
+            fields
+                .iter()
+                .map(|field| format!(
+                    "{}{}: {}",
+                    field.name,
+                    if field.required { "" } else { "?" },
+                    type_name(&field.r#type)
+                ))
+                .collect::<Vec<_>>()
+                .join(", ")
+        ),
+        TypeExpr::List { items } => format!("List<{}>", type_name(items)),
+        TypeExpr::Enum { cases } => format!(
+            "Enum<{}>",
+            cases
+                .iter()
+                .map(|case| case.name.as_str())
+                .collect::<Vec<_>>()
+                .join(" | ")
+        ),
+        TypeExpr::Union { cases } => format!(
+            "Union<{}>",
+            cases
+                .iter()
+                .map(|case| case.name.as_str())
+                .collect::<Vec<_>>()
+                .join(" | ")
+        ),
+    }
+}
+
+fn parse_value(
+    descriptor: &InterfaceDescriptor,
+    r#type: &TypeExpr,
+    input: &str,
+    field: &str,
+) -> Result<Value, String> {
+    if let TypeExpr::Named { name } = r#type {
+        let declaration = descriptor
+            .types
+            .iter()
+            .find(|declaration| declaration.name == *name)
+            .ok_or_else(|| format!("{field}: unknown named type {name}"))?;
+        return parse_value(descriptor, &declaration.definition, input, field);
+    }
+    let value = match r#type {
+        TypeExpr::Unit => {
+            if matches!(input, "null" | "()") {
+                Value::Unit
+            } else {
+                return Err(format!("{field}: expected null"));
+            }
+        }
+        TypeExpr::Boolean => input
+            .parse::<bool>()
+            .map(Value::Boolean)
+            .map_err(|_| format!("{field}: expected true or false"))?,
+        TypeExpr::Integer => input
+            .parse::<i64>()
+            .map(Value::Integer)
+            .map_err(|_| format!("{field}: expected a signed integer"))?,
+        TypeExpr::Number => {
+            let number = input
+                .parse::<f64>()
+                .map_err(|_| format!("{field}: expected a finite number"))?;
+            if !number.is_finite() {
+                return Err(format!("{field}: expected a finite number"));
+            }
+            Value::Number(number)
+        }
+        TypeExpr::String => Value::String(parse_string(input)),
+        TypeExpr::Bytes => Value::Bytes(
+            STANDARD
+                .decode(input)
+                .map_err(|_| format!("{field}: expected RFC 4648 base64"))?,
+        ),
+        TypeExpr::Entry => {
+            let path = parse_string(input);
+            wip_protocol::validate_path(&path)
+                .map_err(|error| format!("{field}: invalid Entry path: {error}"))?;
+            Value::String(path)
+        }
+        TypeExpr::Enum { cases } => {
+            let case = parse_string(input);
+            if !cases.iter().any(|candidate| candidate.name == case) {
+                return Err(format!("{field}: unknown enum case {case}"));
+            }
+            Value::String(case)
+        }
+        TypeExpr::Json => {
+            let json = serde_json::from_str(input)
+                .map_err(|error| format!("{field}: invalid JSON: {error}"))?;
+            json_to_untyped(&json, field)?
+        }
+        TypeExpr::Record { .. } | TypeExpr::List { .. } | TypeExpr::Union { .. } => {
+            let json = serde_json::from_str(input)
+                .map_err(|error| format!("{field}: invalid JSON: {error}"))?;
+            json_to_typed(descriptor, r#type, &json, field)?
+        }
+        TypeExpr::Named { .. } => unreachable!("named types handled above"),
+    };
+    descriptor
+        .validate_value(r#type, &value)
+        .map_err(|error| format!("{field}: {error}"))?;
+    Ok(value)
+}
+
+fn parse_string(input: &str) -> String {
+    serde_json::from_str::<String>(input).unwrap_or_else(|_| input.to_owned())
+}
+
+fn json_to_typed(
+    descriptor: &InterfaceDescriptor,
+    r#type: &TypeExpr,
+    json: &serde_json::Value,
+    field: &str,
+) -> Result<Value, String> {
+    if let TypeExpr::Named { name } = r#type {
+        let declaration = descriptor
+            .types
+            .iter()
+            .find(|declaration| declaration.name == *name)
+            .ok_or_else(|| format!("{field}: unknown named type {name}"))?;
+        return json_to_typed(descriptor, &declaration.definition, json, field);
+    }
+    match r#type {
+        TypeExpr::Unit if json.is_null() => Ok(Value::Unit),
+        TypeExpr::Boolean => json
+            .as_bool()
+            .map(Value::Boolean)
+            .ok_or_else(|| format!("{field}: expected boolean")),
+        TypeExpr::Integer => json
+            .as_i64()
+            .map(Value::Integer)
+            .ok_or_else(|| format!("{field}: expected integer")),
+        TypeExpr::Number => json
+            .as_f64()
+            .filter(|value| value.is_finite())
+            .map(Value::Number)
+            .ok_or_else(|| format!("{field}: expected finite number")),
+        TypeExpr::String => json
+            .as_str()
+            .map(|value| Value::String(value.into()))
+            .ok_or_else(|| format!("{field}: expected string")),
+        TypeExpr::Bytes => json
+            .as_str()
+            .ok_or_else(|| format!("{field}: expected base64 string"))
+            .and_then(|value| {
+                STANDARD
+                    .decode(value)
+                    .map(Value::Bytes)
+                    .map_err(|_| format!("{field}: expected RFC 4648 base64"))
+            }),
+        TypeExpr::Entry => {
+            let path = json
+                .as_str()
+                .ok_or_else(|| format!("{field}: expected Entry string"))?;
+            wip_protocol::validate_path(path)
+                .map_err(|error| format!("{field}: invalid Entry path: {error}"))?;
+            Ok(Value::String(path.into()))
+        }
+        TypeExpr::Enum { cases } => {
+            let case = json
+                .as_str()
+                .ok_or_else(|| format!("{field}: expected enum string"))?;
+            if !cases.iter().any(|candidate| candidate.name == case) {
+                return Err(format!("{field}: unknown enum case {case}"));
+            }
+            Ok(Value::String(case.into()))
+        }
+        TypeExpr::Json => json_to_untyped(json, field),
+        TypeExpr::List { items } => json
+            .as_array()
+            .ok_or_else(|| format!("{field}: expected array"))?
+            .iter()
+            .enumerate()
+            .map(|(index, item)| {
+                json_to_typed(descriptor, items, item, &format!("{field}[{index}]"))
+            })
+            .collect::<Result<Vec<_>, _>>()
+            .map(Value::List),
+        TypeExpr::Record { fields } => {
+            let object = json
+                .as_object()
+                .ok_or_else(|| format!("{field}: expected object"))?;
+            for name in object.keys() {
+                if !fields.iter().any(|candidate| candidate.name == *name) {
+                    return Err(format!("{field}.{name}: unknown field"));
+                }
+            }
+            let mut values = BTreeMap::new();
+            for declaration in fields {
+                match object.get(&declaration.name) {
+                    Some(value) => {
+                        values.insert(
+                            declaration.name.clone(),
+                            json_to_typed(
+                                descriptor,
+                                &declaration.r#type,
+                                value,
+                                &format!("{field}.{}", declaration.name),
+                            )?,
+                        );
+                    }
+                    None if declaration.required => {
+                        return Err(format!(
+                            "{field}.{}: required field is missing",
+                            declaration.name
+                        ));
+                    }
+                    None => {}
+                }
+            }
+            Ok(Value::Record(values))
+        }
+        TypeExpr::Union { cases } => {
+            let object = json
+                .as_object()
+                .ok_or_else(|| format!("{field}: expected union object"))?;
+            if object.keys().any(|name| name != "$case" && name != "value") {
+                return Err(format!("{field}: union accepts only $case and value"));
+            }
+            let case_name = object
+                .get("$case")
+                .and_then(serde_json::Value::as_str)
+                .ok_or_else(|| format!("{field}.$case: required string is missing"))?;
+            let case = cases
+                .iter()
