Storage

memoryStore() is included for local development and simple demos.

It is not production-safe for serverless deployments because data can disappear on cold starts. Use persistent storage for the played-event source and for last-good snapshot recovery.

The store contract is intentionally small:

interface PresenceStore {
  get<T>(key: string): Promise<T | null>;
  set<T>(key: string, value: T, options?: { ttlSeconds?: number }): Promise<void>;
  delete(key: string): Promise<void>;
}

Good production options include Redis, Upstash, Vercel KV, Postgres, or any storage you already run for your portfolio.

TTL behavior

The package owns the cache policy and passes it to PresenceStore.set:

• cache.ttlSeconds expires the regular snapshot cache. The default is 60 seconds.
• cache.lastGoodTtlSeconds optionally expires the last-good fallback snapshot. Omit it to keep fallback data indefinitely.
• playedEventSource({ ttlSeconds }) optionally expires the last recorded game.
• A TTL of 0 means the corresponding key is not retained.
• TTLs must be finite, non-negative numbers.

The store adapter owns the backend-specific operation. For example, a Redis adapter should translate a positive ttlSeconds into its client's expiry option (such as EX) and should write without an expiry when the option is omitted. The snapshot also contains an application-level expiresAt value, which prevents stale reads from stores that cannot enforce physical TTLs.