Antigravity CLI Harness

A meta-skill that turns a one-line domain description into a working multi-agent team for the Antigravity CLI.

Quick start

1. Install the harness plugin

Choose the scope that fits your workflow:

• Global install — available in every Antigravity CLI session:

  git clone https://github.com/Kyeong1024/antigravity-cli-harness
  agy plugin install antigravity-cli-harness

• Workspace install — scoped to a single project. Clone the plugin into .agents/plugins/harness-plugin in the project root:

  git clone https://github.com/Kyeong1024/antigravity-cli-harness .agents/plugins/harness-plugin

Workspace definitions take precedence over global ones, so you can iterate on a project-specific harness without touching the global install.

2. Launch Antigravity CLI and request a harness

agy
> Build me a harness for {your-domain}.

The harness skill auto-triggers and walks you through scaffolding the team — subagents, skills, orchestrator, and the AGENTS.md trigger entry.

What it does

Tell the harness "build me a harness for X" and it scaffolds, in one go:

• A plugin under .agents/plugins/{domain}-plugin/
• A team of subagents (agents/{name}/agent.json), each with a defined role, tool set, and system prompt
• A set of skills (skills/{name}/SKILL.md) those agents use to do their work
• An orchestrator skill that wires the team into a workflow with explicit data-passing and error-handling rules
• A pointer entry in AGENTS.md so future sessions auto-trigger the harness

The result is a reusable, evolvable team architecture — not a one-shot script.

Why a harness?

Single-agent prompts hit a ceiling once a task crosses multiple specializations (e.g. analysis → build → QA). A harness solves this by:

1. Splitting expertise into focused subagents, each with its own context window.
2. Standardizing collaboration through a file-based workspace (_workspace/) and an orchestrator.
3. Surviving across sessions — definitions live on disk, so the team is reproducible and improvable over time.

Generated structure

.agents/
└── plugins/
    └── {domain}-plugin/
        ├── plugin.json
        ├── agents/
        │   └── {agent-name}/
        │       └── agent.json          # subagent definition
        └── skills/
            ├── {orchestrator}/
            │   └── SKILL.md            # workflow that wires the team
            └── {skill-name}/
                ├── SKILL.md            # how a single capability works
                └── rules/              # progressively-loaded references
AGENTS.md                               # trigger pointer + change log

Architectural patterns

The harness picks one of six team patterns based on the domain:

Pattern	When to use
Pipeline	Sequential, dependent steps
Fan-out / Fan-in	Independent work done in parallel
Expert Pool	Conditional routing to specialists
Producer–Reviewer	Generate then QA in a loop
Supervisor	Central agent manages state and dispatch
Hierarchical Delegation	Recursive sub-delegation

Execution modes

Mode	When
Subagent (default)	≥2 specializations collaborating; each runs in an isolated context via invoke_subagent
Parallel subagent	Independent work to run concurrently
Direct execution	Simple, one-shot tasks where agent separation is overhead

Workflow

The meta-skill runs through seven phases:

0. Audit — detect existing plugins, decide new build vs. extension vs. maintenance.
1. Domain analysis — identify task types, codebase, user skill level.
2. Team architecture — choose execution mode + pattern, split work into specializations.
3. Subagent definitions — write each agent.json with role, tools, and I/O protocol.
4. Skill creation — write SKILL.md files with pushy, trigger-friendly descriptions and progressive disclosure into rules/.
5. Orchestration — wire the team with file-based data passing, error handling, and follow-up support.
6. Validation — structure checks, trigger checks (should-trigger + near-miss), dry-run.
7. Evolution — collect feedback after each run; update agents/skills and log changes in AGENTS.md.

Installation

Drop the .agents/plugins/harness-plugin/ directory into any Antigravity CLI project. The harness skill auto-triggers on requests like:

• "build a harness for {domain}"
• "set up a harness", "design a harness"
• "audit / sync the harness", "harness status"

Usage

In an Antigravity CLI session:

> Build a harness for a content marketing pipeline.

The skill will:

1. Audit any existing .agents/plugins/ and AGENTS.md.
2. Propose a team (e.g. researcher → writer → editor → QA) and confirm with you.
3. Generate the plugin, write agent.json/SKILL.md files, and register the trigger in AGENTS.md.
4. Run validation and report.

Follow-up turns ("redo the analyst step", "add a security reviewer", "harness audit") are handled by the same skill in extension / maintenance mode.

References

The skill ships with internal guides under .agents/plugins/harness-plugin/skills/harness/rules/:

• agent-design-patterns.md — pattern catalog, separation criteria
• team-examples.md — full example team definitions
• orchestrator-template.md — orchestrator skeleton with error handling
• skill-writing-guide.md — SKILL.md authoring patterns
• skill-testing-guide.md — trigger and execution testing methodology
• qa-agent-guide.md — designing QA subagents

Acknowledgements

Ported from revfactory/harness, with rework for Antigravity CLI's plugin and subagent model.