+                .find(|candidate| candidate.name == case_name)
+                .ok_or_else(|| format!("{field}.$case: unknown union case {case_name}"))?;
+            let mut values = BTreeMap::from([("$case".into(), Value::String(case_name.into()))]);
+            match (&case.payload, object.get("value")) {
+                (Some(payload), Some(value)) => {
+                    values.insert(
+                        "value".into(),
+                        json_to_typed(descriptor, payload, value, &format!("{field}.value"))?,
+                    );
+                }
+                (Some(_), None) => {
+                    return Err(format!("{field}.value: required payload is missing"));
+                }
+                (None, Some(_)) => {
+                    return Err(format!("{field}.value: payload-free case has a value"));
+                }
+                (None, None) => {}
+            }
+            Ok(Value::Record(values))
+        }
+        TypeExpr::Named { .. } => unreachable!("named types handled above"),
+        _ => Err(format!(
+            "{field}: value does not match {}",
+            type_name(r#type)
+        )),
+    }
+}
+
+fn json_to_untyped(json: &serde_json::Value, field: &str) -> Result<Value, String> {
+    match json {
+        serde_json::Value::Null => Ok(Value::Unit),
+        serde_json::Value::Bool(value) => Ok(Value::Boolean(*value)),
+        serde_json::Value::Number(value) => {
+            if let Some(integer) = value.as_i64() {
+                Ok(Value::Integer(integer))
+            } else {
+                value
+                    .as_f64()
+                    .filter(|number| number.is_finite())
+                    .map(Value::Number)
+                    .ok_or_else(|| format!("{field}: number is not finite"))
+            }
+        }
+        serde_json::Value::String(value) => Ok(Value::String(value.clone())),
+        serde_json::Value::Array(values) => values
+            .iter()
+            .enumerate()
+            .map(|(index, value)| json_to_untyped(value, &format!("{field}[{index}]")))
+            .collect::<Result<Vec<_>, _>>()
+            .map(Value::List),
+        serde_json::Value::Object(values) => values
+            .iter()
+            .map(|(name, value)| {
+                json_to_untyped(value, &format!("{field}.{name}"))
+                    .map(|value| (name.clone(), value))
+            })
+            .collect::<Result<BTreeMap<_, _>, _>>()
+            .map(Value::Record),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use wip_protocol::{
+        EnumCase, FieldDeclaration, INTERFACE_FORMAT_V1, ParameterDeclaration, ReturnDeclaration,
+        TypeDeclaration, UnionCase,
+    };
+
+    fn descriptor(
+        parameters: Vec<ParameterDeclaration>,
+        types: Vec<TypeDeclaration>,
+    ) -> InterfaceDescriptor {
+        InterfaceDescriptor {
+            format: INTERFACE_FORMAT_V1.into(),
+            documentation: None,
+            types,
+            operations: vec![OperationDeclaration {
+                name: "run".into(),
+                documentation: None,
+                parameters,
+                returns: ReturnDeclaration {
+                    documentation: None,
+                    r#type: TypeExpr::Unit,
+                },
+            }],
+        }
+    }
+
+    #[test]
+    fn validates_every_canonical_shape_and_reports_fields() {
+        let parameters = vec![
+            parameter("unit", true, TypeExpr::Unit),
+            parameter("flag", true, TypeExpr::Boolean),
+            parameter("count", true, TypeExpr::Integer),
+            parameter("number", true, TypeExpr::Number),
+            parameter("text", true, TypeExpr::String),
+            parameter("bytes", true, TypeExpr::Bytes),
+            parameter("entry", true, TypeExpr::Entry),
+            parameter("json", true, TypeExpr::Json),
+            parameter(
+                "list",
+                true,
+                TypeExpr::List {
+                    items: Box::new(TypeExpr::Integer),
+                },
+            ),
+            parameter(
+                "record",
+                true,
+                TypeExpr::Record {
+                    fields: vec![FieldDeclaration {
+                        name: "name".into(),
+                        required: true,
+                        documentation: None,
+                        r#type: TypeExpr::String,
+                    }],
+                },
+            ),
+            parameter(
+                "choice",
+                true,
+                TypeExpr::Enum {
+                    cases: vec![EnumCase {
+                        name: "yes".into(),
+                        documentation: None,
+                    }],
+                },
+            ),
+            parameter(
+                "union",
+                true,
+                TypeExpr::Union {
+                    cases: vec![UnionCase {
+                        name: "some".into(),
+                        documentation: None,
+                        payload: Some(TypeExpr::Integer),
+                    }],
+                },
+            ),
+            parameter(
+                "named",
+                true,
+                TypeExpr::Named {
+                    name: "Alias".into(),
+                },
+            ),
+        ];
+        let descriptor = descriptor(
+            parameters,
+            vec![TypeDeclaration {
+                name: "Alias".into(),
+                documentation: None,
+                definition: TypeExpr::String,
+            }],
+        );
+        let operation = descriptor.operations[0].clone();
+        let mut editor = ArgumentEditor::new("test", descriptor, operation);
+        let inputs = [
+            "null",
+            "true",
+            "7",
+            "2.5",
+            "hello",
+            "aGk=",
+            "/item",
+            "{\"safe\":true}",
+            "[1,2]",
+            "{\"name\":\"n\"}",
+            "yes",
+            "{\"$case\":\"some\",\"value\":4}",
+            "value",
+        ];
+        for (field, input) in editor.fields.iter_mut().zip(inputs) {
+            field.input = input.into();
+        }
+        let values = editor.validate().expect("valid values");
+        assert_eq!(values["bytes"], Value::Bytes(b"hi".to_vec()));
+        assert_eq!(values["entry"], Value::String("/item".into()));
+        assert!(editor.fields.iter().all(|field| field.diagnostic.is_none()));
+    }
+
+    #[test]
+    fn missing_invalid_and_optional_fields_are_field_local() {
+        let descriptor = descriptor(
+            vec![
+                parameter("required", true, TypeExpr::Integer),
+                parameter("optional", false, TypeExpr::Boolean),
+            ],
+            vec![],
+        );
+        let operation = descriptor.operations[0].clone();
+        let mut editor = ArgumentEditor::new("test", descriptor, operation);
+        editor.fields[1].input = "not-a-bool".into();
+        assert_eq!(editor.validate(), Err(InvalidArguments));
+        assert!(
+            editor.fields[0]
+                .diagnostic
+                .as_deref()
+                .unwrap()
+                .contains("required")
+        );
+        assert!(
+            editor.fields[1]
+                .diagnostic
+                .as_deref()
+                .unwrap()
+                .contains("true or false")
+        );
+        editor.fields[0].input = "1".into();
+        editor.fields[1].input.clear();
+        assert_eq!(editor.validate().unwrap().len(), 1);
+    }
+
+    fn parameter(name: &str, required: bool, r#type: TypeExpr) -> ParameterDeclaration {
+        ParameterDeclaration {
+            name: name.into(),
+            required,
+            documentation: None,
+            r#type,
+        }
+    }
+}

crates/wip-tui/src/lib.rs

@@ -0,0 +1,10 @@
+//! Presentation and terminal interaction for stateful WIP client sessions.
+
+#![deny(missing_docs)]
+
+pub mod app;
+pub mod config;
+pub mod editor;
+pub mod render;
+pub mod runtime;
+pub mod terminal;

crates/wip-tui/src/main.rs

@@ -0,0 +1,6 @@
+fn main() {
+    if let Err(error) = wip_tui::runtime::run_from_env() {
+        eprintln!("wip-tui: {error}");
+        std::process::exit(1);
+    }
+}

crates/wip-tui/src/render.rs

@@ -0,0 +1,851 @@
+//! Deterministic bounded rendering for real and test terminal backends.
+
+use ratatui::Frame;
+use ratatui::layout::{Alignment, Constraint, Direction, Layout, Rect};
+use ratatui::style::{Color, Modifier, Style};
+use ratatui::text::{Line, Span};
+use ratatui::widgets::{Block, Borders, Clear, List, ListItem, Paragraph, Wrap};
+
+use crate::app::{App, ConnectionState, Focus, HistoryKind, Modal, OperationRow, ViewState};
+use crate::editor::type_name;
+
+const MAX_RENDER_TEXT: usize = 512;
+
+/// Draws the complete application without mutating it.
