Many test helpers removed their temp dir only before the test, or only on pass, so runs left them behind: 117,000 filled /tmp (RAM here) and stopped a mutation run. Each now holds a guard that removes the dir on drop, unwind included; servers started on a test dir hold its guard until they stop. A full cargo test --workspace leaves 0 dirs (859 before). just sweep-test-tmp stays for runs killed mid-test. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01T3gXMVt7XJPi6ens1or9Dj