fix: align interface macros with canonical values

Cargo.lock

@@ -270,9 +270,11 @@ name = "wip-protocol"
 version = "0.1.0"
 
 [[package]]
-name = "wip-rs"
+name = "wip-public-api-example"
 version = "0.1.0"
 dependencies = [
+ "wip-host",
+ "wip-interface",
  "wip-protocol",
 ]
 

Cargo.toml

@@ -9,9 +9,14 @@ members = [
 resolver = "3"
 
 [package]
-name = "wip-rs"
+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

@@ -2,6 +2,66 @@
 
 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.
+
+## Crate graph and responsibilities
+
+```text
+wip-public-api-example (workspace-only executable, integration tests, doctest)
+├── wip-protocol              logical declarations, values, calls, and validation
+├── wip-interface             application DTO codecs and interface authoring facade
+│   ├── wip-protocol
+│   └── wip-interface-macros  proc-macro implementation detail
+└── wip-host                  descriptor registry, publication, and qualified dispatch
+    ├── 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-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-public-api-example` | An independently compiled consumer of only the three public crates. Its DTOs and traits are application-owned; its implementation and backend handle remain host-private. | Reusable library API or a production server. |
+
+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 a future
+transport maps its own routes/envelopes to `CallOperationRequest` and
+`CallOperationResponse` without placing transport-specific types in descriptors
+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:
+
+1. public application DTOs derived as `WipType` records and unions;
+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;
+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.
+
+Run it inside the development shell:
+
+```console
+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.
+
 ## Interface authoring
 
 Applications depend on `wip-interface`, normally imported as `wip`:
@@ -30,42 +90,69 @@ pub trait Messenger {
 ```
 
 The `interface` attribute and `WipType` derive are re-exported by the facade;
-users do not import `wip-interface-macros` directly. The generated
+users do not import `wip-interface-macros` or generated private support symbols.
-`MessengerDefinition` constructs an `InterfaceDescriptor`, decodes named
+The generated `MessengerDefinition` constructs an `InterfaceDescriptor`,
-arguments, encodes results, validates both boundaries, and provides typed
+decodes named arguments, encodes results, validates both boundaries, and
-dispatch for any `T: Messenger`.
+provides typed dispatch for any `T: Messenger`.
 
-### Type mapping
+### Supported Rust syntax
+
+A supported interface is a public, non-generic trait containing methods with:
+
+- exactly an immutable `&self` receiver;
+- simple named, owned parameters;
+- an explicit `wip::OperationResult<T>` return;
+- `()` only as the application return when no value is produced; and
+- direct `Option<T>` only for an omittable parameter.
+
+`WipType` derives support named-field structs, all-unit enums, and unions whose
+cases may be unit variants or variants containing exactly one unnamed payload.
+The macros reject private,
+generic, inherited, unsafe, auto, or associated-item traits; const, async,
+unsafe, extern, variadic, generic, default-bodied, or non-`&self` methods;
+borrowed/custom-lifetime values; tuple/unit/generic structs; Rust unions;
+named-field/multi-field enum variants; explicit discriminants; nested `Option`; and
+`Option` in returns, collections, entries, or union payloads. These diagnostics
+are compile-fail tested under `crates/wip-interface/tests/ui`.
+
+### Rust type mapping
 
 | Rust | Protocol |
 | --- | --- |
-| `()` as an operation result | no returned value |
+| `()` | unit / `Value::Unit` |
 | `bool` | boolean |
 | integer primitives | JavaScript-lossless integer |
 | `f32`, `f64` | finite number |
 | `String` | string |
 | `wip::Bytes` | bytes |
-| `wip::wip_protocol::JsonValue` | JSON |
+| `wip::JsonValue` | JSON interpreted over the schema-neutral `Value` tree |
-| `wip::Entry<K, V>` | entry |
+| `wip::Entry` | canonical absolute Worldspace path encoded as a string |
 | `Vec<T>` | list |
 | named-field `#[derive(wip::WipType)]` struct | named record |
-| all-unit `#[derive(wip::WipType)]` enum | named enum |
+| all-unit `#[derive(wip::WipType)]` enum | named enum encoded as a string |
-| all-newtype `#[derive(wip::WipType)]` enum | named tagged union |
+| mixed unit/newtype or all-newtype enum | named union encoded as a discriminator record |
 
-`Option<T>` is accepted only for a direct DTO field or operation parameter and
+`Option<T>` means that a direct DTO field or operation parameter may be
-means that the named value may be omitted. It is not protocol null. Domain
+omitted; it is not protocol null. JSON null remains available inside
-failures are modeled in the application result (usually a derived union) and
+`wip::JsonValue`.
-returned through `Ok`; `wip::HostError` is only for host/runtime failures.
+
+#### Migration from the pre-canonical value API
+
+The old generic `wip::Entry<K, V>` represented an application key/value pair
+and is no longer available. Use `wip::Entry::new("/canonical/path")` for a
+Worldspace entry path and place any associated application data in a record.
+`Entry` encodes as `Value::String` and validates the canonical absolute path.
+
+The semantic `Value::Json`, `Value::Entry`, `Value::Enum`, and `Value::Union`
+variants have also been removed. JSON recursively uses `Unit`, primitive,
+`List`, and `Record` values and rejects `Bytes`; enums use `String`; unions use
+a `Record` containing `$case` and, for payload-bearing cases, `value`. Unit
+operation results are represented explicitly as `Value::Unit`.
 
 Rust doc comments become descriptor metadata. For an operation, a `# Returns`
 section documents the return declaration; text before that section documents
 the operation itself.
 
-The supported interface slice is deliberately non-generic: public traits,
-`&self`, named parameters, and `OperationResult<T>`. Generic traits or methods,
-associated items, custom lifetimes, inheritance, default method bodies, and
-other receiver forms are rejected at their source spans.
-
 ## Host publication and dispatch
 
 Applications use `wip-host` to register generated definitions and explicitly
@@ -83,17 +170,40 @@ let protocol_object = published.protocol_object();
 `expose` compiles only when the object implements the generated definition's
 interface trait. Implementing a trait does not expose it automatically, empty
 interface sets are valid, insertion order is preserved, and duplicate
-references are rejected. Registry references are opaque; descriptor names and
+references are rejected. Registry references are opaque and remain outside the
-Rust type names are not used as wire identity.
+descriptor; generated descriptors contain neither those references nor Rust
+trait identity.
 
-Dispatch is qualified by interface reference and operation name. The host checks
+Dispatch is qualified by interface reference and operation name. The host
-current object identity and validator policy, current interface membership,
+checks current object identity and validator policy, current interface
-interface validator, descriptor operation, arguments, and result while retaining
+membership, interface validator, descriptor operation, arguments, and result
-the selected object and registered artifact. Host-private fields and backend
+while retaining the selected object and registered artifact. Host-private
-handles are never projected by `WipObject`.
+fields and backend handles are never projected by `WipObject`.
+
+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
+rejected as internal host failures and never returned as application data.
 
 Providers remain responsible for backend atomicity. Enter a transaction, lock,
 stable-handle scope, or conditional-update primitive before constructing and
 dispatching the request-scoped `PublishedObject`, and retain it until dispatch
 returns. The runtime never validates one object and then resolves a second
 snapshot, but it cannot make an arbitrary external backend atomic by itself.
+
+## Validation
+
+Enter the dev shell and run the acceptance commands exactly:
+
+```console
+nix develop
+cargo fmt --all -- --check
+cargo check --workspace --all-targets
+cargo test --workspace --all-targets
+cargo clippy --workspace --all-targets -- -D warnings
+```
+
+`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.

crates/wip-host/src/lib.rs

@@ -31,7 +31,7 @@
 #![deny(missing_docs)]
 
 use std::any::TypeId;
-use std::collections::{HashMap, HashSet};
+use std::collections::{BTreeMap, HashMap, HashSet};
 use std::error::Error;
 use std::fmt::{self, Display, Formatter};
 use std::marker::PhantomData;
@@ -42,8 +42,7 @@ use wip_interface::DispatchError;
 pub use wip_interface::{InterfaceDefinition, InterfaceImplementation};
 pub use wip_protocol;
 use wip_protocol::{
-    InterfaceDescriptor, NamedValue, Object, ObjectId, OperationCall, OperationTarget,
+    InterfaceDescriptor, Object, ProtocolError, ProtocolErrorCode, ValidationError, Value,
-    ProtocolError, ProtocolErrorCategory, ValidationError, Value,
 };
 
 /// Opaque bytes used as a conditional execution precondition.
@@ -64,6 +63,14 @@ impl Validator {
     }
 }
 
+/// Host-local identity used by the legacy request-scoped publication API.
+///
+/// Canonical protocol calls target a Worldspace path. This wrapper remains
+/// temporarily host-local so T-5 can adapt generated values without assigning
+/// object identity semantics to the protocol descriptor model.
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ObjectId(pub String);
+
 /// Opaque host-assigned reference to one registered interface artifact.
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct InterfaceRef(String);
@@ -161,8 +168,8 @@ impl InterfaceRegistry {
     /// `validator` should be present when the host intends the reference to
     /// represent a versioned descriptor. Its presence makes the same value a
     /// mandatory precondition for dispatch. Registration finalizes the
-    /// descriptor's protocol `name` to the assigned opaque reference so it
+    /// descriptor remains independent of both registration and its assigned
-    /// corresponds directly to [`Object::interfaces`].
+    /// opaque reference.
     pub fn register<D>(
         &mut self,
         _definition: D,
@@ -176,7 +183,7 @@ impl InterfaceRegistry {
             return Err(RegistrationError::AlreadyRegistered);
         }
 
-        let mut descriptor = D::descriptor();
+        let descriptor = D::descriptor();
         descriptor
             .validate()
             .map_err(RegistrationError::InvalidDescriptor)?;
@@ -185,11 +192,6 @@ impl InterfaceRegistry {
             "wip-interface:{}:{}",
             self.namespace, self.next_reference
         ));
-        // The protocol model currently carries the interface identifier in the
-        // descriptor's `name` field. Finalize that identity to the same opaque
-        // reference placed on published objects; the generated Rust trait name
-        // is registration-local metadata, not wire identity.
-        descriptor.name = reference.0.clone();
         self.next_reference = self
             .next_reference
             .checked_add(1)
@@ -208,6 +210,18 @@ impl InterfaceRegistry {
         })
     }
 
+    /// Resolves a transport-provided opaque reference string in this registry.
+    ///
+    /// The returned value is registry-scoped and suitable for observation or a
+    /// qualified [`CallRequest`]. Unknown or foreign references return `None`;
+    /// constructing arbitrary `InterfaceRef` values is intentionally not part of
+    /// the public API.
+    #[must_use]
+    pub fn resolve(&self, reference: &str) -> Option<InterfaceRef> {
+        let reference = InterfaceRef(reference.to_owned());
+        self.artifacts.contains_key(&reference).then_some(reference)
+    }
+
     /// Observes the descriptor and optional validator for an opaque reference.
     #[must_use]
     pub fn observe(&self, reference: &InterfaceRef) -> Option<InterfaceObservation> {
@@ -277,7 +291,7 @@ pub trait WipObject {
     }
 }
 
-type DispatchFn<T> = fn(&T, &str, Vec<NamedValue>) -> Result<Option<Value>, DispatchError>;
+type DispatchFn<T> = fn(&T, &str, BTreeMap<String, Value>) -> Result<Value, DispatchError>;
 
 struct BoundInterface<T> {
     artifact: Arc<InterfaceArtifact>,
@@ -338,13 +352,20 @@ impl<T: WipObject> PublishedObject<T> {
     /// Builds the protocol object metadata with interface insertion order intact.
     #[must_use]
     pub fn protocol_object(&self) -> Object {
+        let id = self.implementation.id();
         let object = Object {
-            id: self.implementation.id(),
+            name: id.0.clone(),
+            description: None,
             interfaces: self
                 .interfaces
                 .iter()
                 .map(|bound| bound.artifact.reference.0.clone())
                 .collect(),
+            r#ref: Some(id.0),
+            validator: self
+                .implementation
+                .validator()
+                .map(|validator| validator.0.clone()),
         };
         debug_assert!(object.validate().is_ok());
         object
@@ -426,14 +447,7 @@ impl<T: WipObject> PublishedObject<T> {
         bound
             .artifact
             .descriptor
-            .validate_call(&OperationCall {
+            .validate_arguments(&request.operation, &request.arguments)
-                target: OperationTarget {
-                    object: request.object.clone(),
-                    interface: bound.artifact.descriptor.name.clone(),
-                    operation: request.operation.clone(),
-                },
-                arguments: request.arguments.clone(),
-            })
             .map_err(|error| CallError::new(CallErrorKind::InvalidArguments, error.to_string()))?;
 
         let value = (bound.dispatch)(&self.implementation, &request.operation, request.arguments)
@@ -442,7 +456,7 @@ impl<T: WipObject> PublishedObject<T> {
         bound
             .artifact
             .descriptor
-            .validate_return(&request.operation, value.as_ref())
+            .validate_result(&request.operation, &value)
             .map_err(|error| CallError::new(CallErrorKind::InvalidResult, error.to_string()))?;
 
         Ok(CallResult {
@@ -500,14 +514,14 @@ pub struct CallRequest {
     /// Operation name within the selected interface descriptor.
     pub operation: String,
     /// Named protocol arguments.
-    pub arguments: Vec<NamedValue>,
+    pub arguments: BTreeMap<String, Value>,
 }
 
 /// Successful host dispatch result.
