Claude Code Skills: Domain-Specific Knowledge Injection

Claude Code Skills: Domain-Specific Knowledge Injection

Reference documentation for configuring and using Claude Code skills—markdown files that inject domain expertise into Claude's context when relevant tasks are detected.

Overview

Skills are markdown files that Claude Code automatically loads when it detects relevant tasks. Unlike hooks (which fire on lifecycle events), skills are model-invoked: Claude decides when to use them based on the task at hand.

┌─────────────────────────────────────────────────────────────────┐
│                     Skill Invocation Flow                        │
├─────────────────────────────────────────────────────────────────┤
│  User Request → Claude analyzes task → Matches skill triggers   │
│       ↓                                                          │
│  Claude reads SKILL.md → Applies patterns → Executes task       │
└─────────────────────────────────────────────────────────────────┘

Skills vs Hooks

Skill Locations

Global Skills (All Projects)

~/.claude/skills/
├── nextjs-tanstack-stack/
│   └── SKILL.md
├── prompt-engineering-patterns/
│   └── SKILL.md
└── webapp-testing/
    └── SKILL.md

Project Skills (Single Project)

<project-root>/
└── .claude/
    └── skills/
        └── project-specific-skill/
            └── SKILL.md

Priority: Project skills override global skills with the same name.

Installing Skills

Via Toolkit Installer (Recommended)

If you're using Namshub:

cd prompts && ./scripts/install.sh

This script:

1. Backs up existing ~/.claude configuration
2. Creates symlinks to toolkit commands, skills, and hooks
3. Configures settings.json with proper hook definitions

Manual Installation

# Create skill directory
mkdir -p ~/.claude/skills/my-custom-skill

# Create SKILL.md
cat > ~/.claude/skills/my-custom-skill/SKILL.md << 'EOF'
---
name: my-custom-skill
description: Use when the user asks about [specific domain]...
---

# My Custom Skill

## When to Use This Skill
- Scenario 1
- Scenario 2

## Core Patterns
...
EOF

SKILL.md Format

Required Structure

---
name: skill-name
description: Trigger description for Claude to match tasks against
---

# Skill Title

## When to Use This Skill
- Bullet points of applicable scenarios

## Core Patterns
[Domain-specific patterns with code examples]

## Best Practices
[Numbered guidelines]

## Common Pitfalls
[What to avoid]

Trigger Description

The description field in frontmatter is critical—Claude uses it to decide when to invoke the skill:

# Good: Specific triggers
description: Use when building Next.js applications with TanStack Table, implementing virtualized lists, or optimizing React performance with memoization.

# Bad: Too vague
description: Use for frontend development.

Current Global Skills Registry

1. nextjs-tanstack-stack

Location: ~/.claude/skills/nextjs-tanstack-stack/

Triggers: Next.js App Router, TanStack (Table, Query, Form, Virtual), Zustand, data tables, virtualization, memoization

Coverage:

• Server vs Client component patterns
• TanStack Query (factories, caching, mutations)
• TanStack Table with virtualization (10k+ rows)
• TanStack Form with Zod validation
• Zustand store patterns (slices, selectors)
• Performance optimization

Structure:

nextjs-tanstack-stack/
├── SKILL.md                              # Core patterns
├── references/
│   ├── tanstack-query-patterns.md
│   ├── tanstack-table-patterns.md
│   ├── tanstack-form-patterns.md
│   ├── zustand-patterns.md
│   ├── nextjs-app-router.md
│   └── performance-patterns.md
└── examples/
    ├── virtualized-data-table.tsx
    ├── query-with-error-boundary.tsx
    ├── form-with-validation.tsx
    └── zustand-query-sync.tsx

2. prompt-engineering-patterns

Location: ~/.claude/skills/prompt-engineering-patterns/

Triggers: Prompt engineering, optimize prompt, write a skill, reduce bloat, context engineering

Coverage:

