nexu-io__open-design/docs/skills-protocol.md

Skills Protocol

Parent: spec.md · Siblings: skills-contributing.md · architecture.md · agent-adapters.md · modes.md

Want to ship a skill upstream rather than read the protocol spec? See skills-contributing.md — quick start, merge bar, PR template, common rejections. This file is the what (frontmatter grammar, discovery rules, mode semantics); that file is the how (clone to merged PR).

A Skill is an atomic functional capability in OD. A design template is a rendering-catalogue entry. Both use Claude Code's SKILL.md convention as their portable instruction format and may add od: metadata, but they have different ownership and APIs: functional skills live in skills/ and /api/skills; rendering templates live in design-templates/ and /api/design-templates.

Compatibility promise: A bundle that contains SKILL.md remains readable by agents that support the Agent Skills format. Installation and catalogue placement are separate concerns: the bundled guizang integration is maintained under design-templates/guizang-ppt/, while external distribution normally uses the plugin system.

---

1. Base format (unchanged from Claude Code)

Every skill is a directory containing at minimum a SKILL.md:

<skill-root>/
├── SKILL.md              # manifest + workflow instructions
├── assets/               # templates, images, boilerplate the skill writes
│   └── …
└── references/           # knowledge files the skill reads during planning
    ├── components.md
    ├── layouts.md
    └── …

SKILL.md front-matter (YAML):

---
name: magazine-web-ppt
zh_name: "杂志风网页 PPT"
en_name: "Magazine Web PPT"
description: |
  Magazine-style horizontal-swipe web deck.
  Trigger keywords: 杂志风 PPT, magazine deck, swipe slides.
zh_description: "杂志风横向翻页网页 PPT。"
en_description: |
  Magazine-style horizontal-swipe web deck.
  Trigger keywords: 杂志风 PPT, magazine deck, swipe slides.
triggers:
  - "magazine deck"
  - "杂志风 PPT"
  - "horizontal swipe presentation"
---

Body is free-form Markdown that describes the workflow the agent should follow — typically a numbered step list plus principles. This is what guizang-ppt-skill does.

OD reads all of this as-is. No changes required.

2. OD extensions (optional)

Skills can declare additional front-matter fields to unlock OD-specific UI. All fields are optional; absent fields fall back to sensible defaults.

---
name: magazine-web-ppt
description: …
triggers: […]

# --- OD extensions below this line ---

od:
  mode: deck                        # prototype | deck | template | design-system | image | video | audio
  surface: web                      # web | image | video | audio
  scenario: marketing               # gallery/filter hint
  category: presentations           # free-form lowercase filter slug
  preview:
    type: html                      # registry preview hint
  example_prompt: "Create a magazine-style web deck from my content."
  example_prompt_i18n:
    zh-CN: "用杂志风网页 PPT 模板把我的内容做成横向翻页 deck。"
  design_system:
    requires: true                  # compose the complete active design-system context
  craft:                            # universal, brand-agnostic craft references
    requires: [typography, color, anti-ai-slop]
  critique:
    policy: opt-in                  # required | opt-in | opt-out
---

2.1 What OD uses each field for

Field	Used by
zh_name / en_name	localized picker title; falls back to name
zh_description / en_description	localized picker description; falls back to description
od.mode	registry classification and creation-surface filtering
od.surface	web/image/video/audio surface filtering; defaults from media mode or to web
od.platform	optional desktop/mobile gallery hint
od.scenario / od.category	scenario and category filter hints
od.preview.type	picking the right iframe renderer
od.example_prompt	English fallback starter prompt used by picker CTA
od.example_prompt_i18n	localized starter prompt map (for example zh-CN)
od.design_system.requires	whether to compose the active design-system package into the prompt
od.craft.requires	which brand-agnostic craft/<slug>.md references to inject between design-system context and the skill body
od.default_for, od.featured	creation defaults and gallery ordering hints
od.fidelity, od.speaker_notes, od.animations	optional fast-create defaults for matching template kinds
od.critique.policy	per-skill Critique Theater override (required, opt-in, or opt-out)

Older bundles may also carry fields such as od.inputs, od.parameters, od.outputs, or od.capabilities_required. The skill registry preserves the portable SKILL.md body but does not use those fields to render forms, sliders, choose output files, or gate an agent. The Agent-Skill-to-plugin adapter can translate or retain some of that metadata; plugin behavior is specified in plugins-spec.md, not by this registry protocol.

2.2 If a skill omits od: entirely

Defaults:

• mode: inferred from description and body, falling back to prototype
• surface: the media mode for image/video/audio entries, otherwise web
• preview.type: html
• design_system.requires: true; author false explicitly for bundles that must not receive brand context
• example_prompt: the first sentence of description, capped for the picker
• scenario: inferred from description/body, falling back to general

The goal: zero-config compatibility for existing Claude Code skills.

