skill-developer

# Skill Developer Guide

## Purpose

Comprehensive guide for creating and managing skills in Claude Code with auto-activation system, following Anthropic's official best practices including the 500-line rule and progressive disclosure pattern.

## When to Use This Skill

Automatically activates when you mention:
- Creating or adding skills
- Modifying skill triggers or rules
- Understanding how skill activation works
- Debugging skill activation issues
- Working with skill-rules.json
- Hook system mechanics
- Claude Code best practices
- Progressive disclosure
- YAML frontmatter
- 500-line rule

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## System Overview

### Two-Hook Architecture

**1. UserPromptSubmit Hook** (Proactive Suggestions)
- **File**: `.claude/hooks/skill-activation-prompt.ts`
- **Trigger**: BEFORE Claude sees user's prompt
- **Purpose**: Suggest relevant skills based on keywords + intent patterns
- **Method**: Injects formatted reminder as context (stdout → Claude's input)
- **Use Cases**: Topic-based skills, implicit work detection

**2. Stop Hook - Error Handling Reminder** (Gentle Reminders)
- **File**: `.claude/hooks/error-handling-reminder.ts`
- **Trigger**: AFTER Claude finishes responding
- **Purpose**: Gentle reminder to self-assess error handling in code written
- **Method**: Analyzes edited files for risky patterns, displays reminder if needed
- **Use Cases**: Error handling awareness without blocking friction

**Philosophy Change (2025-10-27):** We moved away from blocking PreToolUse for Sentry/error handling. Instead, use gentle post-response reminders that don't block workflow but maintain code quality awareness.

### Configuration File

**Location**: `.claude/skills/skill-rules.json`

Defines:
- All skills and their trigger conditions
- Enforcement levels (block, suggest, warn)
- File path patterns (glob)
- Content detection patterns (regex)
- Skip conditions (session tracking, file markers, env vars)

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## Skill Types

### 1. Guardrail Skills

**Purpose:** Enforce critica