• Context engineering applied to prompts and skills (Four Buckets)
• The Deletion Test for eliminating bloat
• Compression patterns (tables over prose, constraints over guidance)
• Anti-patterns for AI-writing-prompts-for-AI
• Multi-agent prompt isolation

3. webapp-testing

Location: ~/.claude/skills/webapp-testing/

Source: @anthropics/skills/webapp-testing (customized)

Triggers: Testing web applications, browser automation, Chrome debugging, console errors, authenticated apps

Coverage:

• Chrome Integration (preferred): Real browser testing with claude --chrome
  • Tab management, navigation, element interaction
  • Console log debugging (read_console_messages)
  • Network request inspection (read_network_requests)
  • Authenticated app automation (Google Docs, Notion, etc.)
  • GIF recording for demos
• Playwright Fallback: For CI/CD and headless scenarios
  • Server lifecycle management (with_server.py)
  • Playwright sync API patterns
  • Reconnaissance-then-action pattern

Structure:

webapp-testing/
├── SKILL.md                      # Chrome-first, Playwright fallback
├── examples/
│   ├── chrome/                   # Chrome integration patterns
│   │   ├── form-testing.md
│   │   ├── console-debugging.md
│   │   └── authenticated-apps.md
│   └── playwright/               # Headless/CI patterns
│       └── *.py
└── scripts/
    └── with_server.py

4. async-python-patterns

Location: ~/.claude/skills/async-python-patterns/

Triggers: Python asyncio, concurrent programming, async/await, I/O-bound applications

Coverage:

• 10 fundamental async patterns
• Producer-consumer, semaphores, context managers
• Real-world applications (web scraping, databases, WebSockets)
• Performance best practices

5. frontend-design

Location: ~/.claude/skills/frontend-design/

Triggers: Building web components, pages, frontend interfaces

Coverage:

• Distinctive visual design (avoiding generic AI aesthetics)
• Typography, color, motion, spatial composition
• Design thinking before coding

6. ux-designer

Location: ~/.claude/skills/ux-designer/

Triggers: User experience design, wireframes, accessibility

Coverage:

• User flow design
• Wireframe creation (ASCII or descriptions)
• WCAG 2.1 compliance checklists
• Design tokens
• Responsive behavior specs

7. melt

Location: ~/.claude/skills/melt/

Triggers: /melt, /build (legacy), /forge (legacy), "go do", "just do it", "execute this"

Coverage:

• Task-agnostic autonomous execution with completion checkpoint
• Optional Agent Teams planning before implementation
• Full fix-verify loop: implement → lint → commit → deploy → browser verify
• Cannot stop until checkpoint passes

Guide: Melt Guide

8. appfix

Location: ~/.claude/skills/appfix/

Triggers: /appfix, "fix the app", "debug production", "check staging"

Coverage:

• Autonomous debugging with completion checkpoint (extends build)
• Health check all services
• Collect logs (Azure Container Apps, browser console, LogFire)
• Diagnose → fix → commit → deploy → verify loop

Guide: Appfix Guide

9. heavy

Location: ~/.claude/skills/heavy/

Triggers: /heavy, "heavy analysis", "multiple perspectives", "debate this"

Coverage:

• Multi-perspective analysis with 3-5 parallel Opus agents
• First Principles + AGI-Pilled always, Critical Reviewer + dynamic agents as needed
• Self-educating agents via codebase + web + vendor docs
• Structured disagreements and adversarial dialogue

10. deploy-pipeline

Location: ~/.claude/skills/deploy-pipeline/

Triggers: /deploy, deployment questions, environment promotion

Coverage:

• Motium deployment pipeline guide (local → dev → test → prod)
• Azure Container Apps deployment
• GitHub Actions workflows
• Environment promotion strategy

11. mobileappfix

Location: ~/.claude/skills/mobileappfix/

Triggers: Mobile app debugging, Maestro tests, React Native issues

Coverage:

