Agent Skills

Production-grade engineering skills for AI coding agents.

Skills encode the workflows, quality gates, and best practices that senior engineers use when building software. These ones are packaged so AI agents follow them consistently across every phase of development.

  DEFINE          PLAN           BUILD          VERIFY         REVIEW          SHIP
 ┌──────┐      ┌──────┐      ┌──────┐      ┌──────┐      ┌──────┐      ┌──────┐
 │ Idea │ ───▶ │ Spec │ ───▶ │ Code │ ───▶ │ Test │ ───▶ │  QA  │ ───▶ │  Go  │
 │Refine│      │  PRD │      │ Impl │      │Debug │      │ Gate │      │ Live │
 └──────┘      └──────┘      └──────┘      └──────┘      └──────┘      └──────┘
  /spec          /plan          /build        /test         /review       /ship

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Commands

9 slash commands that map to the development lifecycle. Each one activates the right skills automatically.

What you’re doing	Command	Key principle
Define what to build	/spec	Spec before code
Plan how to build it	/plan	Small, atomic tasks
Build incrementally	/build	One slice at a time
Prove it works	/test	Tests are proof
Set the quality bar	/constraints	Decide it once, enforce it everywhere
Review before merge	/review	Improve code health
Audit web performance	/webperf	Measure before you optimize
Simplify the code	/code-simplify	Clarity over cleverness
Ship to production	/ship	Faster is safer

Want fewer manual steps once the spec exists? /build auto generates the plan and implements every task in a single approved pass — you approve the plan once, then it runs autonomously. It removes the human stepping between tasks, not the verification: every task is still test-driven and committed individually, and it pauses on failures or risky steps.

Skills also activate automatically based on what you’re doing — designing an API triggers api-and-interface-design, building UI triggers frontend-ui-engineering, and so on.

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Quick Start

Fastest path — any agent, one command. The open skills CLI installs into 70+ agents (Claude Code, Cursor, Codex, Copilot, Cline, and more):

npx skills add addyosmani/agent-skills            # install all 25 skills
npx skills add addyosmani/agent-skills --list     # browse before installing

Or grab individual skills:

npx skills add addyosmani/agent-skills --skill code-review-and-quality   # five-axis review before merge
npx skills add addyosmani/agent-skills --skill interview-me              # requirements interrogation, one question at a time
npx skills add addyosmani/agent-skills --skill test-driven-development   # red-green-refactor, enforced

Installing one skill? A per-skill npx install copies only skills/<name>/, not the repo-level references/ directory. The skill still works, but paths to supplementary shared checklists are unavailable. Use a whole-repo integration, clone the repository, or copy the needed checklist into a references/ directory inside the installed skill. This portability gap is tracked in #361.

Prefer a native integration? Pick your tool below.

Marketplace install:

/plugin marketplace add addyosmani/agent-skills
/plugin install agent-skills@addy-agent-skills

SSH errors? The marketplace clones repos via SSH. If you don’t have SSH keys set up on GitHub, either add your SSH key or use the full HTTPS URL to force HTTPS cloning during the marketplace-add step:

/plugin marketplace add https://github.com/addyosmani/agent-skills.git
/plugin install agent-skills@addy-agent-skills

If /plugin install still fails with git@github.com: Permission denied (publickey) on Windows or macOS, the recommended workaround is to configure Git once to rewrite GitHub SSH URLs to HTTPS for subprocess clones:

git config --global url."https://github.com/".insteadOf git@github.com:

Local / development:

git clone https://github.com/addyosmani/agent-skills.git
claude --plugin-dir /path/to/agent-skills

Put workflow skills under .cursor/skills/ (sync from agent-skills/skills/) and short policies in .cursor/rules/*.mdc — do not paste full skills into rules. See docs/cursor-setup.md.

Install as a native plugin for skills, subagents, and slash commands. See docs/antigravity-setup.md.

