What does exit code 2 signify in Claude Code hooks?

Exit code 2 acts as a blocking error that stops execution and feeds the stderr content back to Claude or the user to handle a critical failure or security violation.

What is the primary difference between a hook and a prompt?

Hooks are deterministic, meaning they execute every single time a specific event occurs, whereas prompts are probabilistic and rely on Claude's judgment to follow instructions.

What are matchers used for in hook configuration?

Matchers use exact strings or regex patterns to define which specific tools (like 'Write' or 'Edit') should trigger PreToolUse and PostToolUse hooks.

When should I use a Python script instead of Bash for a hook?

Use Python when you need complex validation, JSON parsing from stdin, or advanced logic requiring external libraries via UV for dependency management.

How do I communicate with both the user and Claude in a single hook?

By returning a JSON object containing 'systemMessage' for user-facing terminal output and 'additionalContext' within 'hookSpecificOutput' for injecting context into Claude's memory.

Claude Code Hook Design Architect

Name: Claude Code Hook Design Architect
Author: racurry

byracurry

学習とドキュメンテーション

Provides expert guidance and implementation patterns for designing robust, deterministic Claude Code hooks.

概要

The Hook Design skill offers comprehensive interpretive guidance for developers building Claude Code extensions, bridging the gap between raw documentation and practical execution. It clarifies complex hook lifecycles, execution flows, and the critical distinction between deterministic hooks and probabilistic AI prompts. By providing standardized patterns for Bash and Python implementations—including advanced JSON communication protocols for user feedback and AI context injection—it ensures developers can create reliable, production-grade automation within the Claude Code environment.

主な機能

0 GitHub stars
Detailed specifications for exit codes and JSON communication protocols
Complete hook lifecycle mapping including Pre/PostToolUse and SessionStart
Deterministic vs. probabilistic execution decision logic
Standardized Python implementation patterns using UV for dependency management
Matcher syntax guidance for precise tool-triggering control

ユースケース

Developing context-aware session initialization for specialized development environments
Building mandatory security and validation gates that must run before tool execution
Implementing automated code formatting and linting with real-time user feedback

概要

主な機能

0 GitHub stars
Detailed specifications for exit codes and JSON communication protocols
Complete hook lifecycle mapping including Pre/PostToolUse and SessionStart
Deterministic vs. probabilistic execution decision logic
Standardized Python implementation patterns using UV for dependency management
Matcher syntax guidance for precise tool-triggering control

ユースケース

Developing context-aware session initialization for specialized development environments
Building mandatory security and validation gates that must run before tool execution
Implementing automated code formatting and linting with real-time user feedback