https://github.com/revfactory/harness

A meta-skill that designs domain-specific agent teams, defines specialized agents, and generates the skills they use.
https://github.com/revfactory/harness

claude-code claude-code-plugin harness harness-engineering

Last synced: 15 days ago
JSON representation

A meta-skill that designs domain-specific agent teams, defines specialized agents, and generates the skills they use.

• Host: GitHub
• URL: https://github.com/revfactory/harness
• Owner: revfactory
• License: apache-2.0
• Created: 2026-03-26T21:22:07.000Z (about 2 months ago)
• Default Branch: main
• Last Pushed: 2026-04-17T19:36:15.000Z (26 days ago)
• Last Synced: 2026-04-17T21:28:16.874Z (25 days ago)
• Topics: claude-code, claude-code-plugin, harness, harness-engineering
• Language: HTML
• Homepage: https://revfactory.github.io/harness/
• Size: 8.84 MB
• Stars: 2,585
• Watchers: 22
• Forks: 372
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-claude-code - **harness** - skill that designs domain-specific agent teams, defines specialized agents, and generates the skills they use. (🔌 Claude Plugins)

README

          


  





  

  

  

  

  

  





  

  

  



# Harness — The Team-Architecture Factory for Claude Code

**English** | [한국어](README_KO.md) | [日本語](README_JA.md)

> **Harness is a team-architecture factory for Claude Code.** Say **"build a harness for this project"** (English) or **"하네스 구성해줘"** (한국어) or **"ハーネスを構成して"** (日本語), and the plugin turns your domain description into an agent team and the skills they use — picked from six pre-defined team-architecture patterns.

## Overview

Harness leverages Claude Code's agent team system to decompose complex tasks into coordinated teams of specialized agents. Say "build a harness for this project" and it automatically generates agent definitions (`.claude/agents/`) and skills (`.claude/skills/`) tailored to your domain.

## Category — Where Harness Sits

Harness lives at the **L3 Meta-Factory** layer of the Claude Code ecosystem — the layer that generates other harnesses rather than being one. Inside L3, we pick a specific sub-layer: **Team-Architecture Factory**.

| Layer | What it does | Neighbors we coexist with |

|-------|--------------|---------------------------|

| **L3 — Meta-Factory / Team-Architecture Factory** (us) | Domain sentence → agent team + skills, via 6 pre-defined team patterns | — |

| L3 — Meta-Factory / Runtime-Configuration Factory | Deterministic, repeatable runtime configurations | [coleam00/Archon](https://github.com/coleam00/Archon) |

| L3 — Meta-Factory / Codex Runtime Port | Same concept, Codex runtime | [SaehwanPark/meta-harness](https://github.com/SaehwanPark/meta-harness) |

| L2 — Cross-Harness Workflow | Standardize skills/rules/hooks across multiple harnesses | [affaan-m/ECC](https://github.com/affaan-m/everything-claude-code) |

> Archon generates deterministic runtime configurations. Harness generates team architectures (pipeline, fan-out/fan-in, expert pool, producer-reviewer, supervisor, hierarchical delegation) plus the skills agents use. Different sub-layers of the same L3. Pick Archon for runtime determinism, Harness for team architecture, or combine them.

## Star History



 

   

   

   

 



## Key Features

- **Agent Team Design** — 6 architectural patterns: Pipeline, Fan-out/Fan-in, Expert Pool, Producer-Reviewer, Supervisor, and Hierarchical Delegation

- **Skill Generation** — Auto-generates skills with Progressive Disclosure for efficient context management

- **Orchestration** — Inter-agent data passing, error handling, and team coordination protocols

- **Validation** — Trigger verification, dry-run testing, and with-skill vs without-skill comparison tests

## Harness Evolution Mechanism

The harness evolution mechanism feeds deltas (what worked / what didn't) back into the factory, so the next generation is measurably better. When a generated harness is used in a real project, the `/harness:evolve` skill captures the delta between the initial architecture and the shipped one, and feeds it back into the factory so the next generation for a similar domain starts closer to the shipped state.

```

Initial harness ──▶ Real project use ──▶ Shipped harness

                                              │

                                              ▼ (delta capture via /harness:evolve)

                                        ┌───────────────┐

                                        │  Factory      │◀── better next-gen draft

                                        └───────────────┘

```

We call this the **Harness Evolution Mechanism** (KR: 하네스 진화 메커니즘; JA: ハーネス進化メカニズム).

