Anvil

Scaffold, validate, test, and review Claude Code plugins — all locally, all in one tool.

Anvil is the official plugin development toolkit for the heurema ecosystem. It gives plugin authors three commands that cover the complete plugin lifecycle: scaffold a new plugin from heurema-standard templates, run six sequential validators to catch schema errors, missing files, and unsafe hook scripts before you publish, and execute fixture-driven hook tests to verify runtime behaviour. A built-in code-review agent applies a 21-item quality checklist and returns an explicit APPROVE or REQUEST CHANGES verdict. Everything runs locally — no network, no credentials.

$ /anvil:new my-plugin
$ /anvil:check ./my-plugin
$ /anvil:test  ./my-plugin

Quick Start

Install via Emporium (recommended)

claude plugin marketplace add heurema/emporium   # once
claude plugin install anvil@emporium

Manual install

git clone https://github.com/heurema/anvil.git ~/.claude/plugins/anvil

Then enable in ~/.claude/settings.json:

{
  "enabledPlugins": {
    "anvil@local": true
  }
}

Verify: ls ~/.claude/plugins/anvil/commands/ should show new.md, check.md, and test.md. Open a new Claude Code session to activate.

First use

# Scaffold a new plugin interactively
/anvil:new my-plugin

# Then validate and test before committing
/anvil:check ./my-plugin
/anvil:test  ./my-plugin

Key Features

• Scaffolding — /anvil:new generates a complete, conventions-compliant plugin skeleton (plugin.json, README, LICENSE, CHANGELOG, .gitignore) from maintained templates; optionally initialises a git repo and creates a GitHub repository under the heurema org.
• Six-layer validation — /anvil:check runs schema, structure, hooks, conventions, consistency, and install-docs validators in sequence and returns a single PASS/FAIL verdict with a JSON-aggregated report.
• Fixture-driven hook testing — /anvil:test executes scripts/test_hooks.py against your hook scripts and checks skill descriptions for presence, voice, length, and keywords.
• AI code review — The anvil-reviewer agent (sonnet, read-only) applies a 21-item checklist and gives an unambiguous APPROVE or REQUEST CHANGES verdict.
• Zero network dependency — all validation and scaffolding is local; the optional gh repo create step is explicit and opt-in.

Privacy & Data

Anvil makes no network calls during validation or scaffolding. No plugin files, metadata, or diagnostic output leave your machine. The optional GitHub repository creation step in /anvil:new uses your local gh CLI and is gated behind an explicit confirmation prompt.

Requirements

• Claude Code with plugin support
• Python 3.14+ (for validator scripts and test framework)
• jq (for hook validators)
• gh CLI — optional, only needed if you want /anvil:new to create a GitHub repository

Documentation

• How it works — architecture, components, data flow, trust boundaries, limitations
• Reference — command usage, scenarios, configuration, output format, troubleshooting

See Also

Other heurema projects:

• sigil — risk-adaptive development pipeline with adversarial consensus code review
• herald — daily curated news digest plugin for Claude Code
• teams-field-guide — comprehensive guide to Claude Code multi-agent teams
• arbiter — multi-AI orchestrator (Codex + Gemini)

License

MIT