Open Design Plugin Spec

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This spec is the compact contract for portable Open Design plugins. The canonical product spec remains docs/plugins-spec.md; this document is optimized for contributors and external coding agents.

1. Minimum Plugin

Every publishable plugin should be a directory with a SKILL.md:

my-plugin/
  SKILL.md

SKILL.md is the portable agent contract. It must have YAML frontmatter with:

---
name: my-plugin
description: Use this plugin when the user wants...
---

The folder name, name, and manifest name should match. Use lowercase letters, numbers, and hyphens.

2. Enriched Open Design Plugin

Add open-design.json when the plugin should appear in Open Design as a marketplace card or starter:

my-plugin/
  SKILL.md
  open-design.json
  README.md
  preview/
  examples/
  assets/
  references/
  evals/

open-design.json points at the skill and declares the product surface:

{
  "$schema": "https://open-design.ai/schemas/plugin.v1.json",
  "specVersion": "1.0.0",
  "name": "my-plugin",
  "title": "My Plugin",
  "version": "0.1.0",
  "description": "One sentence marketplace description.",
  "license": "MIT",
  "tags": ["create", "prototype"],
  "compat": {
    "agentSkills": [{ "path": "./SKILL.md" }]
  },
  "od": {
    "kind": "skill",
    "taskKind": "new-generation",
    "mode": "prototype",
    "scenario": "product",
    "useCase": {
      "query": "Create a prototype for {{audience}} about {{topic}}."
    },
    "pipeline": {
      "stages": [
        { "id": "discovery", "atoms": ["discovery-question-form"] },
        { "id": "plan", "atoms": ["direction-picker", "todo-write"] },
        { "id": "generate", "atoms": ["file-write", "live-artifact"] },
        {
          "id": "critique",
          "atoms": ["critique-theater"],
          "repeat": true,
          "until": "critique.score>=4 || iterations>=3"
        }
      ]
    },
    "inputs": [
      { "name": "audience", "type": "string", "required": true },
      { "name": "topic", "type": "string", "required": true }
    ],
    "capabilities": ["prompt:inject", "fs:write"]
  }
}

3. Workflow Taxonomy

Use one primary lane. Put the lane in tags, od.scenario, or od.mode so search and facets can classify the plugin.

Lane	Use when	Typical taskKind	Useful atoms
import	Bring external sources into OD	figma-migration or code-migration	figma-extract, code-import, design-extract, token-map, rewrite-plan
create	Generate a new artifact	new-generation	discovery-question-form, direction-picker, todo-write, file-write, live-artifact, media-image, media-video, media-audio, critique-theater
export	Convert an accepted artifact to a downstream format	tune-collab or code-migration	file-read, file-write, handoff, diff-review
share	Publish or send an artifact to collaborators	tune-collab	file-read, handoff, connector
deploy	Ship an artifact to hosted infrastructure	code-migration or tune-collab	file-read, build-test, handoff, connector
refine	Improve an existing artifact	tune-collab	file-read, patch-edit, critique-theater, diff-review
extend	Help authors create more plugins	new-generation	file-read, file-write, todo-write, critique-theater

4. Create Modes

Use od.mode for the main output surface:

Mode	Output
prototype	Interactive single-page web artifact
deck	Slide deck artifact
live-artifact	Dashboard, report, calculator, simulator, or other live UI
image	Generated image, storyboard frame, poster, ad, or visual asset
video	Video prompt, storyboard, rendered clip, or motion package
hyperframes	HyperFrames-ready HTML motion composition
audio	Voice, music, sonic branding, or sound-design asset
design-system	Reusable brand or interface system

HyperFrames plugins may use od.mode: "video" plus a hyperframes tag when they should appear beside video tooling, or od.mode: "hyperframes" when the distinction matters more than the broad video bucket.

5. SKILL.md Authoring Rules

• Write the description for activation: "Use this plugin when..."
• Keep SKILL.md under 500 lines when possible.
• Put long API notes, visual rules, or exporter details in references/.
• Reference support files by relative path from the plugin root.
• Include an explicit workflow with checkpoints and expected outputs.
• Describe what to ask the user only when the input is genuinely missing.
• Avoid OD-only marketplace data in SKILL.md; keep it portable.

6. Manifest Rules

• name is the stable plugin id.
• specVersion is the Open Design plugin spec version that this manifest follows. Use the current spec kit value (1.0.0) unless the schema moves.
• version is required. Use semver when possible.
• version is the plugin package version, independent from specVersion.
• compat.agentSkills[0].path should point to ./SKILL.md.
• od.taskKind must be one of new-generation, figma-migration, code-migration, or tune-collab.
• od.pipeline.stages[].atoms[] should use known first-party atoms unless the plugin clearly targets a future OD release.
• A repeated stage must include until.
• od.capabilities should start small. Restricted installs get prompt:inject by default.

Known v1 capabilities:

• prompt:inject
• fs:read
• fs:write
• mcp
• subprocess
• bash
• network
• connector
• connector:<id>

7. Inputs And GenUI

Use od.inputs for simple apply-time values. Use od.genui.surfaces[] when the agent needs controlled human input during a run.

Built-in GenUI surface kinds:

• form
• choice
• confirmation
• oauth-prompt

Persistence options:

• run - only this run.
• conversation - future turns in the same conversation.
• project - future runs in the same project.

8. Examples And Preview

Visual plugins should include one of:

• preview/index.html
• preview/poster.png
• preview/demo.mp4
• examples/<case>/index.html
• examples/<case>/README.md

The preview should show the real output shape, not a decorative splash screen.

9. Evals

Add evals/evals.json for repeatable quality checks:

{
  "skill_name": "my-plugin",
  "evals": [
    {
      "id": "happy-path",
      "prompt": "Create a prototype for a B2B SaaS onboarding flow.",
      "expected_output": "A usable HTML artifact with states, polished layout, and no text overflow.",
      "assertions": [
        "The output includes a runnable artifact file",
        "The visual hierarchy is clear",
        "The workflow has meaningful empty/loading/success states"
      ]
    }
  ]
}

Also add evals/trigger-queries.json for activation testing when the description is easy to over-broaden.

10. Publish And PR

Before opening a PR:

1. Validate JSON syntax.
2. Confirm open-design.json includes specVersion and a bumped plugin version when behavior changed.
3. Run pnpm guard.
4. Run pnpm --filter @open-design/plugin-runtime typecheck.
5. If available, run od plugin validate ./path/to/plugin.
6. Include one screenshot, rendered preview, or example output when the plugin is visual.
7. Explain trust and capabilities in the PR body.

For external registry distribution, follow PUBLISHING-REGISTRIES.md. In short: keep GitHub or the Open Design PR as source of truth, make the folder installable as a generic SKILL.md skill, then publish or list it on skills.sh, ClawHub, or other registries only after local validation passes.