 #[derive(Debug, Clone, PartialEq)]
 pub struct CallResult {
-    /// Encoded application value, or `None` for a no-return operation.
+    /// Encoded application result. No-data operations return [`Value::Unit`].
-    pub value: Option<Value>,
+    pub value: Value,
     /// Object validator observed after the implementation returned.
     pub validator: Option<Validator>,
 }
@@ -598,20 +612,20 @@ impl CallError {
     #[must_use]
     pub fn protocol_error(&self) -> ProtocolError {
         let category = match self.kind {
-            CallErrorKind::ObjectNotFound => ProtocolErrorCategory::ObjectNotFound,
+            CallErrorKind::ObjectNotFound => ProtocolErrorCode::NotFound,
-            CallErrorKind::InterfaceMismatch => ProtocolErrorCategory::InterfaceNotFound,
+            CallErrorKind::InterfaceMismatch => ProtocolErrorCode::InterfaceMismatch,
-            CallErrorKind::OperationNotFound => ProtocolErrorCategory::OperationNotFound,
+            CallErrorKind::OperationNotFound => ProtocolErrorCode::OperationNotFound,
-            CallErrorKind::InvalidArguments => ProtocolErrorCategory::InvalidArguments,
+            CallErrorKind::InvalidArguments => ProtocolErrorCode::InvalidArguments,
             CallErrorKind::ValidatorRequired
             | CallErrorKind::ValidatorMismatch
             | CallErrorKind::InterfaceValidatorRequired
-            | CallErrorKind::InterfaceValidatorMismatch => ProtocolErrorCategory::InvalidRequest,
+            | CallErrorKind::InterfaceValidatorMismatch => ProtocolErrorCode::InvalidRequest,
             CallErrorKind::InvalidResult | CallErrorKind::Implementation => {
-                ProtocolErrorCategory::Internal
+                ProtocolErrorCode::Internal
             }
         };
         ProtocolError {
-            category,
+            code: category,
             message: self.message.clone(),
         }
     }

crates/wip-host/tests/host.rs

@@ -1,14 +1,14 @@
 use std::cell::{Cell, RefCell};
+use std::collections::BTreeMap;
 
 use wip_host::{
-    CallErrorKind, CallRequest, InterfaceRegistry, InterfaceTarget, PublishedObject, Validator,
+    CallErrorKind, CallRequest, InterfaceRegistry, InterfaceTarget, ObjectId, PublishedObject,
-    WipObject,
+    Validator, WipObject,
 };
 use wip_interface::{
-    CodecError, HostError, NamedValue, OperationResult, TypeDeclaration, TypeExpr, Value, WipType,
+    CodecError, HostError, OperationResult, TypeDeclaration, TypeExpr, Value, WipType, interface,
-    interface,
 };
-use wip_protocol::{ObjectId, ProtocolErrorCategory};
+use wip_protocol::ProtocolErrorCode;
 
 #[interface]
 pub trait Reader {
@@ -143,7 +143,7 @@ fn request(
     reference: &wip_host::InterfaceRef,
     interface_validator: Option<&[u8]>,
     operation: &str,
-    arguments: Vec<NamedValue>,
+    arguments: BTreeMap<String, Value>,
 ) -> CallRequest {
     CallRequest {
         object: ObjectId(object.into()),
@@ -163,9 +163,14 @@ fn registry_exposes_opaque_validated_descriptor_observations() {
     let reader = registry.register(ReaderDefinition, None).unwrap();
 
     assert_ne!(reader.reference().as_str(), "Reader");
+    assert_eq!(
+        registry.resolve(reader.reference().as_str()).as_ref(),
+        Some(reader.reference())
+    );
+    assert!(registry.resolve("wip-interface:unknown:0").is_none());
     let observation = registry.observe(reader.reference()).unwrap();
     assert_eq!(observation.reference, *reader.reference());
-    assert_eq!(observation.descriptor.name, reader.reference().as_str());
+    assert_eq!(observation.descriptor, ReaderDefinition::descriptor());
     assert_eq!(observation.validator, None);
     observation.descriptor.validate().unwrap();
 
@@ -174,6 +179,11 @@ fn registry_exposes_opaque_validated_descriptor_observations() {
     let mut other_registry = InterfaceRegistry::new();
     let other_reader = other_registry.register(ReaderDefinition, None).unwrap();
     assert_ne!(reader.reference(), other_reader.reference());
+    assert!(
+        registry
+            .resolve(other_reader.reference().as_str())
+            .is_none()
+    );
 }
 
 #[test]
@@ -197,13 +207,16 @@ fn publication_is_explicit_ordered_qualified_and_request_scoped() {
             reader.reference().as_str().to_owned()
         ]
     );
-    wip_protocol::InterfaceObservation {
+    registry
-        object: object.clone(),
+        .observe(writer.reference())
-        descriptors: vec![
+        .unwrap()
-            registry.observe(writer.reference()).unwrap().descriptor,
+        .descriptor
-            registry.observe(reader.reference()).unwrap().descriptor,
+        .validate()
-        ],
+        .unwrap();
-    }
+    registry
+        .observe(reader.reference())
+        .unwrap()
+        .descriptor
         .validate()
         .unwrap();
     assert!(!format!("{object:?}").contains("private/backend/path"));
@@ -215,7 +228,7 @@ fn publication_is_explicit_ordered_qualified_and_request_scoped() {
             writer.reference(),
             None,
             "label",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap();
     let reader_result = publication
@@ -225,11 +238,11 @@ fn publication_is_explicit_ordered_qualified_and_request_scoped() {
             reader.reference(),
             None,
             "label",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap();
-    assert_eq!(writer_result.value, Some(Value::String("writer".into())));
+    assert_eq!(writer_result.value, Value::String("writer".into()));
-    assert_eq!(reader_result.value, Some(Value::String("reader".into())));
+    assert_eq!(reader_result.value, Value::String("reader".into()));
     assert_eq!(publication.implementation().calls.get(), 2);
     assert_eq!(
         publication
@@ -257,13 +270,13 @@ fn implemented_but_unexposed_interface_is_not_a_member() {
             hidden.reference(),
             None,
             "hidden",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap_err();
     assert_eq!(error.kind(), CallErrorKind::InterfaceMismatch);
     assert_eq!(
-        error.protocol_error().category,
+        error.protocol_error().code,
-        ProtocolErrorCategory::InterfaceNotFound
+        ProtocolErrorCode::InterfaceMismatch
     );
     assert_eq!(publication.implementation().calls.get(), 0);
 }
@@ -272,7 +285,8 @@ fn implemented_but_unexposed_interface_is_not_a_member() {
 fn zero_interface_objects_are_valid() {
     let publication = PublishedObject::new(Document::new("empty"));
     let object = publication.protocol_object();
-    assert_eq!(object.id, ObjectId("empty".into()));
+    assert_eq!(object.name, "empty");
+    assert_eq!(object.r#ref.as_deref(), Some("empty"));
     assert!(object.interfaces.is_empty());
     object.validate().unwrap();
 }
@@ -306,13 +320,13 @@ fn operation_and_argument_failures_are_mapped_without_execution() {
             reader.reference(),
             None,
             "missing",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap_err();
     assert_eq!(missing.kind(), CallErrorKind::OperationNotFound);
     assert_eq!(
-        missing.protocol_error().category,
+        missing.protocol_error().code,
-        ProtocolErrorCategory::OperationNotFound
+        ProtocolErrorCode::OperationNotFound
     );
 
     let invalid = publication
@@ -322,16 +336,13 @@ fn operation_and_argument_failures_are_mapped_without_execution() {
             reader.reference(),
             None,
             "add",
-            vec![NamedValue {
+            BTreeMap::from([("left".into(), Value::String("wrong".into()))]),
-                name: "left".into(),
-                value: Value::String("wrong".into()),
-            }],
         ))
         .unwrap_err();
     assert_eq!(invalid.kind(), CallErrorKind::InvalidArguments);
     assert_eq!(
-        invalid.protocol_error().category,
+        invalid.protocol_error().code,
-        ProtocolErrorCategory::InvalidArguments
+        ProtocolErrorCode::InvalidArguments
     );
     assert_eq!(publication.implementation().calls.get(), 0);
 }
@@ -351,14 +362,11 @@ fn invalid_implementation_result_is_internal_and_not_returned() {
             broken.reference(),
             None,
             "broken",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap_err();
     assert_eq!(error.kind(), CallErrorKind::InvalidResult);
-    assert_eq!(
+    assert_eq!(error.protocol_error().code, ProtocolErrorCode::Internal);
-        error.protocol_error().category,
-        ProtocolErrorCategory::Internal
-    );
     assert_eq!(publication.implementation().calls.get(), 1);
 }
 
@@ -377,7 +385,7 @@ fn object_validator_missing_and_mismatch_are_distinct_and_prevent_execution() {
             reader.reference(),
             None,
             "label",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap_err();
     assert_eq!(missing.kind(), CallErrorKind::ValidatorRequired);
@@ -389,7 +397,7 @@ fn object_validator_missing_and_mismatch_are_distinct_and_prevent_execution() {
             reader.reference(),
             None,
             "label",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap_err();
     assert_eq!(mismatch.kind(), CallErrorKind::ValidatorMismatch);
@@ -402,7 +410,7 @@ fn object_validator_missing_and_mismatch_are_distinct_and_prevent_execution() {
             reader.reference(),
             None,
             "label",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap();
     assert_eq!(result.validator, Some(Validator::new(b"object-v1")));
@@ -429,7 +437,7 @@ fn interface_validator_missing_and_mismatch_are_distinct_and_prevent_execution()
             writer.reference(),
             None,
             "label",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap_err();
     assert_eq!(missing.kind(), CallErrorKind::InterfaceValidatorRequired);
@@ -441,7 +449,7 @@ fn interface_validator_missing_and_mismatch_are_distinct_and_prevent_execution()
             writer.reference(),
             Some(b"schema-v0"),
             "label",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap_err();
     assert_eq!(mismatch.kind(), CallErrorKind::InterfaceValidatorMismatch);
@@ -454,10 +462,10 @@ fn interface_validator_missing_and_mismatch_are_distinct_and_prevent_execution()
             writer.reference(),
             Some(b"schema-v1"),
             "label",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap();
-    assert_eq!(result.value, Some(Value::String("writer".into())));
+    assert_eq!(result.value, Value::String("writer".into()));
 }
 
 #[test]
@@ -486,12 +494,9 @@ fn host_failures_map_to_internal_without_becoming_domain_values() {
             failing.reference(),
             None,
             "fail",
-            vec![],
+            BTreeMap::new(),
         ))
         .unwrap_err();
     assert_eq!(error.kind(), CallErrorKind::Implementation);
-    assert_eq!(
+    assert_eq!(error.protocol_error().code, ProtocolErrorCode::Internal);
-        error.protocol_error().category,
-        ProtocolErrorCategory::Internal
-    );
 }

crates/wip-host/tests/ui/unimplemented_interface.rs

@@ -1,6 +1,5 @@
-use wip_host::{InterfaceRegistry, PublishedObject, WipObject};
+use wip_host::{InterfaceRegistry, ObjectId, PublishedObject, WipObject};
 use wip_interface::{OperationResult, interface};
-use wip_protocol::ObjectId;
 
 #[interface]
 pub trait Search {

crates/wip-host/tests/ui/unimplemented_interface.stderr

@@ -1,27 +1,27 @@
 error[E0277]: the trait bound `Object: Search` is not satisfied
-  --> tests/ui/unimplemented_interface.rs:21:58
+  --> tests/ui/unimplemented_interface.rs:20:58
    |
-21 |     let _published = PublishedObject::new(Object).expose(&search).unwrap();
+20 |     let _published = PublishedObject::new(Object).expose(&search).unwrap();
    |                                                   ------ ^^^^^^^ unsatisfied trait bound
    |                                                   |
    |                                                   required by a bound introduced by this call
    |
 help: the trait `Search` is not implemented for `Object`
-  --> tests/ui/unimplemented_interface.rs:10:1
+  --> tests/ui/unimplemented_interface.rs:9:1
    |
-10 | struct Object;
+ 9 | struct Object;
    | ^^^^^^^^^^^^^
 help: this trait has no implementations, consider adding one
-  --> tests/ui/unimplemented_interface.rs:6:1
-   |
- 6 | pub trait Search {
-   | ^^^^^^^^^^^^^^^^
-note: required for `SearchDefinition` to implement `InterfaceImplementation<Object>`
   --> tests/ui/unimplemented_interface.rs:5:1
    |
- 5 | #[interface]
+ 5 | pub trait Search {
+   | ^^^^^^^^^^^^^^^^
+note: required for `SearchDefinition` to implement `InterfaceImplementation<Object>`
+  --> tests/ui/unimplemented_interface.rs:4:1
+   |
+ 4 | #[interface]
    | ^^^^^^^^^^^^
- 6 | pub trait Search {
+ 5 | pub trait Search {
    |           ^^^^^^
 note: required by a bound in `PublishedObject::<T>::expose`
   --> src/lib.rs

crates/wip-interface-macros/src/lib.rs

@@ -1,4 +1,10 @@
 //! Procedural macros backing the public `wip-interface` authoring facade.
+//!
+//! This is an implementation crate. Applications should depend on
+//! `wip-interface`, which re-exports both macros alongside the traits and types
+//! used by their generated code.
