fix: align protocol error semantics

Cargo.toml

@@ -1,22 +1,3 @@
 [workspace]
-members = [
-    ".",
-    "crates/wip-host",
-    "crates/wip-interface",
-    "crates/wip-interface-macros",
-    "crates/wip-protocol",
-]
+members = ["crates/*"]
 resolver = "3"
-
-[package]
-name = "wip-public-api-example"
-version = "0.1.0"
-edition = "2024"
-description = "End-to-end example of the public WIP Rust APIs"
-license = "MIT OR Apache-2.0"
-publish = false
-
-[dependencies]
-wip-host = { path = "crates/wip-host" }
-wip-interface = { path = "crates/wip-interface" }
-wip-protocol = { path = "crates/wip-protocol" }

README.md

@@ -2,9 +2,12 @@
 
 Rust building blocks for the Web Interface Protocol (WIP).
 
-The repository currently provides a transport-independent protocol model, a
-Rust interface-authoring facade, and a request-scoped host runtime. HTTP and
-other transport bindings are intentionally outside the supported slice.
+The repository is a resolver-3 virtual Cargo workspace whose packages all live
+under `crates/*`. It provides a transport-independent protocol model, a Rust
+interface-authoring facade, a request-scoped host runtime, and a private
+public-API conformance consumer. The repository root is not itself a package.
+HTTP and other transport bindings are intentionally outside the supported
+slice.
 
 ## Crate graph and responsibilities
 
@@ -36,19 +39,25 @@ or application traits.
 
 ## End-to-end example
 
-[`src/lib.rs`](src/lib.rs) is the complete public-API example and
-[`src/main.rs`](src/main.rs) runs it. It demonstrates all of the following:
+[`crates/wip-public-api-example/src/lib.rs`](crates/wip-public-api-example/src/lib.rs)
+is the complete public-API example and
+[`crates/wip-public-api-example/src/main.rs`](crates/wip-public-api-example/src/main.rs)
+runs it. It demonstrates all of the following:
 
-1. public application DTOs derived as `WipType` records and unions;
+1. public application DTOs derived as `WipType` records, enums, and unions,
+   including canonical entry paths and schema-opaque JSON;
 2. two public traits declared with `#[wip::interface]`;
 3. a private host struct implementing both traits;
-4. explicit publication of both interfaces on one object;
-5. registry observation and validation of generated descriptors;
-6. calls made with interface references, operation names, and `Value` arguments;
+4. explicit publication of both interfaces as an ordered set on one object;
+5. separate observation of opaque interface references, descriptors, and
+   descriptor validators;
+6. calls qualified by `target.path`, object validator, interface reference and
+   validator, operation, and schema-neutral `Value` arguments;
 7. validated result values decoded back to the typed application result;
 8. independent dispatch of the same `status` operation name on both interfaces;
-9. a domain rejection returned as data and a backend failure returned as a host
-   error.
+9. distinct domain rejection, host/backend failure, `PermissionDenied`, stale
+   validator recovery, interface membership, and lookup failure codes; and
+10. canonical failure precedence when several request fields are invalid.
 
 Run it inside the development shell:
 
@@ -57,10 +66,17 @@ nix develop
 cargo run --package wip-public-api-example
 ```
 
-The normal integration test is in [`tests/end_to_end.rs`](tests/end_to_end.rs).
-Unit tests beside the example additionally cover every host dispatch failure,
-invalid arguments and results, interface membership, validators, and
-same-named operations.
+The public-only conformance suite is in
+[`crates/wip-public-api-example/tests/end_to_end.rs`](crates/wip-public-api-example/tests/end_to_end.rs).
+It covers canonical object/descriptor shape, ordered interfaces,
+schema-neutral record/enum/union/entry/JSON values, fully qualified calls, and
+the distinct domain, host, authorization, validator-recovery, and interface
+failure classes. Exhaustive public type construction and matching make legacy
+ObjectId, descriptor `name`, and semantic `Value` variants compile-time
+regressions. Unit tests in the public crates additionally cover every host
+dispatch failure, `InvalidRequest` versus descriptor-bound `InvalidArguments`,
+invalid local responses, validators, same-named operations, and exhaustive
+per-interaction protocol error-code sets.
 
 ## Interface authoring
 
@@ -185,11 +201,20 @@ are never projected by `WipObject`; host-private fields and backend handles are
 also excluded.
 
 Application domain failures belong in a derived result union and are returned
-through `Ok`. `wip::HostError` is reserved for runtime/backend failures. Invalid
-arguments are rejected before invocation; malformed encoded results are
-reported as `InvalidResult` and never returned as application data. Validator,
-membership, authorization, and result failures retain their distinct canonical
-protocol error codes.
+through `Ok`. `wip::HostError` is reserved for runtime/backend failures. A
+structurally malformed call is `InvalidRequest`; only argument values checked
+after the current Interface Descriptor is fixed are `InvalidArguments`. A Host
+must never return a wire `InvalidResult`: Clients keep invalid Object,
+Descriptor, operation-result, and error responses as local `InvalidResponse`
+failures, while unsupported descriptor formats remain local
+`UnsupportedDescriptorFormat` failures.
+
+For operation calls, `Internal` and `ResourceLimitExceeded` guarantee that the
+operation did not run or that its effects were rolled back.
+`OperationOutcomeUnknown` is the only protocol code that makes no such
+guarantee, so Clients must not automatically retry it. The current host API maps
+implementation failures and invalid post-execution results conservatively to
+`OperationOutcomeUnknown`.
 
 Providers remain responsible for backend atomicity. Enter a transaction, lock,
 stable-handle scope, or conditional-update primitive before invoking the
@@ -208,10 +233,14 @@ nix develop
 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
 ```
 
-`cargo test --workspace --all-targets` includes the public example integration
-test, runtime failure tests, and `trybuild` compile-fail suites. Run
-`cargo test --workspace --doc` when validating the checked rustdoc examples
-separately.
+`cargo test --workspace --all-targets` includes the public-only conformance
+consumer, runtime failure tests, and `trybuild` compile-fail suites. The separate
+doctest, rustdoc, executable, and whitespace checks are all required acceptance
+steps.

