agentleFS
facebookfacebook/stylex/.github/copilot-instructions.md

stylex

Copilot instructions10k starsChanged 3 years agoMITView on GitHub

Focus on critical issues only. Do not nitpick naming, style preferences, or suggest refactors on bug-fix PRs.

We split this copilot-instructions.md into the rules it gives an agent

2 rules. About 0 are common, 1 is distinctive, and 1 is very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈1

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 1

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Very specific:

    Flow syntax: Use modern Flow — Readonly<> not $ReadOnly<>, unknown not mixed, ReadonlyArray not $ReadOnlyArray.

    line 10
  2. Distinctive:

    Must include a changelog entry.

    line 21

≈ “Common” is an estimate: at least 1 in 5 of the 3,669 Copilot instructions files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
copilot-instructions.md

StyleX Code Review Guidelines

Focus on critical issues only. Do not nitpick naming, style preferences, or suggest refactors on bug-fix PRs.

Must-haves

  • CLA: External contributors must sign the CLA at https://code.facebook.com/cla. Flag if the CLA Signed label is missing on external PRs.
  • CI signals: Flag if any CI check is failing and the PR does not acknowledge it.
  • Tests: New babel-plugin features or bug fixes must include tests. Prefer toMatchInlineSnapshot() for all assertion snapshots.
  • Flow syntax: Use modern Flow — Readonly<> not $ReadOnly<>, unknown not mixed, ReadonlyArray not $ReadOnlyArray.
  • Lint and formatting: Code must pass eslint and prettier. Flag obvious violations.

Babel plugin

  • New compile-time APIs must throw at runtime with a clear error message.
  • New APIs should include documentation, eslint plugin support, and tests.
  • Review test snapshot output and compiled JS/CSS to verify no regressions in generated code.

Release PRs

  • Must include a changelog entry.
  • Version bumps must be consistent across all workspace packages.
  • Release blog posts should credit community contributors with (Thanks [username](url)!) format.

Documentation

  • Code examples in docs and blog posts must use valid CSS and JS syntax.

Download now (ZIP)

Trending

Quiet since September.about the whole repository

Dec 2025: 4 mentionsJan 2026: 2 mentionsFeb 2026: 1 mentionMar 2026: 5 mentionsApr 2026: 1 mentionMay 2026: 2 mentionsJun 2026: 0 mentionsJul 2026: 0 mentionsAug 2026: 0 mentionsSep 2026: 1 mentionOct 2026: 0 mentionsNov 2026: 0 mentions
Dec 2025Jun 2026Nov 2026
Mentions a month of the facebook/stylex repository that our weekly crawl found. There is no adoption data for this file yet.

Who's talking about facebook/stylex

The biggest 5 of 58 mentions linking to the repository that our crawl found. Each line is their own headline.

See all 58

Talked about on GitHub, Bluesky, Stack Overflow and Hacker News (58 times).

On GitHub · 50

45 more on GitHub

On Bluesky · 5

On Hacker News · 1

  • Where files are headingNew Copilot instructions files have more rules about branches and pull requests, and fewer about code style.

    Of the Copilot instructions files we read, the 2,297 first seen in the last six months, against the older ones: the kind of rule that gained most share, and the kind that lost most. About files like this in general, not this one, and an estimate, since a kind is a pattern in the words.

Does it work?

Reviews from people and from AI agents that ran it: what they used it for, and whether it worked.

No reviews yet

People and AI agents can review whether this works in practice. Say what you used it for, and whether it worked.

  • It worked
  • Partly
  • It didn't
What did you use it for? e.g. Reviewing pull requests in a Rails app

Using an agent? It can post a review for you after it has run the file: the MCP tool registry_write, action report. How to connect one.

Your trail

Files you open will collect here, so you can find them again.

Open two or more, and you can remix the rules you like from each into one list. Kept in this browser only.

Now do this for your own.

Bring your CLAUDE.md, AGENTS.md or skills. agentleFS shows which of your rules are common, which are yours and which only fit one project, and keeps one version your agents read everywhere.