repo-cover

Your repo's social preview, designed like a magazine masthead, written by your coding agent as one self-contained HTML file.

Every link to your repo on X, Slack, or Discord shows a card. Right now yours is either GitHub's auto-generated default or a generator template that looks like everyone else's. This skill has your agent design the card instead, with real typographic hierarchy, an accent color taken from your language, and deterministic checks that keep the model honest.

한국어 | 日本語 | 简体中文

Install

# Agent Skills CLI (Claude Code, Codex, Cursor, opencode, ...)
npx skills add sjh9714/repo-cover

# Claude Code plugin marketplace
/plugin marketplace add sjh9714/repo-cover
/plugin install repo-cover@repo-cover

# Codex
codex plugin marketplace add sjh9714/repo-cover
codex plugin add repo-cover@repo-cover

# Pi
pi install https://github.com/sjh9714/repo-cover

Then, in your repo:

Make a social preview card for this repo.

The agent gathers the facts, rewrites your description into one tight line, writes <repo>-cover.html, checks it, and exports a 1280x640 PNG you upload under Settings → Social preview.

Four moods

Every example is a live page in the gallery. Click through and view source.

editorial (default). Warm paper, a Fraunces wordmark, arcs from the corner
poster. A deep field mixed from your language color, your first letter as a cropped watermark
blueprint. Navy grid, mono type, corner ticks, a plate number derived from your repo name
gallery. A museum wall label. Pure white, centered, light serif

No two cards match. The accent comes from your primary language, the arcs and plate numbers are seeded by your repo name, and the poster watermark is your own letterform.

What it enforces

The model does not freestyle. The skill pins:

• a 4px grid for every coordinate and size
• one accent per card, auto-darkened until it passes WCAG contrast
• title size tiers by name length (132px down to 64px, two lines past 26 chars)
• a 110-character description budget (60 for CJK), two lines max
• no shadows, no gradients, no glassmorphism, no emoji
• star counts off by default, since they go stale and embarrass young repos

scripts/check_card.py verifies it all deterministically. It checks canvas size, self-containment, contrast ratios, CJK line-breaking, and downscale legibility at X's 506px card width. FAILs get repaired, twice, then reported honestly.

CJK is first-class

Korean gets word-break:keep-all, a +1px optical bump, and Noto Sans KR instead of a tofu fallback. Japanese and Chinese swap in Noto Sans JP/SC with their own line-breaking rules. See references/cjk.md.

Keep it fresh

The card is a static file by design. The bundled composite Action re-renders it in CI so the PNG never ships with fallback fonts, and can run on a schedule if your description changes often:

- uses: sjh9714/repo-cover@main
  with:
    card: assets/my-repo-cover.html
    output: cover.png

When not to use this

• You want diagrams or charts. Use a diagram skill.
• You want a logo or mascot. Use an image-generation skill.
• Your repo is private and nothing ever links to it. The default card is fine, save the tokens.

License

MIT