3. Skill discovery & precedence

The daemon keeps functional skills and rendering templates in separate registries:

Registry	Roots, highest priority first	API
Functional skills	user-managed skills, then bundled skills/	/api/skills
Design templates	user-managed templates, then bundled design-templates/	/api/design-templates

The user-managed roots derive from the resolved daemon data root; this file intentionally does not restate a concrete path. A duplicate frontmatter name in the first root shadows the bundled entry without deleting it. Each listing request rescans its roots, so local changes appear without a watcher, SIGHUP, or daemon restart. Chat-time lookup spans both registries so projects saved against a design-template id continue to compose its instructions.

Runtime resource staging

OpenDesign does not distribute an active bundle by symlinking it into every agent's global configuration. Before a project run, the daemon makes a real copy of every active skill/template with side files under the project's .od-skills/ alias. The prompt preamble advertises that CWD-relative copy and an absolute fallback. This keeps references and assets reachable across agents, including filesystems where symlink or cross-device rename semantics differ. A local library installation may itself be represented by a managed link, but that storage detail is separate from per-run staging.

4. Registry modes

The daemon normalizes od.mode to one of seven values. These values classify both functional skills and design-template bundles; they are not the same thing as the six New Project tabs described in modes.md.

4.1 prototype

• Purpose: single-screen interactive prototype.
• Preview: html or jsx.
• Primary output: index.html or Prototype.jsx.
• Typical workflow: clarify brief → resolve design tokens → write component tree → write file.
• Example templates: interface and responsive-flow bundles under design-templates/.

4.2 deck

• Purpose: multi-slide presentation.
• Preview: html (single-file deck with in-page navigation).
• Primary output: index.html.
• Secondary output: slides.json (for PPTX export).
• Typical workflow: clarify topic + slide count → pick theme → populate slides from layout catalog → self-check against quality rubric.
• Reference implementation: the bundled design-templates/guizang-ppt/ integration.

4.3 template

• Purpose: start from a pre-built artifact; agent only personalizes content, doesn't design from scratch.
• Preview: inherits from the template bundle (html typically).
• Primary output: a populated copy of the template.
• Typical workflow: copy assets/template/ to artifact dir → replace content placeholders → optionally tweak tokens to match design system.
• Why separate from prototype: it starts from a pre-built shape rather than a blank artifact.

4.4 design-system

• Purpose: classify a functional workflow that creates, extracts, audits, or transforms design-system material.
• Output: defined by the skill. A portable workflow may emit only DESIGN.md; current OpenDesign import/create flows build a package with manifest.json, DESIGN.md, tokens.css, and optional rich resources.
• Schema: no fixed nine headings. Repository packages require substantive coverage and keep prose synchronized with the token contract; see design-systems/README.md.

4.5 image, video, and audio

• Purpose: classify media-generation instruction bundles for the Media creation surface.
• Surface: defaults to the matching media kind unless od.surface overrides it.
• Inputs: provider/model controls and media-specific metadata are owned by the Media UI and shared contracts.
• Design system: media bundles normally opt out because prompt templates, rather than interface tokens, drive these provider-backed generations.

5. The DESIGN.md as skill context

Any bundle may declare whether it consumes the active design system. Interface, deck, and template bundles commonly opt in; media bundles commonly opt out. When enabled, the daemon composes the available package material directly into the system prompt, in this order:

1. package-specific USAGE.md guidance (or the default usage contract);
2. the complete DESIGN.md body;
3. import-mode guidance, when declared;
4. tokens.css;
5. a compact component manifest, or components.html when no manifest can be produced;
6. a manifest-derived index of rich files that the agent may pull on demand;
7. craft references; then
8. the active skill/template body.

Design systems are not copied into the run CWD, section-pruned through od.design_system.sections, or substituted through a {{ design_system }} variable. Missing rich files preserve compatibility with legacy DESIGN.md-only folders. The historical nine-heading upstream sample remains useful as an interoperability example at docs/examples/DESIGN.sample.md, but it is not the current repository package schema.

5.5 Craft references (craft/)

Some craft knowledge is universal — true regardless of brand. ALL CAPS always needs ≥0.06em letter-spacing; var(--accent) should appear at most 2 times per screen; #6366f1 is always the AI-default tell. These rules don't belong in any one DESIGN.md because they apply across every brand.