crates/wip-host/src/lib.rs

@@ -545,9 +545,9 @@ pub trait ObjectProvider {
         self.with_object(path, PublishedObject::protocol_object)
             .ok_or_else(|| CallError::new(CallErrorKind::NotFound, "target path is not published"))
             .and_then(|object| {
-                object.validate_at_path(path).map_err(|error| {
-                    CallError::new(CallErrorKind::InvalidResult, error.to_string())
-                })?;
+                object
+                    .validate_at_path(path)
+                    .map_err(|error| CallError::new(CallErrorKind::Internal, error.to_string()))?;
                 Ok(object)
             })
     }
@@ -607,7 +607,9 @@ pub enum CallErrorKind {
     OperationNotFound,
     /// Supplied named values do not satisfy the operation declaration.
     InvalidArguments,
-    /// The encoded implementation result violates its declaration.
+    /// The Host constructed an invalid response before operation execution.
+    Internal,
+    /// The encoded implementation result violates its declaration after execution.
     InvalidResult,
     /// This operation requires a validator and the call omitted it.
     ValidatorRequired,
@@ -683,7 +685,10 @@ impl CallError {
             CallErrorKind::InterfaceMismatch => ProtocolErrorCode::InterfaceMismatch,
             CallErrorKind::OperationNotFound => ProtocolErrorCode::OperationNotFound,
             CallErrorKind::InvalidArguments => ProtocolErrorCode::InvalidArguments,
-            CallErrorKind::InvalidResult => ProtocolErrorCode::InvalidResult,
+            CallErrorKind::Internal => ProtocolErrorCode::Internal,
+            CallErrorKind::InvalidResult | CallErrorKind::Implementation => {
+                ProtocolErrorCode::OperationOutcomeUnknown
+            }
             CallErrorKind::ValidatorRequired => ProtocolErrorCode::ValidatorRequired,
             CallErrorKind::ValidatorMismatch => ProtocolErrorCode::ValidatorMismatch,
             CallErrorKind::InterfaceValidatorRequired => {
@@ -693,7 +698,6 @@ impl CallError {
                 ProtocolErrorCode::InterfaceValidatorMismatch
             }
             CallErrorKind::PermissionDenied => ProtocolErrorCode::PermissionDenied,
-            CallErrorKind::Implementation => ProtocolErrorCode::Internal,
         };
         ProtocolError {
             code,

crates/wip-host/tests/host.rs

@@ -235,6 +235,10 @@ impl ObjectProvider for TestProvider {
                 )
             }
             "/empty" => (Document::open("empty", None, Rc::clone(&self.calls)), 0),
+            "/invalid-object" => (
+                Document::open("wrong-name", None, Rc::clone(&self.calls)),
+                0,
+            ),
             "/broken" => (
                 Document::open("broken", Some("broken-ref"), Rc::clone(&self.calls)),
                 3,
@@ -624,9 +628,15 @@ fn immutable_interface_rejects_a_supplied_validator() {
 }
 
 #[test]
-fn invalid_results_and_backend_failures_keep_distinct_protocol_codes() {
+fn invalid_host_responses_and_uncertain_operation_failures_use_canonical_codes() {
     let (_, provider, _) = registry_and_provider();
 
+    assert_failure(
+        provider.fetch("/invalid-object").unwrap_err(),
+        CallErrorKind::Internal,
+        ProtocolErrorCode::Internal,
+    );
+
     assert_failure(
         provider
             .call_operation(request(
@@ -639,7 +649,7 @@ fn invalid_results_and_backend_failures_keep_distinct_protocol_codes() {
             ))
             .unwrap_err(),
         CallErrorKind::InvalidResult,
-        ProtocolErrorCode::InvalidResult,
+        ProtocolErrorCode::OperationOutcomeUnknown,
     );
     assert_failure(
         provider
@@ -653,6 +663,6 @@ fn invalid_results_and_backend_failures_keep_distinct_protocol_codes() {
             ))
             .unwrap_err(),
         CallErrorKind::Implementation,
-        ProtocolErrorCode::Internal,
+        ProtocolErrorCode::OperationOutcomeUnknown,
     );
 }