+pub fn draw(frame: &mut Frame<'_>, app: &App) {
+    let area = frame.area();
+    if area.width < 48 || area.height < 14 {
+        frame.render_widget(
+            Paragraph::new("wip-tui\nTerminal is too small. Resize to at least 48 x 14.\nq: quit")
+                .block(
+                    Block::default()
+                        .borders(Borders::ALL)
+                        .title(" Minimum size "),
+                )
+                .alignment(Alignment::Center)
+                .wrap(Wrap { trim: true }),
+            area,
+        );
+        return;
+    }
+
+    let vertical = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([
+            Constraint::Length(2),
+            Constraint::Min(8),
+            Constraint::Length(2),
+        ])
+        .split(area);
+    render_header(frame, vertical[0], app);
+    let columns = Layout::default()
+        .direction(Direction::Horizontal)
+        .constraints([Constraint::Percentage(38), Constraint::Percentage(62)])
+        .split(vertical[1]);
+    render_tree(frame, columns[0], app);
+    let right = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([
+            Constraint::Percentage(31),
+            Constraint::Percentage(39),
+            Constraint::Percentage(30),
+        ])
+        .split(columns[1]);
+    render_selected(frame, right[0], app);
+    render_operations(frame, right[1], app);
+    render_history(frame, right[2], app);
+    render_footer(frame, vertical[2], app);
+    render_modal(frame, app);
+}
+
+fn render_header(frame: &mut Frame<'_>, area: Rect, app: &App) {
+    let connection = match &app.connection {
+        ConnectionState::Disconnected => "DISCONNECTED",
+        ConnectionState::Connecting => "CONNECTING",
+        ConnectionState::Connected => "CONNECTED",
+        ConnectionState::Failed(_) => "FAILED (R reconnect / q quit)",
+    };
+    let text = format!(
+        " wip-tui  {}  [{}]  in-flight: {}",
+        sanitize(&app.endpoint),
+        connection,
+        app.in_flight.len()
+    );
+    frame.render_widget(
+        Paragraph::new(text).style(Style::default().add_modifier(Modifier::BOLD)),
+        area,
+    );
+}
+
+fn render_tree(frame: &mut Frame<'_>, area: Rect, app: &App) {
+    let mut paths = app.visible_paths();
+    let selected_index = paths
+        .iter()
+        .position(|path| path == &app.selected_path)
+        .unwrap_or(0);
+    let (start, end) = list_window(paths.len(), selected_index, area.height.saturating_sub(2));
+    let rows = paths.drain(start..end).map(|path| {
+        let node = app.entries.get(&path);
+        let selected = path == app.selected_path;
+        let depth = if path == "/" {
+            0
+        } else {
+            path.trim_start_matches('/').split('/').count()
+        };
+        let marker = node.map_or('·', |node| if node.expanded { '▼' } else { '▶' });
+        let label = node.and_then(|node| node.object.as_ref()).map_or_else(
+            || path.clone(),
+            |object| {
+                if path == "/" {
+                    "/".into()
+                } else {
+                    object.name.clone()
+                }
+            },
+        );
+        let mut suffix = node.map_or_else(
+            || " [unloaded]".into(),
+            |node| {
+                let tree = match &node.tree_state {
+                    ViewState::Loading(_) => " [loading children]",
+                    ViewState::Stale => " [stale children]",
+                    ViewState::Error(_) => " [failed children]",
+                    ViewState::Fresh if node.children.is_empty() => " [empty]",
+                    _ => "",
+                };
+                let object = state_suffix(&node.state);
+                format!("{object}{tree}")
+            },
+        );
+        suffix = sanitize(&suffix);
+        let style = if selected {
+            Style::default().fg(Color::Black).bg(Color::Cyan)
+        } else {
+            Style::default()
+        };
+        ListItem::new(Line::from(vec![
+            Span::raw("  ".repeat(depth)),
+            Span::raw(format!("{marker} {}", sanitize(&label))),
+            Span::styled(suffix, state_style(node.map(|value| &value.state))),
+        ]))
+        .style(style)
+    });
+    frame.render_widget(
+        List::new(rows).block(focused_block(" Worldspace tree ", app.focus == Focus::Tree)),
+        area,
+    );
+}
+
+fn render_selected(frame: &mut Frame<'_>, area: Rect, app: &App) {
+    let mut lines = vec![Line::from(format!(
+        "Path: {}",
+        sanitize(&app.selected_path)
+    ))];
+    if let Some(entry) = app.entries.get(&app.selected_path) {
+        lines.push(Line::from(format!("State: {}", state_label(&entry.state))));
+        if entry.state == ViewState::Fresh {
+            if let Some(object) = &entry.object {
+                lines.push(Line::from(format!("Name: {}", sanitize(&object.name))));
+                lines.push(Line::from(format!(
+                    "Description: {}",
+                    object
+                        .description
+                        .as_deref()
+                        .map(sanitize)
+                        .unwrap_or_else(|| "(none)".into())
+                )));
+                lines.push(Line::from(format!(
+                    "Interfaces (ordered): {}",
+                    if object.interfaces.is_empty() {
+                        "(none)".into()
+                    } else {
+                        object
+                            .interfaces
+                            .iter()
+                            .map(|value| sanitize(value))
+                            .collect::<Vec<_>>()
+                            .join(", ")
+                    }
+                )));
+            }
+        } else {
+            lines.push(Line::from(
+                "No current object metadata; refresh required (old metadata hidden).",
+            ));
+        }
+    }
+    frame.render_widget(
+        Paragraph::new(lines)
+            .block(focused_block(" Selected Entry ", app.focus == Focus::Entry))
+            .wrap(Wrap { trim: false }),
+        area,
+    );
+}
+
+fn render_operations(frame: &mut Frame<'_>, area: Rect, app: &App) {
+    let rows = app.operation_rows();
+    let selected_index = app.operation_cursor.min(rows.len().saturating_sub(1));
+    let (start, end) = list_window(rows.len(), selected_index, area.height.saturating_sub(2));
+    let items = rows[start..end].iter().enumerate().map(|(offset, row)| {
+        let index = start + offset;
+        let (text, style) = operation_line(app, row);
+        let selected = app.focus == Focus::Operations && index == app.operation_cursor;
+        ListItem::new(text).style(if selected {
+            Style::default().fg(Color::Black).bg(Color::Cyan)
+        } else {
+            style
+        })
+    });
+    let title = " Interfaces / Operations (Enter: load or edit) ";
+    if rows.is_empty() {
+        frame.render_widget(
+            Paragraph::new("No declared interfaces or no current object.")
+                .block(focused_block(title, app.focus == Focus::Operations)),
+            area,
+        );
+    } else {
+        frame.render_widget(
+            List::new(items).block(focused_block(title, app.focus == Focus::Operations)),
+            area,
+        );
+    }
+}
+
+fn operation_line(app: &App, row: &OperationRow) -> (Line<'static>, Style) {
+    if let Some(name) = &row.operation {
+        let descriptor = app
+            .interfaces
+            .get(&row.interface)
+            .and_then(|view| view.descriptor.as_ref());
+        let declaration = descriptor.and_then(|descriptor| {
+            descriptor
+                .operations
+                .iter()
+                .find(|operation| operation.name == *name)
+        });
+        let signature = declaration.map_or_else(
+            || format!("  ({}, {})", row.interface, name),
+            |operation| {
+                let parameters = operation
+                    .parameters
+                    .iter()
+                    .map(|parameter| {
+                        format!(
+                            "{}{}: {}",
+                            parameter.name,
+                            if parameter.required { "" } else { "?" },
+                            type_name(&parameter.r#type)
+                        )
+                    })
+                    .collect::<Vec<_>>()
+                    .join(", ");
+                let documentation = operation
+                    .documentation
+                    .as_ref()
+                    .map(|documentation| format!(" — {}", documentation.summary))
+                    .unwrap_or_default();
+                format!(
+                    "  ({}, {}) ({parameters}) -> {}{}",
+                    row.interface,
+                    name,
+                    type_name(&operation.returns.r#type),
+                    documentation
+                )
+            },
+        );
+        (Line::from(sanitize(&signature)), Style::default())
+    } else {
+        let interface = app.interfaces.get(&row.interface);
+        let state = interface.map_or("unloaded".into(), |view| state_label(&view.state));
+        let documentation = interface
+            .filter(|view| view.state == ViewState::Fresh)
+            .and_then(|view| view.descriptor.as_ref())
+            .and_then(|descriptor| descriptor.documentation.as_ref())
+            .map(|documentation| format!(" — {}", sanitize(&documentation.summary)))
+            .unwrap_or_default();
+        (
+            Line::from(format!(
+                "Interface {} [{}]{}",
+                sanitize(&row.interface),
+                state,
+                documentation
+            )),
+            Style::default().add_modifier(Modifier::BOLD),