OD ships these as a separate packaged resource tree:

craft/
├── README.md
├── accessibility-baseline.md
├── animation-discipline.md
├── anti-ai-slop.md
├── color.md
├── form-validation.md
├── laws-of-ux.md
├── rtl-and-bidi.md
├── state-coverage.md
├── typography.md
├── typography-hierarchy.md
└── typography-hierarchy-editorial.md

A skill opts in by listing the slugs it needs:

od:
  craft:
    requires: [typography, color, anti-ai-slop]

Resolution at compose time:

1. apps/daemon/src/skills.ts reads od.craft.requires from front-matter and surfaces it on the skill record.
2. apps/daemon/src/craft.ts reads each <slug>.md from CRAFT_DIR. Runtime loading remains tolerant of absent files for compatibility.
3. apps/daemon/src/prompts/system.ts injects the concatenated craft body between the active DESIGN.md and the skill body. Brand tokens in DESIGN.md win on conflict; craft rules cover everything DESIGN.md does not override.

Repository authoring is stricter than runtime loading: pnpm lint:craft and pnpm guard reject invalid or unresolved references unless the slug is explicitly listed in craft/FUTURE_SECTIONS.md. See craft/README.md for the canonical list.

The split keeps DESIGN.md authors free of universal-craft duplication and keeps craft authors free of brand-specific drift.

6. Skill inspection and distribution

od skills list
# → id and display label for entries returned by /api/skills

od skills show <id>
# → the daemon's JSON representation of one skill

od skill install github:owner/repo
od skill install https://example.com/my-skill.tar.gz
# → installs one public skill bundle through POST /api/skills/install

Remote skill import accepts the same source grammar as Plugin URL import: github:owner/repo or a public HTTPS .tar.gz / .tgz archive containing one top-level SKILL.md. Downloads are size-capped and reject private-network targets, path traversal, symbolic/hard links, malformed manifests, and duplicate skill ids. An intentional replacement is explicit: uninstall the existing user skill first, then install the new bundle. od skills remains the compatibility alias for list/show/install/uninstall. Repository-owned functional skills and rendering templates still live under skills/ and design-templates/ respectively. Do not document a concrete daemon-managed install path here; the root AGENTS.md Daemon data directory contract is the only path authority.

7. Worked example — running the bundled guizang deck template

The upstream-inspired bundle ships at design-templates/guizang-ppt/ with its license preserved and OpenDesign metadata applied:

1. The daemon lists it through /api/design-templates, independently of the functional /api/skills registry.
2. The user opens the Deck creation tab and selects the guizang template from the rendering catalogue.
3. OpenDesign stores the selected template id as the project's primary skillId. The daemon's combined skill-like resolver loads that template's SKILL.md and resources; it does not also inject the Deck tab's default functional skill.
4. The agent follows the template workflow, writes the deck files into the project workspace, and performs its checklist before final handoff.
5. File writes stream into the UI, index.html becomes previewable, and the deck export surfaces consume the produced project files.

The protocol intentionally does not define the workspace's concrete path; read the root AGENTS.md Daemon data directory contract before changing or documenting artifact storage.

8. Writing a rendering template — minimal example

design-templates/saas-landing/
├── SKILL.md
└── assets/
    └── base.html

---
name: saas-landing
description: |
  Produce a single-page SaaS landing with hero, features, social proof, pricing, CTA.
  Trigger: "saas landing", "marketing page", "product landing".
triggers:
  - "saas landing"
  - "marketing page"
od:
  mode: prototype
  surface: web
  scenario: marketing
  preview:
    type: html
  design_system:
    requires: true
  craft:
    requires: [typography, color, anti-ai-slop, accessibility-baseline]
---

# Workflow

1. Apply the active design-system context supplied above this skill.
2. Copy `.od-skills/saas-landing/assets/base.html` to `index.html` in the project workspace.
3. Fill sections: hero, features (3–6), social proof, pricing, CTA, footer.
4. Inline all CSS. Use system font stack as fallback if DESIGN.md typography fails to load.
5. Write `index.html`. Done.

9. Testing skills

There is no od skills test command and no runtime contract for a tests/basic.prompt tree. Repository-owned entries are checked by the root guard, localized-content coverage, registry tests, and any focused tests for their assets or prompt behavior. Run at least pnpm guard and pnpm typecheck, plus the package-scoped checks appropriate to the files changed. Plugin bundles have their own validation and doctor surfaces.

10. Open questions

• Skill provenance. URL-imported functional skills do not yet persist their source after installation; richer provenance, integrity pinning, and trust UI should reuse the plugin model instead of growing a second incompatible one.
• Skill composition. Can a prototype-mode instruction bundle invoke a deck-mode bundle for a sub-artifact? The current registries treat them as leaf-level inputs; composition requires an explicit orchestration contract.
• Richer skill inputs. Typed apply-time inputs and deferred parameters now belong to the plugin manifest contract. A future skill-native form should reuse that contract rather than reviving a second slider schema.