+
+#![deny(missing_docs)]
 
 use std::collections::HashSet;
 
@@ -162,9 +168,11 @@ fn expand_interface(attribute: TokenStream2, item: ItemTrait) -> syn::Result<Tok
                 #(#declaration_collectors)*
 
                 ::wip_interface::wip_protocol::InterfaceDescriptor {
-                    name: ::std::string::String::from(stringify!(#trait_ident)),
+                    format: ::std::string::String::from(
+                        ::wip_interface::wip_protocol::INTERFACE_FORMAT_V1,
+                    ),
                     documentation: #trait_doc,
-                    declarations,
+                    types: declarations,
                     operations: ::std::vec![#(#operation_declarations),*],
                 }
             }
@@ -174,9 +182,12 @@ fn expand_interface(attribute: TokenStream2, item: ItemTrait) -> syn::Result<Tok
             fn dispatch(
                 implementation: &T,
                 operation: &str,
-                arguments: ::std::vec::Vec<::wip_interface::wip_protocol::NamedValue>,
+                arguments: ::std::collections::BTreeMap<
+                    ::std::string::String,
+                    ::wip_interface::wip_protocol::Value,
+                >,
             ) -> ::std::result::Result<
-                ::std::option::Option<::wip_interface::wip_protocol::Value>,
+                ::wip_interface::wip_protocol::Value,
                 ::wip_interface::DispatchError,
             > {
                 let descriptor = Self::descriptor();
@@ -201,9 +212,12 @@ fn expand_interface(attribute: TokenStream2, item: ItemTrait) -> syn::Result<Tok
             pub fn dispatch<T: #trait_ident>(
                 implementation: &T,
                 operation: &str,
-                arguments: ::std::vec::Vec<::wip_interface::wip_protocol::NamedValue>,
+                arguments: ::std::collections::BTreeMap<
+                    ::std::string::String,
+                    ::wip_interface::wip_protocol::Value,
+                >,
             ) -> ::std::result::Result<
-                ::std::option::Option<::wip_interface::wip_protocol::Value>,
+                ::wip_interface::wip_protocol::Value,
                 ::wip_interface::DispatchError,
             > {
                 <Self as ::wip_interface::InterfaceImplementation<T>>::dispatch(
@@ -470,13 +484,18 @@ fn parse_operation_result(output: &ReturnType) -> syn::Result<Type> {
         _ => None,
     });
     let result = types.next().cloned();
-    if arguments.args.len() != 1 || result.is_none() || types.next().is_some() {
+    if arguments.args.len() != 1 || types.next().is_some() {
         return Err(Error::new_spanned(
             arguments,
             "`OperationResult` must have exactly one application result type",
         ));
     }
-    let result = result.expect("checked above");
+    let result = result.ok_or_else(|| {
+        Error::new_spanned(
+            arguments,
+            "`OperationResult` must have exactly one application result type",
+        )
+    })?;
     if direct_option(&result)?.is_some() || contains_option(&result) {
         return Err(Error::new_spanned(
             result,
@@ -490,8 +509,13 @@ fn argument_item(operation: &Operation) -> TokenStream2 {
     let arguments_ident = &operation.arguments_ident;
     let fields = operation.parameters.iter().map(|parameter| {
         let ident = &parameter.ident;
+        let name = &parameter.name;
         let ty = parameter_rust_type(parameter);
-        quote!(pub #ident: #ty)
+        let documentation = format!("Decoded `{name}` operation argument.");
+        quote!(
+            #[doc = #documentation]
+            pub #ident: #ty
+        )
     });
     let decoders = operation.parameters.iter().map(|parameter| {
         let ident = &parameter.ident;
@@ -507,12 +531,11 @@ fn argument_item(operation: &Operation) -> TokenStream2 {
     let encode_result = if operation.unit_result {
         quote! {
             let () = result;
-            ::std::result::Result::Ok(::std::option::Option::None)
+            ::std::result::Result::Ok(::wip_interface::wip_protocol::Value::Unit)
         }
     } else {
         quote! {
             <#result_ty as ::wip_interface::WipType>::encode(result)
-                .map(::std::option::Option::Some)
         }
     };
 
@@ -525,9 +548,12 @@ fn argument_item(operation: &Operation) -> TokenStream2 {
         impl #arguments_ident {
             /// Decodes named logical values into typed operation arguments.
             pub fn decode(
-                arguments: ::std::vec::Vec<::wip_interface::wip_protocol::NamedValue>,
+                arguments: ::std::collections::BTreeMap<
+                    ::std::string::String,
+                    ::wip_interface::wip_protocol::Value,
+                >,
             ) -> ::std::result::Result<Self, ::wip_interface::CodecError> {
-                let mut decoder = ::wip_interface::__private::RecordDecoder::new(arguments)?;
+                let mut decoder = ::wip_interface::__private::RecordDecoder::new(arguments);
                 let decoded = Self {
                     #(#decoders,)*
                 };
@@ -539,7 +565,7 @@ fn argument_item(operation: &Operation) -> TokenStream2 {
             pub fn encode_result(
                 result: #result_ty,
             ) -> ::std::result::Result<
-                ::std::option::Option<::wip_interface::wip_protocol::Value>,
+                ::wip_interface::wip_protocol::Value,
                 ::wip_interface::CodecError,
             > {
                 #encode_result
@@ -559,22 +585,18 @@ fn operation_declaration(operation: &Operation) -> TokenStream2 {
         quote! {
             ::wip_interface::wip_protocol::ParameterDeclaration {
                 name: ::std::string::String::from(#parameter_name),
+                required: !#optional,
                 documentation: #parameter_doc,
-                ty: <#ty as ::wip_interface::WipType>::type_expr(),
+                r#type: <#ty as ::wip_interface::WipType>::type_expr(),
-                optional: #optional,
             }
         }
     });
-    let returns = if operation.unit_result {
-        quote!(::std::option::Option::None)
-    } else {
     let result_ty = &operation.result_ty;
     let return_doc = documentation_tokens(operation.return_documentation.as_ref());
-        quote! {
+    let returns = quote! {
-            ::std::option::Option::Some(::wip_interface::wip_protocol::ReturnDeclaration {
+        ::wip_interface::wip_protocol::ReturnDeclaration {
             documentation: #return_doc,
-                ty: <#result_ty as ::wip_interface::WipType>::type_expr(),
+            r#type: <#result_ty as ::wip_interface::WipType>::type_expr(),
-            })
         }
     };
 
@@ -630,7 +652,7 @@ fn dispatch_arm(operation: &Operation) -> TokenStream2 {
             let encoded = #arguments_ident::encode_result(result)
                 .map_err(::wip_interface::DispatchError::Encode)?;
             descriptor
-                .validate_return(#operation_name, encoded.as_ref())
+                .validate_result(#operation_name, &encoded)
                 .map_err(::wip_interface::DispatchError::InvalidResult)?;
             ::std::result::Result::Ok(encoded)
         }
@@ -698,7 +720,12 @@ fn derive_record(
     let mut parsed_fields = Vec::new();
     let mut names = HashSet::new();
     for field in fields {
-        let field_ident = field.ident.clone().expect("named fields have identifiers");
+        let Some(field_ident) = field.ident.clone() else {
+            return Err(Error::new_spanned(
+                field,
+                "`WipType` record fields must be named",
+            ));
+        };
         let name = source_name(&field_ident);
         if !names.insert(name.clone()) {
             return Err(Error::new(
@@ -726,9 +753,9 @@ fn derive_record(
         quote! {
             ::wip_interface::wip_protocol::FieldDeclaration {
                 name: ::std::string::String::from(#name),
+                required: !#optional,
                 documentation: #documentation,
-                ty: <#ty as ::wip_interface::WipType>::type_expr(),
+                r#type: <#ty as ::wip_interface::WipType>::type_expr(),
-                optional: #optional,
             }
         }
     });
@@ -744,18 +771,18 @@ fn derive_record(
         if field.optional {
             quote! {
                 if let ::std::option::Option::Some(value) = #field_ident {
-                    fields.push(::wip_interface::wip_protocol::NamedValue {
+                    fields.insert(
-                        name: ::std::string::String::from(#field_name),
+                        ::std::string::String::from(#field_name),
-                        value: <#ty as ::wip_interface::WipType>::encode(value)?,
+                        <#ty as ::wip_interface::WipType>::encode(value)?,
-                    });
+                    );
                 }
             }
         } else {
             quote! {
-                fields.push(::wip_interface::wip_protocol::NamedValue {
+                fields.insert(
-                    name: ::std::string::String::from(#field_name),
+                    ::std::string::String::from(#field_name),
-                    value: <#ty as ::wip_interface::WipType>::encode(#field_ident)?,
+                    <#ty as ::wip_interface::WipType>::encode(#field_ident)?,
-                });
+                );
             }
         }
     });
@@ -773,9 +800,9 @@ fn derive_record(
     Ok(quote! {
         impl ::wip_interface::WipType for #ident {
             fn type_expr() -> ::wip_interface::wip_protocol::TypeExpr {
-                ::wip_interface::wip_protocol::TypeExpr::Named(
+                ::wip_interface::wip_protocol::TypeExpr::Named {
-                    ::std::string::String::from(#type_name),
+                    name: ::std::string::String::from(#type_name),
-                )
+                }
             }
 
             fn collect_declarations(
@@ -783,13 +810,13 @@ fn derive_record(
                     ::wip_interface::wip_protocol::TypeDeclaration,
                 >,
             ) {
-                let declaration = ::wip_interface::wip_protocol::TypeDeclaration::Record(
+                let declaration = ::wip_interface::wip_protocol::TypeDeclaration {
-                    ::wip_interface::wip_protocol::RecordDeclaration {
                     name: ::std::string::String::from(#type_name),
                     documentation: #declaration_doc,
+                    definition: ::wip_interface::wip_protocol::TypeExpr::Record {
                         fields: ::std::vec![#(#field_declarations),*],
                     },
-                );
+                };
                 if ::wip_interface::__private::register_declaration(declarations, declaration) {
                     #(#dependency_collectors)*
                 }
@@ -802,7 +829,7 @@ fn derive_record(
                 ::wip_interface::CodecError,
             > {
                 let Self { #(#destructured_fields),* } = self;
-                let mut fields = ::std::vec::Vec::new();
+                let mut fields = ::std::collections::BTreeMap::new();
                 #(#encoders)*
                 ::std::result::Result::Ok(
                     ::wip_interface::wip_protocol::Value::Record(fields),
@@ -814,7 +841,7 @@ fn derive_record(
             ) -> ::std::result::Result<Self, ::wip_interface::CodecError> {
                 match value {
                     ::wip_interface::wip_protocol::Value::Record(fields) => {
-                        let mut decoder = ::wip_interface::__private::RecordDecoder::new(fields)?;
+                        let mut decoder = ::wip_interface::__private::RecordDecoder::new(fields);
                         let decoded = Self {
                             #(#decoders,)*
                         };
@@ -849,14 +876,14 @@ fn derive_enum(
         .variants
         .iter()
         .all(|variant| matches!(variant.fields, Fields::Unit));
-    let all_payload = !data.variants.is_empty()
+    let valid_union = data.variants.iter().all(|variant| {
-        && data.variants.iter().all(|variant| {
+        matches!(variant.fields, Fields::Unit)
-            matches!(&variant.fields, Fields::Unnamed(fields) if fields.unnamed.len() == 1)
+            || matches!(&variant.fields, Fields::Unnamed(fields) if fields.unnamed.len() == 1)
     });
 
     if all_unit {
         derive_unit_enum(ident, type_name, type_documentation, data)
-    } else if all_payload {
+    } else if valid_union {
         derive_union_enum(ident, type_name, type_documentation, data)
     } else {
         let span = data
@@ -869,7 +896,7 @@ fn derive_enum(
             .map_or_else(|| data.enum_token.span, Spanned::span);
         Err(Error::new(
             span,
-            "a `WipType` enum must contain either only unit variants or only single-field tuple variants; mixed and named-field variants are unsupported",
+            "a `WipType` enum must contain unit variants and/or single-field tuple variants; named-field and multi-field variants are unsupported",
         ))
     }
 }
@@ -885,7 +912,7 @@ fn derive_unit_enum(
         let name = source_name(&variant.ident);
         let documentation = documentation_tokens(documentation(&variant.attrs).as_ref());
         quote! {
-            ::wip_interface::wip_protocol::EnumVariantDeclaration {
+            ::wip_interface::wip_protocol::EnumCase {
                 name: ::std::string::String::from(#name),
                 documentation: #documentation,
             }
@@ -905,9 +932,9 @@ fn derive_unit_enum(
     Ok(quote! {
         impl ::wip_interface::WipType for #ident {
             fn type_expr() -> ::wip_interface::wip_protocol::TypeExpr {
-                ::wip_interface::wip_protocol::TypeExpr::Named(
+                ::wip_interface::wip_protocol::TypeExpr::Named {
-                    ::std::string::String::from(#type_name),
+                    name: ::std::string::String::from(#type_name),
-                )
+                }
             }
 
             fn collect_declarations(
@@ -915,13 +942,13 @@ fn derive_unit_enum(
                     ::wip_interface::wip_protocol::TypeDeclaration,
                 >,
             ) {
-                let declaration = ::wip_interface::wip_protocol::TypeDeclaration::Enum(
+                let declaration = ::wip_interface::wip_protocol::TypeDeclaration {
-                    ::wip_interface::wip_protocol::EnumDeclaration {
                     name: ::std::string::String::from(#type_name),
                     documentation: #declaration_doc,
-                        variants: ::std::vec![#(#declarations),*],
+                    definition: ::wip_interface::wip_protocol::TypeExpr::Enum {