Install from the repo:

agy plugin install https://github.com/addyosmani/agent-skills.git

Install from a local clone:

git clone https://github.com/addyosmani/agent-skills.git
agy plugin install ./agent-skills

Install as native skills for auto-discovery, or add to GEMINI.md for persistent context. See docs/gemini-cli-setup.md.

Install from the repo:

gemini skills install https://github.com/addyosmani/agent-skills.git --path skills

Install from a local clone:

gemini skills install ./agent-skills/skills/

Add skill contents to your Windsurf rules configuration. See docs/windsurf-setup.md.

Copy skills to .opencode/skills/ (or ~/.config/opencode/skills/), add a project-local AGENTS.md, and use the built-in skill tool for agent-driven execution. Optional slash commands can be added under .opencode/commands/.

See docs/opencode-setup.md.

Use agent definitions from agents/ as Copilot personas and skill content in .github/copilot-instructions.md. See docs/copilot-setup.md.

Install as a native Codex plugin (Codex CLI v0.122+):

codex plugin marketplace add addyosmani/agent-skills
codex plugin add agent-skills@agent-skills

The first command registers the marketplace; the second installs the plugin. Codex reads the root skills/ directory directly through .codex-plugin/plugin.json. Once installed, invoke skills in chat using @ (e.g., @spec-driven-development). See docs/codex-setup.md for local installation and troubleshooting.

Install natively with the built-in cmd skills command. Command Code clones the repo, discovers every SKILL.md, and installs into .commandcode/skills/:

cmd skills add addyosmani/agent-skills            # pick skills to install (project)
cmd skills add addyosmani/agent-skills --global   # install for all projects (~/.commandcode/skills/)
cmd skills add addyosmani/agent-skills -s spec-driven-development  # install a specific skill

Installed skills show up in the TUI slash menu, e.g. /spec-driven-development. See docs/commandcode-setup.md.

Skills are plain Markdown - they work with any agent that accepts system prompts or instruction files. See docs/getting-started.md.

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Adoption

Already installed? How you roll the pack out depends on your codebase. The Adoption Guide covers two paths: the full lifecycle from day one for a greenfield project, or an incremental, verification-first rollout for an established codebase.

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All 24 Skills

The commands above are entry points. The pack includes 25 skills total — 24 lifecycle skills plus the using-agent-skills meta-skill. Each skill is a structured workflow with steps, verification gates, and anti-rationalization tables. You can also reference any skill directly.

Meta - Discover which skill applies

Skill	What It Does	Use When
using-agent-skills	Maps incoming work to the right skill workflow and defines shared operating rules	Starting a session or deciding which skill applies

Define - Clarify what to build

Skill	What It Does	Use When
interview-me	One-question-at-a-time interview that extracts what the user actually wants instead of what they think they should want, until ~95% confidence	The ask is underspecified, or the user invokes “interview me” / “grill me”
idea-refine	Structured divergent/convergent thinking to turn vague ideas into concrete proposals	You have a rough concept that needs exploration
spec-driven-development	Write a PRD covering objectives, commands, structure, code style, testing, and boundaries before any code	Starting a new project, feature, or significant change
constraint-driven-development	Interviews you for a quality bar with sane default thresholds, writes CONSTRAINTS.md, places each check by cost, and catches agents silencing checks or skipping tests to get green	No standards are written down, or an agent is producing more than anyone reads

Plan - Break it down

Skill	What It Does	Use When
planning-and-task-breakdown	Decompose specs into small, verifiable tasks with acceptance criteria and dependency ordering	You have a spec and need implementable units

