stylex

What changed / motivation ? JS arithmetic on / token references inside silently produced broken CSS ( → , → ). This PR compiles arithmetic to CSS instead — without violating the "transforming a file must not read other files" constraint: the emitted expression is built from the same hash-derived strings as today, and values are substituted by the existing CSS aggregation step. → (→ for consts) → → Works for , (incl. sibling refs), and mixed expressions Everything that can't map to is now a compile-time error. Breaking change ⚠️ Comparisons on token refs (e.g. ) previously evaluated silently (string comparison, usually picking the wrong branch) and now fail the build with an actionable error. Null/undefined guards are exempt and keep working. Linked PR/Issues Fixes #1597 Additional Context Screenshots, Tests, Anything Else Pre-flight checklist [ ] I have read the contributing guidelines Contribution Guidelines [ ] Performed a self-review of my code

Creating a place to centralize our broader plans for 2026, consolidate open ideas and discussions, and taskify progress towards v1.0.0. See also (https://github.com/facebook/stylex/discussions/1355) Conveniences One of the common complaints about StyleX is that it leans verbose certain use cases. These are ideas to address that. [ ] #1357 [x] #1359 [x] https://github.com/facebook/stylex/issues/1395 [x] #1423 Features [x] #1358 [ ] #1232 [ ] #1174 [x] #1363 [x] #1365 [ ] #1366 Website + docs Most of the docs need an overhaul, and the examples should be updated to use the unplugin whenever possible, or require a general update (as with NextJS). Doc improvements are especially important to support LLM readiness. [x] #732 [x] #1361 [ ] #1256 [ ] Documentation improvements: [ ] https://github.com/facebook/stylex/issues/1061 [x] https://github.com/facebook/stylex/issues/1364 CSS bundling improvements Improvements and optimizations to CSS bundling and build process [ ] https://github.com/facebook/stylex/issues/717 [ ] CSS normalization (dedupe rules, group at-rules) (nice to have) [ ] #1482 [ ] Baseline CSS resets and overrides Dev tools [ ] https://github.com/facebook/stylex/pull/1401 (and possibly VS Code extension) [ ] ESLint improvements (valid-styles, sort keys, stylelint integration) [ ] https://github.com/facebook/stylex/issues/1203 [x] https://github.com/facebook/stylex/issues/787 [ ] Library codemods for migration from other frameworks React Strict DOM [ ] Native polyfills (via RSD) [ ] APIs [ ] inline styles functions [ ] if we decide to bring it back

What changed / motivation ? This PR adds an exported configuration to . This enables users of the new ESLint Flat Config system (ESLint 9+) to set up StyleX rules easily using . Previously, users had to manually register the plugin and enable every rule. This change aligns StyleX with standard ESLint plugin patterns like or . Linked PR/Issues Fixes #1632 Additional Context The configuration automatically handles the plugin registration under the namespace and enables the following core rules: : : : : : Screenshots, Tests, Anything Else Changes: Modified to export a object. Updated Flow type definitions to support the new exports. Tests: Verified that the plugin correctly exports the object. Confirmed the configuration structure is compatible with ESLint Flat Config. Pre-flight checklist [x] I have read the contributing guidelines