## Workflow

```

Phase 1: Domain Analysis

    ↓

Phase 2: Team Architecture Design (Agent Teams vs Subagents)

    ↓

Phase 3: Agent Definition Generation (.claude/agents/)

    ↓

Phase 4: Skill Generation (.claude/skills/)

    ↓

Phase 5: Integration & Orchestration

    ↓

Phase 6: Validation & Testing

```

## Installation

### Via Marketplace

#### Add the marketplace

```shell

/plugin marketplace add revfactory/harness

```

#### Install the plugin

```shell

/plugin install harness@harness

```

### Direct Installation as Global Skill

```shell

# Copy the skills directory to ~/.claude/skills/harness/

cp -r skills/harness ~/.claude/skills/harness

```

## Plugin Structure

```

harness/

├── .claude-plugin/

│   └── plugin.json                 # Plugin manifest

├── skills/

│   └── harness/

│       ├── SKILL.md                # Main skill definition (6-Phase workflow)

│       └── references/

│           ├── agent-design-patterns.md   # 6 architectural patterns

│           ├── orchestrator-template.md   # Team/subagent orchestrator templates

│           ├── team-examples.md           # 5 real-world team configurations

│           ├── skill-writing-guide.md     # Skill authoring guide

│           ├── skill-testing-guide.md     # Testing & evaluation methodology

│           └── qa-agent-guide.md          # QA agent integration guide

└── README.md

```

## Usage

Trigger in Claude Code with prompts like:

```

Build a harness for this project

Design an agent team for this domain

Set up a harness

```

### Execution Modes

| Mode | Description | Recommended For |

|------|-------------|-----------------|

| **Agent Teams** (default) | TeamCreate + SendMessage + TaskCreate | 2+ agents requiring collaboration |

| **Subagents** | Direct Agent tool invocation | One-off tasks, no inter-agent communication needed |



  



### Architecture Patterns

| Pattern | Description |

|---------|-------------|

| Pipeline | Sequential dependent tasks |

| Fan-out/Fan-in | Parallel independent tasks |

| Expert Pool | Context-dependent selective invocation |

| Producer-Reviewer | Generation followed by quality review |

| Supervisor | Central agent with dynamic task distribution |

| Hierarchical Delegation | Top-down recursive delegation |

## Output

Files generated by Harness:

```

your-project/

├── .claude/

│   ├── agents/          # Agent definition files

│   │   ├── analyst.md

│   │   ├── builder.md

│   │   └── qa.md

│   └── skills/          # Skill files

│       ├── analyze/

│       │   └── SKILL.md

│       └── build/

│           ├── SKILL.md

│           └── references/

```

## Use Cases — Try These Prompts

Copy any prompt below into Claude Code after installing Harness:

**Deep Research**

```

Build a harness for deep research. I need an agent team that can investigate

any topic from multiple angles — web search, academic sources, community

sentiment — then cross-validate findings and produce a comprehensive report.

```

**Website Development**

```

Build a harness for full-stack website development. The team should handle

design, frontend (React/Next.js), backend (API), and QA testing in a

coordinated pipeline from wireframe to deployment.

```

**Webtoon / Comic Production**

```

Build a harness for webtoon episode production. I need agents for story

writing, character design prompts, panel layout planning, and dialogue

editing. They should review each other's work for style consistency.

```

**YouTube Content Planning**

```

Build a harness for YouTube content creation. The team should research

trending topics, write scripts, optimize titles/tags for SEO, and plan

thumbnail concepts — all coordinated by a supervisor agent.

```

**Code Review & Refactoring**

```

Build a harness for comprehensive code review. I want parallel agents

checking architecture, security vulnerabilities, performance bottlenecks,

and code style — then merging all findings into a single report.

```

**Technical Documentation**

```

Build a harness that generates API documentation from this codebase.

Agents should analyze endpoints, write descriptions, generate usage

examples, and review for completeness.

```

**Data Pipeline Design**

```

Build a harness for designing data pipelines. I need agents for schema

design, ETL logic, data validation rules, and monitoring setup that

delegate sub-tasks hierarchically.

```

**Marketing Campaign**

```

Build a harness for marketing campaign creation. The team should research

the target market, write ad copy, design visual concepts, and set up

A/B test plans with iterative quality review.

```

## Coexistence — Harness and Neighbors

Harness is not alone in the Claude Code / agent-framework ecosystem. The following repos live in adjacent layers; each is described in a parallel "X is …, Harness is …" form so you can pick the one that fits your need or combine several.

