durable-objects

Extend the DurableObject class from cloudflare:workers and configure new_sqlite_classes in your wrangler migrations. Initialize tables inside the constructor using ctx.blockConcurrencyWhile, then run synchronous queries via this.ctx.storage.sql.exec.

Use @cloudflare/vitest-pool-workers with defineWorkersConfig pointing at your wrangler config. Access stubs via env from cloudflare:test, inspect internals with runInDurableObject, and trigger alarms instantly with runDurableObjectAlarm.

Use Durable Objects for coordination, strong consistency, per-entity storage, persistent WebSocket connections, or scheduled per-entity work. Use plain Workers for stateless request handling, maximum global distribution, or high fan-out independent requests.

No, PRAGMA user_version is not supported in Durable Objects SQLite storage. Track schema versions in a dedicated _sql_schema_migrations table and apply incremental migrations inside the constructor.

Class properties are lost when the instance is evicted or crashes. Always persist critical state to SQLite storage first, then update in-memory caches, since only storage survives eviction.

Each Durable Object supports exactly one alarm; calling setAlarm replaces any existing alarm. Reschedule inside the alarm handler for recurring work, and keep handlers idempotent because failed alarms auto-retry.