Build - Write the code

Skill	What It Does	Use When
incremental-implementation	Thin vertical slices - implement, test, verify, commit. Feature flags, safe defaults, rollback-friendly changes	Any change touching more than one file
test-driven-development	Red-Green-Refactor, test pyramid (80/15/5), test sizes, DAMP over DRY, Beyonce Rule, browser testing	Implementing logic, fixing bugs, or changing behavior
context-engineering	Feed agents the right information at the right time - rules files, context packing, MCP integrations	Starting a session, switching tasks, or when output quality drops
source-driven-development	Ground every framework decision in official documentation - verify, cite sources, flag what’s unverified	You want authoritative, source-cited code for any framework or library
doubt-driven-development	Adversarial fresh-context review of every non-trivial decision in-flight - CLAIM → EXTRACT → DOUBT → RECONCILE → STOP, with optional user-authorized cross-model escalation	Stakes are high (production, security, irreversible), working in unfamiliar code, or a confident output is cheaper to verify now than to debug later
frontend-ui-engineering	Component architecture, design systems, state management, responsive design, WCAG 2.1 AA accessibility	Building or modifying user-facing interfaces
api-and-interface-design	Contract-first design, Hyrum’s Law, One-Version Rule, error semantics, boundary validation	Designing APIs, module boundaries, or public interfaces

Verify - Prove it works

Skill	What It Does	Use When
browser-testing-with-devtools	Chrome DevTools MCP for live runtime data - DOM inspection, console logs, network traces, performance profiling	Building or debugging anything that runs in a browser
debugging-and-error-recovery	Five-step triage: reproduce, localize, reduce, fix, guard. Stop-the-line rule, safe fallbacks	Tests fail, builds break, or behavior is unexpected

Review - Quality gates before merge

Skill	What It Does	Use When
code-review-and-quality	Five-axis review, change sizing (~100 lines), severity labels (Nit/Optional/FYI), review speed norms, splitting strategies	Before merging any change
code-simplification	Chesterton’s Fence, Rule of 500, reduce complexity while preserving exact behavior	Code works but is harder to read or maintain than it should be
security-and-hardening	OWASP Top 10 prevention, auth patterns, secrets management, dependency auditing, three-tier boundary system	Handling user input, auth, data storage, or external integrations
performance-optimization	Measure-first approach - Core Web Vitals targets, profiling workflows, bundle analysis, anti-pattern detection	Performance requirements exist or you suspect regressions

Ship - Deploy with confidence

Skill	What It Does	Use When
git-workflow-and-versioning	Trunk-based development, atomic commits, change sizing (~100 lines), the commit-as-save-point pattern	Making any code change (always)
ci-cd-and-automation	Shift Left, Faster is Safer, feature flags, quality gate pipelines, failure feedback loops	Setting up or modifying build and deploy pipelines
deprecation-and-migration	Code-as-liability mindset, compulsory vs advisory deprecation, migration patterns, zombie code removal	Removing old systems, migrating users, or sunsetting features
documentation-and-adrs	Architecture Decision Records, API docs, inline documentation standards - document the why	Making architectural decisions, changing APIs, or shipping features
observability-and-instrumentation	Structured logging, RED metrics, OpenTelemetry tracing, symptom-based alerting - instrument as you build	Adding telemetry, or shipping anything that runs in production
shipping-and-launch	Pre-launch checklists, feature flag lifecycle, staged rollouts, rollback procedures, monitoring setup	Preparing to deploy to production

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Agent Personas

Pre-configured specialist personas for targeted reviews:

Agent	Role	Perspective
code-reviewer	Senior Staff Engineer	Five-axis code review with “would a staff engineer approve this?” standard
test-engineer	QA Specialist	Test strategy, coverage analysis, and the Prove-It pattern
security-auditor	Security Engineer	Vulnerability detection, threat modeling, OWASP assessment
web-performance-auditor	Web Performance Engineer	Core Web Vitals audit with Quick/Deep modes and a metric-honesty rule; run it via /webperf

See docs/agents.md for the decision matrix, orchestration rules, and how personas compose with skills and slash commands.

