docs(wit): document capability and component contracts

components/fault/src/lib.rs

@@ -1,4 +1,10 @@
+//! Deliberately trapping Component used to verify Actor fault isolation.
+//!
+//! Sending the exact bytes `fault` triggers a panic. This crate is a test
+//! fixture and must not be deployed as an application service.
+
 mod bindings {
+    // Compile the versioned WIT world into canonical ABI Rust bindings.
     wit_bindgen::generate!({
         path: "wit",
         world: "fault-component",
@@ -13,6 +19,8 @@ impl bindings::Guest for Fault {
     }
 
     fn invoke(input: Vec<u8>) -> Result<Vec<u8>, bindings::ServiceError> {
+        // A panic becomes a Wasm trap so Runtime tests can assert that one
+        // faulted Actor does not corrupt other service instances.
         assert_ne!(input, b"fault", "intentional test fault");
         Ok(input)
     }

components/fault/wit.lock

@@ -4,5 +4,5 @@ schema_version = 1
 name = "wasmeld:service"
 version = "0.1.0"
 source = "path+../../wit/service"
-sha256 = "d5497307bbcd1e159f7707f385b488a6f2e26362d5256d5bc1080ac603a51305"
+sha256 = "1b2069606ccbf5202789667570bc824f702f34b147aa38e81c2ab677444ffa0e"
 replaced = true

components/fault/wit/world.wit

@@ -1,5 +1,6 @@
 package component:fault@0.1.0;
 
+/// Fault fixture exports only the base service lifecycle.
 world fault-component {
   include wasmeld:service/service-component@0.1.0;
 }