+                        cases: ::std::vec![#(#declarations),*],
                     },
-                );
+                };
                 let _ = ::wip_interface::__private::register_declaration(
                     declarations,
                     declaration,
@@ -938,7 +965,7 @@ fn derive_unit_enum(
                     #(#encoders,)*
                 };
                 ::std::result::Result::Ok(
-                    ::wip_interface::wip_protocol::Value::Enum(
+                    ::wip_interface::wip_protocol::Value::String(
                         ::std::string::String::from(variant),
                     ),
                 )
@@ -948,7 +975,7 @@ fn derive_unit_enum(
                 value: ::wip_interface::wip_protocol::Value,
             ) -> ::std::result::Result<Self, ::wip_interface::CodecError> {
                 match value {
-                    ::wip_interface::wip_protocol::Value::Enum(variant) => {
+                    ::wip_interface::wip_protocol::Value::String(variant) => {
                         match variant.as_str() {
                             #(#decoders,)*
                             _ => ::std::result::Result::Err(
@@ -977,30 +1004,36 @@ fn derive_union_enum(
     struct Variant<'a> {
         ident: &'a Ident,
         name: String,
-        ty: &'a Type,
+        payload: Option<&'a Type>,
         documentation: Option<Documentation>,
     }
 
     let mut variants = Vec::new();
     for variant in &data.variants {
-        let Fields::Unnamed(fields) = &variant.fields else {
+        let payload = match &variant.fields {
-            unreachable!("enum shape was checked before union generation");
+            Fields::Unit => None,
-        };
+            Fields::Unnamed(fields) if fields.unnamed.len() == 1 => {
-        let field = fields
+                let field = fields.unnamed.first().expect("length checked");
-            .unnamed
-            .first()
-            .expect("union variants have one field");
                 if direct_option(&field.ty)?.is_some() || contains_option(&field.ty) {
                     return Err(Error::new_spanned(
                         &field.ty,
                         "`Option<T>` is only supported directly on DTO fields and operation parameters",
                     ));
                 }
-        validate_value_type(&field.ty, "union variant payload")?;
+                validate_value_type(&field.ty, "union case payload")?;
+                Some(&field.ty)
+            }
+            _ => {
+                return Err(Error::new_spanned(
+                    variant,
+                    "a `WipType` union case must be unit-like or contain exactly one unnamed payload",
+                ));
+            }
+        };
         variants.push(Variant {
             ident: &variant.ident,
             name: source_name(&variant.ident),
-            ty: &field.ty,
+            payload,
             documentation: documentation(&variant.attrs),
         });
     }
@@ -1009,50 +1042,95 @@ fn derive_union_enum(
     let declarations = variants.iter().map(|variant| {
         let name = &variant.name;
         let documentation = documentation_tokens(variant.documentation.as_ref());
-        let ty = variant.ty;
+        let payload = match variant.payload {
+            Some(ty) => quote! {
+                ::std::option::Option::Some(
+                    <#ty as ::wip_interface::WipType>::type_expr(),
+                )
+            },
+            None => quote!(::std::option::Option::None),
+        };
         quote! {
-            ::wip_interface::wip_protocol::UnionVariantDeclaration {
+            ::wip_interface::wip_protocol::UnionCase {
                 name: ::std::string::String::from(#name),
                 documentation: #documentation,
-                ty: <#ty as ::wip_interface::WipType>::type_expr(),
+                payload: #payload,
             }
         }
     });
-    let dependency_collectors = variants.iter().map(|variant| {
+    let dependency_collectors = variants.iter().filter_map(|variant| {
-        let ty = variant.ty;
+        variant.payload.map(
-        quote!(<#ty as ::wip_interface::WipType>::collect_declarations(declarations);)
+            |ty| quote!(<#ty as ::wip_interface::WipType>::collect_declarations(declarations);),
+        )
     });
     let encoders = variants.iter().map(|variant| {
         let variant_ident = variant.ident;
         let name = &variant.name;
-        let ty = variant.ty;
+        match variant.payload {
-        quote! {
+            Some(ty) => quote! {
                 Self::#variant_ident(value) => {
-                ::wip_interface::wip_protocol::Value::Union {
+                    let mut fields = ::std::collections::BTreeMap::new();
-                    variant: ::std::string::String::from(#name),
+                    fields.insert(
-                    value: ::std::boxed::Box::new(
+                        ::std::string::String::from(
-                        <#ty as ::wip_interface::WipType>::encode(value)?,
+                            ::wip_interface::wip_protocol::UNION_CASE_FIELD,
                         ),
+                        ::wip_interface::wip_protocol::Value::String(
+                            ::std::string::String::from(#name),
+                        ),
+                    );
+                    fields.insert(
+                        ::std::string::String::from(
+                            ::wip_interface::wip_protocol::UNION_VALUE_FIELD,
+                        ),
+                        <#ty as ::wip_interface::WipType>::encode(value)?,
+                    );
+                    ::wip_interface::wip_protocol::Value::Record(fields)
                 }
+            },
+            None => quote! {
+                Self::#variant_ident => {
+                    let mut fields = ::std::collections::BTreeMap::new();
+                    fields.insert(
+                        ::std::string::String::from(
+                            ::wip_interface::wip_protocol::UNION_CASE_FIELD,
+                        ),
+                        ::wip_interface::wip_protocol::Value::String(
+                            ::std::string::String::from(#name),
+                        ),
+                    );
+                    ::wip_interface::wip_protocol::Value::Record(fields)
                 }
+            },
         }
     });
     let decoders = variants.iter().map(|variant| {
         let variant_ident = variant.ident;
         let name = &variant.name;
-        let ty = variant.ty;
+        match variant.payload {
-        quote! {
+            Some(ty) => quote! {
-            #name => <#ty as ::wip_interface::WipType>::decode(*value)
+                #name => {
-                .map(Self::#variant_ident)
+                    let value = decoder.required::<#ty>(
+                        ::wip_interface::wip_protocol::UNION_VALUE_FIELD,
+                    )?;
+                    decoder.finish()?;
+                    ::std::result::Result::Ok(Self::#variant_ident(value))
+                }
+            },
+            None => quote! {
+                #name => {
+                    decoder.finish()?;
+                    ::std::result::Result::Ok(Self::#variant_ident)
+                }
+            },
         }
     });
 
     Ok(quote! {
         impl ::wip_interface::WipType for #ident {
             fn type_expr() -> ::wip_interface::wip_protocol::TypeExpr {
-                ::wip_interface::wip_protocol::TypeExpr::Named(
+                ::wip_interface::wip_protocol::TypeExpr::Named {
-                    ::std::string::String::from(#type_name),
+                    name: ::std::string::String::from(#type_name),
-                )
+                }
             }
 
             fn collect_declarations(
@@ -1060,13 +1138,13 @@ fn derive_union_enum(
                     ::wip_interface::wip_protocol::TypeDeclaration,
                 >,
             ) {
-                let declaration = ::wip_interface::wip_protocol::TypeDeclaration::Union(
+                let declaration = ::wip_interface::wip_protocol::TypeDeclaration {
-                    ::wip_interface::wip_protocol::UnionDeclaration {
                     name: ::std::string::String::from(#type_name),
                     documentation: #declaration_doc,
-                        variants: ::std::vec![#(#declarations),*],
+                    definition: ::wip_interface::wip_protocol::TypeExpr::Union {
+                        cases: ::std::vec![#(#declarations),*],
                     },
-                );
+                };
                 if ::wip_interface::__private::register_declaration(declarations, declaration) {
                     #(#dependency_collectors)*
                 }
@@ -1088,26 +1166,30 @@ fn derive_union_enum(
                 value: ::wip_interface::wip_protocol::Value,
             ) -> ::std::result::Result<Self, ::wip_interface::CodecError> {
                 match value {
-                    ::wip_interface::wip_protocol::Value::Union { variant, value } => {
+                    ::wip_interface::wip_protocol::Value::Record(fields) => {
-                        match variant.as_str() {
+                        let mut decoder =
+                            ::wip_interface::__private::RecordDecoder::new(fields);
+                        let case = decoder.required::<::std::string::String>(
+                            ::wip_interface::wip_protocol::UNION_CASE_FIELD,
+                        )?;
+                        match case.as_str() {
                             #(#decoders,)*
                             _ => ::std::result::Result::Err(
                                 ::wip_interface::__private::decode_unknown_variant(
                                     #type_name,
-                                    variant,
+                                    case,
                                 ),
                             ),
                         }
                     }
                     actual => ::std::result::Result::Err(
-                        ::wip_interface::__private::decode_type_mismatch("union", actual),
+                        ::wip_interface::__private::decode_type_mismatch("union record", actual),
                     ),
                 }
             }
         }
     })
 }
-
 fn optional_type(ty: &Type, context: &str) -> syn::Result<(bool, Type)> {
     if let Some(inner) = direct_option(ty)? {
         if contains_option(&inner) {

crates/wip-interface/src/lib.rs

@@ -30,37 +30,63 @@
 //!
 //! | Rust type | Protocol type/value |
 //! | --- | --- |
-//! | `()` as an operation result | no return declaration / no value |
+//! | `()` | `Unit` |
 //! | `bool` | `Boolean` |
 //! | signed and unsigned integer primitives | JavaScript-lossless `Integer` |
 //! | `f32`, `f64` | finite `Number` |
 //! | `String` | `String` |
 //! | [`Bytes`] | `Bytes` |
-//! | [`wip_protocol::JsonValue`] | `Json` |
+//! | [`JsonValue`] | schema-neutral `Json` value tree |
-//! | [`Entry<K, V>`] | `Entry<K, V>` |
+//! | [`Entry`] | canonical absolute Worldspace path (`Entry`) |
 //! | `Vec<T>` | `List<T>` |
 //! | a named-field struct deriving [`WipType`] | named record |
 //! | an all-unit enum deriving [`WipType`] | named enum |
-//! | an all-newtype enum deriving [`WipType`] | named tagged union |
+//! | an enum mixing unit and single-payload cases deriving [`WipType`] | named union |
 //!
 //! `Option<T>` is supported only directly as a record field or operation
 //! parameter. It means omission, not a null value. A domain failure belongs in
 //! an application return enum/union and is returned as `Ok(value)`.
 //! [`HostError`] is reserved for host/runtime failure, so the required
 //! [`OperationResult`] convention keeps those two failure classes distinct.
+//!
+//! # Migration to canonical values
+//!
+//! Earlier releases exposed `Entry<K, V>` and semantic `Value::Json`,
+//! `Value::Entry`, `Value::Enum`, and `Value::Union` variants. Those forms are
+//! intentionally gone: [`Entry`] is now one validated absolute Worldspace path,
+//! while JSON, enum, and union meaning comes only from the descriptor. Codecs
+//! exchange only raw [`Value`] strings, records, lists, and primitives. Unit
+//! operation results now cross the boundary as [`Value::Unit`] rather than an
+//! absent value.
+//!
+//! # Supported interface syntax
+//!
+//! An interface is a public, non-generic trait whose operations use exactly
+//! `&self`, simple named owned parameters, and an explicit
+//! `OperationResult<T>`. `WipType` derives support named-field structs,
+//! all-unit enums as protocol enums, and enums made from any mix of unit and
+//! single-payload cases as protocol unions.
+//!
+//! The macros reject trait inheritance and associated items; const, async,
+//! unsafe, extern, variadic, generic, default-bodied, or non-`&self` methods;
+//! borrowed values and custom lifetimes; tuple, unit, or generic structs;
+//! unsupported named-field or multi-field enum variants; explicit discriminants; Rust unions;
+//! and `Option` anywhere except a direct DTO field or operation parameter.
+//! Unsupported inputs produce source-located compile errors rather than
+//! generating a partial interface.
 
 #![deny(missing_docs)]
 
+use std::collections::BTreeMap;
 use std::error::Error;
 use std::fmt::{self, Display, Formatter};
 
 pub use wip_interface_macros::{WipType, interface};
 pub use wip_protocol;
 pub use wip_protocol::{
-    Documentation, EnumDeclaration, EnumVariantDeclaration, FieldDeclaration, InterfaceDescriptor,
+    Documentation, EnumCase, FieldDeclaration, InterfaceDescriptor, MAX_SAFE_INTEGER,
-    JsonMember, JsonValue, MAX_SAFE_INTEGER, MIN_SAFE_INTEGER, NamedValue, OperationDeclaration,
+    MIN_SAFE_INTEGER, OperationDeclaration, ParameterDeclaration, ReturnDeclaration,
-    ParameterDeclaration, RecordDeclaration, ReturnDeclaration, TypeDeclaration, TypeExpr,
+    TypeDeclaration, TypeExpr, UnionCase, ValidationError, Value,
-    UnionDeclaration, UnionVariantDeclaration, ValidationError, Value,
 };
 
 /// Converts one Rust application type to and from its protocol representation.
@@ -103,8 +129,8 @@ pub trait InterfaceImplementation<T>: InterfaceDefinition {
     fn dispatch(
         implementation: &T,
         operation: &str,
-        arguments: Vec<NamedValue>,
+        arguments: BTreeMap<String, Value>,
-    ) -> Result<Option<Value>, DispatchError>;
+    ) -> Result<Value, DispatchError>;
 }
 
 /// Result convention required for generated interface operations.
@@ -266,13 +292,101 @@ impl From<Bytes> for Vec<u8> {
     }
 }
 
-/// A typed protocol key/value entry.
+/// A canonical absolute path to an entry in the current Worldspace.