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Reference Checklists

Quick-reference material that skills pull in when needed:

Reference	Covers
definition-of-done.md	Project-wide standing bar every change clears, contrasted with per-task acceptance criteria
testing-patterns.md	Test structure, naming, mocking, React/API/E2E examples, anti-patterns (JavaScript/TypeScript)
security-checklist.md	Pre-commit checks, auth, input validation, headers, CORS, OWASP Top 10
performance-checklist.md	Core Web Vitals targets, frontend/backend checklists, measurement commands
accessibility-checklist.md	Keyboard nav, screen readers, visual design, ARIA, testing tools
observability-checklist.md	On-call questions, structured logging, RED/USE metrics, tracing, symptom-based alerting, pre-launch gate
orchestration-patterns.md	Endorsed multi-persona orchestration patterns, anti-patterns, and the “personas don’t invoke personas” rule

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How Skills Work

Every skill follows a consistent anatomy:

┌─────────────────────────────────────────────────┐
│  SKILL.md                                       │
│                                                 │
│  ┌─ Frontmatter ─────────────────────────────┐  │
│  │ name: lowercase-hyphen-name               │  │
│  │ description: Guides agents through [task].│  │
│  │              Use when…                    │  │
│  └───────────────────────────────────────────┘  │                                                                                                
│  Overview         → What this skill does        │
│  When to Use      → Triggering conditions       │
│  Process          → Step-by-step workflow       │
│  Rationalizations → Excuses + rebuttals         │
│  Red Flags        → Signs something's wrong     │
│  Verification     → Evidence requirements       │
└─────────────────────────────────────────────────┘

Key design choices:

• Process, not prose. Skills are workflows agents follow, not reference docs they read. Each has steps, checkpoints, and exit criteria.
• Anti-rationalization. Every skill includes a table of common excuses agents use to skip steps (e.g., “I’ll add tests later”) with documented counter-arguments.
• Verification is non-negotiable. Every skill ends with evidence requirements - tests passing, build output, runtime data. “Seems right” is never sufficient.
• Progressive disclosure. The SKILL.md is the entry point. Supporting references load only when needed, keeping token usage minimal.

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Project Structure

agent-skills/
├── skills/                            # 25 skills (24 lifecycle + 1 meta)
│   ├── interview-me/                  #   Define
│   ├── idea-refine/                   #   Define
│   ├── spec-driven-development/       #   Define
│   ├── constraint-driven-development/ #   Define
│   ├── planning-and-task-breakdown/   #   Plan
│   ├── incremental-implementation/    #   Build
│   ├── context-engineering/           #   Build
│   ├── source-driven-development/     #   Build
│   ├── doubt-driven-development/      #   Build
│   ├── frontend-ui-engineering/       #   Build
│   ├── test-driven-development/       #   Build
│   ├── api-and-interface-design/      #   Build
│   ├── browser-testing-with-devtools/ #   Verify
│   ├── debugging-and-error-recovery/  #   Verify
│   ├── code-review-and-quality/       #   Review
│   ├── code-simplification/           #   Review
│   ├── security-and-hardening/        #   Review
│   ├── performance-optimization/      #   Review
│   ├── git-workflow-and-versioning/   #   Ship
│   ├── ci-cd-and-automation/          #   Ship
│   ├── deprecation-and-migration/     #   Ship
│   ├── documentation-and-adrs/        #   Ship
│   ├── observability-and-instrumentation/ # Ship
│   ├── shipping-and-launch/           #   Ship
│   └── using-agent-skills/            #   Meta: how to use this pack
├── agents/                            # 4 specialist personas
├── references/                        # 7 supplementary checklists
├── hooks/                             # Session lifecycle hooks
├── .claude/commands/                  # 8 slash commands (Claude Code)
├── .gemini/commands/                  # 8 slash commands (Gemini CLI)
├── commands/                          # 8 slash commands (Antigravity CLI)
├── plugin.json                        # Antigravity plugin manifest
└── docs/                              # Setup guides per tool

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