• Mobile app debugging with Maestro E2E tests
• React Native / Expo diagnostics
• iOS and Android platform-specific debugging

12. skill-sandbox

Location: ~/.claude/skills/skill-sandbox/

Triggers: /skill-sandbox, "test skill", "sandbox test"

Coverage:

• Test Claude Code skills in isolated tmux sandboxes
• Spawn multiple sessions, verify hook behavior
• Run integration tests for skills

13. toolkit

Location: ~/.claude/skills/toolkit/

Triggers: /toolkit, "update toolkit", "toolkit status", "optimize CLAUDE.md"

Coverage:

• Toolkit management and information
• CLAUDE.md optimization and auditing
• Auto-update status and configuration

14. design-improver

Location: ~/.claude/skills/design-improver/

Triggers: "improve design", "audit UI", "fix styling", "grade the interface"

Coverage:

• Recursively improve web UI design via vision-based screenshot analysis
• Design grading and targeted fix suggestions
• Iterative improvement loop

15. ux-improver

Location: ~/.claude/skills/ux-improver/

Triggers: "improve UX", "fix usability", "audit user experience"

Coverage:

• Recursively improve web application UX via vision-based analysis
• User flow analysis and interaction audit
• Iterative usability improvement loop

16. docs-navigator

Location: ~/.claude/skills/docs-navigator/

Triggers: "read the docs", "check documentation", unfamiliar codebase tasks

Coverage:

• Navigate project documentation efficiently
• Identify relevant docs before starting unfamiliar tasks
• Documentation discovery and orientation

17. revonc-eas-deploy

Location: ~/.claude/skills/revonc-eas-deploy/

Triggers: /eas, "deploy to testflight", "push ota update", "build ios/android"

Coverage:

• RevOnc mobile app EAS deployment guide
• Build, deploy, and publish OTA updates via Expo Application Services
• iOS (TestFlight) and Android deployment workflows
• Build profiles and environment configuration

18. audiobook

Location: ~/.claude/skills/audiobook/

Triggers: /audiobook, "create an audiobook", "turn this into audio", "make TTS-ready"

Coverage:

• Transform technical documents into TTS-optimized audiobooks
• 4-agent heavy analysis (First Principles, AGI-Pilled, TTS Expert, Stop-Slop Expert)
• Michael Caine oration style with conversational asides
• TTS-specific formatting (pause markers, number handling, no markdown syntax)
• 35-item stop-slop watchlist for eliminating AI patterns
• 5-dimension quality scoring (Directness, Rhythm, Trust, Authenticity, Density)

Structure:

audiobook/
└── SKILL.md                    # Complete workflow + voice guide + stop-slop reference

19. repair

Location: ~/.claude/skills/repair/

Triggers: /repair, "fix the app", "debug", "repair"

Coverage:

• Unified debugging router (auto-detects web vs mobile)
• Routes to /appfix (web) or /mobileappfix (mobile)

20. burndown

Location: ~/.claude/skills/burndown/

Triggers: /burndown, "burn down debt", "clean up codebase"

Coverage:

• Autonomous tech debt elimination (combines /deslop + /qa)
• 3 detection agents scan for slop and architecture issues
• Iterative fix loop until clean

21. compound

Location: ~/.claude/skills/compound/

Triggers: /compound, "document this solution", "capture this learning"

Coverage:

• Manual deep memory capture (LESSON/PROBLEM/CAUSE/FIX)
• Cross-session learning via append-only event store

22. episode

Location: ~/.claude/skills/episode/

Triggers: /episode, "generate an episode", "create educational video"

Coverage:

• Educational video episode generation with Minecraft-style graphics
• Orchestrates fal.ai, ElevenLabs TTS, and FFmpeg

23. essay

Location: ~/.claude/skills/essay/

Triggers: /essay, "write an essay", "essay about"

Coverage:

• Long-form essay writing with 5-agent heavy analysis
• Anti-slop enforcement and self-scoring rubric