+        )
+    }
+}
+
+fn render_history(frame: &mut Frame<'_>, area: Rect, app: &App) {
+    let selected_index = app.history_cursor.min(app.history.len().saturating_sub(1));
+    let (start, end) = list_window(
+        app.history.len(),
+        selected_index,
+        area.height.saturating_sub(2),
+    );
+    let items = app.history[start..end]
+        .iter()
+        .enumerate()
+        .map(|(offset, item)| {
+            let index = start + offset;
+            let label = match item.kind {
+                HistoryKind::Success => "SUCCESS",
+                HistoryKind::DomainFailure => "HOST FAILURE",
+                HistoryKind::ProtocolError => "PROTOCOL ERROR",
+                HistoryKind::TransportFailure => "TRANSPORT FAILURE",
+                HistoryKind::ClientFailure => "CLIENT FAILURE",
+                HistoryKind::OutcomeUnknown => "OUTCOME UNKNOWN",
+                HistoryKind::Information => "INFO",
+            };
+            let link = item
+                .entry_target
+                .as_ref()
+                .map_or("", |_| " [Enter: go to Entry]");
+            let text = format!(
+                "[{label}] {}: {}{link}",
+                sanitize(&item.title),
+                sanitize(&item.detail)
+            );
+            let selected = app.focus == Focus::History && index == app.history_cursor;
+            ListItem::new(text).style(if selected {
+                Style::default().fg(Color::Black).bg(Color::Cyan)
+            } else if item.kind == HistoryKind::OutcomeUnknown {
+                Style::default().fg(Color::Red).add_modifier(Modifier::BOLD)
+            } else {
+                Style::default()
+            })
+        });
+    let block = focused_block(
+        " Recent results / diagnostics ",
+        app.focus == Focus::History,
+    );
+    if app.history.is_empty() {
+        frame.render_widget(Paragraph::new("No results yet.").block(block), area);
+    } else {
+        frame.render_widget(List::new(items).block(block), area);
+    }
+}
+
+fn render_footer(frame: &mut Frame<'_>, area: Rect, app: &App) {
+    let help = " ↑↓/jk move  ←→/hl parent/expand  Tab focus  Enter select  r refresh  + larger tree  c cancel read  ? help  q quit ";
+    let text = format!("{}\n{}", help, sanitize(&app.status));
+    frame.render_widget(
+        Paragraph::new(text).style(Style::default().fg(Color::DarkGray)),
+        area,
+    );
+}
+
+fn render_modal(frame: &mut Frame<'_>, app: &App) {
+    match &app.modal {
+        Modal::None => {}
+        Modal::Help => {
+            let area = centered(frame.area(), 76, 70);
+            frame.render_widget(Clear, area);
+            frame.render_widget(
+                Paragraph::new(
+                    "Keyboard help\n\n↑/↓ or j/k  move selection / editor field\n←/→ or h/l  collapse/expand or parent\nTab          next pane\nEnter        load interface, edit operation, confirm execute\nr            refresh selected Entry and subtree\nc            cancel newest retrieval (never cancels a sent operation)\nR            reconnect after failure\nEsc          close modal\nq            quit\n\nOperations are never sent until the confirmation screen is accepted.",
+                )
+                .block(Block::default().borders(Borders::ALL).title(" Help "))
+                .wrap(Wrap { trim: false }),
+                area,
+            );
+        }
+        Modal::Editor(editor) => {
+            let area = centered(frame.area(), 86, 78);
+            frame.render_widget(Clear, area);
+            let mut lines = vec![Line::from(format!(
+                "Target: {}  Operation: ({}, {})",
+                sanitize(&app.selected_path),
+                sanitize(&editor.interface),
+                sanitize(&editor.operation.name)
+            ))];
+            if editor.fields.is_empty() {
+                lines.push(Line::from("(no parameters)"));
+            }
+            for (index, field) in editor.fields.iter().enumerate() {
+                let cursor = if index == editor.cursor { ">" } else { " " };
+                let requirement = if field.required {
+                    "required"
+                } else {
+                    "optional"
+                };
+                lines.push(Line::from(format!(
+                    "{cursor} {} [{requirement}, {}] = {}",
+                    sanitize(&field.name),
+                    sanitize(&type_name(&field.r#type)),
+                    sanitize(&field.input)
+                )));
+                if let Some(diagnostic) = &field.diagnostic {
+                    lines.push(Line::styled(
+                        format!("    ERROR: {}", sanitize(diagnostic)),
+                        Style::default().fg(Color::Red),
+                    ));
+                }
+            }
+            lines.push(Line::from(""));
+            lines.push(Line::from("Enter: validate and review  Esc: cancel"));
+            frame.render_widget(
+                Paragraph::new(lines)
+                    .block(
+                        Block::default()
+                            .borders(Borders::ALL)
+                            .title(" Argument editor "),
+                    )
+                    .wrap(Wrap { trim: false }),
+                area,
+            );
+        }
+        Modal::Confirm { editor, arguments } => {
+            let area = centered(frame.area(), 82, 58);
+            frame.render_widget(Clear, area);
+            let mut lines = vec![
+                Line::styled(
+                    "EXPLICIT EXECUTION CONFIRMATION",
+                    Style::default()
+                        .fg(Color::Yellow)
+                        .add_modifier(Modifier::BOLD),
+                ),
+                Line::from(format!("Entry: {}", sanitize(&app.selected_path))),
+                Line::from(format!("Interface: {}", sanitize(&editor.interface))),
+                Line::from(format!("Operation: {}", sanitize(&editor.operation.name))),
+                Line::from("Input values:"),
+            ];
+            for (name, value) in arguments {
+                lines.push(Line::from(format!(
+                    "  {} = {}",
+                    sanitize(name),
+                    sanitize(&bounded_value(value))
+                )));
+            }
+            lines.push(Line::from(""));
+            lines.push(Line::styled(
+                "Enter/e: EXECUTE ONCE   Esc: back to editor",
+                Style::default().add_modifier(Modifier::BOLD),
+            ));
+            frame.render_widget(
+                Paragraph::new(lines)
+                    .block(Block::default().borders(Borders::ALL).title(" Confirm "))
+                    .wrap(Wrap { trim: false }),
+                area,
+            );
+        }
+    }
+}
+
+fn list_window(total: usize, selected: usize, area_height: u16) -> (usize, usize) {
+    let capacity = usize::from(area_height);
+    if total == 0 || capacity == 0 {
+        return (0, 0);
+    }
+    let selected = selected.min(total - 1);
+    let start = selected
+        .saturating_add(1)
+        .saturating_sub(capacity)
+        .min(total.saturating_sub(capacity));
+    (start, start.saturating_add(capacity).min(total))
+}
+
+fn focused_block(title: &'static str, focused: bool) -> Block<'static> {
+    let style = if focused {
+        Style::default().fg(Color::Cyan)
+    } else {
+        Style::default()
+    };
+    Block::default()
+        .borders(Borders::ALL)
+        .title(title)
+        .border_style(style)
+}
+
+fn centered(area: Rect, percent_x: u16, percent_y: u16) -> Rect {
+    let vertical = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([
+            Constraint::Percentage((100 - percent_y) / 2),
+            Constraint::Percentage(percent_y),
+            Constraint::Percentage((100 - percent_y) / 2),
+        ])
+        .split(area);
+    Layout::default()
+        .direction(Direction::Horizontal)
+        .constraints([
+            Constraint::Percentage((100 - percent_x) / 2),
+            Constraint::Percentage(percent_x),
+            Constraint::Percentage((100 - percent_x) / 2),
+        ])
+        .split(vertical[1])[1]
+}
+
+fn state_suffix(state: &ViewState) -> &'static str {
+    match state {
+        ViewState::Unloaded => " [unloaded]",
+        ViewState::Loading(_) => " [loading]",
+        ViewState::Fresh => "",
+        ViewState::Stale => " [stale: refresh required]",
+        ViewState::Error(_) => " [error]",
+    }
+}
+
+fn state_label(state: &ViewState) -> String {
+    match state {
+        ViewState::Unloaded => "unloaded".into(),
+        ViewState::Loading(id) => format!("loading request #{id}"),
+        ViewState::Fresh => "fresh".into(),
+        ViewState::Stale => "stale — refresh required".into(),
+        ViewState::Error(error) => format!("error — {}", sanitize(error)),
+    }
+}
+
+fn state_style(state: Option<&ViewState>) -> Style {
+    match state {
+        Some(ViewState::Stale) => Style::default().fg(Color::Yellow),
+        Some(ViewState::Error(_)) => Style::default().fg(Color::Red),
+        Some(ViewState::Loading(_)) => Style::default().fg(Color::Blue),
+        _ => Style::default(),
+    }
+}
+
+/// Replaces terminal control characters and bounds user/remote text by Unicode scalars.
+#[must_use]
+pub fn sanitize(input: &str) -> String {
+    let mut output = String::new();
+    for (count, character) in input.chars().enumerate() {
+        if count >= MAX_RENDER_TEXT {
+            output.push('…');
+            break;
+        }
+        if character.is_control() && !matches!(character, '\n' | '\t') {
+            output.push('�');
+        } else {
+            output.push(character);
+        }
+    }
+    output
+}
+
+/// Formats a protocol value with strict byte and collection bounds.
