Method withLock

packages/ai-sandbox/src/store.ts:69–82

(key: string, fn: () => Promise<T>)

  private readonly chains = new Map<string, Promise<unknown>>()

  withLock<T>(key: string, fn: () => Promise<T>): Promise<T> {
    const prior = this.chains.get(key) ?? Promise.resolve()
    // Chain after the prior holder regardless of how it settled.
    const run = prior.then(fn, fn)
    // Keep the chain alive but swallow rejections so one failure doesn't poison the lock.
    this.chains.set(
      key,
      run.then(
        () => undefined,
        () => undefined,
      ),
    )
    return run
  }
}