feat(host): add object publication and dispatch

README.md

@@ -65,3 +65,35 @@ 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
+choose the ordered interface set for each object publication:
+
+```rust,ignore
+let mut interfaces = wip_host::InterfaceRegistry::new();
+let messenger = interfaces.register(MessengerDefinition, None)?;
+
+let published = wip_host::PublishedObject::new(request_scoped_object)
+    .expose(&messenger)?;
+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
+Rust type names are not used as wire identity.
+
+Dispatch is qualified by interface reference and operation name. The host checks
+current object identity and validator policy, current interface membership,
+interface validator, descriptor operation, arguments, and result while retaining
+the selected object and registered artifact. Host-private fields and backend
+handles are never projected by `WipObject`.
+
+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.