Careful skill

/careful — Destructive Command Guardrails

Safety mode is now active. Every Bash and PowerShell command will be checked for destructive patterns before running. If a destructive command is detected, you'll be warned and can choose to proceed or cancel.

GSTACK_STATE_ROOT=$(~/.claude/skills/gstack/bin/gstack-paths --get GSTACK_STATE_ROOT); : "${GSTACK_STATE_ROOT:?gstack-paths failed; reinstall with ./setup or /gstack-upgrade}"
mkdir -p "$GSTACK_STATE_ROOT"/analytics
echo '{"skill":"careful","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","repo":"'$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" 2>/dev/null || echo "unknown")'"}'  >> "$GSTACK_STATE_ROOT"/analytics/skill-usage.jsonl 2>/dev/null || true

What's protected

Pattern	Example	Risk
rm -rf / rm -r / rm --recursive	rm -rf /var/data	Recursive delete
DROP TABLE / DROP DATABASE	DROP TABLE users;	Data loss
TRUNCATE	TRUNCATE orders;	Data loss
git push --force / -f	git push -f origin main	History rewrite
git reset --hard	git reset --hard HEAD~3	Uncommitted work loss
git checkout . / git restore .	git checkout .	Uncommitted work loss
kubectl delete	kubectl delete pod	Production impact
docker rm -f / docker system prune	docker system prune -a	Container/image loss

PowerShell and cmd (Windows)

The hook also checks the PowerShell tool (Claude Code's main Windows shell) and any pwsh/powershell/cmd launched from Bash. Matching ignores case, covers aliases in command position, accepts parameter prefixes (-r, -fo) and strips cmd ^ escapes. All rows above apply there too.

Pattern	Example
Remove-Item/rm/ri/del/erase/rd/rmdir + -Recurse or -Force	gci | ri -r -fo
cmd rd /s, rmdir /s, del /s, erase /s	cmd /c rd /s /q C:\proj
Format-Volume, Clear-Disk, Clear-Content, [IO.Directory]::Delete, [IO.File]::Delete	Clear-Disk -Number 1
-EncodedCommand, iex, Start-Process of a shell, & $cmd (can't be inspected)	irm $url | iex

Best-effort on PowerShell. String matching can't see a command built at runtime. For a hard stop, add Claude Code permission deny rules, which parse PowerShell and its aliases: "deny": ["PowerShell(Remove-Item *)"] in .claude/settings.json. The hook runs through bash, so Windows needs Git Bash.

Safe exceptions

These patterns are allowed without warning:

• rm -rf node_modules / .next / dist / __pycache__ / .cache / build / .turbo / coverage

How it works

The hook reads tool_name and the command from the tool input JSON, checks it against the patterns above, and returns a hookSpecificOutput payload with permissionDecision: "ask" and a warning reason if a match is found (the decision must be nested under hookSpecificOutput — Claude Code ignores a top-level permissionDecision). You can always override a MEDIUM warning and proceed.

HIGH tier (hard deny)

Two catastrophic shapes are denied, not asked: rm -r/-R of exactly /, ~, or $HOME, and force-push to the repo's default branch. SIMPLE commands only (no ;, &&, ||, |, newline) — compound shapes fall through to the MEDIUM ask; --force-with-lease is never HIGH. A best-effort advisory hard-stop, not a policy boundary: the escape hatch is ending the opt-in, session-scoped /careful session.

Project patterns (additive only)

Add warn rules — one POSIX ERE per line, # comments OK — in ~/.gstack/careful-patterns.txt (global) or ~/.gstack/projects/<slug>/careful-patterns.txt (per-project). Consulted after the built-in families, so config can only ADD rules, never suppress a baseline warning. Invalid regex lines are skipped.

To deactivate, end the conversation or start a new one. Hooks are session-scoped.