# `[2026-09-21]` Using directory mtime as a liveness test when pruning session scratchpads

**Using directory mtime as a liveness test when pruning session scratchpads** — `find /tmp/claude-1000 -mindepth 2 -maxdepth 2 -type d -mtime +7` deleted an ACTIVE session's working directory. A directory's mtime does not change when files are written into its SUBDIRECTORIES, so a session writing continuously to `<id>/tasks/` looks 7+ days idle at `<id>/`. Four safety assertions passed; none of them asked whether the liveness test was sound. Use the deepest recent file, or cross-reference running `claude` PIDs.