claude-sonnet-5 × coding

{
  "code": "type GuardStatus = 'pending' | 'resolved';\n\ninterface GuardEntry<T> {\n  status: GuardStatus;\n  promise: Promise<T>;\n  value?: T;\n  expiresAt?: number;\n  timer?: ReturnType<typeof setTimeout>;\n}\n\n// Module-level store shared across all calls to createIdempotencyGuard.\n// Keyed by the caller-supplied idempotency key.\nconst store = new Map<string, GuardEntry<any>>();\n\ninterface IdempotencyGuardOptions<T> {\n  key: string;\n  ttlMs: number;\n  handler: () => Promise<T>;\n}\n\n/**\n * Ensures that concurrent or repeated calls sharing the same `key`\n * are deduplicated:\n *  - While a call for `key` is in flight, subsequent calls receive\n *    the SAME Promise (no duplicate handler execution).\n *  - After a successful resolution, the result is cached and returned\n *    for `ttlMs` milliseconds without re-invoking the handler.\n *  - If the handler rejects, nothing is cached; the next call for the\n *    same key will re-run the handler from scratch.\n */\nexport function createIdempotencyGuard<T>(\n  options: IdempotencyGuardOptions<T>\n): Promise<T> {\n  const { key, ttlMs, handler } = options;\n  const now = Date.now();\n\n  const existing = store.get(key);\n\n  if (existing) {\n    if (existing.status === 'pending') {\n      // A call for this key is already running; piggyback on it.\n      return existing.promise;\n    }\n\n    if (\n      existing.status === 'resolved' &&\n      existing.expiresAt !== undefined &&\n      existing.expiresAt > now\n    ) {\n      // Cached and still fresh.\n      return Promise.resolve(existing.value as T);\n    }\n\n    // Entry exists but is stale (expired) or otherwise invalid; drop it\n    // and fall through to re-run the handler.\n    if (existing.timer) clearTimeout(existing.timer);\n    store.delete(key);\n  }\n\n  const promise: Promise<T> = handler()\n    .then((result) => {\n      const expiresAt = Date.now() + ttlMs;\n      const timer = setTimeout(() => {\n        const current = store.get(key);\n        // Only delete if it's still the same resolved entry (not replaced).\n        if (current && current.status === 'resolved' && current.expiresAt === expiresAt)