| Repo | Their position | Relationship to Harness |

|------|----------------|-------------------------|

| [coleam00/Archon](https://github.com/coleam00/Archon) | "harness builder" — deterministic, repeatable runtime configurations | **Same L3, neighbor sub-layer.** Archon is a Runtime-Configuration Factory, Harness is a Team-Architecture Factory. Pick Archon for runtime determinism, Harness for team architecture, or combine them. |

| [SaehwanPark/meta-harness](https://github.com/SaehwanPark/meta-harness) | Codex port of the same concept | **Same L3, different runtime.** Use Harness on Claude Code, meta-harness on Codex. |

| [affaan-m/ECC](https://github.com/affaan-m/everything-claude-code) | "Agent harness performance & workflow layer" (sits on top of existing harnesses) | **Different layer.** ECC is a standardization layer across harnesses; Harness is a factory that generates harnesses. Serial combination possible. |

| [wshobson/agents](https://github.com/wshobson/agents) | Subagent / skill catalog (182 agents, 149 skills) | **Factory ↔ parts supply.** wshobson is a catalog to shop from; Harness designs the team. Absorb wshobson entries as parts inside a Harness-generated team. |

| [LangGraph](https://langchain-ai.github.io/langgraph/) | State-graph orchestration, LLM-agnostic | **Different track.** LangGraph is for long-running, state-recoverable orchestration; Harness is for fast Claude-Code-native team design. |

## Built with Harness

### Harness 100

**[revfactory/harness-100](https://github.com/revfactory/harness-100)** — 100 production-ready agent team harnesses across 10 domains, available in both English and Korean (200 packages total). Each harness ships with 4-5 specialist agents, an orchestrator skill, and domain-specific skills — all generated by this plugin. 1,808 markdown files covering content creation, software development, data/AI, business strategy, education, legal, health, and more.

### Research: A/B Testing Harness Effectiveness

**[revfactory/claude-code-harness](https://github.com/revfactory/claude-code-harness)** — A controlled experiment across 15 software engineering tasks measuring the impact of structured pre-configuration on LLM code agent output quality.

| Metric | Without Harness | With Harness | Improvement |

|--------|:-:|:-:|:-:|

| Average Quality Score | 49.5 | 79.3 | **+60%** |

| Win Rate | — | — | **100%** (15/15) |

| Output Variance | — | — | **-32%** |

Key finding: effectiveness scales with task complexity — the harder the task, the greater the improvement (+23.8 Basic, +29.6 Advanced, +36.2 Expert).

**Exact phrasing to use everywhere:** +60% avg quality (49.5 → 79.3), 15/15 win-rate, −32% variance (n=15, author-measured A/B, third-party replications pending).

> Full paper: *Hwang, M. (2026). Harness: Structured Pre-Configuration for Enhancing LLM Code Agent Output Quality.*

## Requirements

- [Agent Teams enabled](https://code.claude.com/docs/en/agent-teams): `CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1`

## FAQ

Q1. Isn't "+60%" oversold?

**A.** The +60% figure comes from an **author-measured A/B (n=15, 15 tasks, measured on the sister repo `claude-code-harness`)**. Every citation in this repo pairs the number with the disclosure "n=15, author-measured, third-party replications pending" in the same sentence. For adoption decisions, we recommend running a 2–4 week internal pilot and measuring your own numbers.

**Evidence:**

- Author A/B: [revfactory/claude-code-harness](https://github.com/revfactory/claude-code-harness)

- Paper: *Hwang, M. (2026). Harness: Structured Pre-Configuration for Enhancing LLM Code Agent Output Quality*

Q2. Why "harness factory" and not "harness builder"? Isn't this competing with Archon?

**A.** Archon generates deterministic runtime configurations — it's a **Runtime-Configuration Factory**. Harness generates agent team architectures (team structure, message protocols, review gates) — it's a **Team-Architecture Factory**. They are **neighbor sub-layers of the same L3 Meta-Factory** and serve different needs. Pick Archon for runtime determinism, Harness for team-architecture patterns, or combine them (design architecture with Harness → deploy runtime with Archon).

**Evidence:**

- Archon self-definition: [clawfit docs/reference-levels.md](https://github.com/hongsw/clawfit/blob/main/docs/reference-levels.md)

- Sub-layer declaration: see the **Category — Where Harness Sits** section above

- Archon repo: [github.com/coleam00/Archon](https://github.com/coleam00/Archon)

Q3. Isn't "Claude Code only" too narrow? What about Gemini/Codex?

**A.** Currently the official runtime is Claude Code only. A Codex port of the same concept — [SaehwanPark/meta-harness](https://github.com/SaehwanPark/meta-harness) — is already public, so Codex teams can start there. Harness chose "Claude-Code-native, deep" over "multi-runtime, shallow"; cross-runtime collaboration with sibling repos (meta-harness, harness-init, OpenRig) is on the roadmap.

**Evidence:**

- Codex port: [github.com/SaehwanPark/meta-harness](https://github.com/SaehwanPark/meta-harness)

- Cross-runtime scaffolder: [github.com/Gizele1/harness-init](https://github.com/Gizele1/harness-init)

## License

Apache 2.0