plugin: implement component model runtime

docs/examples/plugin-component-tool/lib.rs

@@ -0,0 +1,23 @@
+//! Minimal Component Model Tool plugin authoring sketch.
+//!
+//! Build this as a `wasm32-unknown-unknown` cdylib with `wit-bindgen`-generated
+//! exports and package the adapted component as `plugin.component.wasm`.
+
+wit_bindgen::generate!({
+    world: "tool",
+    path: "../../../resources/plugin/wit",
+});
+
+struct Plugin;
+
+impl Guest for Plugin {
+    fn call(tool_name: String, input_json: String) -> String {
+        // Ordinary ToolOutput JSON. The runtime routes this through the normal
+        // Worker/Tool result path; no context is injected by the component.
+        format!(
+            r#"{{"summary":"component tool {tool_name}","content":"input was {input_json}"}}"#
+        )
+    }
+}
+
+export!(Plugin);