A session asked to clean up older Pythons removed the uv-managed base
interpreter its own venv depended on; the next boot died with 'uv
trampoline failed to spawn Python child process' and no agent tool could
repair it, because the agent itself no longer started (#58748). Prior
uninstall detection (85ce25687e) only flagged package-manager commands.
Add agent/runtime_self_protection.py and wire it into both layers:
- The approval floor (_floor_block) now blocks shell commands that
delete the running interpreter, its own venv, the pyvenv.cfg base, or
the uv-managed install directory — rm/rmdir/rd/del/erase/Remove-Item
with any flags, find <root> -delete, and uv python uninstall of the
running version (including --all). The floor runs before yolo /
approvals.mode=off / cron approve mode, so no session setting can
bypass it.
- The file-safety write classifier denies write/patch/move/delete to the
same paths, so the file tools cannot overwrite the interpreter either.
Only the runtime the process itself boots from is protected; every other
venv and interpreter on the machine stays manageable.
Fixes#58748
541e4dc0ba