+#[must_use]
+pub fn bounded_value(value: &wip_protocol::Value) -> String {
+    bounded_value_at(value, 0)
+}
+
+fn bounded_value_at(value: &wip_protocol::Value, depth: usize) -> String {
+    if depth >= 8 {
+        return "…".into();
+    }
+    match value {
+        wip_protocol::Value::Unit => "null".into(),
+        wip_protocol::Value::Boolean(value) => value.to_string(),
+        wip_protocol::Value::Integer(value) => value.to_string(),
+        wip_protocol::Value::Number(value) => value.to_string(),
+        wip_protocol::Value::String(value) => format!("{:?}", sanitize(value)),
+        wip_protocol::Value::Bytes(bytes) => {
+            let shown = bytes
+                .iter()
+                .take(32)
+                .map(|byte| format!("{byte:02x}"))
+                .collect::<String>();
+            if bytes.len() > 32 {
+                format!("bytes[{}]: {shown}…", bytes.len())
+            } else {
+                format!("bytes[{}]: {shown}", bytes.len())
+            }
+        }
+        wip_protocol::Value::Record(values) => {
+            let mut fields = values
+                .iter()
+                .take(16)
+                .map(|(name, value)| {
+                    format!("{}: {}", sanitize(name), bounded_value_at(value, depth + 1))
+                })
+                .collect::<Vec<_>>();
+            if values.len() > 16 {
+                fields.push("…".into());
+            }
+            format!("{{{}}}", fields.join(", "))
+        }
+        wip_protocol::Value::List(values) => {
+            let mut items = values
+                .iter()
+                .take(16)
+                .map(|value| bounded_value_at(value, depth + 1))
+                .collect::<Vec<_>>();
+            if values.len() > 16 {
+                items.push("…".into());
+            }
+            format!("[{}]", items.join(", "))
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use ratatui::Terminal;
+    use ratatui::backend::TestBackend;
+
+    use super::*;
+    use crate::app::{EntryView, HistoryItem};
+    use crate::editor::ArgumentEditor;
+    use wip_client::{InterfaceObservation, ObjectObservation, ObservationState};
+    use wip_protocol::{
+        INTERFACE_FORMAT_V1, InterfaceDescriptor, Object, OperationDeclaration,
+        ParameterDeclaration, ReturnDeclaration, TypeExpr,
+    };
+
+    fn rendered(app: &App, width: u16, height: u16) -> String {
+        let backend = TestBackend::new(width, height);
+        let mut terminal = Terminal::new(backend).unwrap();
+        terminal.draw(|frame| draw(frame, app)).unwrap();
+        terminal
+            .backend()
+            .buffer()
+            .content
+            .iter()
+            .map(|cell| cell.symbol())
+            .collect::<Vec<_>>()
+            .chunks(width as usize)
+            .map(|line| line.concat())
+            .collect::<Vec<_>>()
+            .join("\n")
+    }
+
+    #[test]
+    fn observed_empty_visible_entry_is_labeled_without_expansion() {
+        let mut app = App::new("https://example.test/wip/");
+        {
+            let root = app.entries.get_mut("/").unwrap();
+            root.children = vec!["/empty".into()];
+            root.tree_state = ViewState::Fresh;
+        }
+        app.entries.insert(
+            "/empty".into(),
+            EntryView {
+                path: "/empty".into(),
+                object: Some(Object {
+                    name: "empty".into(),
+                    description: None,
+                    interfaces: vec![],
+                    r#ref: None,
+                    validator: None,
+                }),
+                state: ViewState::Fresh,
+                children: vec![],
+                tree_state: ViewState::Fresh,
+                expanded: false,
+            },
+        );
+
+        let snapshot = rendered(&app, 80, 20);
+        assert!(snapshot.contains("empty [empty]"));
+    }
+
+    #[test]
+    fn snapshot_contains_non_color_state_markers_and_hides_validators() {
+        let mut app = App::new("https://example.test/wip/");
+        app.connection = ConnectionState::Connected;
+        app.entries.get_mut("/").unwrap().state = ViewState::Stale;
+        app.push_history(HistoryItem {
+            kind: HistoryKind::OutcomeUnknown,
+            title: "replace".into(),
+            detail: "execution and side effects are unknown; refresh before deciding again".into(),
+            entry_target: None,
+        });
+        let snapshot = rendered(&app, 110, 30);
+        assert!(snapshot.contains("stale"));
+        assert!(snapshot.contains("OUTCOME UNKNOWN"));
+        assert!(!snapshot.contains("validator"));
+    }
+
+    #[test]
+    fn snapshots_cover_selected_operation_editor_and_failure_categories() {
+        let mut app = App::new("https://example.test/wip/");
+        app.connection = ConnectionState::Connected;
+        app.apply_object(ObjectObservation {
+            path: "/".into(),
+            object: Some(Object {
+                name: String::new(),
+                description: Some("public root description".into()),
+                interfaces: vec!["demo-interface".into()],
+                r#ref: None,
+                validator: Some(b"must-not-render".to_vec()),
+            }),
+            validator: Some(b"must-not-render".to_vec()),
+            state: ObservationState::Fresh,
+        });
+        let descriptor = InterfaceDescriptor {
+            format: INTERFACE_FORMAT_V1.into(),
+            documentation: None,
+            types: vec![],
+            operations: vec![OperationDeclaration {
+                name: "run".into(),
+                documentation: None,
+                parameters: vec![ParameterDeclaration {
+                    name: "count".into(),
+                    required: true,
+                    documentation: None,
+                    r#type: TypeExpr::Integer,
+                }],
+                returns: ReturnDeclaration {
+                    documentation: None,
+                    r#type: TypeExpr::String,
+                },
+            }],
+        };
+        app.apply_interface(InterfaceObservation {
+            reference: "demo-interface".into(),
+            descriptor: Some(descriptor.clone()),
+            validator: Some(b"must-not-render".to_vec()),
+            state: ObservationState::Fresh,
+        });
+        for (kind, title) in [
+            (HistoryKind::Success, "result"),
+            (HistoryKind::ProtocolError, "invalid response"),
+            (HistoryKind::TransportFailure, "network"),
+            (HistoryKind::ClientFailure, "local"),
+        ] {
+            app.push_history(HistoryItem {
+                kind,
+                title: title.into(),
+                detail: "bounded detail".into(),
+                entry_target: None,
+            });
+        }
+        let snapshot = rendered(&app, 140, 40);
+        assert!(snapshot.contains("public root description"));
+        assert!(snapshot.contains("(demo-interface, run)"));
+        assert!(snapshot.contains("SUCCESS"));
+        assert!(snapshot.contains("PROTOCOL ERROR"));
+        assert!(snapshot.contains("TRANSPORT FAILURE"));
+        assert!(snapshot.contains("CLIENT FAILURE"));
+        assert!(!snapshot.contains("must-not-render"));
+
+        let mut editor = ArgumentEditor::new(
+            "demo-interface",
+            descriptor.clone(),
+            descriptor.operations[0].clone(),
+        );
+        editor.fields[0].diagnostic = Some("expected integer".into());
+        app.modal = Modal::Editor(editor);
+        let snapshot = rendered(&app, 140, 40);
+        assert!(snapshot.contains("Argument editor"));
+        assert!(snapshot.contains("count [required, Integer]"));
+        assert!(snapshot.contains("ERROR: expected integer"));
+    }
+
+    #[test]
+    fn list_panes_keep_the_active_row_inside_the_bounded_viewport() {
+        let mut app = App::new("https://example.test/wip/");
+        app.connection = ConnectionState::Connected;
+
+        let children = (0..40)
+            .map(|index| format!("/tree-row-{index:02}"))
+            .collect::<Vec<_>>();
+        {
+            let root = app.entries.get_mut("/").unwrap();
+            root.children = children.clone();
+            root.tree_state = ViewState::Fresh;
+            root.expanded = true;
+        }
+        for child in &children {
+            app.entries.insert(
+                child.clone(),
+                EntryView {
+                    path: child.clone(),
+                    object: None,
+                    state: ViewState::Unloaded,
+                    children: vec![],
+                    tree_state: ViewState::Unloaded,
+                    expanded: false,
+                },
+            );
+        }
+        app.selected_path = children.last().unwrap().clone();
+        app.focus = Focus::Tree;
+        let snapshot = rendered(&app, 100, 30);
+        let tree_pane = snapshot
+            .lines()
+            .map(|line| line.chars().take(38).collect::<String>())
+            .collect::<Vec<_>>()
+            .join("\n");
+        assert!(tree_pane.contains("tree-row-39"));
+
+        app.selected_path = "/".into();
+        app.apply_object(ObjectObservation {
+            path: "/".into(),
+            object: Some(Object {
+                name: String::new(),
+                description: None,
+                interfaces: vec!["many".into()],
+                r#ref: None,
+                validator: None,
+            }),
+            validator: None,
+            state: ObservationState::Fresh,
+        });
+        let operations = (0..20)
+            .map(|index| OperationDeclaration {
+                name: format!("operation-{index:02}"),
+                documentation: None,
+                parameters: vec![],
+                returns: ReturnDeclaration {
+                    documentation: None,
+                    r#type: TypeExpr::Unit,
+                },
+            })
+            .collect::<Vec<_>>();
+        app.apply_interface(InterfaceObservation {
+            reference: "many".into(),
+            descriptor: Some(InterfaceDescriptor {
+                format: INTERFACE_FORMAT_V1.into(),
+                documentation: None,
+                types: vec![],
+                operations,
+            }),
+            validator: None,
+            state: ObservationState::Fresh,
+        });
+        app.focus = Focus::Operations;
+        app.operation_cursor = app.operation_rows().len() - 1;
+        let snapshot = rendered(&app, 100, 30);
+        assert!(snapshot.contains("(many, operation-19)"));
+
+        for index in 0..20 {
+            app.push_history(HistoryItem {
+                kind: HistoryKind::Information,
+                title: format!("history-{index:02}"),
+                detail: "diagnostic".into(),
+                entry_target: None,
+            });
+        }
+        app.focus = Focus::History;
+        app.history_cursor = app.history.len() - 1;
+        let snapshot = rendered(&app, 100, 30);
+        assert!(snapshot.contains("[INFO] history-00"));
+    }
+
+    #[test]
+    fn tiny_terminal_has_a_safe_fallback() {
+        let snapshot = rendered(&App::new("https://example.test/"), 30, 8);
+        assert!(snapshot.contains("too small"));
+    }
+
+    #[test]
+    fn control_characters_and_large_bytes_are_bounded() {
+        assert_eq!(sanitize("safe\u{1b}[31m"), "safe�[31m");
+        let display = bounded_value(&wip_protocol::Value::Bytes(vec![7; 1000]));
+        assert!(display.starts_with("bytes[1000]"));
+        assert!(display.ends_with('…'));
+    }
+
+    #[test]
+    fn entry_view_type_remains_constructible_for_external_snapshots() {
+        let entry = EntryView {
+            path: "/".into(),
+            object: None,
+            state: ViewState::Unloaded,
+            children: vec![],
+            tree_state: ViewState::Unloaded,
+            expanded: false,
+        };
+        assert_eq!(entry.path, "/");
+    }
+}

crates/wip-tui/src/terminal.rs

@@ -0,0 +1,131 @@
+//! Terminal lifecycle guard and crossterm input translation.
