harness

Sun, 31 May 2026 17:59:30 +0800

revfactory/harness

Harness — The Team-Architecture Factory for Claude Code

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
L3 — Meta-Factory / Codex Runtime Port	Same concept, Codex runtime	SaehwanPark/meta-harness
L2 — Cross-Harness Workflow	Standardize skills/rules/hooks across multiple harnesses	affaan-m/ECC

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

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

`1`	`/plugin marketplace add revfactory/harness`

Install the plugin

`1`	`/plugin install harness@harness-marketplace`

Direct Installation as Global Skill

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# 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:

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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

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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

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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

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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

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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

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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

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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

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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

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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	“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	Codex port of the same concept	Same L3, different runtime. Use Harness on Claude Code, meta-harness on Codex.
affaan-m/ECC	“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	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	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 — 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 — 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: 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
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
Sub-layer declaration: see the Category — Where Harness Sits section above
Archon repo: 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 — 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
Cross-runtime scaffolder: github.com/Gizele1/harness-init

License

Apache 2.0

Harness on Producthunt daily

harness

revfactory/harness

Harness — The Team-Architecture Factory for Claude Code

Overview

Category — Where Harness Sits

Star History

Key Features

Workflow

Installation

Via Marketplace

Add the marketplace

Install the plugin

Direct Installation as Global Skill

Plugin Structure

Usage

Execution Modes

Architecture Patterns

Output

Use Cases — Try These Prompts

Coexistence — Harness and Neighbors

Built with Harness

Harness 100

Research: A/B Testing Harness Effectiveness

Requirements

FAQ

License