Class FakeWorker

__tests__/query-pool.test.ts:28–57

* Fake worker speaking the same {type:'ready'|'result'} protocol as the real * one. `behavior` decides per call whether to return a result, crash (exit≠0), * hang (never reply — exercises the backstop), or wait on a promise (lets a test * hold a call in-flight to observe concurrency). Emits 'read

 * the pool has wired its listeners first.
 */
class FakeWorker implements PoolWorker {
  private msgCb?: (m: unknown) => void;
  private exitCb?: (code: number) => void;
  alive = true;
  constructor(private behavior: (m: CallMsg) => Action, readyOk = true) {
    setTimeout(() => { if (this.alive) this.msgCb?.({ type: 'ready', ok: readyOk }); }, 0);
  }
  on(event: string, cb: (...args: any[]) => void): void {
    if (event === 'message') this.msgCb = cb;
    else if (event === 'exit') this.exitCb = cb;
    // 'error' unused by the fakes
  }
  private reply(id: number, result: ToolResult): void {
    if (this.alive) this.msgCb?.({ type: 'result', id, result });
  }
  postMessage(msg: unknown): void {
    const m = msg as CallMsg;
    if (!m || m.type !== 'call') return;
    const action = this.behavior(m);
    if ('crash' in action) {
      this.alive = false;
      setTimeout(() => this.exitCb?.(13), 0); // simulate a crash exit
      return;
    }
    if ('hang' in action) return; // never reply
    if ('wait' in action) { void action.wait.then((r) => this.reply(m.id, r)); return; }
    setTimeout(() => this.reply(m.id, action.result), 0);
  }
  terminate(): Promise<number> { this.alive = false; return Promise.resolve(0); }
}

const ok = (text: string): ToolResult => ({ content: [{ type: 'text', text }] });