Guardian hooks and safe prefixes

cm guardian check inspects a shell command string before you run it. It blocks common destructive patterns (rm -rf /, git push --force, DROP TABLE, pipes to sh, etc.) and can enforce path freeze roots for edits.

Config merges with defaults: copy .cm/config.example.yaml → .cm/config.yaml and edit guardian.whitelist_prefixes / guardian.freeze_roots.

CLI examples

# Allowed (matches built-in safe prefixes such as npm run build)
cm guardian check -- npm run build

# Blocked — exits non-zero
cm guardian check -- "rm -rf /"
echo "exit=$?"   # expect 1

# Path check — only allow changes under given roots (comma-separated)
cm guardian path-check --file ./src/app.ts --roots src,lib

Violations append to .cm/guardian.log.

Cursor — beforeShellExecution hook (concept)

Cursor can run a command before executing terminal/shell actions. Point it at cm (global) or node /absolute/path/to/codymaster/dist/index.js.

Pattern: invoke guardian with the proposed command as arguments. Exact hook file format depends on your Cursor version; typical shape:

{
  "hooks": {
    "beforeShellExecution": [
      {
        "command": "cm",
        "args": ["guardian", "check", "--", "{{command}}"]
      }
    ]
  }
}

Replace with whatever placeholder your hook schema provides for the pending shell string. If the hook only passes the command as a single argument, you may need a thin wrapper script that builds cm guardian check -- "$@".

Behavior: When guardian exits 1, the hook should block execution; exit 0 allows the shell to proceed.

Codex / other agents

Use the same idea: pre-tool or pre-exec step that runs:

cm guardian check -- "<proposed command>"

If your agent cannot chain hooks, run guardian manually before pasting risky commands from the model.

Quick reference — often blocked vs allowed

Intent	Example	Guardian
Delete system	rm -rf /	Blocked
Force push	git push --force	Blocked
Safe build	npm run build	Allowed (prefix whitelist)
Tests	npx vitest run	Usually allowed if prefix matches
Custom safe command	pnpm exec eslint .	Add prefix in .cm/config.yaml under guardian.whitelist_prefixes

Related

• Skill: skills/cm-guardian-runtime/SKILL.md
• Implementation: src/guardian-core.ts
• Engineering pipeline