What is the difference between command hooks and prompt-based hooks?

Command hooks execute bash scripts for deterministic checks and tasks, while prompt-based hooks utilize LLM-driven decision making for more complex, context-aware validation.

What are Claude Code hooks?

Hooks are shell commands or prompt-based scripts that execute automatically in response to specific events within the Claude Code environment, such as starting a session or using a tool.

How do I make my hooks portable across different machines?

To ensure portability, use standard environment variables provided by Claude Code, such as $CLAUDE_PROJECT_DIR and $CLAUDE_PLUGIN_ROOT, rather than hardcoded file paths.

Can I use hooks to manage environment variables?

Yes, specifically during the SessionStart event, you can use $CLAUDE_ENV_FILE to persist and manage environment variables for the duration of the session.

Which event types are supported by this skill?

It covers a wide range of events including PreToolUse, PostToolUse, SessionStart, SessionEnd, Stop, SubagentStop, UserPromptSubmit, PreCompact, and Notification.

Claude Code Hook Development

Name: Claude Code Hook Development
Author: CANTAGESTUDIO

byCANTAGESTUDIO

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Developer Tools

Facilitates the creation, debugging, and optimization of event-driven shell commands and automated workflows within Claude Code.

This skill provides comprehensive guidance for developers looking to extend Claude Code's capabilities through custom hooks. It assists in building, debugging, and refining scripts that trigger automatically during specific events—such as tool usage, session starts, or user prompts—enabling seamless automation for tasks like linting, logging, and environment configuration. Whether you are implementing prompt-based decision logic or deterministic bash commands, this utility ensures your hooks are portable, secure, and highly efficient within your development lifecycle.

Key Features

01Best practices for portable bash script development using environment variables

021 GitHub stars

03Optimization patterns for custom workflow automation and context management

04Support for all Claude Code event types including PreToolUse and SessionStart

05Guidance on implementing LLM-driven prompt-based hooks for context-aware validation

06Debugging strategies for notification reactions and subagent task validation

Use Cases

01Enforcing project-specific policies and context loading during session startup

02Creating custom notifications and logging systems for agent activities

03Automating code linting and formatting checks before tool execution

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add cantagestudio/cosmicatlaspacker hook-development

For use in Claude.ai and ChatGPT

Download Skill