+
+use std::io::{self, Stdout};
+use std::sync::Arc;
+
+use crossterm::cursor::{Hide, Show};
+use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
+use crossterm::execute;
+use crossterm::terminal::{
+    EnterAlternateScreen, LeaveAlternateScreen, disable_raw_mode, enable_raw_mode,
+};
+use ratatui::Terminal;
+use ratatui::backend::CrosstermBackend;
+
+use crate::app::InputKey;
+
+type PanicHook = dyn for<'a> Fn(&std::panic::PanicHookInfo<'a>) + Send + Sync + 'static;
+
+/// RAII owner of raw mode, alternate screen, cursor visibility, and panic recovery.
+pub struct TerminalGuard {
+    terminal: Terminal<CrosstermBackend<Stdout>>,
+    previous_hook: Arc<PanicHook>,
+}
+
+impl TerminalGuard {
+    /// Enters terminal UI mode, restoring partial setup on failure.
+    pub fn enter() -> io::Result<Self> {
+        enable_raw_mode()?;
+        let mut stdout = io::stdout();
+        if let Err(error) = execute!(stdout, EnterAlternateScreen, Hide) {
+            let _ = disable_raw_mode();
+            return Err(error);
+        }
+        let terminal = match Terminal::new(CrosstermBackend::new(stdout)) {
+            Ok(terminal) => terminal,
+            Err(error) => {
+                restore_terminal();
+                return Err(error);
+            }
+        };
+        let previous_hook: Arc<PanicHook> = std::panic::take_hook().into();
+        let panic_hook = Arc::clone(&previous_hook);
+        let terminal_owner = std::thread::current().id();
+        std::panic::set_hook(Box::new(move |information| {
+            if std::thread::current().id() == terminal_owner {
+                restore_terminal();
+            }
+            panic_hook(information);
+        }));
+        Ok(Self {
+            terminal,
+            previous_hook,
+        })
+    }
+
+    /// Returns the ratatui terminal for drawing.
+    pub fn terminal_mut(&mut self) -> &mut Terminal<CrosstermBackend<Stdout>> {
+        &mut self.terminal
+    }
+}
+
+impl Drop for TerminalGuard {
+    fn drop(&mut self) {
+        let previous = Arc::clone(&self.previous_hook);
+        std::panic::set_hook(Box::new(move |information| previous(information)));
+        restore_terminal();
+    }
+}
+
+fn restore_terminal() {
+    let _ = disable_raw_mode();
+    let _ = execute!(io::stdout(), Show, LeaveAlternateScreen);
+}
+
+/// Converts one crossterm key event into a terminal-independent reducer key.
+///
+/// When `editing` is true, printable command letters remain text input and only
+/// Ctrl-C/Escape retain global meaning.
+#[must_use]
+pub fn translate_key(event: KeyEvent, editing: bool) -> Option<InputKey> {
+    if event.modifiers.contains(KeyModifiers::CONTROL) && event.code == KeyCode::Char('c') {
+        return Some(InputKey::Quit);
+    }
+    let key = match event.code {
+        KeyCode::Up => InputKey::Up,
+        KeyCode::Down => InputKey::Down,
+        KeyCode::Left => InputKey::Left,
+        KeyCode::Right => InputKey::Right,
+        KeyCode::Tab => InputKey::Tab,
+        KeyCode::Enter => InputKey::Enter,
+        KeyCode::Esc => InputKey::Escape,
+        KeyCode::Backspace => InputKey::Backspace,
+        KeyCode::Char(character) if editing => InputKey::Character(character),
+        KeyCode::Char('k') => InputKey::Up,
+        KeyCode::Char('j') => InputKey::Down,
+        KeyCode::Char('h') => InputKey::Left,
+        KeyCode::Char('l') => InputKey::Right,
+        KeyCode::Char('r') => InputKey::Refresh,
+        KeyCode::Char('R') => InputKey::Reconnect,
+        KeyCode::Char('c') => InputKey::CancelRead,
+        KeyCode::Char('?') => InputKey::Help,
+        KeyCode::Char('q') => InputKey::Quit,
+        KeyCode::Char(character) => InputKey::Character(character),
+        _ => return None,
+    };
+    Some(key)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn editing_keeps_command_letters_as_text_but_ctrl_c_quits() {
+        assert_eq!(
+            translate_key(KeyEvent::new(KeyCode::Char('q'), KeyModifiers::NONE), true),
+            Some(InputKey::Character('q'))
+        );
+        assert_eq!(
+            translate_key(KeyEvent::new(KeyCode::Char('q'), KeyModifiers::NONE), false),
+            Some(InputKey::Quit)
+        );
+        assert_eq!(
+            translate_key(
+                KeyEvent::new(KeyCode::Char('c'), KeyModifiers::CONTROL),
+                true
+            ),
+            Some(InputKey::Quit)
+        );
+    }
+}

crates/wip-tui/tests/filesystem_e2e.rs

@@ -0,0 +1,205 @@
+use std::sync::Arc;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::thread;
+use std::time::{Duration, Instant};
+
+use tempfile::tempdir;
+use wip_fs_server::{AccessMode, ServerConfig, WipFsServer};
+use wip_tui::app::{Focus, HistoryKind, InputKey, Modal, ViewState};
+use wip_tui::config::Config;
+use wip_tui::runtime::{HttpTransport, Runtime, default_wire_limits};
+
+#[test]
+fn real_http_filesystem_workflow_is_lazy_validator_safe_and_symlink_confined() {
+    let temporary = tempdir().expect("temporary root");
+    let outside = tempdir().expect("outside root");
+    std::fs::write(temporary.path().join("hello.txt"), b"hello world").expect("write file");
+    std::fs::create_dir(temporary.path().join("nested")).expect("create nested directory");
+    std::fs::write(outside.path().join("secret.txt"), b"outside-secret").expect("outside file");
+    #[cfg(unix)]
+    std::os::unix::fs::symlink(outside.path(), temporary.path().join("outside-link"))
+        .expect("create symlink");
+
+    let mut server_config = ServerConfig::for_root(temporary.path());
+    server_config.access = AccessMode::ReadWrite;
+    let bound = Arc::new(
+        WipFsServer::new(server_config)
+            .expect("build filesystem server")
+            .bind()
+            .expect("bind filesystem server"),
+    );
+    let shutdown = Arc::new(AtomicBool::new(false));
+    let worker = {
+        let bound = Arc::clone(&bound);
+        let shutdown = Arc::clone(&shutdown);
+        thread::spawn(move || bound.serve_until(shutdown))
+    };
+    let endpoint = format!("http://127.0.0.1:{}/wip", bound.local_addr().port());
+    let config = Config::parse([endpoint], None, Some("filesystem-test".into()), |_| None)
+        .expect("development config");
+    let transport = HttpTransport::new(&config, default_wire_limits().max_response_bytes())
+        .expect("HTTP transport");
+    let mut runtime = Runtime::new(&config, transport).expect("runtime");
+
+    runtime.connect();
+    settle(&mut runtime);
+    assert_eq!(runtime.app().selected_path, "/");
+    assert!(runtime.app().entries.contains_key("/hello.txt"));
+    assert!(runtime.app().entries.contains_key("/nested"));
+    assert!(runtime.app().entries.contains_key("/outside-link"));
+    let empty_directory = &runtime.app().entries["/nested"];
+    assert_eq!(empty_directory.tree_state, ViewState::Fresh);
+    assert!(empty_directory.children.is_empty());
+    assert!(!empty_directory.expanded);
+
+    // Visible Objects have their interface descriptors prefetched before selection.
+    let file_interfaces = runtime.app().entries["/hello.txt"]
+        .object
+        .as_ref()
+        .expect("file object")
+        .interfaces
+        .clone();
+    assert!(!file_interfaces.is_empty());
+    for reference in &file_interfaces {
+        assert_eq!(runtime.app().interfaces[reference].state, ViewState::Fresh);
+        assert!(runtime.app().interfaces[reference].descriptor.is_some());
+    }
+    let read_reference = file_interfaces[0].clone();
+    assert_eq!(
+        runtime.app().interfaces[&read_reference]
+            .descriptor
+            .as_ref()
+            .expect("read descriptor")
+            .operations[0]
+            .name,
+        "read"
+    );
+
+    // Keyboard-select the already prefetched read operation.
+    runtime.app_mut().selected_path = "/hello.txt".into();
+    runtime.app_mut().focus = Focus::Operations;
+    runtime.app_mut().operation_cursor = 1;
+    assert!(!runtime.handle_key(InputKey::Enter));
+
+    // Descriptor-driven read editor, explicit confirmation, and execution.
