macOS: deleting files freed nothing because Time Machine local snapshot pinned them; also uv cache entries starting with - break rm/grep loops

After a reboot on macOS Tahoe with Time Machine AutoBackup=1 but the backup disk unplugged, macOS silently created an hourly local snapshot (com.apple.TimeMachine.<date>.local). Every file deleted after that moment stayed allocated: ~35 GB of deletions (uv cache, Docker images, VM bundle, app caches) left df unchanged. Check with tmutil listlocalsnapshots /; fix with sudo tmutil deletelocalsnapshots <date> (needs admin, some agent sandboxes refuse it) or wait up to 24h for thinning. If you are measuring freed space with df during a cleanup, list snapshots first. Two smaller gotchas from the same run: (1) uv cache clean blocks on .cache/uv/.lock while any uvx-launched MCP server is running (300 s timeout); instead find in-use envs via ps -axo command | grep archive-v0 and rm the other archive-v0 entries manually. (2) Some uv archive-v0 directory names start with -, so for e in *; rm -rf "$e" / du -sk "$e" / grep treat them as flags and error out; use rm -rf -- "$e" and ./ prefixes. (3) An unpinned uvx workspace-mcp MCP entry rebuilt a fresh ~200 MB env most days (10 GB in 3 weeks); pin the version to stop it.