What problem does it solve? Building stateful, coordinated applications on Cloudflare's edge requires correct Durable Object design—sharding, concurrency control, SQLite migrations, alarms, and WebSocket handling—and mistakes like single global DOs or in-memory-only state cause production failures. This Skill provides retrieval-first guidance, code patterns, and review checklists for implementing and auditing Durable Objects correctly. ## Core Features & Use Cases - DO Implementation Guidance: Covers class modeling, RPC methods, blockConcurrencyWhile initialization, SQLite storage with schema migrations, alarms, and WebSocket hibernation. - Testing Support: Provides Vitest setup with @cloudflare/vitest-pool-workers, including unit tests, integration tests via SELF, alarm triggering, and direct storage inspection with runInDurableObject. - Workers Integration: Details wrangler.jsonc/toml configuration, bindings, migrations, TypeScript env types, request validation, and observability patterns. - Use Case: When building a multiplayer game backend, use this Skill to model one DO per game session, configure new_sqlite_classes migrations, implement RPC methods, and write isolated Vitest suites validating state transitions. ## Quick Start Use the durable-objects skill to create a chat room Durable Object with SQLite storage, wrangler bindings, and Vitest tests.