+    assert!(matches!(runtime.app().modal, Modal::Editor(_)));
+    runtime.handle_key(InputKey::Enter);
+    assert!(matches!(runtime.app().modal, Modal::Confirm { .. }));
+    runtime.handle_key(InputKey::Enter);
+    settle(&mut runtime);
+    assert_eq!(runtime.app().history[0].kind, HistoryKind::Success);
+    assert!(
+        runtime.app().history[0]
+            .detail
+            .contains("68656c6c6f20776f726c64")
+    );
+
+    assert_eq!(runtime.app().entries["/hello.txt"].state, ViewState::Fresh);
+    runtime.app_mut().focus = Focus::Operations;
+
+    // Use the separately-qualified prefetched write interface and replace with the
+    // automatically attached observed validator.
+    runtime.app_mut().operation_cursor = 3;
+    runtime.handle_key(InputKey::Enter);
+    set_only_field(&mut runtime, "dXBkYXRlZA=="); // "updated"
+    confirm_and_execute(&mut runtime);
+    settle(&mut runtime);
+    assert_eq!(
+        std::fs::read(temporary.path().join("hello.txt")).expect("updated file"),
+        b"updated"
+    );
+    assert_eq!(runtime.app().entries["/hello.txt"].state, ViewState::Fresh);
+
+    // Prepare another replacement using the post-operation validator, then mutate
+    // the file externally before explicit execution. The stale validator is rejected,
+    // the Entry becomes stale, and no automatic call is created.
+    runtime.app_mut().focus = Focus::Operations;
+    runtime.app_mut().operation_cursor = 3;
+    runtime.handle_key(InputKey::Enter);
+    set_only_field(&mut runtime, "c3RhbGUtd3JpdGU=");
+    runtime.handle_key(InputKey::Enter); // confirmation fixes user input only
+    std::fs::write(temporary.path().join("hello.txt"), b"external").expect("external change");
+    let history_before = runtime.app().history.len();
+    runtime.handle_key(InputKey::Enter);
+    settle(&mut runtime);
+    assert_eq!(
+        std::fs::read(temporary.path().join("hello.txt")).expect("externally changed file"),
+        b"external"
+    );
+    assert_eq!(runtime.app().entries["/hello.txt"].state, ViewState::Stale);
+    assert!(runtime.app().in_flight.is_empty());
+    assert_eq!(runtime.app().history.len(), history_before + 1);
+    assert_eq!(runtime.app().history[0].kind, HistoryKind::DomainFailure);
+    assert!(
+        runtime.app().history[0]
+            .detail
+            .contains("no automatic retry")
+    );
+
+    // Refresh enables a new, separately confirmed execution.
+    runtime.app_mut().focus = Focus::Tree;
+    runtime.handle_key(InputKey::Refresh);
+    settle(&mut runtime);
+    runtime.app_mut().focus = Focus::Operations;
+    runtime.app_mut().operation_cursor = 3;
+    runtime.handle_key(InputKey::Enter);
+    set_only_field(&mut runtime, "ZmluYWw=");
+    confirm_and_execute(&mut runtime);
+    settle(&mut runtime);
+    assert_eq!(
+        std::fs::read(temporary.path().join("hello.txt")).expect("final file"),
+        b"final"
+    );
+
+    // Symlink inspection exposes the link payload only. It never traverses or
+    // materializes the target directory outside the configured root.
+    #[cfg(unix)]
+    {
+        runtime.app_mut().selected_path = "/outside-link".into();
+        runtime.app_mut().focus = Focus::Operations;
+        runtime.app_mut().operation_cursor = 0;
+        runtime.handle_key(InputKey::Enter);
+        settle(&mut runtime);
+        runtime.app_mut().operation_cursor = 1;
+        runtime.handle_key(InputKey::Enter);
+        runtime.handle_key(InputKey::Enter);
+        runtime.handle_key(InputKey::Enter);
+        settle(&mut runtime);
+        assert_eq!(runtime.app().history[0].kind, HistoryKind::Success);
+        assert!(!runtime.app().history[0].detail.contains("outside-secret"));
+        assert!(
+            !runtime
+                .app()
+                .entries
+                .contains_key("/outside-link/secret.txt")
+        );
+    }
+
+    shutdown.store(true, Ordering::Release);
+    worker
+        .join()
+        .expect("join filesystem listener")
+        .expect("filesystem listener exits");
+}
+
+fn settle(runtime: &mut Runtime<HttpTransport>) {
+    let deadline = Instant::now() + Duration::from_secs(5);
+    while !runtime.app().in_flight.is_empty() {
+        assert!(Instant::now() < deadline, "runtime requests did not settle");
+        runtime.wait_and_poll(Duration::from_millis(20));
+    }
+}
+
+fn set_only_field(runtime: &mut Runtime<HttpTransport>, input: &str) {
+    let Modal::Editor(editor) = &mut runtime.app_mut().modal else {
+        panic!("operation editor was not open")
+    };
+    assert_eq!(editor.fields.len(), 1);
+    editor.fields[0].input = input.into();
+}
+
+fn confirm_and_execute(runtime: &mut Runtime<HttpTransport>) {
+    runtime.handle_key(InputKey::Enter);
+    assert!(matches!(runtime.app().modal, Modal::Confirm { .. }));
+    runtime.handle_key(InputKey::Enter);
+}

crates/wip-tui/tests/runtime_async.rs

@@ -0,0 +1,329 @@
+use std::sync::Arc;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::thread;
+use std::time::{Duration, Instant};
+
+use tempfile::tempdir;
+use wip_fs_server::{ServerConfig, WipFsServer};
+use wip_http::encode_protocol_error_response;
+use wip_http::http::{Request, Response};
+use wip_protocol::{ProtocolError, ProtocolErrorCode, ProtocolInteraction};
+use wip_tui::app::{ConnectionState, Focus, HistoryKind, InputKey, Modal, ViewState};
+use wip_tui::config::Config;
+use wip_tui::runtime::{
+    Runtime, Transport, TransportError, TransportErrorKind, default_wire_limits,
+};
+
+struct ScriptedTransport {
+    server: Arc<WipFsServer>,
+    sequence: Arc<AtomicUsize>,
+    delayed_after_startup: bool,
+    unknown_calls: bool,
+    fail_call_prepare: bool,
+    fail_tree_prepare: bool,
+    panic_calls: bool,
+    root_tree_protocol_failures: Arc<AtomicUsize>,
+}
+
+impl ScriptedTransport {
+    fn new(server: Arc<WipFsServer>) -> Self {
+        Self {
+            server,
+            sequence: Arc::new(AtomicUsize::new(0)),
+            delayed_after_startup: false,
+            unknown_calls: false,
+            fail_call_prepare: false,
+            fail_tree_prepare: false,
+            panic_calls: false,
+            root_tree_protocol_failures: Arc::new(AtomicUsize::new(0)),
+        }
+    }
+}
+
+impl Transport for ScriptedTransport {
+    type Prepared = Request<Vec<u8>>;
+
+    fn prepare(&self, request: Request<Vec<u8>>) -> Result<Self::Prepared, TransportError> {
+        if self.fail_call_prepare && request.uri().path().ends_with("/v1/call_operation") {
+            return Err(TransportError {
+                kind: TransportErrorKind::Disconnect,
+                detail: "scripted local conversion failure".into(),
+            });
+        }
+        if self.fail_tree_prepare && request.uri().path().ends_with("/v1/observe") {
+            return Err(TransportError {
+                kind: TransportErrorKind::Disconnect,
+                detail: "scripted tree conversion failure".into(),
+            });
+        }
+        Ok(request)
+    }
+
+    fn execute(&self, request: Self::Prepared) -> Result<Response<Vec<u8>>, TransportError> {
+        let sequence = self.sequence.fetch_add(1, Ordering::AcqRel);
+        if request.uri().path().ends_with("/v1/observe")
+            && self
+                .root_tree_protocol_failures
+                .fetch_update(Ordering::AcqRel, Ordering::Acquire, |remaining| {
+                    remaining.checked_sub(1)
+                })
+                .is_ok()
+        {
+            return Ok(encode_protocol_error_response(
+                ProtocolInteraction::Observe,
+                &ProtocolError {
+                    code: ProtocolErrorCode::Internal,
+                    message: "scripted startup failure".into(),
+                },
+                default_wire_limits(),
+            )
+            .expect("encode tree failure"));
+        }
+        if self.delayed_after_startup && sequence > 0 {
+            // Delay the first refresh so the second wins and exercises exact
+            // RequestId ownership.
