Create Goose Graphics Format

Authors a new graphics format and publishes it to the central Gooseworks library via npx gooseworks formats publish. The output is a working directory with a gooseworks-format.json manifest plus at least one rendered example PNG paired with an existing style.

When to use this skill

Use when the user wants a new named format with its own content rules — a story cover, a podcast cover, a square testimonial — that maps to one of the seven built-in canvas sizes (carousel, infographic, slides, poster, story, chart, tweet). The new format defines new rules and a new slug; it inherits dimensions from one of those canvases.

Custom canvas dimensions are not supported. If the user wants a canvas size that isn't in the seven built-ins (e.g. LinkedIn banner 1584×396, US Letter 2550×3300), tell them honestly — that requires a code change to the goose-graphics skill pack's FORMAT_CONFIGS and is out of scope for this skill. Suggest the closest existing canvas instead.

Always check first: run npx gooseworks formats list (or formats search "banner" etc.) to see whether a community-published format already covers the use case. If one fits, just use it via the regular goose-graphics flow.

Prerequisites

• The goose-graphics skill must be installed in the same workspace — this skill uses goose-graphics/screenshot/screenshot.js to render examples and pulls style specs via npx gooseworks styles get <slug>. Install via:

  npx gooseworks install --claude --with goose-graphics
  

  (Swap --claude for --cursor or --codex as needed.) See the install page on the hub for the canonical command: https://skills.gooseworks.ai/skills/goose-graphics
• The screenshot tool's dependencies must be installed (goose-graphics/screenshot/node_modules/ must exist). If not:

  cd <path-to>/goose-graphics/screenshot && npm install && npx playwright install chromium
  

• The user must be signed in to gooseworks (npx gooseworks login) for publish to authenticate.

Inputs

• A brief describing the canvas: dimensions, intended use (platform / surface), and content density rules.
• Optional: a reference image showing the desired layout.

Outputs (in a working directory)

<working-dir>/
  gooseworks-format.json    # manifest (see "Manifest format" below)
  example-1.png             # at least one rendered example (REQUIRED)
  example-2.png             # optional; recommend 2–3 examples across styles
  example-3.png

The backend rejects publish with an empty examples array — at least one rendered example is mandatory.

Workflow

Step 1 — Pick a canvas (from the fixed allow-list) and confirm intent

A new format is a new slug + new content rules over one of the seven built-in canvas sizes — not a new canvas. Custom dimensions are not supported: every renderer in the system (CLI screenshot tool, hub, other agents) is locked to this allow-list, and creating a format with custom width/height would produce something nobody can render.

Pick the canvas the new format should use:

Then ask the user:

• Which canvas best fits the use case? (Pick from the table above.)
• What is this format for? (Surface, platform, audience.)
• What is the maximum content density? (Title length, body length, item counts, whether it's single-panel or multi-panel.)

The new format inherits the canvas's width/height exactly. Set the manifest's width/height fields to the canvas's dimensions verbatim (e.g. 1080/1350 for a poster-canvas format). Do not invent new dimensions — the publish step will reject anything that doesn't match one of the seven canvases.

If the user wants a canvas that isn't in the list (e.g. LinkedIn banner 1584×396), tell them honestly: that's a code change to the goose-graphics skill pack's FORMAT_CONFIGS and is out of scope for this skill. Suggest the closest existing canvas instead.

Step 2 — Pick a name and slug

Suggest 2–3 descriptive names that lead with the platform / surface (e.g., linkedin-banner, story-cover, podcast-cover, event-flyer-letter). Slug must be lowercase-kebab-case ([a-z0-9-]+).

Collision check: run npx gooseworks formats get <slug> — if the catalog returns a hit, the slug is taken. Suggest an alternative.

(The user may omit slug from the manifest; the backend auto-generates one. On 409 the CLI prompts you to accept the server's suggested slug; pass --yes at publish time to auto-accept.)

Step 3 — Draft contentRulesMd

This is the load-bearing field — it teaches future agents how to fill the canvas. Cover, in this order:

• When to use this format vs the alternatives. One or two sentences.
• Maximum content density. Exact limits: title word count, body word count, number of items / panels / slides, whether images are required or optional.
• Per-section content rules. Header, body, CTA, footer — what goes where, what shape, what size. If the format is single-panel, list the elements (title, hero, byline, etc.) and their max sizes.
• Typography signals. Recommended display font sizes and hierarchy at this canvas size (e.g., "Display hero ~140–180px on a 1584×396 banner").
• Spacing and rhythm. Padding, margins, vertical rhythm.

Aim for at least 50 chars (the minimum) but 300–800 chars is the sweet spot. Treat contentRulesMd as the spec a fresh agent would read to render this format correctly without further guidance.

Step 4 — Render at least one example

Pair the new format with an existing published style. Recommended: render 2–3 examples across different styles so the catalog tile demonstrates the format's flexibility.

For each example:

1. Pick a style: npx gooseworks styles list | head and choose 2–3 with contrasting moods (e.g., matt-gray, neon-dashboard, brutalist).
2. Fetch its slim spec: npx gooseworks styles get <slug>.
3. Generate HTML at the exact target dimensions, using the chosen style's palette, fonts, and signature visual moves. The HTML rules from the goose-graphics rendering pipeline apply:
   • Self-contained single HTML file with inline <style> block + Google Fonts <link>.
   • Fixed pixel sizes only — no vw/vh/%/rem/em/clamp().
   • Outer dimensions match exactly: html, body { width: <W>px; height: <H>px; overflow: hidden; }.
4. Render via the screenshot tool from the goose-graphics skill pack, passing the canvas slug (carousel/infographic/slides/poster/story/ chart/tweet — the one chosen in Step 1), not the new format's slug:

   node <path-to>/goose-graphics/screenshot/screenshot.js \
     --format <canvas-slug> \
     --input <path-to-html> \
     --output <working-dir>/example-N.png \
     --font-delay 1500
   

   This works out of the box — the new format inherits the canvas's dimensions, so no code changes are needed anywhere.

Step 5 — Write gooseworks-format.json

Match the shape documented in goose-graphics/SKILL.md §17.2. Required:

{
  "name": "Story Cover",
  "slug": "story-cover",
  "description": "1080×1920 vertical cover slide for Instagram and TikTok stories. Single hero panel, 5-word title max, optional brand mark in the lower 10%. Use for produ