hookify-rules

SKILL.md

---
name: hookify-rules
description: Create and configure hookify rules — markdown files with YAML frontmatter that match bash, file, prompt, or stop events by regex or conditions and show warn/block messages to the agent. Use when creating a hookify rule, writing hook rule syntax, configuring hookify, or adding pattern guardrails such as blocking dangerous commands, .env edits, or debug code.
---

# Writing Hookify Rules

## Overview

ECC evaluates project-local Hookify rules with its built-in Node runtime. No
separate Hookify plugin or Python installation is required when ECC hooks are
enabled.

Hookify rules are markdown files with YAML frontmatter that define patterns to watch for and messages to show when those patterns match. Rules are stored in `.claude/hookify.{rule-name}.local.md` files.

## Rule File Format

### Basic Structure

```markdown
---
name: rule-identifier
enabled: true
event: bash|file|stop|prompt|all
pattern: regex-pattern-here
---

Message to show Claude when this rule triggers.
Can include markdown formatting, warnings, suggestions, etc.
```

### Frontmatter Fields

| Field | Required | Values | Description |
|-------|----------|--------|-------------|
| name | Yes | kebab-case string | Unique identifier (verb-first: warn-*, block-*, require-*) |
| enabled | Yes | true/false | Toggle without deleting |
| event | Yes | bash/file/stop/prompt/all | Which hook event triggers this |
| action | No | warn/block | warn (default) shows message; block prevents operation |
| pattern | Yes* | regex string | Pattern to match (*or use conditions for complex rules) |

### Advanced Format (Multiple Conditions)

```markdown
---
name: warn-env-api-keys
enabled: true
event: file
conditions:
  - field: file_path
    operator: regex_match
    pattern: \.env$
  - field: new_text
    operator: contains
    pattern: API_KEY
---

You're adding an API key to a .env file. Ensure this file is in .gitignore!
```

**Condition fields by event:**
- bash: `command`
- file: `file_path`, `new_text`, `old_text`, `content`
- prompt: `user_prompt`

**Operators:** `regex_match`, `contains`, `equals`, `not_contains`, `starts_with`, `ends_with`

All conditions must match for rule to trigger.

## Event Type Guide

### bash Events
Match Bash command patterns:
- Dangerous commands: `rm\s+-rf`, `dd\s+if=`, `mkfs`
- Privilege escalation: `sudo\s+`, `su\s+`
- Permission issues: `chmod\s+777`

### file Events
Match Edit/Write/MultiEdit operations:
- Debug code: `console\.log\(`, `debugger`
- Security risks: `eval\(`, `innerHTML\s*=`
- Sensitive files: `\.env$`, `credentials`, `\.pem$`

### stop Events
Completion checks and reminders. Pattern `.*` matches always.

### prompt Events
Match user prompt content for workflow enforcement.

## Pattern Writing Tips

### Regex Basics
- Escape special chars: `.` to `\.`, `(` to `\(`
- `\s` whitespace, `\d` digit, `\w` word char
- `+` one or more, `*` zero or more, `?` optional
- `|` OR operator

### Common Pitfalls
- **Too broad**: `log` matches "login", "dialog" — use `console\.log\(`
- **Too specific**: `rm -rf /tmp` — use `rm\s+-rf`
- **YAML escaping**: Use unquoted patterns; quoted strings need `\\s`

### Testing
```bash
python3 -c "import re; print(re.search(r'your_pattern', 'test text'))"
```

Avoid nested quantifiers such as `(a+)+`. The runtime rejects patterns with
common catastrophic-backtracking shapes because rules run synchronously in the
hook path, and every regex evaluation has a 25 ms hard timeout. Invalid,
symlinked, or oversized local rules fail open and emit a
diagnostic without disabling other Hookify rules.

Git-tracked local rules are disabled by default. Set
`ECC_HOOKIFY_ALLOW_TRACKED=1` only after reviewing those files; ordinary
gitignored rules created locally remain active without that override.

## Runtime Behavior

- `warn` injects the message as event-specific additional context and does not block.
- `block` denies matching Bash, PowerShell, Write, Edit, or MultiEdit calls before execution.
- On prompt, post-tool, and stop events, `block` uses Claude Code's structured block decision.
- Stop rules skip recursive `stop_hook_active` events to prevent infinite continuation loops.

## File Organization

- **Location**: `.claude/` directory in project root
- **Naming**: `.claude/hookify.{descriptive-name}.local.md`
- **Gitignore**: Add `.claude/*.local.md` to `.gitignore`

## Commands

- `/hookify [description]` - Create new rules (auto-analyzes conversation if no args)
- `/hookify-list` - View all rules in table format
- `/hookify-configure` - Toggle rules on/off interactively
- `/hookify-help` - Full documentation

## Quick Reference

Minimum viable rule:
```markdown
---
name: my-rule
enabled: true
event: bash
pattern: dangerous_command
---
Warning message here
```