-#[derive(Debug, Clone, PartialEq, Eq)]
+///
-pub struct Entry<K, V> {
+/// This replaces the pre-canonical `Entry<K, V>` key/value pair. Construct an
-    /// Entry key.
+/// entry from a path such as `/articles/1`; application data associated with
-    pub key: K,
+/// that entry belongs in an ordinary record alongside this value.
-    /// Entry value.
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
-    pub value: V,
+pub struct Entry(String);
+
+impl Entry {
+    /// Validates and creates an entry path.
+    pub fn new(path: impl Into<String>) -> Result<Self, CodecError> {
+        let path = path.into();
+        validate_entry_path(&path)?;
+        Ok(Self(path))
+    }
+
+    /// Returns the canonical absolute Worldspace path.
+    #[must_use]
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+
+    /// Consumes the entry and returns its path.
+    #[must_use]
+    pub fn into_string(self) -> String {
+        self.0
+    }
+}
+
+impl TryFrom<String> for Entry {
+    type Error = CodecError;
+
+    fn try_from(path: String) -> Result<Self, Self::Error> {
+        Self::new(path)
+    }
+}
+
+impl std::str::FromStr for Entry {
+    type Err = CodecError;
+
+    fn from_str(path: &str) -> Result<Self, Self::Err> {
+        Self::new(path)
+    }
+}
+
+/// One member in a [`JsonValue::Object`].
+#[derive(Debug, Clone, PartialEq)]
+pub struct JsonMember {
+    /// Member name.
+    pub name: String,
+    /// Member value.
+    pub value: JsonValue,
+}
+
+/// JSON data represented independently of any application schema.
+///
+/// Its codec uses the ordinary schema-neutral [`Value`] variants. JSON null is
+/// [`Value::Unit`], arrays are [`Value::List`], and objects are
+/// [`Value::Record`]. Protocol bytes have no JSON representation and decoding
+/// a tree containing [`Value::Bytes`] is rejected.
+#[derive(Debug, Clone, PartialEq)]
+pub enum JsonValue {
+    /// JSON null.
+    Null,
+    /// A JSON boolean.
+    Boolean(bool),
+    /// An interoperable integral JSON number.
+    Integer(i64),
+    /// A finite non-integral JSON number.
+    Number(f64),
+    /// A JSON string.
+    String(String),
+    /// A JSON array.
+    Array(Vec<JsonValue>),
+    /// A JSON object. Duplicate member names are rejected while encoding.
+    Object(Vec<JsonMember>),
+}
+
+impl WipType for () {
+    fn type_expr() -> TypeExpr {
+        TypeExpr::Unit
+    }
+
+    fn collect_declarations(_: &mut Vec<TypeDeclaration>) {}
+
+    fn encode(self) -> Result<Value, CodecError> {
+        Ok(Value::Unit)
+    }
+
+    fn decode(value: Value) -> Result<Self, CodecError> {
+        match value {
+            Value::Unit => Ok(()),
+            other => Err(CodecError::expected("unit", &other)),
+        }
+    }
 }
 
 impl WipType for bool {
@@ -441,52 +555,87 @@ impl WipType for JsonValue {
     fn collect_declarations(_: &mut Vec<TypeDeclaration>) {}
 
     fn encode(self) -> Result<Value, CodecError> {
-        validate_json(&self)?;
+        encode_json(self)
-        Ok(Value::Json(self))
     }
 
     fn decode(value: Value) -> Result<Self, CodecError> {
-        match value {
+        decode_json(value)
-            Value::Json(value) => {
-                validate_json(&value)?;
-                Ok(value)
     }
-            other => Err(CodecError::expected("json", &other)),
+}
+
+fn encode_json(value: JsonValue) -> Result<Value, CodecError> {
+    match value {
+        JsonValue::Null => Ok(Value::Unit),
+        JsonValue::Boolean(value) => Ok(Value::Boolean(value)),
+        JsonValue::Integer(value) => {
+            ensure_safe_integer(value)?;
+            Ok(Value::Integer(value))
+        }
+        JsonValue::Number(value) => {
+            ensure_finite(value)?;
+            Ok(Value::Number(value))
+        }
+        JsonValue::String(value) => Ok(Value::String(value)),
+        JsonValue::Array(values) => values
+            .into_iter()
+            .enumerate()
+            .map(|(index, value)| encode_json(value).map_err(|error| error.at(index.to_string())))
+            .collect::<Result<Vec<_>, _>>()
+            .map(Value::List),
+        JsonValue::Object(members) => {
+            let mut fields = BTreeMap::new();
+            for member in members {
+                let name = member.name;
+                let value = encode_json(member.value).map_err(|error| error.at(name.clone()))?;
+                if fields.insert(name.clone(), value).is_some() {
+                    return Err(CodecError::new(format!("duplicate JSON member `{name}`")).at(name));
+                }
+            }
+            Ok(Value::Record(fields))
         }
     }
 }
 
-fn validate_json(value: &JsonValue) -> Result<(), CodecError> {
+fn decode_json(value: Value) -> Result<JsonValue, CodecError> {
     match value {
-        JsonValue::Integer(value) => ensure_safe_integer(*value),
+        Value::Unit => Ok(JsonValue::Null),
-        JsonValue::Number(value) => ensure_finite(*value),
+        Value::Boolean(value) => Ok(JsonValue::Boolean(value)),
-        JsonValue::Array(values) => {
+        Value::Integer(value) => {
-            for (index, value) in values.iter().enumerate() {
+            ensure_safe_integer(value)?;
-                validate_json(value).map_err(|error| error.at(index.to_string()))?;
+            Ok(JsonValue::Integer(value))
         }
-            Ok(())
+        Value::Number(value) => {
+            ensure_finite(value)?;
+            Ok(JsonValue::Number(value))
         }
-        JsonValue::Object(members) => {
+        Value::String(value) => Ok(JsonValue::String(value)),
-            let mut names = std::collections::HashSet::new();
+        Value::Bytes(_) => Err(CodecError::new("bytes are not valid inside JSON")),
-            for member in members {
+        Value::List(values) => values
-                if !names.insert(member.name.as_str()) {
+            .into_iter()
-                    return Err(CodecError::new(format!(
+            .enumerate()
-                        "duplicate JSON member `{}`",
+            .map(|(index, value)| decode_json(value).map_err(|error| error.at(index.to_string())))
-                        member.name
+            .collect::<Result<Vec<_>, _>>()
-                    ))
+            .map(JsonValue::Array),
-                    .at(member.name.clone()));
+        Value::Record(fields) => fields
-                }
+            .into_iter()
-                validate_json(&member.value).map_err(|error| error.at(member.name.clone()))?;
+            .map(|(name, value)| {
-            }
+                decode_json(value)
-            Ok(())
+                    .map(|value| JsonMember {
-        }
+                        name: name.clone(),
-        JsonValue::Null | JsonValue::Boolean(_) | JsonValue::String(_) => Ok(()),
+                        value,
+                    })
+                    .map_err(|error| error.at(name))
+            })
+            .collect::<Result<Vec<_>, _>>()
+            .map(JsonValue::Object),
     }
 }
 
 impl<T: WipType> WipType for Vec<T> {
     fn type_expr() -> TypeExpr {
-        TypeExpr::List(Box::new(T::type_expr()))
+        TypeExpr::List {
+            items: Box::new(T::type_expr()),
+        }
     }
 
     fn collect_declarations(declarations: &mut Vec<TypeDeclaration>) {
@@ -513,37 +662,31 @@ impl<T: WipType> WipType for Vec<T> {
     }
 }
 
-impl<K: WipType, V: WipType> WipType for Entry<K, V> {
+impl WipType for Entry {
     fn type_expr() -> TypeExpr {
-        TypeExpr::Entry {
+        TypeExpr::Entry
-            key: Box::new(K::type_expr()),
-            value: Box::new(V::type_expr()),
-        }
     }
 
-    fn collect_declarations(declarations: &mut Vec<TypeDeclaration>) {
+    fn collect_declarations(_: &mut Vec<TypeDeclaration>) {}
-        K::collect_declarations(declarations);
-        V::collect_declarations(declarations);
-    }
 
     fn encode(self) -> Result<Value, CodecError> {
-        Ok(Value::Entry {
+        validate_entry_path(&self.0)?;
-            key: Box::new(self.key.encode().map_err(|error| error.at("key"))?),
+        Ok(Value::String(self.0))
-            value: Box::new(self.value.encode().map_err(|error| error.at("value"))?),
-        })
     }
 
     fn decode(value: Value) -> Result<Self, CodecError> {
-        let Value::Entry { key, value } = value else {
+        let Value::String(path) = value else {
-            return Err(CodecError::expected("entry", &value));
+            return Err(CodecError::expected("entry path string", &value));
         };
-        Ok(Self {
+        Self::new(path)
-            key: K::decode(*key).map_err(|error| error.at("key"))?,
-            value: V::decode(*value).map_err(|error| error.at("value"))?,
-        })
     }
 }
 
+fn validate_entry_path(path: &str) -> Result<(), CodecError> {
+    wip_protocol::validate_path(path)
+        .map_err(|error| CodecError::new(format!("invalid canonical Worldspace path: {error}")))
+}
+
 /// Implementation details used by code emitted from the facade's macros.
 ///
 /// These APIs are public only because macro expansions execute in the
@@ -551,12 +694,9 @@ impl<K: WipType, V: WipType> WipType for Entry<K, V> {
 /// and are not intended for direct use.
 #[doc(hidden)]
 pub mod __private {
-    use std::collections::HashSet;
+    use std::collections::BTreeMap;
 
-    use wip_protocol::{
+    use wip_protocol::{InterfaceDescriptor, TypeDeclaration, ValidationError, Value};
-        InterfaceDescriptor, NamedValue, ObjectId, OperationCall, OperationTarget, TypeDeclaration,
-        ValidationError, Value,
-    };
 
     use crate::{CodecError, Documentation, WipType};
 
@@ -591,16 +731,9 @@ pub mod __private {
     pub fn validate_arguments(
         descriptor: &InterfaceDescriptor,
         operation: &str,
-        arguments: &[NamedValue],
+        arguments: &BTreeMap<String, Value>,
     ) -> Result<(), ValidationError> {
-        descriptor.validate_call(&OperationCall {
+        descriptor.validate_arguments(operation, arguments)
-            target: OperationTarget {
-                object: ObjectId("<typed-dispatch>".into()),
-                interface: descriptor.name.clone(),
-                operation: operation.into(),
-            },
-            arguments: arguments.to_vec(),
-        })
     }
 
     /// Builds a codec error for a generated structural mismatch.
@@ -618,22 +751,13 @@ pub mod __private {
 
     /// Decoder for a protocol record or operation's named argument collection.
     pub struct RecordDecoder {
-        fields: Vec<NamedValue>,
+        fields: BTreeMap<String, Value>,
-        seen: HashSet<String>,
     }
 
     impl RecordDecoder {
-        /// Starts decoding record fields or named operation arguments and
+        /// Starts decoding record fields or named operation arguments.
-        /// rejects duplicate names.
+        pub fn new(fields: BTreeMap<String, Value>) -> Self {
-        pub fn new(fields: Vec<NamedValue>) -> Result<Self, CodecError> {
+            Self { fields }
-            let mut seen = HashSet::new();
-            for field in &fields {
-                if !seen.insert(field.name.clone()) {
-                    return Err(CodecError::new(format!("duplicate field `{}`", field.name))
-                        .at(field.name.clone()));
-                }
-            }
-            Ok(Self { fields, seen })
         }
 
         /// Decodes a required field.
@@ -654,23 +778,15 @@ pub mod __private {
 
         /// Rejects any fields that were not consumed by generated code.
         pub fn finish(self) -> Result<(), CodecError> {
-            if let Some(field) = self.fields.first() {
+            if let Some(name) = self.fields.keys().next() {
-                Err(CodecError::new(format!("unknown field `{}`", field.name))
+                Err(CodecError::new(format!("unknown field `{name}`")).at(name.clone()))
-                    .at(field.name.clone()))
             } else {
                 Ok(())
             }
         }
 
         fn take(&mut self, name: &str) -> Option<Value> {
-            let index = self.fields.iter().position(|field| field.name == name)?;
+            self.fields.remove(name)
-            Some(self.fields.remove(index).value)
-        }
-
-        /// Returns the set of names supplied to this decoder.
-        #[allow(dead_code)]
-        pub fn supplied_names(&self) -> &HashSet<String> {
-            &self.seen
         }
     }
 }

crates/wip-interface/tests/codecs.rs

@@ -1,8 +1,7 @@
-use wip_interface::wip_protocol::{
+use std::collections::BTreeMap;
-    EnumDeclaration, JsonMember, JsonValue, NamedValue, RecordDeclaration, TypeDeclaration,
+
-    TypeExpr, UnionDeclaration, Value,
+use wip_interface::wip_protocol::{TypeExpr, UNION_CASE_FIELD, UNION_VALUE_FIELD, Value};
-};
+use wip_interface::{Bytes, Entry, JsonMember, JsonValue, WipType};
-use wip_interface::{Bytes, Entry, WipType};
 
 /// A request record.
 #[derive(Debug, Clone, PartialEq, WipType)]
@@ -11,8 +10,8 @@ struct Request {
     title: String,
     /// Optional priority.
     priority: Option<i32>,
-    /// Related entries.
+    /// Related Worldspace entries.
-    related: Vec<Entry<String, bool>>,
+    related: Vec<Entry>,
     /// Opaque bytes.
     body: Bytes,
     /// Arbitrary metadata.
@@ -38,33 +37,53 @@ struct Receipt {
 /// Application-level publication outcome.
