Free the key-info buffer and owned crypto context on pre-KDF errors,
preserving borrowed contexts and avoiding uninitialized drain resources.
Inject every setup allocation and event failure to verify cleanup.
Close admission and retain references for accepted requests, KDF workers
and submitters until they stop using pool resources. Run new work
synchronously while stopping, then join workers and release handles.
Test queued work, delayed requester wakeup, fallback and restart.
Join created workers and release allocated handles when startup fails before
the pool is published. Close worker handles on normal shutdown as well.
Test each startup allocation failure and subsequent restart.
Hold a requester reference until header parsing can no longer enqueue KDFs.
This prevents stale completion signals from allowing cleanup while workers
still use request-owned state.
Add bounded tests of the production pool and caller completion protocol.
Mounir IDRASSI