fix: use fetch() instead of RPC for DO WebSocket upgrades

DO RPC doesn't support WebSocket upgrade requests. Forward the request
via stub.fetch() and pass userId/channelId via custom headers.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/chat-worker/src/durable-objects/ChatRoom.ts

@@ -12,7 +12,18 @@ export class ChatRoom extends DurableObject<Env> {
     return this.postgrest;
   }
 
-  async handleWebSocket(request: Request, userId: string, channelId: string): Promise<Response> {
+  /**
+   * Handle incoming fetch requests — WebSocket upgrades are forwarded here by the Worker.
+   * userId and channelId are passed via custom headers set by the Worker.
+   */
+  async fetch(request: Request): Promise<Response> {
+    const userId = request.headers.get("X-User-Id");
+    const channelId = request.headers.get("X-Channel-Id");
+
+    if (!userId || !channelId) {
+      return new Response("Missing user or channel identity", { status: 400 });
+    }
+
     const pair = new WebSocketPair();
     const [client, server] = [pair[0], pair[1]];
 

apps/chat-worker/src/index.ts

@@ -70,7 +70,14 @@ app.get("/chat/ws/:channelId", async (c) => {
 
   const id = c.env.CHAT_ROOM.idFromName(channelId);
   const stub = c.env.CHAT_ROOM.get(id);
-  return (stub as any).handleWebSocket(c.req.raw, userId, channelId);
+
+  // Forward the WebSocket upgrade via fetch — DO RPC doesn't support WebSocket upgrades.
+  // Pass userId and channelId via headers so the DO can read them.
+  const url = new URL(c.req.url);
+  const doRequest = new Request(url.toString(), c.req.raw);
+  doRequest.headers.set("X-User-Id", userId);
+  doRequest.headers.set("X-Channel-Id", channelId);
+  return stub.fetch(doRequest);
 });
 
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