hookify-rules

SKILL.md

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
---
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)

---
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

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:

---
name: my-rule
enabled: true
event: bash
pattern: dangerous_command
---
Warning message here

2a:[