go-concurrency

Disciplined Go concurrency. ALWAYS use this skill when writing or reviewing Go code that touches goroutines, channels, `context.Context`, `sync.WaitGroup`, `sync.Mutex` / `sync.RWMutex`, `sync.Once`, `errgroup.Group`, worker pools, fan-out/fan-in pipelines, request cancellation, timeouts, deadlines, or any "run this in the background" pattern. Also use when debugging deadlocks, goroutine leaks, race conditions, or channel-related bugs. Pair with go-errors for error propagation across goroutines.