Fix model fallback across main/background/sync agents

src/features/opencode-skill-loader/blocking.ts

@@ -25,13 +25,13 @@ export function discoverAllSkillsBlocking(dirs: string[], scopes: SkillScope[]):
   const { port1, port2 } = new MessageChannel()
   
   const worker = new Worker(new URL("./discover-worker.ts", import.meta.url), {
-    workerData: { signal }
+    // workerData is structured-cloned; pass the SharedArrayBuffer and recreate the view in the worker.
+    workerData: { signalBuffer: signal.buffer },
   })
 
-  worker.postMessage({ port: port2 }, [port2])
-  
   const input: WorkerInput = { dirs, scopes }
-  port1.postMessage(input)
+  // Avoid a race where the worker hasn't attached listeners to the MessagePort yet.
+  worker.postMessage({ port: port2, input }, [port2])
 
   const waitResult = Atomics.wait(signal, 0, 0, TIMEOUT_MS)
 

src/features/opencode-skill-loader/discover-worker.ts

@@ -18,25 +18,24 @@ interface WorkerOutputError {
   error: { message: string; stack?: string }
 }
 
-const { signal } = workerData as { signal: Int32Array }
+const { signalBuffer } = workerData as { signalBuffer: SharedArrayBuffer }
+const signal = new Int32Array(signalBuffer)
 
 if (!parentPort) {
   throw new Error("Worker must be run with parentPort")
 }
 
-parentPort.once("message", (data: { port: MessagePort }) => {
-  const { port } = data
+parentPort.once("message", (data: { port: MessagePort; input: WorkerInput }) => {
+  const { port, input } = data
 
-  port.on("message", async (input: WorkerInput) => {
+  void (async () => {
     try {
-      const results = await Promise.all(
-        input.dirs.map(dir => discoverSkillsInDirAsync(dir))
-      )
-      
+      const results = await Promise.all(input.dirs.map((dir) => discoverSkillsInDirAsync(dir)))
+
       const skills = results.flat()
-      
+
       const output: WorkerOutputSuccess = { ok: true, skills }
-      
+
       port.postMessage(output)
       Atomics.store(signal, 0, 1)
       Atomics.notify(signal, 0)
@@ -48,10 +47,10 @@ parentPort.once("message", (data: { port: MessagePort }) => {
           stack: error instanceof Error ? error.stack : undefined,
         },
       }
-      
+
       port.postMessage(output)
       Atomics.store(signal, 0, 1)
       Atomics.notify(signal, 0)
     }
-  })
+  })()
 })