How the Metapowers plugin system works — domains, skills, quality gates, and the marketplace.

Domain-as-Plugin Architecture

Metapowers organizes work into domains — self-contained plugins that each implement a methodology for a specific discipline. Each domain plugin lives under plugins/<domain>/ and contains:

plugins/design/
  .claude-plugin/
    plugin.json        # Plugin manifest
  skills/              # Slash command implementations
    empathize/SKILL.md
    define/SKILL.md
    ...
  hooks/               # Quality gate enforcement
    hooks.json
    phase-gate.sh
    phase-deps.json
  shared/              # Shared resources (templates, criteria)
    component-contract-template.md
    wcag-criteria.md
  .mcp.json            # MCP server configuration

Each skill is a Markdown file (SKILL.md) with YAML frontmatter and structured instructions. When you run a slash command like /design:empathize button, your AI coding assistant loads the corresponding skill file and follows its instructions.

Skills define:

Description — what the skill does (used for matching)
Prerequisites — what artifacts must exist before running
Process — step-by-step instructions for Claude to follow
Output — what artifacts to create and where to save them

The MCP Server

The design plugin uses a custom MCP server (@metapowers/figma-mcp) that provides 45 tools for Figma integration. The server communicates with Figma through two channels:

Figma REST API — for reading design data:

Design tokens, variables, and styles
Component metadata and node trees
Image exports (PNG, SVG, JPG, PDF)

Desktop Bridge Plugin — for write operations:

Creating and modifying nodes (frames, components, text, shapes)
FigJam content (stickies, connectors, tables)
Slides management (create, edit, transitions)
Runs inside Figma Desktop, connected via WebSocket

See the MCP Server documentation for setup and tool reference.

Quality Gates

Three layers of quality enforcement:

Soft Gates (Prerequisites)

Each skill checks for prerequisite artifacts at the start of execution. If missing, it warns you but allows proceeding with --skip-checks.

Hard Gates (Hooks)

A PreToolUse hook, hooks/phase-gate.sh, blocks writing a phase artifact until the prerequisites its skill declares exist, driven by each plugin's generated hooks/phase-deps.json. Design also runs a Figma-specific gate that blocks Figma writes until a component contract exists; that gate has no --skip-checks path, only METAPOWERS_SKIP_CHECKS=1 bypasses it. Bypass a single write with --skip-checks (logged to skip-log.md), or disable gating globally with METAPOWERS_SKIP_CHECKS=1.

Evals (on demand)

Each plugin carries a claude plugin eval suite under plugins/<plugin>/evals/. bun run evals runs every case with and without the plugin and reports whether the skill fired and how much its output improves on the baseline. Evals spend Claude credits, so they run on demand rather than in CI; see How Skills Are Tested.

The Marketplace

The marketplace manifest (.claude-plugin/marketplace.json) registers all available plugins. When users install metapowers, they get access to every published domain plugin.

Monorepo Structure

metapowers/
  packages/
    skill-validator/    # Validates SKILL.md format
    plugin-tools/       # Plugin consistency checks and fixers
    figma-mcp/          # Custom Figma MCP server (45 tools)
  plugins/
    design/             # First domain plugin
  apps/
    docs/               # This documentation site

Built with Turborepo + Bun. Packages are internal utilities; plugins are the user-facing product.

Architecture Overview