24. harness-test

Location: ~/.claude/skills/harness-test/

Triggers: /harness-test, "test harness changes"

Coverage:

• Test hook/skill changes in isolated sandbox
• Auto-triggers in /melt when modifying toolkit

25. health

Location: ~/.claude/skills/health/

Triggers: /health, "system health", "how is memory doing"

Coverage:

• Toolkit health metrics and memory state diagnostics
• Injection effectiveness and session state

26. improve

Location: ~/.claude/skills/improve/

Triggers: /improve, "improve design", "improve UX"

Coverage:

• Universal recursive improvement (design, UX, performance, a11y)
• Observe-grade-fix loop targeting 9/10

Creating Custom Skills

Step 1: Identify the Domain

Define clear boundaries:

• What tasks should trigger this skill?
• What patterns/knowledge does it provide?
• What does it NOT cover (delegate to other skills)?

Step 2: Structure the SKILL.md

---
name: my-domain-skill
description: Use when [specific triggers]. Triggers on [keywords].
---

# Domain Skill Title

## When to Use This Skill

**Use for:**
- Specific scenario 1
- Specific scenario 2

**Do NOT use for (delegate to):**
- Other scenario → other-skill

## Core Patterns

### Pattern 1: [Name]

[Explanation]

```language
[Code example]

Pattern 2: [Name]

...

Best Practices

1. First practice
2. Second practice ...

Common Pitfalls

• Anti-pattern 1: Why it's bad and what to do instead
• Anti-pattern 2: ...

Resources

• Link to reference doc
• Link to example

### Step 3: Add Reference Files (Optional)

For comprehensive skills, add supporting documentation:

my-domain-skill/ ├── SKILL.md # Core patterns (entry point) ├── references/ # Deep-dive documentation │ ├── topic-1-patterns.md │ └── topic-2-patterns.md └── examples/ # Working code examples └── complete-example.tsx

### Step 4: Test the Skill

1. Start a new Claude Code session
2. Ask a question that should trigger the skill
3. Verify Claude loads and applies the skill patterns
4. Refine trigger description if needed

## Skill Philosophy Alignment

Skills should align with the core development philosophy:

| Principle | Skill Implementation |
|-----------|---------------------|
| **Boring over clever** | Document explicit, obvious patterns |
| **Local over abstract** | Self-contained examples, not abstract theory |
| **Small composable units** | Break patterns into single-purpose sections |
| **Fail loud** | Include error handling patterns |
| **Tests as specification** | Include testing patterns where applicable |

## Integration with Hooks

Skills and hooks complement each other:

1. **SessionStart hook** reminds Claude to read project docs
2. **Skills** provide domain expertise for specific tasks
3. **Stop hook** reminds Claude to verify compliance

Session Start │ ├── Hook: "Read CLAUDE.md, docs/index.md" │ ├── User Request: "Build a data table" │ │ │ └── Skill: nextjs-tanstack-stack activated │ └── Applies TanStack Table patterns │ └── Session End │ └── Hook: "Verify CLAUDE.md compliance"

## Troubleshooting

### Skill Not Triggered

| Symptom | Cause | Fix |
|---------|-------|-----|
| Skill never activates | Vague description | Add specific trigger keywords |
| Wrong skill activates | Overlapping descriptions | Make descriptions more distinct |
| Skill partially applied | Too long/complex | Split into focused skills |

### Skill Conflicts

If multiple skills could apply:
1. Claude will choose the most specific match
2. Project skills override global skills
3. Consider merging overlapping skills

## Related Documentation

- [Claude Code Hooks](./hooks.md) - Lifecycle event handlers
- [Commands Reference](./commands.md) - Custom slash commands
- [Config Files](../../config/) - Actual hook/skill/command files for installation
- [CLAUDE.md Standards](../philosophy.md) - Core philosophy
- [Official Skills Documentation](https://docs.anthropic.com/en/docs/claude-code/skills) - Anthropic reference