 #[derive(Debug, Clone, PartialEq, WipType)]
 enum PublishOutcome {
+    /// Work has not completed and carries no payload.
+    Pending,
     /// Application success.
     Published(Receipt),
     /// Domain rejection, not a host failure.
     Rejected(String),
 }
 
+fn field<'a>(record: &'a BTreeMap<String, Value>, name: &str) -> &'a Value {
+    record
+        .get(name)
+        .unwrap_or_else(|| panic!("missing `{name}`"))
+}
+
 #[test]
-fn supported_values_round_trip() {
+fn primitive_unit_record_list_entry_and_json_values_round_trip() {
+    assert_eq!(().encode().unwrap(), Value::Unit);
+    assert_eq!(<()>::decode(Value::Unit).unwrap(), ());
+    assert_eq!(<()>::type_expr(), TypeExpr::Unit);
+
     let request = Request {
         title: "hello".into(),
         priority: None,
-        related: vec![Entry {
+        related: vec![Entry::new("/articles/1").unwrap()],
-            key: "/articles/1".into(),
-            value: true,
-        }],
         body: Bytes(vec![1, 2, 3]),
         metadata: JsonValue::Object(vec![JsonMember {
             name: "source".into(),
-            value: JsonValue::String("test".into()),
+            value: JsonValue::Array(vec![JsonValue::String("test".into()), JsonValue::Null]),
         }]),
     };
 
     let encoded = request.clone().encode().unwrap();
     let Value::Record(fields) = &encoded else {
-        panic!("record derive must encode a protocol record")
+        panic!("record derive must encode a raw protocol record")
     };
-    assert!(fields.iter().all(|field| field.name != "priority"));
+    assert!(!fields.contains_key("priority"));
+    assert_eq!(
+        field(fields, "related"),
+        &Value::List(vec![Value::String("/articles/1".into())])
+    );
+    assert_eq!(
+        field(fields, "metadata"),
+        &Value::Record(BTreeMap::from([(
+            "source".into(),
+            Value::List(vec![Value::String("test".into()), Value::Unit]),
+        )]))
+    );
     assert_eq!(Request::decode(encoded).unwrap(), request);
 
     let number = 42.5_f64;
@@ -77,92 +96,136 @@ fn supported_values_round_trip() {
         f32::decode(narrow_number.encode().unwrap()).unwrap(),
         narrow_number
     );
-
-    for color in [Color::Red, Color::Blue] {
-        let encoded = color.clone().encode().unwrap();
-        let decoded = Color::decode(encoded).unwrap();
-        assert_eq!(decoded, color);
 }
 
+#[test]
+fn enums_are_strings_and_unions_are_discriminated_records() {
+    for color in [Color::Red, Color::Blue] {
+        let encoded = color.clone().encode().unwrap();
+        assert!(matches!(encoded, Value::String(_)));
+        assert_eq!(Color::decode(encoded).unwrap(), color);
+    }
+
+    let pending = PublishOutcome::Pending.encode().unwrap();
+    assert_eq!(
+        pending,
+        Value::Record(BTreeMap::from([(
+            UNION_CASE_FIELD.into(),
+            Value::String("Pending".into()),
+        )]))
+    );
+
+    let published = PublishOutcome::Published(Receipt { number: 7 })
+        .encode()
+        .unwrap();
+    let Value::Record(fields) = &published else {
+        panic!("union must encode as a record")
+    };
+    assert_eq!(
+        fields.get(UNION_CASE_FIELD),
+        Some(&Value::String("Published".into()))
+    );
+    assert!(matches!(
+        fields.get(UNION_VALUE_FIELD),
+        Some(Value::Record(_))
+    ));
+
     for outcome in [
+        PublishOutcome::Pending,
         PublishOutcome::Published(Receipt { number: 7 }),
         PublishOutcome::Rejected("policy".into()),
     ] {
         let encoded = outcome.clone().encode().unwrap();
-        let decoded = PublishOutcome::decode(encoded).unwrap();
+        assert_eq!(PublishOutcome::decode(encoded).unwrap(), outcome);
-        assert_eq!(decoded, outcome);
     }
 }
 
 #[test]
-fn derived_declarations_include_docs_optionality_and_dependencies() {
+fn derived_declarations_use_canonical_named_type_expressions() {
     let mut declarations = Vec::new();
     Request::collect_declarations(&mut declarations);
     Color::collect_declarations(&mut declarations);
     PublishOutcome::collect_declarations(&mut declarations);
 
-    let TypeDeclaration::Record(RecordDeclaration {
+    let request = declarations
-        documentation,
+        .iter()
-        fields,
+        .find(|declaration| declaration.name == "Request")
-        ..
+        .unwrap();
-    }) = &declarations[0]
+    assert_eq!(
-    else {
+        request.documentation.as_ref().unwrap().summary,
+        "A request record."
+    );
+    let TypeExpr::Record { fields } = &request.definition else {
         panic!("Request must be a record declaration")
     };
-    assert_eq!(documentation.as_ref().unwrap().summary, "A request record.");
     assert_eq!(
         fields[0].documentation.as_ref().unwrap().summary,
         "Required title."
     );
-    assert!(!fields[0].optional);
+    assert!(fields[0].required);
-    assert!(fields[1].optional);
+    assert!(!fields[1].required);
-    assert_eq!(fields[1].ty, TypeExpr::Integer);
+    assert_eq!(fields[1].r#type, TypeExpr::Integer);
     assert_eq!(
-        fields[2].ty,
+        fields[2].r#type,
-        TypeExpr::List(Box::new(TypeExpr::Entry {
+        TypeExpr::List {
-            key: Box::new(TypeExpr::String),
+            items: Box::new(TypeExpr::Entry),
-            value: Box::new(TypeExpr::Boolean),
+        }
-        }))
     );
 
     let color = declarations
         .iter()
-        .find(|declaration| declaration.name() == "Color")
+        .find(|declaration| declaration.name == "Color")
         .unwrap();
-    let TypeDeclaration::Enum(EnumDeclaration { variants, .. }) = color else {
+    let TypeExpr::Enum { cases } = &color.definition else {
         panic!("Color must be an enum declaration")
     };
     assert_eq!(
-        variants[0].documentation.as_ref().unwrap().summary,
+        cases[0].documentation.as_ref().unwrap().summary,
         "Warm red."
     );
 
     let outcome = declarations
         .iter()
-        .find(|declaration| declaration.name() == "PublishOutcome")
+        .find(|declaration| declaration.name == "PublishOutcome")
         .unwrap();
-    let TypeDeclaration::Union(UnionDeclaration { variants, .. }) = outcome else {
+    let TypeExpr::Union { cases } = &outcome.definition else {
         panic!("PublishOutcome must be a union declaration")
     };
-    assert_eq!(variants[0].ty, TypeExpr::Named("Receipt".into()));
+    assert_eq!(cases[0].payload, None);
+    assert_eq!(
+        cases[1].payload,
+        Some(TypeExpr::Named {
+            name: "Receipt".into(),
+        })
+    );
     assert!(
         declarations
             .iter()
-            .any(|declaration| declaration.name() == "Receipt")
+            .any(|declaration| declaration.name == "Receipt")
     );
 }
 
 #[test]
-fn codecs_reject_invalid_boundaries() {
+fn codecs_reject_invalid_boundaries_and_json_bytes() {
     assert!(i64::MAX.encode().is_err());
     assert!(f64::NAN.encode().is_err());
-    assert!(Request::decode(Value::Record(vec![])).is_err());
+    assert!(Request::decode(Value::Record(BTreeMap::new())).is_err());
     assert!(
-        Request::decode(Value::Record(vec![NamedValue {
+        Request::decode(Value::Record(BTreeMap::from([(
-            name: "unknown".into(),
+            "unknown".into(),
-            value: Value::String("value".into()),
+            Value::String("value".into()),
-        }]))
+        )])))
+        .is_err()
+    );
+    assert!(Color::decode(Value::String("Green".into())).is_err());
+    assert!(Entry::new("articles/1").is_err());
+    assert!(Entry::decode(Value::String("/articles/../1".into())).is_err());
+    assert!(JsonValue::decode(Value::Bytes(vec![1])).is_err());
+    assert!(
+        JsonValue::decode(Value::Record(BTreeMap::from([(
+            "nested".into(),
+            Value::List(vec![Value::Bytes(vec![1])]),
+        )])))
         .is_err()
     );
-    assert!(Color::decode(Value::Enum("Green".into())).is_err());
 }

crates/wip-interface/tests/interface.rs

@@ -1,4 +1,6 @@
-use wip_interface::wip_protocol::{NamedValue, TypeDeclaration, TypeExpr, Value};
+use std::collections::BTreeMap;
+
+use wip_interface::wip_protocol::{INTERFACE_FORMAT_V1, TypeExpr, Value};
 use wip_interface::{DispatchError, HostError, OperationResult, WipType, interface};
 
 /// Publication request.
@@ -36,7 +38,7 @@ pub trait Catalog {
         note: Option<String>,
     ) -> OperationResult<PublishOutcome>;
 
-    /// Checks connectivity without returning an application value.
+    /// Checks connectivity without returning application data.
     fn ping(&self) -> OperationResult<()>;
 
     /// Demonstrates a host/runtime failure.
@@ -88,36 +90,29 @@ impl Catalog for RejectingCatalog {
     }
 }
 
-fn named(name: &str, value: Value) -> NamedValue {
+fn publish_arguments(with_note: bool) -> BTreeMap<String, Value> {
-    NamedValue {
+    let mut arguments = BTreeMap::from([(
-        name: name.into(),
+        "request".into(),
-        value,
-    }
-}
-
-fn publish_arguments(with_note: bool) -> Vec<NamedValue> {
-    let mut arguments = vec![named(
-        "request",
         PublishRequest {
             title: "example".into(),
         }
         .encode()
         .unwrap(),
-    )];
+    )]);
     if with_note {
-        arguments.push(named("note", Value::String("audit".into())));
+        arguments.insert("note".into(), Value::String("audit".into()));
     }
     arguments
 }
 
 #[test]
-fn descriptor_is_generated_only_from_the_trait_declaration() {
+fn descriptor_is_canonical_and_generated_only_from_the_trait_declaration() {
     let first = CatalogDefinition::descriptor();
     let second = CatalogDefinition::descriptor();
     assert_eq!(first, second);
     first.validate().unwrap();
 
-    assert_eq!(first.name, "Catalog");
+    assert_eq!(first.format, INTERFACE_FORMAT_V1);
     assert_eq!(
         first.documentation.as_ref().unwrap().summary,
         "Catalog editing capability."
@@ -139,81 +134,82 @@ fn descriptor_is_generated_only_from_the_trait_declaration() {
             .summary,
         "Item to publish."
     );
-    assert!(!publish.parameters[0].optional);
+    assert!(publish.parameters[0].required);
-    assert!(publish.parameters[1].optional);
+    assert!(!publish.parameters[1].required);
     assert_eq!(
-        publish
+        publish.returns.documentation.as_ref().unwrap().summary,
-            .returns
-            .as_ref()
-            .unwrap()
-            .documentation
-            .as_ref()
-            .unwrap()
-            .summary,
         "The application publication outcome."
     );
     assert_eq!(
-        publish.returns.as_ref().unwrap().ty,
+        publish.returns.r#type,
-        TypeExpr::Named("PublishOutcome".into())
+        TypeExpr::Named {
+            name: "PublishOutcome".into(),
+        }
     );
-    assert!(first.operations[1].returns.is_none());
+    assert_eq!(first.operations[1].returns.r#type, TypeExpr::Unit);
     assert!(
         first
-            .declarations
+            .types
             .iter()
-            .any(|declaration| matches!(declaration, TypeDeclaration::Record(_)))
+            .any(|declaration| matches!(declaration.definition, TypeExpr::Record { .. }))
     );
     assert!(
         first
-            .declarations
+            .types
             .iter()
-            .any(|declaration| matches!(declaration, TypeDeclaration::Union(_)))
+            .any(|declaration| matches!(declaration.definition, TypeExpr::Union { .. }))
     );
 
-    // Both implementation types satisfy the same generated dispatch boundary;
+    // Both implementation types satisfy one immutable generated definition;
-    // neither can affect the descriptor shape.