crates/wip-protocol/src/error.rs

@@ -223,10 +223,29 @@ impl Display for ValidationError {
 
 impl Error for ValidationError {}
 
-/// Stable protocol failure code returned by a host or produced by a client.
+/// 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.
+    Fetch,
+    /// Fetch a bounded tree of objects.
+    FetchTree,
+    /// Fetch one interface descriptor by its opaque reference.
+    FetchInterface,
+    /// Invoke one operation on a path-targeted object.
+    CallOperation,
+}
+
+/// Stable protocol failure code returned by a host.
+///
+/// This is the complete wire-level code set. A Client treats a malformed success
+/// or failure response, including a code disallowed for its interaction, as a
+/// Client-local `InvalidResponse`. An unsupported descriptor format is likewise
+/// a Client-local `UnsupportedDescriptorFormat`; neither condition is a code a
+/// Host can return.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum ProtocolErrorCode {
-    /// The request is structurally invalid.
+    /// The request is structurally invalid before an operation descriptor is fixed.
     InvalidRequest,
     /// The target object is not published.
     NotFound,
@@ -236,10 +255,8 @@ pub enum ProtocolErrorCode {
     InterfaceMismatch,
     /// The selected operation is not declared by the current interface.
     OperationNotFound,
-    /// Supplied operation arguments are invalid.
+    /// Supplied arguments do not match the fixed operation declaration.
     InvalidArguments,
-    /// A host result does not satisfy the declaration.
-    InvalidResult,
     /// The operation requires an object validator and none was supplied.
     ValidatorRequired,
     /// The supplied object validator does not match current state.
@@ -251,9 +268,88 @@ pub enum ProtocolErrorCode {
     /// A published operation is not permitted for the caller.
     PermissionDenied,
     /// A bounded protocol resource limit was exceeded.
+    ///
+    /// For `call_operation`, the Host guarantees that the operation was not run
+    /// or that all of its effects were rolled back.
     ResourceLimitExceeded,
-    /// The host encountered an internal failure.
+    /// The Host encountered an internal failure.
+    ///
+    /// For `call_operation`, the Host guarantees that the operation was not run
+    /// or that all of its effects were rolled back.
     Internal,
+    /// The Host cannot guarantee that the operation was not run or rolled back.
+    ///
+    /// A Client must not automatically retry because the operation may have
+    /// committed effects even though no success response was available.
+    OperationOutcomeUnknown,
+}
+
+impl ProtocolErrorCode {
+    /// Every canonical wire-level error code.
+    pub const ALL: [Self; 14] = [
+        Self::InvalidRequest,
+        Self::NotFound,
+        Self::InterfaceNotFound,
+        Self::InterfaceMismatch,
+        Self::OperationNotFound,
+        Self::InvalidArguments,
+        Self::ValidatorRequired,
+        Self::ValidatorMismatch,
+        Self::InterfaceValidatorRequired,
+        Self::InterfaceValidatorMismatch,
+        Self::PermissionDenied,
+        Self::ResourceLimitExceeded,
+        Self::Internal,
+        Self::OperationOutcomeUnknown,
+    ];
+
+    /// Whether a Host may return this code for `interaction`.
+    ///
+    /// `false` identifies an invalid error response; it does not turn that
+    /// response into another wire-level protocol failure.
+    #[must_use]
+    pub const fn is_allowed_for(self, interaction: ProtocolInteraction) -> bool {
+        use ProtocolErrorCode::{
+            InterfaceMismatch, InterfaceNotFound, InterfaceValidatorMismatch,
+            InterfaceValidatorRequired, Internal, InvalidArguments, InvalidRequest, NotFound,
+            OperationNotFound, OperationOutcomeUnknown, PermissionDenied, ResourceLimitExceeded,
+            ValidatorMismatch, ValidatorRequired,
+        };
+        use ProtocolInteraction::{CallOperation, Fetch, FetchInterface, FetchTree};
+
+        match (interaction, self) {
+            (_, InvalidRequest | ResourceLimitExceeded | Internal) => true,
+            (Fetch | FetchTree, NotFound) => true,
+            (FetchInterface, InterfaceNotFound) => true,
+            (
+                CallOperation,
+                NotFound
+                | InterfaceMismatch
+                | OperationNotFound
+                | InvalidArguments
+                | ValidatorRequired
+                | ValidatorMismatch
+                | InterfaceValidatorRequired
+                | InterfaceValidatorMismatch
+                | PermissionDenied
+                | OperationOutcomeUnknown,
+            ) => true,
+            (
+                _,
+                NotFound
+                | InterfaceNotFound
+                | InterfaceMismatch
+                | OperationNotFound
+                | InvalidArguments
+                | ValidatorRequired
+                | ValidatorMismatch
+                | InterfaceValidatorRequired
+                | InterfaceValidatorMismatch
+                | PermissionDenied
+                | OperationOutcomeUnknown,
+            ) => false,
+        }
+    }
 }
 
 /// Transport-independent protocol failure.

crates/wip-protocol/src/lib.rs

@@ -16,7 +16,20 @@
 //! | `fetch_interface` | [`FetchInterfaceRequest`] / [`FetchInterfaceResponse`] |
 //! | Object and interface call preconditions | [`Target`] / [`InterfaceTarget`] |
 //! | `call_operation` | [`CallOperationRequest`] / [`CallOperationResponse`] |
-//! | Stable failure taxonomy | [`ProtocolErrorCode`] / [`ProtocolError`] |
+//! | Stable Host failure taxonomy | [`ProtocolErrorCode`] / [`ProtocolError`] |
+//! | Per-interaction allowed failure codes | [`ProtocolInteraction`] / [`ProtocolErrorCode::is_allowed_for`] |
+//!
+//! [`ProtocolErrorCode`] is a closed set of Host-returned wire failures. After a
+//! Client receives a response, an invalid Object, Descriptor, operation result,
+//! malformed error, or error code disallowed by [`ProtocolInteraction`] is a
+//! Client-local `InvalidResponse`, not another wire error. A descriptor whose
+//! `format` is not supported is a Client-local `UnsupportedDescriptorFormat`.
+//!
+//! For `call_operation`, [`ProtocolErrorCode::Internal`] and
+//! [`ProtocolErrorCode::ResourceLimitExceeded`] guarantee that the operation did
+//! not run or that all effects were rolled back. Only
+//! [`ProtocolErrorCode::OperationOutcomeUnknown`] means the Host cannot make that
+//! guarantee; Clients must not automatically retry it.
 //!
 //! Paths, object refs, interface refs, and validators remain separate concepts.
 //! They are represented by ordinary protocol strings/bytes in the corresponding
@@ -35,8 +48,8 @@ mod model;
 mod validation;
 
 pub use error::{
-    NameNamespace, PathSegment, ProtocolError, ProtocolErrorCode, ValidationError,
-    ValidationErrorKind, ValueKind,
+    NameNamespace, PathSegment, ProtocolError, ProtocolErrorCode, ProtocolInteraction,
+    ValidationError, ValidationErrorKind, ValueKind,
 };
 pub use model::{
     CallOperationRequest, CallOperationResponse, Documentation, EnumCase, FetchInterfaceRequest,

crates/wip-protocol/src/model.rs

@@ -379,6 +379,9 @@ impl FetchRequest {
     }
 
     /// Validates an object returned for this request.
+    ///
+    /// 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> {
         response.validate_at_path(&self.path)
     }
@@ -393,6 +396,9 @@ impl FetchTreeRequest {
 
 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)
     }
@@ -400,6 +406,11 @@ impl FetchTreeResponse {
 
 impl FetchInterfaceResponse {
     /// Validates request correspondence and descriptor semantics.
+    ///
+    /// Failure means the Client received an invalid success response; it is not a
+    /// Host-returned [`crate::ProtocolErrorCode`]. Descriptor format support is a
+    /// separate Client concern: an otherwise valid descriptor with an unsupported
+    /// `format` is a Client-local `UnsupportedDescriptorFormat`.
     pub fn validate_for(&self, request: &FetchInterfaceRequest) -> Result<(), ValidationError> {
         crate::validation::validate_fetch_interface_response(self, request)
     }
@@ -414,6 +425,9 @@ impl CallOperationRequest {
 
 impl CallOperationResponse {
     /// Validates this result against the named operation in `descriptor`.
+    ///
+    /// Failure means the Client received an invalid success response; it is not a
+    /// Host-returned [`crate::ProtocolErrorCode`].
     pub fn validate_for(
         &self,
         descriptor: &InterfaceDescriptor,

crates/wip-protocol/tests/validation.rs

@@ -5,8 +5,8 @@ use wip_protocol::{
     FetchInterfaceResponse, FetchRequest, FetchTreeRequest, FetchTreeResponse, FieldDeclaration,
     INTERFACE_FORMAT_V1, InterfaceDescriptor, InterfaceTarget, MAX_SAFE_INTEGER, NameNamespace,
     Object, ObjectTreeNode, OperationDeclaration, ParameterDeclaration, PathSegment, ProtocolError,
-    ProtocolErrorCode, ProtocolResult, ReturnDeclaration, Target, TypeDeclaration, TypeExpr,
-    UnionCase, ValidationErrorKind, Value, ValueKind,
+    ProtocolErrorCode, ProtocolInteraction, ProtocolResult, ReturnDeclaration, Target,
+    TypeDeclaration, TypeExpr, UnionCase, ValidationErrorKind, Value, ValueKind,
 };
 
 fn record(entries: impl IntoIterator<Item = (&'static str, Value)>) -> Value {
@@ -729,24 +729,26 @@ fn fetch_tree_dtos_validate_names_depth_limit_and_siblings() {
 }
 
