This skill should be used when the user asks to "review this Go code for goroutine leaks", "should I use a channel or a mutex", "use sync.WaitGroup vs errgroup", "audit this Go code for race conditions", "write a Go pipeline with fan-out/fan-in", "add a bounded worker pool in Go", or is choosing between sync primitives, debugging a goroutine leak, or designing a concurrent pipeline. For the one-paragraph "use errgroup for fanning out work" default in ordinary service code, use go-service-idioms instead; this skill is for the deeper decision (which primitive, how the goroutine exits, leak/race auditing) once concurrency itself is the question.