+            let delay = if sequence == 1 { 80 } else { 5 };
+            thread::sleep(Duration::from_millis(delay));
+        }
+        if self.panic_calls && request.uri().path().ends_with("/v1/call_operation") {
+            panic!("scripted transport worker panic");
+        }
+        if self.unknown_calls && request.uri().path().ends_with("/v1/call_operation") {
+            return Ok(encode_protocol_error_response(
+                ProtocolInteraction::CallOperation,
+                &ProtocolError {
+                    code: ProtocolErrorCode::OperationOutcomeUnknown,
+                    message: "scripted commit uncertainty".into(),
+                },
+                default_wire_limits(),
+            )
+            .expect("encode unknown outcome"));
+        }
+        Ok(self.server.handle_http(request))
+    }
+}
+
+#[test]
+fn out_of_order_refresh_and_cancel_keep_request_identity_safe() {
+    let temporary = tempdir().expect("temporary root");
+    std::fs::write(temporary.path().join("file"), b"contents").expect("file");
+    let server = Arc::new(
+        WipFsServer::new(ServerConfig::for_root(temporary.path())).expect("filesystem server"),
+    );
+    let mut transport = ScriptedTransport::new(server);
+    transport.delayed_after_startup = true;
+    let config = config();
+    let mut runtime = Runtime::new(&config, transport).expect("runtime");
+    runtime.connect();
+    settle(&mut runtime);
+
+    runtime.app_mut().focus = Focus::Tree;
+    runtime.handle_key(InputKey::Refresh);
+    runtime.handle_key(InputKey::Refresh);
+    settle(&mut runtime);
+    assert_eq!(runtime.app().entries["/"].state, ViewState::Fresh);
+    assert!(runtime.app().history.iter().any(|item| {
+        item.kind == HistoryKind::Information && item.title.contains("stale response")
+    }));
+
+    runtime.handle_key(InputKey::Refresh);
+    runtime.handle_key(InputKey::CancelRead);
+    runtime.handle_key(InputKey::CancelRead);
+    settle(&mut runtime);
+    assert!(runtime.app().in_flight.is_empty());
+    assert!(
+        runtime
+            .app()
+            .history
+            .iter()
+            .any(|item| item.title == "retrieval canceled")
+    );
+
+    // When a refreshed tree omits a formerly selected Entry, the client marks
+    // it stale and the presentation no longer exposes old metadata/operations
+    // as current.
+    std::fs::remove_file(temporary.path().join("file")).expect("remove file");
+    runtime.app_mut().selected_path = "/".into();
+    runtime.handle_key(InputKey::Refresh);
+    settle(&mut runtime);
+    assert_eq!(runtime.app().entries["/file"].state, ViewState::Stale);
+    runtime.app_mut().selected_path = "/file".into();
+    assert!(runtime.app().operation_rows().is_empty());
+}
+
+#[test]
+fn startup_transport_preparation_failure_enters_failed_state() {
+    let temporary = tempdir().expect("temporary root");
+    let server = Arc::new(
+        WipFsServer::new(ServerConfig::for_root(temporary.path())).expect("filesystem server"),
+    );
+    let mut transport = ScriptedTransport::new(server);
+    transport.fail_tree_prepare = true;
+    let config = config();
+    let mut runtime = Runtime::new(&config, transport).expect("runtime");
+
+    runtime.connect();
+    settle(&mut runtime);
+    assert!(matches!(
+        runtime.app().connection,
+        ConnectionState::Failed(ref detail) if detail.contains("scripted tree conversion failure")
+    ));
+    assert!(runtime.app().status.contains("press R to reconnect"));
+    assert!(runtime.app().in_flight.is_empty());
+}
+
+#[test]
+fn startup_protocol_failure_enters_failed_state_and_reconnects() {
+    let temporary = tempdir().expect("temporary root");
+    let server = Arc::new(
+        WipFsServer::new(ServerConfig::for_root(temporary.path())).expect("filesystem server"),
+    );
+    let transport = ScriptedTransport::new(server);
+    transport
+        .root_tree_protocol_failures
+        .store(1, Ordering::Release);
+    let config = config();
+    let mut runtime = Runtime::new(&config, transport).expect("runtime");
+
+    runtime.connect();
+    settle(&mut runtime);
+    assert!(matches!(
+        runtime.app().connection,
+        ConnectionState::Failed(ref detail) if detail.contains("scripted startup failure")
+    ));
+    assert!(runtime.app().status.contains("press R to reconnect"));
+    assert!(runtime.app().history.iter().any(|item| {
+        item.kind == HistoryKind::DomainFailure && item.detail.contains("scripted startup failure")
+    }));
+
+    runtime.handle_key(InputKey::Reconnect);
+    settle(&mut runtime);
+    assert_eq!(runtime.app().connection, ConnectionState::Connected);
+}
+
+#[test]
+fn local_transport_preparation_failure_is_definitely_not_dispatched() {
+    let temporary = tempdir().expect("temporary root");
+    std::fs::write(temporary.path().join("file"), b"contents").expect("file");
+    let server = Arc::new(
+        WipFsServer::new(ServerConfig::for_root(temporary.path())).expect("filesystem server"),
+    );
+    let mut transport = ScriptedTransport::new(server);
+    transport.fail_call_prepare = true;
+    let execute_calls = Arc::clone(&transport.sequence);
+    let config = config();
+    let mut runtime = Runtime::new(&config, transport).expect("runtime");
+    runtime.connect();
+    settle(&mut runtime);
+
+    open_read_editor(&mut runtime);
+    let calls_before_operation = execute_calls.load(Ordering::Acquire);
+    runtime.handle_key(InputKey::Enter);
+    runtime.handle_key(InputKey::Enter);
+    assert_eq!(
+        execute_calls.load(Ordering::Acquire),
+        calls_before_operation,
+        "preparation failure must not invoke transport I/O"
+    );
+    assert!(runtime.app().in_flight.is_empty());
+    assert_eq!(runtime.app().history[0].kind, HistoryKind::TransportFailure);
+    assert!(runtime.app().history[0].detail.contains("not dispatched"));
+    assert_eq!(
+        runtime.app().status,
+        "operation not dispatched; not executed"
+    );
+    assert_eq!(runtime.app().entries["/file"].state, ViewState::Fresh);
+}
+
+#[test]
+fn worker_panic_settles_as_unknown_instead_of_stranding_the_main_loop() {
+    let temporary = tempdir().expect("temporary root");
+    std::fs::write(temporary.path().join("file"), b"contents").expect("file");
+    let server = Arc::new(
+        WipFsServer::new(ServerConfig::for_root(temporary.path())).expect("filesystem server"),
+    );
+    let mut transport = ScriptedTransport::new(server);
+    transport.panic_calls = true;
+    let config = config();
+    let mut runtime = Runtime::new(&config, transport).expect("runtime");
+    runtime.connect();
+    settle(&mut runtime);
+
+    open_read_editor(&mut runtime);
+    runtime.handle_key(InputKey::Enter);
+    runtime.handle_key(InputKey::Enter);
+    settle(&mut runtime);
+    assert!(runtime.app().in_flight.is_empty());
+    assert_eq!(runtime.app().history[0].kind, HistoryKind::OutcomeUnknown);
+    assert!(
+        runtime.app().history[0]
+            .detail
+            .contains("transport worker failed")
+    );
+}
+
+#[test]
+fn post_dispatch_unknown_is_prominent_stale_and_never_retried() {
+    let temporary = tempdir().expect("temporary root");
+    std::fs::write(temporary.path().join("file"), b"contents").expect("file");
+    let server = Arc::new(
+        WipFsServer::new(ServerConfig::for_root(temporary.path())).expect("filesystem server"),
+    );
+    let mut transport = ScriptedTransport::new(server);
+    transport.unknown_calls = true;
+    let config = config();
+    let mut runtime = Runtime::new(&config, transport).expect("runtime");
+    runtime.connect();
+    settle(&mut runtime);
+
+    open_read_editor(&mut runtime);
+    runtime.handle_key(InputKey::Enter);
+    runtime.handle_key(InputKey::Enter);
+    settle(&mut runtime);
+
+    assert_eq!(runtime.app().history[0].kind, HistoryKind::OutcomeUnknown);
+    assert!(
+        runtime.app().history[0]
+            .detail
+            .contains("side effects are unknown")
+    );
+    assert_eq!(runtime.app().entries["/file"].state, ViewState::Stale);
+    assert!(runtime.app().in_flight.is_empty());
+    let history = runtime.app().history.len();
+    thread::sleep(Duration::from_millis(20));
+    runtime.poll();
+    assert_eq!(
+        runtime.app().history.len(),
+        history,
+        "no retry was manufactured"
+    );
+}
+
+fn config() -> Config {
+    Config::parse(
+        ["https://example.test/wip"],
+        None,
+        Some("scripted-test".into()),
+        |_| None,
+    )
+    .expect("config")
+}
+
+fn open_read_editor(runtime: &mut Runtime<ScriptedTransport>) {
+    runtime.app_mut().selected_path = "/file".into();
+    runtime.app_mut().focus = Focus::Operations;
+    runtime.app_mut().operation_cursor = 0;
+    runtime.handle_key(InputKey::Enter);
+    settle(runtime);
+    runtime.app_mut().operation_cursor = 1;
+    runtime.handle_key(InputKey::Enter);
+    assert!(matches!(runtime.app().modal, Modal::Editor(_)));
+}
+
+fn settle(runtime: &mut Runtime<ScriptedTransport>) {
+    let deadline = Instant::now() + Duration::from_secs(5);
+    while !runtime.app().in_flight.is_empty() {
+        assert!(Instant::now() < deadline, "scripted runtime did not settle");
+        runtime.wait_and_poll(Duration::from_millis(10));
+    }
+}