 #[test]
-fn protocol_result_and_every_canonical_error_code_are_available() {
-    let codes = [
-        ProtocolErrorCode::InvalidRequest,
-        ProtocolErrorCode::NotFound,
-        ProtocolErrorCode::InterfaceNotFound,
-        ProtocolErrorCode::InterfaceMismatch,
-        ProtocolErrorCode::OperationNotFound,
-        ProtocolErrorCode::InvalidArguments,
-        ProtocolErrorCode::InvalidResult,
-        ProtocolErrorCode::ValidatorRequired,
-        ProtocolErrorCode::ValidatorMismatch,
-        ProtocolErrorCode::InterfaceValidatorRequired,
-        ProtocolErrorCode::InterfaceValidatorMismatch,
-        ProtocolErrorCode::PermissionDenied,
-        ProtocolErrorCode::ResourceLimitExceeded,
-        ProtocolErrorCode::Internal,
-    ];
-    assert_eq!(codes.len(), 14);
+fn protocol_result_exposes_the_exact_canonical_wire_error_codes() {
+    assert_eq!(
+        ProtocolErrorCode::ALL,
+        [
+            ProtocolErrorCode::InvalidRequest,
+            ProtocolErrorCode::NotFound,
+            ProtocolErrorCode::InterfaceNotFound,
+            ProtocolErrorCode::InterfaceMismatch,
+            ProtocolErrorCode::OperationNotFound,
+            ProtocolErrorCode::InvalidArguments,
+            ProtocolErrorCode::ValidatorRequired,
+            ProtocolErrorCode::ValidatorMismatch,
+            ProtocolErrorCode::InterfaceValidatorRequired,
+            ProtocolErrorCode::InterfaceValidatorMismatch,
+            ProtocolErrorCode::PermissionDenied,
+            ProtocolErrorCode::ResourceLimitExceeded,
+            ProtocolErrorCode::Internal,
+            ProtocolErrorCode::OperationOutcomeUnknown,
+        ]
+    );
 
     let failure: ProtocolResult<()> = ProtocolResult::Failure(ProtocolError {
         code: ProtocolErrorCode::InvalidArguments,
@@ -758,3 +760,127 @@ fn protocol_result_and_every_canonical_error_code_are_available() {
         ProtocolResult::Success(Value::Unit)
     );
 }
+
+fn assert_allowed_codes(interaction: ProtocolInteraction, expected: &[ProtocolErrorCode]) {
+    let actual: Vec<_> = ProtocolErrorCode::ALL
+        .into_iter()
+        .filter(|code| code.is_allowed_for(interaction))
+        .collect();
+    assert_eq!(actual, expected);
+
+    for code in ProtocolErrorCode::ALL {
+        assert_eq!(
+            code.is_allowed_for(interaction),
+            expected.contains(&code),
+            "unexpected {code:?} validity for {interaction:?}"
+        );
+    }
+}
+
+#[test]
+fn fetch_error_codes_are_exhaustive() {
+    assert_allowed_codes(
+        ProtocolInteraction::Fetch,
+        &[
+            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,
+            ProtocolErrorCode::ResourceLimitExceeded,
+            ProtocolErrorCode::Internal,
+        ],
+    );
+}
+
+#[test]
+fn fetch_interface_error_codes_are_exhaustive() {
+    assert_allowed_codes(
+        ProtocolInteraction::FetchInterface,
+        &[
+            ProtocolErrorCode::InvalidRequest,
+            ProtocolErrorCode::InterfaceNotFound,
+            ProtocolErrorCode::ResourceLimitExceeded,
+            ProtocolErrorCode::Internal,
+        ],
+    );
+}
+
+#[test]
+fn call_operation_error_codes_are_exhaustive() {
+    assert_allowed_codes(
+        ProtocolInteraction::CallOperation,
+        &[
+            ProtocolErrorCode::InvalidRequest,
+            ProtocolErrorCode::NotFound,
+            ProtocolErrorCode::InterfaceMismatch,
+            ProtocolErrorCode::OperationNotFound,
+            ProtocolErrorCode::InvalidArguments,
+            ProtocolErrorCode::ValidatorRequired,
+            ProtocolErrorCode::ValidatorMismatch,
+            ProtocolErrorCode::InterfaceValidatorRequired,
+            ProtocolErrorCode::InterfaceValidatorMismatch,
+            ProtocolErrorCode::PermissionDenied,
+            ProtocolErrorCode::ResourceLimitExceeded,
+            ProtocolErrorCode::Internal,
+            ProtocolErrorCode::OperationOutcomeUnknown,
+        ],
+    );
+}
+
+#[test]
+fn invalid_success_payloads_remain_client_local_validation_failures() {
+    let fetch = FetchRequest {
+        path: "/articles/one".into(),
+    };
+    assert!(matches!(
+        fetch.validate_response(&object("other")).unwrap_err().kind,
+        ValidationErrorKind::ObjectNameMismatch { .. }
+    ));
+
+    let interface_request = FetchInterfaceRequest {
+        interface: "catalog-v1".into(),
+    };
+    let mut invalid_descriptor = descriptor();
+    invalid_descriptor
+        .operations
+        .push(invalid_descriptor.operations[0].clone());
+    assert!(matches!(
+        FetchInterfaceResponse {
+            interface: interface_request.interface.clone(),
+            descriptor: invalid_descriptor,
+            validator: None,
+        }
+        .validate_for(&interface_request)
+        .unwrap_err()
+        .kind,
+        ValidationErrorKind::DuplicateName {
+            namespace: NameNamespace::Operation,
+            ..
+        }
+    ));
+
+    assert!(matches!(
+        CallOperationResponse {
+            result: Value::String("not a boolean".into()),
+            validator: None,
+        }
+        .validate_for(&descriptor(), "publish")
+        .unwrap_err()
+        .kind,
+        ValidationErrorKind::TypeMismatch {
+            expected: ValueKind::Boolean,
+            actual: ValueKind::String,
+        }
+    ));
+}