+    // implementation selection cannot contribute fields to the descriptor.
     fn accepts_definition<T: Catalog>(_: &T) {}
     accepts_definition(&AcceptingCatalog);
     accepts_definition(&RejectingCatalog);
+    assert_eq!(CatalogDefinition::descriptor(), first);
 }
 
 #[test]
-fn generated_argument_decoder_and_result_encoder_round_trip() {
+fn generated_argument_decoder_and_result_encoder_use_raw_values() {
     let decoded = CatalogPublishArguments::decode(publish_arguments(false)).unwrap();
     assert_eq!(decoded.request.title, "example");
     assert_eq!(decoded.note, None);
 
-    let encoded = CatalogPublishArguments::encode_result(PublishOutcome::Rejected("domain".into()))
+    let encoded =
-        .unwrap()
+        CatalogPublishArguments::encode_result(PublishOutcome::Rejected("domain".into())).unwrap();
-        .unwrap();
     assert_eq!(
         PublishOutcome::decode(encoded).unwrap(),
         PublishOutcome::Rejected("domain".into())
     );
+    assert_eq!(
+        CatalogPingArguments::encode_result(()).unwrap(),
+        Value::Unit
+    );
 }
 
 #[test]
 fn typed_dispatch_validates_decodes_invokes_encodes_and_validates() {
-    let value = CatalogDefinition::dispatch(&AcceptingCatalog, "publish", publish_arguments(true))
+    let value =
-        .unwrap()
+        CatalogDefinition::dispatch(&AcceptingCatalog, "publish", publish_arguments(true)).unwrap();
-        .unwrap();
     assert_eq!(
         PublishOutcome::decode(value).unwrap(),
         PublishOutcome::Published(true)
     );
 
     assert_eq!(
-        CatalogDefinition::dispatch(&AcceptingCatalog, "ping", vec![]).unwrap(),
+        CatalogDefinition::dispatch(&AcceptingCatalog, "ping", BTreeMap::new()).unwrap(),
-        None
+        Value::Unit
     );
 
-    let invalid = CatalogDefinition::dispatch(&AcceptingCatalog, "publish", vec![]).unwrap_err();
+    let invalid =
+        CatalogDefinition::dispatch(&AcceptingCatalog, "publish", BTreeMap::new()).unwrap_err();
     assert!(matches!(invalid, DispatchError::InvalidArguments(_)));
 
-    let host = CatalogDefinition::dispatch(&AcceptingCatalog, "host_value", vec![]).unwrap_err();
+    let host =
+        CatalogDefinition::dispatch(&AcceptingCatalog, "host_value", BTreeMap::new()).unwrap_err();
     assert!(matches!(host, DispatchError::Host(error) if error.message() == "backend unavailable"));
 
-    let unknown = CatalogDefinition::dispatch(&AcceptingCatalog, "missing", vec![]).unwrap_err();
+    let unknown =
+        CatalogDefinition::dispatch(&AcceptingCatalog, "missing", BTreeMap::new()).unwrap_err();
     assert!(matches!(unknown, DispatchError::UnknownOperation(name) if name == "missing"));
 }
 
@@ -245,11 +241,11 @@ fn distinct_operation_names_always_generate_distinct_public_items() {
     assert_eq!(descriptor.operations[0].name, "item");
     assert_eq!(descriptor.operations[1].name, "item_");
 
-    let first = DistinctOperationsDefinition::dispatch(&DistinctImplementation, "item", vec![])
+    let first =
-        .unwrap()
+        DistinctOperationsDefinition::dispatch(&DistinctImplementation, "item", BTreeMap::new())
             .unwrap();
-    let second = DistinctOperationsDefinition::dispatch(&DistinctImplementation, "item_", vec![])
+    let second =
-        .unwrap()
+        DistinctOperationsDefinition::dispatch(&DistinctImplementation, "item_", BTreeMap::new())
             .unwrap();
     assert_eq!(first, Value::String("item".into()));
     assert_eq!(second, Value::String("item_".into()));

crates/wip-interface/tests/ui/async_operation.rs

@@ -0,0 +1,8 @@
+use wip_interface::interface;
+
+#[interface]
+pub trait AsyncOperation {
+    async fn status(&self) -> wip_interface::OperationResult<String>;
+}
+
+fn main() {}

crates/wip-interface/tests/ui/async_operation.stderr

@@ -0,0 +1,5 @@
+error: async operations are not supported
+ --> tests/ui/async_operation.rs:5:5
+  |
+5 |     async fn status(&self) -> wip_interface::OperationResult<String>;
+  |     ^^^^^

crates/wip-interface/tests/ui/default_method.rs

@@ -0,0 +1,10 @@
+use wip_interface::interface;
+
+#[interface]
+pub trait DefaultMethod {
+    fn status(&self) -> wip_interface::OperationResult<String> {
+        Ok(String::new())
+    }
+}
+
+fn main() {}

crates/wip-interface/tests/ui/default_method.stderr

@@ -0,0 +1,8 @@
+error: WIP operation methods must not have a body
+ --> tests/ui/default_method.rs:5:64
+  |
+5 |       fn status(&self) -> wip_interface::OperationResult<String> {
+  |  ________________________________________________________________^
+6 | |         Ok(String::new())
+7 | |     }
+  | |_____^

crates/wip-interface/tests/ui/generic_dto.rs

@@ -0,0 +1,8 @@
+use wip_interface::WipType;
+
+#[derive(WipType)]
+struct GenericDto<T> {
+    value: T,
+}
+
+fn main() {}

crates/wip-interface/tests/ui/generic_dto.stderr

@@ -0,0 +1,5 @@
+error: generic DTOs are not supported by `WipType`
+ --> tests/ui/generic_dto.rs:4:18
+  |
+4 | struct GenericDto<T> {
+  |                  ^^^

crates/wip-interface/tests/ui/mixed_enum.rs

@@ -1,9 +1,9 @@
 use wip_interface::WipType;
 
 #[derive(WipType)]
-enum MixedEnum {
+enum UnsupportedEnum {
     Empty,
-    Payload(String),
+    Payload { value: String },
 }
 
 fn main() {}

crates/wip-interface/tests/ui/mixed_enum.stderr

@@ -1,5 +1,5 @@
-error: a `WipType` enum must contain either only unit variants or only single-field tuple variants; mixed and named-field variants are unsupported
+error: a `WipType` enum must contain unit variants and/or single-field tuple variants; named-field and multi-field variants are unsupported
- --> tests/ui/mixed_enum.rs:4:1
+ --> tests/ui/mixed_enum.rs:6:5
   |
-4 | enum MixedEnum {
+6 |     Payload { value: String },
-  | ^^^^
+  |     ^^^^^^^

crates/wip-interface/tests/ui/nested_option.rs

@@ -0,0 +1,8 @@
+use wip_interface::WipType;
+
+#[derive(WipType)]
+struct NestedOption {
+    values: Vec<Option<String>>,
+}
+
+fn main() {}

crates/wip-interface/tests/ui/nested_option.stderr

@@ -0,0 +1,5 @@
+error: `Option<T>` must appear directly as the DTO field type
+ --> tests/ui/nested_option.rs:5:13
+  |
+5 |     values: Vec<Option<String>>,
+  |             ^^^^^^^^^^^^^^^^^^^

crates/wip-interface/tests/ui/unsupported_type.stderr

@@ -4,16 +4,11 @@ error[E0277]: the trait bound `(std::string::String, std::string::String): WipTy
 5 |     fn load(&self, pair: (String, String)) -> OperationResult<String>;
   |                          ^^^^^^^^^^^^^^^^ the trait `WipType` is not implemented for `(std::string::String, std::string::String)`
   |
-  = help: the following other types implement trait `WipType`:
+help: the trait `WipType` is implemented for `()`
-            JsonValue
+ --> src/lib.rs
-            Vec<T>
+  |
-            bool
+  | impl WipType for () {
-            f32
+  | ^^^^^^^^^^^^^^^^^^^
-            f64
-            i128
-            i16
-            i32
-          and $N others
 
 error[E0277]: the trait bound `(std::string::String, std::string::String): WipType` is not satisfied
  --> tests/ui/unsupported_type.rs:5:26
@@ -24,16 +19,11 @@ error[E0277]: the trait bound `(std::string::String, std::string::String): WipTy
 5 |     fn load(&self, pair: (String, String)) -> OperationResult<String>;
   |                          ^^^^^^^^^^^^^^^^ the trait `WipType` is not implemented for `(std::string::String, std::string::String)`
   |
-  = help: the following other types implement trait `WipType`:
+help: the trait `WipType` is implemented for `()`
-            JsonValue
+ --> src/lib.rs
-            Vec<T>
+  |
-            bool
+  | impl WipType for () {
-            f32
+  | ^^^^^^^^^^^^^^^^^^^
-            f64
-            i128
-            i16
-            i32
-          and $N others
 note: required by a bound in `wip_interface::__private::RecordDecoder::required`
  --> src/lib.rs
   |

src/lib.rs

@@ -0,0 +1,617 @@
+//! End-to-end use of the public WIP protocol, interface, and host APIs.
+//!
+//! This workspace package is deliberately separate from the three library
+//! crates. It defines application DTOs and interfaces with `wip-interface`,
+//! keeps its implementation private, publishes that implementation with
+//! `wip-host`, and crosses the call boundary only with `wip-protocol` values.
+//!
+//! The complete scenario can be run as a normal binary or called directly:
+//!
+//! ```
+//! let report = wip_public_api_example::run()?;
+//!
+//! assert_eq!(report.published_interfaces.len(), 2);
+//! assert_eq!(report.catalog_status, "catalog-ready");
+//! assert_eq!(report.audit_status, "audit-ready");
+//! assert_eq!(
+//!     report.host_failure,
+//!     wip_host::CallErrorKind::Implementation,
+//! );
+//! # Ok::<(), Box<dyn std::error::Error>>(())
+//! ```
+
+#![deny(missing_docs)]
+
+use std::collections::BTreeMap;
+use std::error::Error;
+use std::io;
+
+use wip_host::{
+    CallErrorKind, CallRequest, InterfaceRef, InterfaceRegistry, InterfaceTarget, ObjectId,
+    PublishedObject, Validator, WipObject,
+};
+use wip_interface as wip;
+use wip_interface::WipType;
+use wip_protocol::ProtocolError;
+
+const OBJECT_ID: &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.
+#[derive(Debug, Clone, PartialEq, Eq, 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>,
+}
+
+/// The application domain result of a publication attempt.
+///
+/// Rejection is an ordinary typed result. It is intentionally distinct from a
+/// host or backend failure, which uses [`wip::HostError`].
+#[derive(Debug, Clone, PartialEq, Eq, wip::WipType)]
+pub enum PublishOutcome {
+    /// Publication succeeded and returned its application identifier.
+    Published(String),
+    /// An application policy rejected the publication.
+    Rejected(String),
+}
+
+/// Article publication operations.
+#[wip::interface]
+pub trait Catalog {
+    /// Publishes an article or reports an application-domain rejection.
+    ///
+    /// # Returns
+    /// The typed application outcome.
+    fn publish(
+        &self,
+        /// Application publication request.
+        request: PublishRequest,
+    ) -> wip::OperationResult<PublishOutcome>;
+
+    /// Returns the catalog-qualified status.
+    ///
+    /// # Returns
+    /// A catalog status label.
+    fn status(&self) -> wip::OperationResult<String>;
+
+    /// Demonstrates a host/backend failure rather than a domain result.
+    ///
+    /// # Returns
+    /// A backend status only when the host can reach it.
+    fn backend_status(&self) -> wip::OperationResult<String>;
+}
+
+/// Audit operations exposed by the same object.
+#[wip::interface]
+pub trait Audit {
+    /// Returns the audit-qualified status.
+    ///
+    /// This deliberately has the same operation name as [`Catalog::status`].
+    ///
+    /// # Returns
+    /// An audit status label.
+    fn status(&self) -> wip::OperationResult<String>;
+}
+
+/// A registered but deliberately unexposed interface used to demonstrate that
+/// Rust trait implementation does not imply protocol membership.
+#[wip::interface]
+pub trait Diagnostics {
+    /// Returns host-private diagnostics when the interface is explicitly exposed.
+    ///
+    /// # Returns
+    /// A diagnostic label.
+    fn diagnostics(&self) -> wip::OperationResult<String>;
+}
+
+/// Observable outcomes from the complete public-API scenario.
+#[derive(Debug, Clone, PartialEq)]
+pub struct DemoReport {
+    /// Opaque interface references published by the object, in exposure order.
+    pub published_interfaces: Vec<String>,
+    /// Descriptor format observed for the catalog interface.
+    pub catalog_descriptor_format: String,
+    /// Descriptor format observed for the audit interface.
+    pub audit_descriptor_format: String,
+    /// Typed successful application result decoded from a validated `Value`.
+    pub published: PublishOutcome,
+    /// Typed application-domain rejection decoded from a validated `Value`.
+    pub rejected: PublishOutcome,
+    /// Result of the catalog-qualified `status` operation.
+    pub catalog_status: String,
+    /// Result of the audit-qualified `status` operation.
+    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.
+    pub protocol_failure: ProtocolError,
+}
+
+/// Runs the complete end-to-end example.
+///
+/// The function registers and observes generated descriptors, explicitly
+/// exposes two interfaces on one host-private object, validates the resulting
+/// protocol observation, dispatches interface-qualified calls using named
+/// [`wip_protocol::Value`] arguments, decodes validated values back to
+/// application types, and keeps a domain rejection distinct from a host
+/// failure.
+///
+/// # Errors
+///
+/// Returns an error if registration, publication, observation validation,
+/// dispatch, or application-value decoding fails unexpectedly.
+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 publication = PublishedObject::new(ApplicationService::new())
+        .expose(&catalog)?
+        .expose(&audit)?;
+    let object = publication.protocol_object();
+
+    // Model a transport/provider that retained only the protocol object's
+    // opaque strings, then resolved them back through the registry's public API.
