writing-rules

Original：🇺🇸 English

Translated

Create markdown-based behavioral rules preventing unwanted actions. create hookify rule, behavioral rule, prevent behavior, block command Use when: preventing dangerous commands, blocking debug commits, enforcing conventions DO NOT use when: hook scope (abstract:hook-scope-guide), SDK hooks (abstract:hook-authoring), evaluating hooks (abstract:hooks-eval).

2installs

Sourceathola/claude-night-market

Added on2026-03-02

NPX Install

npx skill4agent add athola/claude-night-market writing-rules

SKILL.md Content

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Hookify Rule Writing Guide

When To Use

Creating behavioral rules to prevent unwanted actions
Defining persistent guardrails for Claude Code sessions

When NOT To Use

Complex multi-step workflows - use agents instead
One-time operations that do not need persistent behavioral rules

Overview

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.

Quick Start

Create

.claude/hookify.dangerous-rm.local.md

:

yaml

---
name: dangerous-rm
enabled: true
event: bash
pattern: rm\s+-rf
action: block
---

🛑 **Dangerous rm command detected!**

This command could delete important files.

Verification: Run the command with

--help

flag to verify availability.

The rule activates immediately - no restart needed!

Rule File Format

Frontmatter Fields

name (required): Unique identifier (kebab-case) enabled (required):

true

or

false

event (required):

bash

,

file

,

stop

,

prompt

, or

all

action (optional):

warn

(default) or

block

pattern (simple): Regex pattern to match

Event Types

bash: Bash tool commands
file: Edit, Write, MultiEdit tools
stop: When agent wants to stop
prompt: User prompt submission
all: All events

Advanced Conditions

For multiple field checks:

yaml

---
name: warn-env-edits
enabled: true
event: file
action: warn
conditions:
  - field: file_path
    operator: regex_match
    pattern: \.env$
  - field: new_text
    operator: contains
    pattern: API_KEY
---

🔐 **API key in .env file!**
Ensure file is in .gitignore.

Operators

```
regex_match
```
: Pattern matching
```
contains
```
: Substring check
```
equals
```
: Exact match
```
not_contains
```
: Must NOT contain
```
starts_with
```
: Prefix check
```
ends_with
```
: Suffix check

Field Reference

bash events:

command

file events:

file_path

,

new_text

,

old_text

,

content

prompt events:

user_prompt

stop events:

transcript

Pattern Writing

Regex Basics

```
\s
```
- whitespace
```
\d
```
- digit
```
\w
```
- word character
```
.
```
- any character (use
```
\.
```
for literal dot)
```
+
```
- one or more
```
*
```
- zero or more
```
|
```
- OR

Examples

rm\s+-rf          → rm -rf
console\.log\(    → console.log(
chmod\s+777       → chmod 777

Test Patterns

bash

python3 -c "import re; print(re.search(r'pattern', 'text'))"

Example Rules

Block Destructive Commands

yaml

---
name: block-destructive
enabled: true
event: bash
pattern: rm\s+-rf|dd\s+if=|mkfs
action: block
---

🛑 **Destructive operation blocked!**
Can cause data loss.

Warn About Debug Code

yaml

---
name: warn-debug
enabled: true
event: file
pattern: console\.log\(|debugger;
action: warn
---

🐛 **Debug code detected!**
Remove before committing.

Require Tests

yaml

---
name: require-tests
enabled: true
event: stop
action: warn
conditions:
  - field: transcript
    operator: not_contains
    pattern: pytest|npm test
---

⚠️ **Tests not run!**
Please verify changes.

Protect Production Files

yaml

---
name: protect-prod
enabled: true
event: file
action: block
conditions:
  - field: file_path
    operator: regex_match
    pattern: /production/|\.prod\.
---

🚨 **Production file!**
Requires review.

Management

Enable/Disable: Edit

.local.md

file:

enabled: false

Delete:

bash

rm .claude/hookify.my-rule.local.md

List:

bash

/hookify:list

Related Skills

abstract:hook-scope-guide - Hook placement decisions
abstract:hook-authoring - SDK hook development
abstract:hooks-eval - Hook evaluation

Best Practices

Start with simple patterns
Test regex thoroughly
Use clear, helpful messages
Prefer warnings over blocks initially
Name rules descriptively
Document intent in messages

Troubleshooting

Common Issues

If a rule doesn't trigger, verify that the

event

type matches the tool being used (e.g., use

bash

for command line tools). Check that the regex

pattern

is valid and matches the target text by testing it with a short Python script. If you encounter permission errors when creating rule files in

.claude/

, ensure that the directory is writable by your user.

writing-rules

NPX Install

Tags

SKILL.md Content

Table of Contents

Hookify Rule Writing Guide

When To Use

When NOT To Use

Overview

Quick Start

Rule File Format

Frontmatter Fields

Event Types

Advanced Conditions

Operators

Field Reference

Pattern Writing

Regex Basics

Examples

Test Patterns

Example Rules

Block Destructive Commands

Warn About Debug Code

Require Tests

Protect Production Files

Management

Related Skills

Best Practices

Troubleshooting

Common Issues