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

@@ -0,0 +1,12 @@
+[package]
+name = "wip-public-api-example"
+version = "0.1.0"
+edition = "2024"
+description = "Public-only end-to-end conformance consumer for the WIP Rust APIs"
+license = "MIT OR Apache-2.0"
+publish = false
+
+[dependencies]
+wip-host = { path = "../wip-host" }
+wip-interface = { path = "../wip-interface" }
+wip-protocol = { path = "../wip-protocol" }

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

@@ -1,9 +1,37 @@
-//! End-to-end use of the public WIP protocol, interface, and host APIs.
+//! Public-only conformance consumer for the WIP Rust crates.
 //!
-//! This workspace package defines application DTOs and interfaces with
-//! `wip-interface`, keeps its implementation private, publishes it through a
-//! request-scoped `wip-host` provider, and crosses the call boundary only with
-//! canonical `wip-protocol` values and path targets.
+//! # Architectural boundary
+//!
+//! This package is an ordinary application consumer. Its direct dependencies are
+//! the public `wip-protocol`, `wip-interface`, and `wip-host` crates; it neither
+//! imports workspace-private modules nor depends on `wip-interface-macros`.
+//! `wip-protocol` owns transport-independent DTOs and schema-neutral values,
+//! while this package owns its application DTOs and interface traits. The
+//! request-scoped implementation, backend handle, authorization policy, and
+//! publication wiring remain host-private. A transport binding would translate
+//! its own wire routes and envelopes to the protocol call DTOs; no HTTP type is
+//! part of an application trait or interface descriptor.
+//!
+//! # Breaking migration exercised here
+//!
+//! The canonical API targets operations by `target.path` rather than a mandatory
+//! object identifier. Object `ref` and object/interface validators are separate,
+//! optional observation fields. Interface references are opaque values observed
+//! separately from descriptors, and descriptors contain neither a Rust trait
+//! name nor an opaque-reference `name` field. Application records, enums,
+//! unions, entry paths, and JSON all encode through the schema-neutral [`Value`]
+//! variants: entries and enums are strings, unions are discriminator records,
+//! and JSON recursively uses ordinary records/lists/primitives. The former
+//! `Entry<K, V>` and semantic `Value::Entry`, `Value::Enum`, `Value::Union`, and
+//! `Value::Json` forms are intentionally unsupported.
+//!
+//! # Supported authoring subset
+//!
+//! Public, non-generic traits use immutable `&self` receivers, owned named
+//! parameters, and explicit `wip::OperationResult<T>` returns. Derived DTOs are
+//! named-field records, all-unit enums, or unions with unit and single-payload
+//! cases. A direct `Option<T>` means field/argument omission, never protocol
+//! null. See `wip-interface` for the complete rejected-syntax list.
 
 #![deny(missing_docs)]
 
@@ -17,19 +45,34 @@ use wip_host::{
 };
 use wip_interface as wip;
 use wip_interface::WipType;
-use wip_protocol::ProtocolError;
+use wip_protocol::{ProtocolError, ProtocolErrorCode, Value};
 
 const OBJECT_PATH: &str = "/article-service";
 const OBJECT_VALIDATOR: &[u8] = b"object-v1";
 const CATALOG_VALIDATOR: &[u8] = b"catalog-v1";
 
-/// An application-owned request DTO mapped to a protocol record.
+/// Publication visibility represented as a protocol enum string.
 #[derive(Debug, Clone, PartialEq, Eq, wip::WipType)]
+pub enum Visibility {
+    /// Visible to every authorized caller.
+    Public,
+    /// Visible only inside the application domain.
+    Private,
+}
+
+/// An application-owned request DTO mapped to a protocol record.
+#[derive(Debug, Clone, PartialEq, wip::WipType)]
 pub struct PublishRequest {
     /// Title of the article to publish.
     pub title: String,
     /// Optional article body; omission is distinct from JSON null.
     pub body: Option<String>,
+    /// Canonical Worldspace path to the source entry.
+    pub source: wip::Entry,
+    /// Application enum represented by a schema-neutral string.
+    pub visibility: Visibility,
+    /// Schema-opaque JSON represented by ordinary protocol values.
+    pub metadata: wip::JsonValue,
 }
 
 /// The application domain result of a publication attempt.
@@ -59,6 +102,9 @@ pub trait Catalog {
 
     /// Demonstrates a host/backend failure rather than a domain result.
     fn backend_status(&self) -> wip::OperationResult<String>;
+
+    /// Demonstrates denial after every structural precondition succeeds.
+    fn restricted_status(&self) -> wip::OperationResult<String>;
 }
 
 /// Audit operations exposed by the same object.
@@ -78,15 +124,25 @@ pub trait Diagnostics {
 /// Observable outcomes from the complete public-API scenario.
 #[derive(Debug, Clone, PartialEq)]
 pub struct DemoReport {
+    /// Path-segment name from the canonical object projection.
+    pub object_name: String,
+    /// Optional object identity, distinct from the resolution path.
+    pub object_reference: Option<String>,
+    /// Optional object-state validator.
+    pub object_validator: Option<Vec<u8>>,
     /// Opaque interface references published by the object, in exposure order.
     pub published_interfaces: Vec<String>,
-    /// Descriptor format observed for the catalog interface.
+    /// Opaque reference assigned to the catalog descriptor.
+    pub catalog_interface_reference: String,
+    /// Opaque reference assigned to the audit descriptor.
+    pub audit_interface_reference: String,
+    /// Descriptor format observed separately for the catalog reference.
     pub catalog_descriptor_format: String,
-    /// Descriptor format observed for the audit interface.
+    /// Descriptor format observed separately for the audit reference.
     pub audit_descriptor_format: String,
-    /// Typed successful application result decoded from a validated `Value`.
+    /// Typed successful application result decoded from a validated [`Value`].
     pub published: PublishOutcome,
-    /// Typed application-domain rejection decoded from a validated `Value`.
+    /// Typed application-domain rejection decoded from a validated [`Value`].
     pub rejected: PublishOutcome,
     /// Result of the catalog-qualified `status` operation.
     pub catalog_status: String,
@@ -94,15 +150,25 @@ pub struct DemoReport {
     pub audit_status: String,
     /// Stable failure kind produced by the deliberate host/backend failure.
     pub host_failure: CallErrorKind,
-    /// A protocol-level failure built from the host failure.
+    /// A protocol failure whose operation effects cannot be guaranteed absent.
     pub protocol_failure: ProtocolError,
+    /// Authorization failure after a fully qualified valid request.
+    pub permission_failure: ProtocolErrorCode,
+    /// Recovery signal for a stale object validator.
+    pub validator_failure: ProtocolErrorCode,
+    /// Failure for a known but unexposed interface reference.
+    pub interface_mismatch: ProtocolErrorCode,
+    /// Failure for an unknown interface observation reference.
+    pub interface_not_found: ProtocolErrorCode,
+    /// First failure for a request with an invalid path and later invalid fields.
+    pub precedence_failure: ProtocolErrorCode,
 }
 
