sth-harness

sth-harness

A Claude Code, Codex, Pi, GitHub Copilot CLI, and Google Antigravity CLI plugin/package that installs and drives the model-agnostic ai-harness (spec-driven, hexagonal, stateful, resumable development in folders + Markdown).

ai-harness template version is bundled and pinned see template/VENDOR.md

Commands

Claude Code exposes slash commands:

• /sth-harness:init [feature-name] — copy the harness into this repo, interview to fill context/project.md, then create your first feature's spec.md + state.md.
• /sth-harness:add-spec [feature-name] — in an initialized repo, interview for a new feature and create its files.
• /sth-harness:implement-next-spec — pick the next pending spec (you confirm) and implement it through the harness until blocked, a decision is needed, or it is done.

Codex exposes the sth-harness skill instead of slash commands. Ask Codex to:

• "Initialize this repo with the ai-harness."
• "Add a new ai-harness spec for ."
• "Implement the next pending ai-harness spec."

Pi exposes prompt templates:

• /sth-harness-init [feature-name]
• /sth-harness-add-spec [feature-name]
• /sth-harness-implement-next-spec

GitHub Copilot CLI exposes the sth-harness skill. Ask Copilot CLI to:

• "Initialize this repo with the ai-harness."
• "Add a new ai-harness spec for ."
• "Implement the next pending ai-harness spec."

Google Antigravity CLI (agy) exposes the sth-harness skill. Ask AGY to:

• "Initialize this repo with the ai-harness."
• "Add a new ai-harness spec for ."
• "Implement the next pending ai-harness spec."

What it ships

• template/ai-harness/ — the harness payload, copied verbatim on init.
• scripts/copy-harness.sh — deterministic, no-clobber install.
• scripts/link-codex.sh — idempotent AGENTS.md wiring for Codex.
• scripts/link-pi.sh — idempotent AGENTS.md wiring for Pi.
• scripts/link-copilot-cli.sh — idempotent AGENTS.md wiring for Copilot CLI.
• scripts/link-agy.sh — idempotent AGENTS.md wiring for Google Antigravity CLI.
• skills/ — the interview and implementation logic the commands and skills rely on.
• prompts/ — Pi prompt templates for the three harness workflows.

The copied folder is always named ai-harness/; this plugin is sth-harness.

Install (local dev)

For Claude Code, add this directory as a plugin (plugin marketplace/local path), then run /sth-harness:init in a target repo.

For Codex, install this directory as a local plugin. Codex reads .codex-plugin/plugin.json, loads the bundled skills/, and exposes the sth-harness skill.

For Pi, install this directory as a local package:

pi install /path/to/sth-harness-plugin

Pi reads package.json, loads the bundled skills/ and prompts/, and exposes the namespaced prompt templates above.

For GitHub Copilot CLI, install this directory as a local plugin:

copilot plugin install /path/to/sth-harness-plugin

Copilot CLI reads plugin.json and loads the bundled skills/. Direct local installs are useful for development; Copilot CLI warns that marketplace installs will be the supported path for durable distribution.

For Google Antigravity CLI, install this directory as a local plugin:

agy plugin install /path/to/sth-harness-plugin

Antigravity CLI reads plugin.json, loads the bundled skills/, and converts the bundled commands/ into skills. You can check the package with agy plugin validate /path/to/sth-harness-plugin.