Typed atomic counter

Atomic increment/decrement

RWMutex for registry

RLock for registry reads

No RLock-to-Lock upgrade

Mutex embedded in struct

Mutex above protected fields

sync.Once or OnceValue for config

sync.Pool for buffers

Reset before Pool.Put

No persistent state in pool

Race detector test

goleak in TestMain

Directional channel params

ctx.Done in parse select

ctx.Done in enrich select

Producer closes output channel

Bounded fan-out workers

wg.Go for simple goroutines

errgroup for bounded fan-out

Cancellation test

No goroutine pipeline for transforms

Iterators or plain loops for transforms

errgroup for concurrent fetches

errgroup.WithContext for cancellation

errgroup.SetLimit(8)

No hand-rolled worker pool

Copies not pointers in goroutines

Context propagated to fetches

First error returned