-/// Runs the complete end-to-end example.
+/// Runs the complete end-to-end conformance example.
 ///
 /// The provider resolves the current object from a Worldspace path for each
 /// call. Interface observations remain separate from object projection, and all
-/// calls carry independent object and interface validators.
+/// successful calls carry independent object and interface validators.
 ///
 /// # Errors
 ///
@@ -112,7 +178,7 @@ pub fn run() -> Result<DemoReport, Box<dyn Error>> {
     let mut registry = InterfaceRegistry::new();
     let catalog = registry.register(CatalogDefinition, Some(Validator::new(CATALOG_VALIDATOR)))?;
     let audit = registry.register(AuditDefinition, None)?;
-    let _diagnostics = registry.register(DiagnosticsDefinition, None)?;
+    let diagnostics = registry.register(DiagnosticsDefinition, None)?;
     let provider = ApplicationProvider {
         catalog: catalog.clone(),
         audit: audit.clone(),
@@ -138,6 +204,12 @@ pub fn run() -> Result<DemoReport, Box<dyn Error>> {
         PublishRequest {
             title: "Public APIs".into(),
             body: Some("protocol values in, validated values out".into()),
+            source: wip::Entry::new("/drafts/public-apis")?,
+            visibility: Visibility::Public,
+            metadata: wip::JsonValue::Object(vec![wip::JsonMember {
+                name: "reviewed".into(),
+                value: wip::JsonValue::Boolean(true),
+            }]),
         },
     )?;
     let rejected = dispatch_publish(
@@ -146,11 +218,15 @@ pub fn run() -> Result<DemoReport, Box<dyn Error>> {
         PublishRequest {
             title: String::new(),
             body: None,
+            source: wip::Entry::new("/drafts/untitled")?,
+            visibility: Visibility::Private,
+            metadata: wip::JsonValue::Null,
         },
     )?;
     let catalog_status = dispatch_string(
         &provider,
         request(
+            OBJECT_PATH,
             catalog.reference(),
             Some(CATALOG_VALIDATOR),
             "status",
@@ -159,28 +235,97 @@ pub fn run() -> Result<DemoReport, Box<dyn Error>> {
     )?;
     let audit_status = dispatch_string(
         &provider,
-        request(audit.reference(), None, "status", BTreeMap::new()),
+        request(
+            OBJECT_PATH,
+            audit.reference(),
+            None,
+            "status",
+            BTreeMap::new(),
+        ),
     )?;
 
     let host_error = provider
         .call_operation(request(
+            OBJECT_PATH,
             catalog.reference(),
             Some(CATALOG_VALIDATOR),
             "backend_status",
             BTreeMap::new(),
         ))
-        .unwrap_err();
-    if host_error.kind() != CallErrorKind::Implementation {
-        return Err(io::Error::other(format!(
-            "unexpected host failure kind: {:?}",
-            host_error.kind()
-        ))
-        .into());
-    }
+        .expect_err("backend_status must model a host failure");
+    ensure_kind(&host_error, CallErrorKind::Implementation)?;
     let protocol_failure = host_error.protocol_error();
 
+    let permission_failure = provider
+        .call_operation(request(
+            OBJECT_PATH,
+            catalog.reference(),
+            Some(CATALOG_VALIDATOR),
+            "restricted_status",
+            BTreeMap::new(),
+        ))
+        .expect_err("restricted_status must be denied")
+        .protocol_error()
+        .code;
+
+    let validator_failure = provider
+        .call_operation(CallRequest {
+            target: Target {
+                path: OBJECT_PATH.into(),
+                validator: Some(b"stale-object".to_vec()),
+            },
+            interface: InterfaceTarget {
+                reference: diagnostics.reference().as_str().to_owned(),
+                validator: Some(b"stale-interface".to_vec()),
+            },
+            operation: "missing".into(),
+            arguments: BTreeMap::from([("unknown".into(), Value::Unit)]),
+        })
+        .expect_err("the stale object validator must fail first")
+        .protocol_error()
+        .code;
+
+    let interface_mismatch = provider
+        .call_operation(request(
+            OBJECT_PATH,
+            diagnostics.reference(),
+            None,
+            "diagnostics",
+            BTreeMap::new(),
+        ))
+        .expect_err("registered but unexposed interface must not dispatch")
+        .protocol_error()
+        .code;
+
+    let interface_not_found = registry
+        .fetch_interface("missing-interface")
+        .expect_err("unknown interface references must not resolve")
+        .code;
+
+    let precedence_failure = provider
+        .call_operation(CallRequest {
+            target: Target {
+                path: "relative/path".into(),
+                validator: Some(b"stale-object".to_vec()),
+            },
+            interface: InterfaceTarget {
+                reference: diagnostics.reference().as_str().to_owned(),
+                validator: Some(b"stale-interface".to_vec()),
+            },
+            operation: "missing".into(),
+            arguments: BTreeMap::from([("unknown".into(), Value::Unit)]),
+        })
+        .expect_err("invalid path must have canonical precedence")
+        .protocol_error()
+        .code;
+
     Ok(DemoReport {
+        object_name: object.name,
+        object_reference: object.r#ref,
+        object_validator: object.validator,
         published_interfaces: object.interfaces,
+        catalog_interface_reference: catalog.reference().as_str().to_owned(),
+        audit_interface_reference: audit.reference().as_str().to_owned(),
         catalog_descriptor_format: catalog_observation.descriptor.format,
         audit_descriptor_format: audit_observation.descriptor.format,
         published,
@@ -189,9 +334,25 @@ pub fn run() -> Result<DemoReport, Box<dyn Error>> {
         audit_status,
         host_failure: host_error.kind(),
         protocol_failure,
+        permission_failure,
+        validator_failure,
+        interface_mismatch,
+        interface_not_found,
+        precedence_failure,
     })
 }
 