+    let catalog_wire_reference = object
+        .interfaces
+        .first()
+        .ok_or_else(|| io::Error::other("catalog interface was not published"))?;
+    let audit_wire_reference = object
+        .interfaces
+        .get(1)
+        .ok_or_else(|| io::Error::other("audit interface was not published"))?;
+    let catalog_reference = registry
+        .resolve(catalog_wire_reference)
+        .ok_or_else(|| io::Error::other("published catalog reference did not resolve"))?;
+    let audit_reference = registry
+        .resolve(audit_wire_reference)
+        .ok_or_else(|| io::Error::other("published audit reference did not resolve"))?;
+    let catalog_observation = registry
+        .observe(&catalog_reference)
+        .ok_or_else(|| io::Error::other("registered catalog descriptor was not observable"))?;
+    let audit_observation = registry
+        .observe(&audit_reference)
+        .ok_or_else(|| io::Error::other("registered audit descriptor was not observable"))?;
+
+    catalog_observation.descriptor.validate()?;
+    audit_observation.descriptor.validate()?;
+
+    let published = dispatch_publish(
+        &publication,
+        &catalog_observation.reference,
+        PublishRequest {
+            title: "Public APIs".into(),
+            body: Some("protocol values in, validated values out".into()),
+        },
+    )?;
+    let rejected = dispatch_publish(
+        &publication,
+        &catalog_observation.reference,
+        PublishRequest {
+            title: String::new(),
+            body: None,
+        },
+    )?;
+
+    let catalog_status = dispatch_string(
+        &publication,
+        request(
+            catalog_observation.reference.clone(),
+            Some(Validator::new(CATALOG_VALIDATOR)),
+            "status",
+            BTreeMap::new(),
+        ),
+        "catalog status",
+    )?;
+    let audit_status = dispatch_string(
+        &publication,
+        request(
+            audit_observation.reference.clone(),
+            None,
+            "status",
+            BTreeMap::new(),
+        ),
+        "audit status",
+    )?;
+
+    let host_error = match publication.dispatch(request(
+        catalog_observation.reference.clone(),
+        Some(Validator::new(CATALOG_VALIDATOR)),
+        "backend_status",
+        BTreeMap::new(),
+    )) {
+        Ok(_) => {
+            return Err(io::Error::other(
+                "the deliberately unavailable example backend unexpectedly succeeded",
+            )
+            .into());
+        }
+        Err(error) => error,
+    };
+    if host_error.kind() != CallErrorKind::Implementation {
+        return Err(io::Error::other(format!(
+            "unexpected host failure kind: {:?}",
+            host_error.kind()
+        ))
+        .into());
+    }
+    let protocol_failure = host_error.protocol_error();
+
+    Ok(DemoReport {
+        published_interfaces: object.interfaces,
+        catalog_descriptor_format: catalog_observation.descriptor.format,
+        audit_descriptor_format: audit_observation.descriptor.format,
+        published,
+        rejected,
+        catalog_status,
+        audit_status,
+        host_failure: host_error.kind(),
+        protocol_failure,
+    })
+}
+
+fn dispatch_publish(
+    publication: &PublishedObject<ApplicationService>,
+    catalog: &InterfaceRef,
+    request_value: PublishRequest,
+) -> Result<PublishOutcome, Box<dyn Error>> {
+    let encoded_request = request_value.encode()?;
+    let result = publication.dispatch(request(
+        catalog.clone(),
+        Some(Validator::new(CATALOG_VALIDATOR)),
+        "publish",
+        BTreeMap::from([("request".into(), encoded_request)]),
+    ))?;
+    let value = result.value;
+    Ok(PublishOutcome::decode(value)?)
+}
+
+fn dispatch_string(
+    publication: &PublishedObject<ApplicationService>,
+    request: CallRequest,
+    _context: &str,
+) -> Result<String, Box<dyn Error>> {
+    let result = publication.dispatch(request)?;
+    let value = result.value;
+    Ok(String::decode(value)?)
+}
+
+fn request(
+    interface: InterfaceRef,
+    interface_validator: Option<Validator>,
+    operation: &str,
+    arguments: BTreeMap<String, wip_protocol::Value>,
+) -> CallRequest {
+    CallRequest {
+        object: ObjectId(OBJECT_ID.into()),
+        object_validator: Some(Validator::new(OBJECT_VALIDATOR)),
+        interface: InterfaceTarget {
+            reference: interface,
+            validator: interface_validator,
+        },
+        operation: operation.into(),
+        arguments,
+    }
+}
+
+struct ApplicationService {
+    object_validator: Validator,
+    backend_connection: String,
+}
+
+impl ApplicationService {
+    fn new() -> Self {
+        Self {
+            object_validator: Validator::new(OBJECT_VALIDATOR),
+            backend_connection: "private://article-database".into(),
+        }
+    }
+}
+
+impl WipObject for ApplicationService {
+    fn id(&self) -> ObjectId {
+        ObjectId(OBJECT_ID.into())
+    }
+
+    fn validator(&self) -> Option<&Validator> {
+        Some(&self.object_validator)
+    }
+
+    fn requires_validator(&self) -> bool {
+        true
+    }
+}
+
+impl Catalog for ApplicationService {
+    fn publish(&self, request: PublishRequest) -> wip::OperationResult<PublishOutcome> {
+        if request.title.trim().is_empty() {
+            Ok(PublishOutcome::Rejected("a title is required".into()))
+        } else {
+            Ok(PublishOutcome::Published("article-1".into()))
+        }
+    }
+
+    fn status(&self) -> wip::OperationResult<String> {
+        Ok("catalog-ready".into())
+    }
+
+    fn backend_status(&self) -> wip::OperationResult<String> {
+        if self.backend_connection.starts_with("private://") {
+            Err(wip::HostError::new("backend unavailable"))
+        } else {
+            Ok("backend-ready".into())
+        }
+    }
+}
+
+impl Audit for ApplicationService {
+    fn status(&self) -> wip::OperationResult<String> {
+        Ok("audit-ready".into())
+    }
+}
+
+impl Diagnostics for ApplicationService {
+    fn diagnostics(&self) -> wip::OperationResult<String> {
+        Ok("host-private".into())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use wip_host::CallError;
+    use wip_interface::{CodecError, TypeDeclaration, TypeExpr};
+    use wip_protocol::{ProtocolErrorCode, Value};
+
+    /// A deliberately inconsistent custom codec used to prove result validation.
+    pub struct InvalidValue;
+
+    impl WipType for InvalidValue {
+        fn type_expr() -> TypeExpr {
+            TypeExpr::String
+        }
+
+        fn collect_declarations(_: &mut Vec<TypeDeclaration>) {}
+
+        fn encode(self) -> Result<Value, CodecError> {
+            Ok(Value::Integer(7))
+        }
+
+        fn decode(_: Value) -> Result<Self, CodecError> {
+            Ok(Self)
+        }
+    }
+
+    /// Test-only interface whose custom codec emits an invalid result.
+    #[wip::interface]
+    pub trait BrokenResult {
+        /// Returns a value that violates its declared protocol type.
+        fn broken_result(&self) -> wip::OperationResult<InvalidValue>;
+    }
+
+    impl BrokenResult for ApplicationService {
+        fn broken_result(&self) -> wip::OperationResult<InvalidValue> {
+            Ok(InvalidValue)
+        }
+    }
+
+    struct Fixture {
+        publication: PublishedObject<ApplicationService>,
+        catalog: InterfaceRef,
+        audit: InterfaceRef,
+        diagnostics: InterfaceRef,
+    }
+
+    fn fixture() -> Fixture {
+        let mut registry = InterfaceRegistry::new();
+        let catalog = registry
+            .register(CatalogDefinition, Some(Validator::new(CATALOG_VALIDATOR)))
+            .unwrap();
+        let audit = registry.register(AuditDefinition, None).unwrap();
+        let diagnostics = registry.register(DiagnosticsDefinition, None).unwrap();
+        let publication = PublishedObject::new(ApplicationService::new())
+            .expose(&catalog)
+            .unwrap()
+            .expose(&audit)
+            .unwrap();
+        Fixture {
+            publication,
+            catalog: catalog.reference().clone(),
+            audit: audit.reference().clone(),
+            diagnostics: diagnostics.reference().clone(),
+        }
+    }
+
+    fn assert_failure(error: CallError, kind: CallErrorKind, code: ProtocolErrorCode) {
+        assert_eq!(error.kind(), kind);
+        assert_eq!(error.protocol_error().code, code);
+    }
+
+    #[test]
+    fn interface_membership_and_same_name_operations_are_qualified() {
+        let fixture = fixture();
+
+        let catalog = dispatch_string(
+            &fixture.publication,
+            request(
+                fixture.catalog.clone(),
+                Some(Validator::new(CATALOG_VALIDATOR)),
+                "status",
+                BTreeMap::new(),
+            ),
+            "catalog status",
+        )
+        .unwrap();
+        let audit = dispatch_string(
+            &fixture.publication,
+            request(fixture.audit.clone(), None, "status", BTreeMap::new()),
+            "audit status",
+        )
+        .unwrap();
+        assert_eq!(catalog, "catalog-ready");
+        assert_eq!(audit, "audit-ready");
+
+        let not_exposed = fixture
+            .publication
+            .dispatch(request(
+                fixture.diagnostics,
+                None,
+                "diagnostics",
+                BTreeMap::new(),
+            ))
+            .unwrap_err();
+        assert_failure(
+            not_exposed,
+            CallErrorKind::InterfaceMismatch,
+            ProtocolErrorCode::InterfaceMismatch,
+        );
+    }
+
+    #[test]
+    fn every_host_precondition_and_dispatch_failure_is_typed() {
+        let fixture = fixture();
+
+        let mut wrong_object = request(
+            fixture.catalog.clone(),
+            Some(Validator::new(CATALOG_VALIDATOR)),
+            "status",
+            BTreeMap::new(),
+        );
+        wrong_object.object = ObjectId("other-object".into());
+        assert_failure(
+            fixture.publication.dispatch(wrong_object).unwrap_err(),
+            CallErrorKind::ObjectNotFound,
+            ProtocolErrorCode::NotFound,
+        );
+
+        let mut missing_object_validator = request(
+            fixture.catalog.clone(),
+            Some(Validator::new(CATALOG_VALIDATOR)),
+            "status",
+            BTreeMap::new(),
+        );
+        missing_object_validator.object_validator = None;
+        assert_failure(
+            fixture
+                .publication
+                .dispatch(missing_object_validator)
+                .unwrap_err(),
+            CallErrorKind::ValidatorRequired,
+            ProtocolErrorCode::InvalidRequest,
+        );
+
+        let mut stale_object_validator = request(
+            fixture.catalog.clone(),
+            Some(Validator::new(CATALOG_VALIDATOR)),
+            "status",
+            BTreeMap::new(),
+        );
+        stale_object_validator.object_validator = Some(Validator::new(b"stale-object"));
+        assert_failure(
+            fixture
+                .publication
+                .dispatch(stale_object_validator)
+                .unwrap_err(),
+            CallErrorKind::ValidatorMismatch,
+            ProtocolErrorCode::InvalidRequest,
+        );
+
+        assert_failure(
+            fixture
+                .publication
+                .dispatch(request(
+                    fixture.catalog.clone(),
+                    None,
+                    "status",
+                    BTreeMap::new(),
+                ))
+                .unwrap_err(),
+            CallErrorKind::InterfaceValidatorRequired,
+            ProtocolErrorCode::InvalidRequest,
+        );
+
+        assert_failure(
+            fixture
+                .publication
+                .dispatch(request(
+                    fixture.catalog.clone(),
+                    Some(Validator::new(b"stale-interface")),
+                    "status",
+                    BTreeMap::new(),
+                ))
+                .unwrap_err(),
+            CallErrorKind::InterfaceValidatorMismatch,
+            ProtocolErrorCode::InvalidRequest,
+        );
+
+        assert_failure(
+            fixture
+                .publication
+                .dispatch(request(
+                    fixture.catalog.clone(),
+                    Some(Validator::new(CATALOG_VALIDATOR)),
+                    "missing",
+                    BTreeMap::new(),
+                ))
+                .unwrap_err(),
+            CallErrorKind::OperationNotFound,
+            ProtocolErrorCode::OperationNotFound,
+        );
+
+        assert_failure(
+            fixture
+                .publication
+                .dispatch(request(
+                    fixture.catalog.clone(),
+                    Some(Validator::new(CATALOG_VALIDATOR)),
+                    "publish",
+                    BTreeMap::from([("request".into(), Value::String("not a record".into()))]),
+                ))
+                .unwrap_err(),
+            CallErrorKind::InvalidArguments,
+            ProtocolErrorCode::InvalidArguments,
+        );
+
+        assert_failure(
+            fixture
+                .publication
+                .dispatch(request(
+                    fixture.catalog,
+                    Some(Validator::new(CATALOG_VALIDATOR)),
+                    "backend_status",
+                    BTreeMap::new(),
+                ))
+                .unwrap_err(),
+            CallErrorKind::Implementation,
+            ProtocolErrorCode::Internal,
+        );
+    }
+
+    #[test]
+    fn invalid_implementation_result_never_crosses_the_host_boundary() {
+        let mut registry = InterfaceRegistry::new();
+        let broken = registry.register(BrokenResultDefinition, None).unwrap();
+        let publication = PublishedObject::new(ApplicationService::new())
+            .expose(&broken)
+            .unwrap();
+
+        let error = publication
+            .dispatch(request(
+                broken.reference().clone(),
+                None,
+                "broken_result",
+                BTreeMap::new(),
+            ))
+            .unwrap_err();
+        assert_failure(
+            error,
+            CallErrorKind::InvalidResult,
+            ProtocolErrorCode::Internal,
+        );
+    }
+}

src/main.rs

@@ -1,3 +1,14 @@
-fn main() {
+use std::error::Error;
-    println!("Hello, world!");
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let report = wip_public_api_example::run()?;
+    println!(
+        "published {} interfaces; catalog={}, audit={}; domain={:?}; host={:?}",
+        report.published_interfaces.len(),
+        report.catalog_status,
+        report.audit_status,
+        report.rejected,
+        report.host_failure,
+    );
+    Ok(())
 }

tests/end_to_end.rs

@@ -0,0 +1,24 @@
+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);
+}