Go Context

context.Context controls cancellation, deadlines, and request-scoped values across API boundaries. Misusing it causes goroutine leaks, orphaned work, and subtle production bugs.

1. Core Rules

Context is always the first parameter:

// ✅ Good — context is first
func GetUser(ctx context.Context, id string) (*User, error)
func (s *Service) Process(ctx context.Context, req Request) error

// ❌ Bad — context buried in the middle or end
func GetUser(id string, ctx context.Context) (*User, error)
func Process(req Request, ctx context.Context) error