+fn ensure_kind(error: &wip_host::CallError, expected: CallErrorKind) -> Result<(), io::Error> {
+    if error.kind() == expected {
+        Ok(())
+    } else {
+        Err(io::Error::other(format!(
+            "unexpected host failure kind: {:?}",
+            error.kind()
+        )))
+    }
+}
+
 fn dispatch_publish(
     provider: &ApplicationProvider,
     catalog: &InterfaceRef,
@@ -199,6 +360,7 @@ fn dispatch_publish(
 ) -> Result<PublishOutcome, Box<dyn Error>> {
     let encoded_request = request_value.encode()?;
     let result = provider.call_operation(request(
+        OBJECT_PATH,
         catalog,
         Some(CATALOG_VALIDATOR),
         "publish",
@@ -216,14 +378,15 @@ fn dispatch_string(
 }
 
 fn request(
+    path: &str,
     interface: &InterfaceRef,
     interface_validator: Option<&[u8]>,
     operation: &str,
-    arguments: BTreeMap<String, wip_protocol::Value>,
+    arguments: BTreeMap<String, Value>,
 ) -> CallRequest {
     CallRequest {
         target: Target {
-            path: OBJECT_PATH.into(),
+            path: path.into(),
             validator: Some(OBJECT_VALIDATOR.to_vec()),
         },
         interface: InterfaceTarget {
@@ -258,6 +421,16 @@ impl ObjectProvider for ApplicationProvider {
             .expect("ApplicationService implements Audit");
         Some(operation(&publication))
     }
+
+    fn authorize(
+        &self,
+        _: &str,
+        _: &ApplicationService,
+        _: &InterfaceRef,
+        operation: &str,
+    ) -> bool {
+        operation != "restricted_status"
+    }
 }
 
 struct ApplicationService {
@@ -316,6 +489,10 @@ impl Catalog for ApplicationService {
             Ok("backend-ready".into())
         }
     }
+
+    fn restricted_status(&self) -> wip::OperationResult<String> {
+        Ok("authorization hook should prevent this call".into())
+    }
 }
 
 impl Audit for ApplicationService {
@@ -329,32 +506,3 @@ impl Diagnostics for ApplicationService {
         Ok("host-private".into())
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use wip_protocol::ProtocolErrorCode;
-
-    #[test]
-    fn unexposed_interfaces_are_membership_failures() {
-        let mut registry = InterfaceRegistry::new();
-        let catalog = registry.register(CatalogDefinition, None).unwrap();
-        let audit = registry.register(AuditDefinition, None).unwrap();
-        let diagnostics = registry.register(DiagnosticsDefinition, None).unwrap();
-        let provider = ApplicationProvider { catalog, audit };
-
-        let error = provider
-            .call_operation(request(
-                diagnostics.reference(),
-                None,
-                "diagnostics",
-                BTreeMap::new(),
-            ))
-            .unwrap_err();
-        assert_eq!(error.kind(), CallErrorKind::InterfaceMismatch);
-        assert_eq!(
-            error.protocol_error().code,
-            ProtocolErrorCode::InterfaceMismatch
-        );
-    }
-}

