Harness Engineering Skills

Agent skills for Cursor, Claude Code, and Codex — help coding agents finish work reliably, not just write code faster.

Based on Learn Harness Engineering by Walking Labs.

What you get

Without a harness, agents often:

• forget context between sessions
• declare “done” without running tests
• do too much at once and leave things half-finished
• need you to re-explain the project every time

These skills guide the agent through a proven workflow:

You install the skills once in your IDE. Your project stays separate — skills are not copied into your app repo unless you choose to add harness files there.

Works with Cursor, Claude Code, and Codex (same SKILL.md format, different install folders).

Quick start

1. Install skills

npx harness-skills install

Pick global (all projects) or project-only. By default, skills install for Cursor, Claude Code, and Codex.

Install for one tool only:

npx harness-skills install --ide cursor
npx harness-skills install --ide claude
npx harness-skills install --ide codex

2. Open your project in Cursor, Claude Code, or Codex

3. Ask the agent to use a skill

Use harness-scaffold to set up this project

That’s it. No config file required to start.

Optional: add harness files to a project

If you want AGENTS.md, init.sh, and tracking files inside a repo:

cd /path/to/your-project
npx harness-skills create --target .

Then in your IDE:

Use harness-scaffold — replace the example features with real ones

Check the result:

npx harness-skills validate --target .

How it works

Skills live in your IDE (Cursor, Claude Code, or Codex). Harness files (optional) live in your project repo.

flowchart LR
    A["npx harness-skills install"] --> B[Skills in your IDE]
    B --> C[Open your project]
    C --> D["Ask: Use harness-…"]
    D --> E[Agent follows the skill]
    E --> F{Optional}
    F --> G["create + validate in project"]

Which skill should I use?

Start with scaffold on a new project or audit on an existing one. Use the table below when something specific goes wrong.

Suggested order (first time)

flowchart LR
    A[harness-scaffold] --> B[harness-audit]
    B --> C[harness-instructions]
    C --> D[harness-repo-knowledge]
    D --> E[harness-state]
    E --> F[harness-lifecycle]
    F --> G[harness-environment]
    G --> H[harness-scope]
    H --> I[harness-verification]
    I --> J[harness-e2e]
    J --> K[harness-evaluator]
    K --> L[harness-observability]
    L --> M[harness-diagnose]

You don’t need all of them on day one. Install everything once, then invoke only what you need.

All skills

Install options

Remove skills

npx harness-skills uninstall

Removes only skills from this package (harness-*). Other skills in the same folder are left untouched.

Legacy package name: harness-engineering-skills (still works).

CLI reference

Common flags: --target . (project path), --force (overwrite on install), --project (current repo), --ide all|cursor|claude|codex, --yes (skip prompts).

For contributors

Templates live in templates/. Scripts: create-harness.mjs, validate-harness.mjs. Local dev:

git clone https://github.com/solanodz/harness-engineering-skills.git
cd harness-engineering-skills
npm run dev:install

Publishing: see .github/PUBLISHING.md.

Troubleshooting

Permission denied when running npx harness-skills inside this repo

If you cloned this repository and run npx harness-skills install from the repo root, npm may use the local package instead of the published one. Use one of these instead:

npm run dev:install          # recommended for local development
node scripts/cli.mjs install # explicit
npx harness-skills@latest install  # force published package

Install from your own project (not this repo):

cd ~/your-app
npx harness-skills install

Learn more

• Learn Harness Engineering
• OpenAI: Harness engineering
• Anthropic: Effective harnesses for long-running agents

License

MIT — adapted from walkinglabs/learn-harness-engineering.