hook-development

# Hook Development for Claude Code Plugins ## Overview Hooks are event-driven automation scripts that execute in response to Claude Code events. Use hooks to validate operations, enforce policies, add context, and integrate external tools into workflows. **Key capabilities:** - Validate tool calls before execution (PreToolUse) - React to tool results (PostToolUse) - Enforce completion standards (Stop, SubagentStop) - Load project context (SessionStart) - Automate workflows across the development lifecycle ## Hook Types ### Prompt-Based Hooks (Recommended) Use LLM-driven decision making for context-aware validation: ```json { "type": "prompt", "prompt": "Evaluate if this tool use is appropriate: $TOOL_INPUT", "timeout": 30 } ``` **Supported events:** Stop, SubagentStop, UserPromptSubmit, PreToolUse **Benefits:** - Context-aware decisions based on natural language reasoning - Flexible evaluation logic without bash scripting - Better edge case handling - Easier to maintain and extend ### Command Hooks Execute bash commands for deterministic checks: ```json { "type": "command", "command": "bash ${CLAUDE_PLUGIN_ROOT}/scripts/validate.sh", "timeout": 60 } ``` **Use for:** - Fast deterministic validations - File system operations - External tool integrations - Performance-critical checks ## Hook Configuration Formats ### Plugin hooks.json Format **For plugin hooks** in `hooks/hooks.json`, use wrapper format: ```json { "description": "Brief explanation ...