Database Driver Design

This skill provides expert guidance on building production-quality database client libraries in Swift, covering wire protocol implementation, connection management, type-safe APIs, and integration with Swift Concurrency. Patterns are derived from exemplary implementations: valkey-swift and postgres-nio.

Agent Behavior Contract (Follow These Rules)

1. Prefer parameterized queries - Never concatenate user input into SQL/command strings
2. Use string interpolation for safety - Implement ExpressibleByStringInterpolation to convert values to bindings
3. Design commands as types - Each command/query should be a struct with associated response type
4. Implement state machines for protocols - Complex connection lifecycles need explicit state transitions
5. Support backpressure - Row/result streaming must respect consumer demand
6. Align actor executors - Use unownedExecutor to align with NIO event loops
7. Pool connections properly - Implement keep-alive, idle timeout, and graceful shutdown

Core Patterns

Command as Type Pattern

Define commands as types with associated response types for compile-time safety: