How do I install the Cc Hooks skill?

Run npx skillmds@latest add lev-os/cc-hooks in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Cc Hooks safe to use?

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Which AI agents work with Cc Hooks?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Cc Hooks free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Cc Hooks?

lev-os (@lev-os) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Cc Hooks by lev-os — Agent Skill

Name: Cc Hooks
Rating: 4.2 (5 reviews)
Author: lev-os

File contents

Claude Code Hooks

Shell commands that fire at specific points in Claude Code's lifecycle.

Quick Start

Add to ~/.claude/settings.json (user) or .claude/settings.json (project):

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          { "type": "command", "command": "my-validator.sh" }
        ]
      }
    ]
  }
}

Hook Events

Event	When	Blocks?	Common Use
`PreToolUse`	Before tool runs	Yes	Block/modify commands
`PostToolUse`	After tool succeeds	Feedback	Auto-format, lint
`PermissionRequest`	Permission dialog	Yes	Auto-approve/deny
`UserPromptSubmit`	Prompt submitted	Yes	Add context, validate
`Stop`	Claude finishes	Yes	Force continue
`SessionStart`	Session begins	No	Load context, set env
`Notification`	Notifications	No	Desktop alerts

Full schemas: HOOK-EVENTS.md

Matchers

"Bash"              → exact match
"Edit|Write"        → regex OR
"mcp__.*__write"    → MCP tools
"*" or ""           → all tools

Tools: Bash, Read, Write, Edit, Glob, Grep, Task, WebFetch, WebSearch

Exit Codes

Code	Effect
0	Success - JSON parsed from stdout
2	Block - stderr fed to Claude
Other	Non-blocking error

Blocking a Tool

Simple (exit 2):

echo "Blocked: reason" >&2 && exit 2

JSON (exit 0):

{"hookSpecificOutput":{"hookEventName":"PreToolUse","permissionDecision":"deny","permissionDecisionReason":"Blocked"}}

Decisions: "allow" (auto-approve), "deny" (block), "ask" (show dialog)

Modifying Input

{"hookSpecificOutput":{"hookEventName":"PreToolUse","permissionDecision":"allow",
  "updatedInput":{"command":"modified-command"}}}

Real-World: DCG + RCH

{"hooks":{"PreToolUse":[{"matcher":"Bash","hooks":[
  {"type":"command","command":"dcg"},
  {"type":"command","command":"rch"}
]}]}}

DCG: Blocks git reset --hard, rm -rf, git push --force
RCH: Routes builds to remote workers

Details: DCG-RCH.md

Writing Your Own Hook

Minimal Python:

#!/usr/bin/env python3
import json, sys

data = json.load(sys.stdin)
cmd = data.get('tool_input', {}).get('command', '')

if 'dangerous' in cmd:
    print("Blocked: dangerous", file=sys.stderr)
    sys.exit(2)

sys.exit(0)  # Allow

Hook input (stdin):

{"tool_name":"Bash","tool_input":{"command":"npm test"},"session_id":"...","cwd":"..."}

Environment Variables

Variable	Scope	Purpose
`CLAUDE_PROJECT_DIR`	All	Project root
`CLAUDE_ENV_FILE`	SessionStart/Setup	Persist env vars

Stop Hook (Force Continue)

{"decision":"block","reason":"Tests failing. Fix before stopping."}

Critical: Check stop_hook_active to prevent infinite loops.

Anti-Patterns

Don't	Do
Old object format	Array format with `matcher`
Unquoted `$VAR`	`"$VAR"`
Exit 2 with JSON	Exit 2 uses stderr only
Skip `stop_hook_active` check	Always check in Stop hooks

Debugging

claude --debug  # Hook execution details
/hooks          # View/edit in REPL

References

HOOK-EVENTS.md - All events with full schemas
DCG-RCH.md - Production examples (dcg, rch)
PATTERNS.md - Auto-format, logging, notifications
JSON-OUTPUT.md - Response schemas

---name: cc-hooksdescription: Configure Claude Code hooks for PreToolUse, PostToolUse, Stop, Notification. Use when blocking commands, auto-formatting, custom permissions, or writing hooks.---# Claude Code HooksShell commands that fire at specific points in Claude Code's lifecycle.## Quick StartAdd to `~/.claude/settings.json` (user) or `.claude/settings.json` (project):```json{ "hooks": { "PreToolUse": [ { "matcher": "Bash", "hooks": [ { "type": "command", "command": "my-validator.sh" } ] } ] }}```## Hook Events| Event | When | Blocks? | Common Use ||-------|------|---------|------------|| `PreToolUse` | Before tool runs | Yes | Block/modify commands || `PostToolUse` | After tool succeeds | Feedback | Auto-format, lint || `PermissionRequest` | Permission dialog | Yes | Auto-approve/deny || `UserPromptSubmit` | Prompt submitted | Yes | Add context, validate || `Stop` | Claude finishes | Yes | Force continue || `SessionStart` | Session begins | No | Load context, set env || `Notification` | Notifications | No | Desktop alerts |Full schemas: [HOOK-EVENTS.md](references/HOOK-EVENTS.md)## Matchers```"Bash" → exact match"Edit|Write" → regex OR"mcp__.*__write" → MCP tools"*" or "" → all tools```Tools: `Bash`, `Read`, `Write`, `Edit`, `Glob`, `Grep`, `Task`, `WebFetch`, `WebSearch`## Exit Codes| Code | Effect ||------|--------|| 0 | Success - JSON parsed from stdout || 2 | **Block** - stderr fed to Claude || Other | Non-blocking error |## Blocking a Tool**Simple (exit 2):**```bashecho "Blocked: reason" >&2 && exit 2```**JSON (exit 0):**```json{"hookSpecificOutput":{"hookEventName":"PreToolUse","permissionDecision":"deny","permissionDecisionReason":"Blocked"}}```Decisions: `"allow"` (auto-approve), `"deny"` (block), `"ask"` (show dialog)## Modifying Input```json{"hookSpecificOutput":{"hookEventName":"PreToolUse","permissionDecision":"allow", "updatedInput":{"command":"modified-command"}}}```## Real-World: DCG + RCH```json{"hooks":{"PreToolUse":[{"matcher":"Bash","hooks":[ {"type":"command","command":"dcg"}, {"type":"command","command":"rch"}]}]}}```- **DCG**: Blocks `git reset --hard`, `rm -rf`, `git push --force`- **RCH**: Routes builds to remote workersDetails: [DCG-RCH.md](references/DCG-RCH.md)## Writing Your Own Hook**Minimal Python:**```python#!/usr/bin/env python3import json, sysdata = json.load(sys.stdin)cmd = data.get('tool_input', {}).get('command', '')if 'dangerous' in cmd: print("Blocked: dangerous", file=sys.stderr) sys.exit(2)sys.exit(0) # Allow```**Hook input (stdin):**```json{"tool_name":"Bash","tool_input":{"command":"npm test"},"session_id":"...","cwd":"..."}```## Environment Variables| Variable | Scope | Purpose ||----------|-------|---------|| `CLAUDE_PROJECT_DIR` | All | Project root || `CLAUDE_ENV_FILE` | SessionStart/Setup | Persist env vars |## Stop Hook (Force Continue)```json{"decision":"block","reason":"Tests failing. Fix before stopping."}```**Critical:** Check `stop_hook_active` to prevent infinite loops.## Anti-Patterns| Don't | Do ||-------|-----|| Old object format | Array format with `matcher` || Unquoted `$VAR` | `"$VAR"` || Exit 2 with JSON | Exit 2 uses stderr only || Skip `stop_hook_active` check | Always check in Stop hooks |## Debugging```bashclaude --debug # Hook execution details/hooks # View/edit in REPL```## References- [HOOK-EVENTS.md](references/HOOK-EVENTS.md) - All events with full schemas- [DCG-RCH.md](references/DCG-RCH.md) - Production examples (dcg, rch)- [PATTERNS.md](references/PATTERNS.md) - Auto-format, logging, notifications- [JSON-OUTPUT.md](references/JSON-OUTPUT.md) - Response schemas

Frequently asked questions

Cc Hooks