Writing Guidelines

Writing Guidelines

Review or write files for compliance with Writing Guidelines: the upstream Vercel ruleset, plus this repo's house style additions below. The house style section is a local repo patch that npx skills update can overwrite; re-apply it after updates and recompute the skill hash.

How It Works

1. Fetch the latest guidelines from the source URL below
2. Read the specified files (or prompt user for files/pattern)
3. Check against all rules in the fetched guidelines, plus the cva house style below
4. Output findings in the terse file:line format (review mode) or apply the rules directly (writing mode)

Guidelines Source

Fetch fresh guidelines before each review:

https://raw.githubusercontent.com/vercel-labs/writing-guidelines/main/command.md

Use WebFetch to retrieve the latest rules. The fetched content contains all the rules and output format instructions. If the fetch fails, fall back to the cva house style below.

Usage

Reviewing (a user provides a file or pattern argument, or asks for a docs/prose review):

1. Fetch guidelines from the source URL above
2. Read the specified files
3. Apply all rules from the fetched guidelines, then the house style rules below (house style wins on conflict)
4. Output findings using the fetched guidelines' format

If no files are specified, ask the user which files to review.

Writing (creating or editing content under docs/src/content/docs/): apply both rule sets as you write, don't wait to be asked for a review pass afterwards.

cva house style

These extend or override the fetched guidelines for this repo specifically. They come from lessons learned auditing and rewriting the docs corpus.

• Voice: sentence-case headings, active voice, front-loaded intros, no filler words ("just"/"simply"/"really" as minimizers), lists introduced with a colon. Exception: the FAQs and What's New pages carry a deliberate personal, informal author voice (asides, mild profanity, jokes). Don't flatten it to neutral documentation tone; only fix mechanics (headings, dashes, factual errors) around it. If genuinely unsure whether a line is voice vs. sloppiness, ask rather than rewrite.
• Spelling: US English throughout (favor, behavior, while; not favour, behaviour, whilst).
• Punctuation: no em dash or en dash as punctuation anywhere in prose or list items. Rephrase with a colon, comma, period, or parentheses instead. Straight quotes ('/") in source are fine and expected; don't "fix" them to curly quotes. Astro's markdown.smartypants already renders them curly in the built HTML, so a source-level change would be redundant.
• Frontmatter: every page requires a one-line, front-loaded description:. Starlight's schema enforces this at build time in docs/src/content.config.ts. No page may omit it.
• Code examples with // => output comments: never hand-write or hand-derive the output string. Build the relevant package (pnpm --filter cva build or pnpm --filter class-variance-authority build) and execute the example verbatim against the built dist/index.mjs (a throwaway Node script in the scratchpad works well) to get the real string, then paste it in verbatim. Stale or wrong output comments are a high-value docs bug; don't reintroduce them.
• Beta vs. stable: docs/src/content/docs/beta/** is a starlight-versions snapshot of the beta docs, not a live mirror. Editing a stable page never updates its beta counterpart or vice versa. Every fix that applies to both needs two explicit edits. Stable pages import cva from "class-variance-authority" and call it with the two-argument form (cva(base, options)); beta pages import from "cva" and use the single-object form (cva({ base, ...options })). Don't mix them up when writing or copying examples between the two trees.
• Navigation vs. in-page casing: sidebar/nav labels (docs/astro.config.ts, docs/src/content/versions/beta.json) stay Title Case as navigation proper nouns; in-page ##/### headings use sentence case. Proper nouns (Tailwind CSS, TypeScript, React, BEM, 11ty, YouTube) keep their normal casing in either context.
• Markdown source formatting: never hard-wrap prose. Use one line per paragraph in the source and let the editor soft-wrap (see the repo-wide rule in AGENTS.md).