crates/wip-public-api-example/tests/end_to_end.rs

@@ -0,0 +1,239 @@
+use std::collections::BTreeMap;
+
+use wip_host::CallErrorKind;
+use wip_interface::{Entry, JsonMember, JsonValue, WipType};
+use wip_protocol::{INTERFACE_FORMAT_V1, InterfaceDescriptor, Object, ProtocolErrorCode, Value};
+use wip_public_api_example::{CatalogDefinition, PublishOutcome, PublishRequest, Visibility, run};
+
+#[test]
+fn public_crates_support_the_complete_qualified_end_to_end_scenario() {
+    let report = run().unwrap();
+
+    assert_eq!(report.object_name, "article-service");
+    assert_eq!(
+        report.object_reference.as_deref(),
+        Some("article-service-instance")
+    );
+    assert_eq!(
+        report.object_validator.as_deref(),
+        Some(b"object-v1".as_slice())
+    );
+    assert_eq!(
+        report.published_interfaces,
+        [
+            report.catalog_interface_reference.clone(),
+            report.audit_interface_reference.clone(),
+        ],
+        "interfaces must retain explicit publication order"
+    );
+    assert_ne!(
+        report.catalog_interface_reference, report.audit_interface_reference,
+        "interfaces form an ordered set of distinct opaque references"
+    );
+    assert_eq!(report.catalog_descriptor_format, INTERFACE_FORMAT_V1);
+    assert_eq!(report.audit_descriptor_format, INTERFACE_FORMAT_V1);
+    assert_eq!(
+        report.published,
+        PublishOutcome::Published("article-1".into())
+    );
+    assert_eq!(
+        report.rejected,
+        PublishOutcome::Rejected("a title is required".into())
+    );
+    assert_eq!(report.catalog_status, "catalog-ready");
+    assert_eq!(report.audit_status, "audit-ready");
+}
+
+#[test]
+fn domain_host_permission_and_validator_failures_remain_distinct() {
+    let report = run().unwrap();
+
+    assert!(matches!(report.rejected, PublishOutcome::Rejected(_)));
+    assert_eq!(report.host_failure, CallErrorKind::Implementation);
+    assert_eq!(
+        report.protocol_failure.code,
+        ProtocolErrorCode::OperationOutcomeUnknown
+    );
+    assert_eq!(
+        report.permission_failure,
+        ProtocolErrorCode::PermissionDenied
+    );
+    assert_eq!(
+        report.validator_failure,
+        ProtocolErrorCode::ValidatorMismatch,
+        "validator recovery signals must not collapse to InvalidRequest"
+    );
+}
+
+#[test]
+fn interface_mismatch_is_not_interface_not_found() {
+    let report = run().unwrap();
+
+    assert_eq!(
+        report.interface_mismatch,
+        ProtocolErrorCode::InterfaceMismatch
+    );
+    assert_eq!(
+        report.interface_not_found,
+        ProtocolErrorCode::InterfaceNotFound
+    );
+    assert_ne!(report.interface_mismatch, report.interface_not_found);
+}
+
+#[test]
+fn invalid_path_keeps_canonical_failure_precedence() {
+    let report = run().unwrap();
+
+    assert_eq!(report.precedence_failure, ProtocolErrorCode::InvalidRequest);
+    assert_ne!(report.precedence_failure, report.validator_failure);
+    assert_ne!(report.precedence_failure, report.interface_mismatch);
+}
+
+#[test]
+fn object_fields_keep_path_context_and_optional_ref_separate() {
+    // Listing every field makes this test fail to compile if a mandatory
+    // ObjectId is reintroduced into the canonical object DTO.
+    let object = Object {
+        name: "article".into(),
+        description: None,
+        interfaces: vec!["catalog-ref".into(), "audit-ref".into()],
+        r#ref: None,
+        validator: None,
+    };
+
+    object.validate_at_path("/library/article").unwrap();
+    assert_eq!(object.name, "article");
+    assert_eq!(object.r#ref, None);
+    assert_eq!(object.interfaces, ["catalog-ref", "audit-ref"]);
+}
+
+#[test]
+fn interface_reference_is_observed_separately_from_descriptor_fields() {
+    // An exact destructuring pattern is compile-time coverage that the
+    // descriptor has no trait-name or opaque-reference `name` field.
+    let InterfaceDescriptor {
+        format,
+        documentation,
+        types,
+        operations,
+    } = CatalogDefinition::descriptor();
+
+    assert_eq!(format, INTERFACE_FORMAT_V1);
+    assert!(documentation.is_some());
+    assert!(!types.is_empty());
+    assert_eq!(
+        operations
+            .iter()
+            .map(|operation| operation.name.as_str())
+            .collect::<Vec<_>>(),
+        ["publish", "status", "backend_status", "restricted_status"]
+    );
+}
+
+#[test]
+fn application_record_enum_union_entry_and_json_use_schema_neutral_values() {
+    let request = PublishRequest {
+        title: "Canonical values".into(),
+        body: None,
+        source: Entry::new("/drafts/canonical-values").unwrap(),
+        visibility: Visibility::Public,
+        metadata: JsonValue::Object(vec![
+            JsonMember {
+                name: "tags".into(),
+                value: JsonValue::Array(vec![JsonValue::String("wip".into()), JsonValue::Null]),
+            },
+            JsonMember {
+                name: "ready".into(),
+                value: JsonValue::Boolean(true),
+            },
+        ]),
+    };
+
+    let encoded = request.encode().unwrap();
+    assert_schema_neutral(&encoded);
+    let Value::Record(fields) = encoded else {
+        panic!("derived DTO record must use Value::Record")
+    };
+    assert_eq!(
+        fields.get("title"),
+        Some(&Value::String("Canonical values".into()))
+    );
+    assert!(!fields.contains_key("body"));
+    assert_eq!(
+        fields.get("source"),
+        Some(&Value::String("/drafts/canonical-values".into()))
+    );
+    assert_eq!(
+        fields.get("visibility"),
+        Some(&Value::String("Public".into()))
+    );
+    assert_eq!(
+        fields.get("metadata"),
+        Some(&Value::Record(BTreeMap::from([
+            ("ready".into(), Value::Boolean(true)),
+            (
+                "tags".into(),
+                Value::List(vec![Value::String("wip".into()), Value::Unit])
+            ),
+        ])))
+    );
+
+    let outcome = PublishOutcome::Rejected("policy".into()).encode().unwrap();
+    assert_schema_neutral(&outcome);
+    assert_eq!(
+        outcome,
+        Value::Record(BTreeMap::from([
+            ("$case".into(), Value::String("Rejected".into())),
+            ("value".into(), Value::String("policy".into())),
+        ]))
+    );
+}
+
+#[test]
+fn entry_is_a_validated_canonical_absolute_path_string() {
+    let entry = Entry::new("/articles/one").unwrap();
+    assert_eq!(
+        entry.encode().unwrap(),
+        Value::String("/articles/one".into())
+    );
+
+    for invalid in [
+        "articles/one",
+        "/articles/",
+        "/articles//one",
+        "/articles/./one",
+        "/articles/../one",
+    ] {
+        assert!(
+            Entry::new(invalid).is_err(),
+            "accepted invalid path {invalid}"
+        );
+        assert!(
+            Entry::decode(Value::String(invalid.into())).is_err(),
+            "decoded invalid path {invalid}"
+        );
+    }
+}
+
+fn assert_schema_neutral(value: &Value) {
+    // This exhaustive match is a compile-time regression guard: reintroducing
+    // semantic Entry/Enum/Union/Json variants makes the consumer non-exhaustive.
+    match value {
+        Value::Unit
+        | Value::Boolean(_)
+        | Value::Integer(_)
+        | Value::Number(_)
+        | Value::String(_)
+        | Value::Bytes(_) => {}
+        Value::Record(fields) => {
+            for value in fields.values() {
+                assert_schema_neutral(value);
+            }
+        }
+        Value::List(values) => {
+            for value in values {
+                assert_schema_neutral(value);
+            }
+        }
+    }
+}

tests/end_to_end.rs

@@ -1,24 +0,0 @@
-use wip_host::CallErrorKind;
-use wip_protocol::{INTERFACE_FORMAT_V1, ProtocolErrorCode};
-use wip_public_api_example::{PublishOutcome, run};
-
-#[test]
-fn public_crates_support_the_complete_end_to_end_scenario() {
-    let report = run().unwrap();
-
-    assert_eq!(report.published_interfaces.len(), 2);
-    assert_eq!(report.catalog_descriptor_format, INTERFACE_FORMAT_V1);
-    assert_eq!(report.audit_descriptor_format, INTERFACE_FORMAT_V1);
-    assert_eq!(
-        report.published,
-        PublishOutcome::Published("article-1".into())
-    );
-    assert_eq!(
-        report.rejected,
-        PublishOutcome::Rejected("a title is required".into())
-    );
-    assert_eq!(report.catalog_status, "catalog-ready");
-    assert_eq!(report.audit_status, "audit-ready");
-    assert_eq!(report.host_failure, CallErrorKind::Implementation);
-    assert_eq!(report.protocol_failure.code, ProtocolErrorCode::Internal);
-}