[eslint-plugin] Add shorthand expansion for logical borders, overflow, inset, place-*, flexFlow, columns, listStyle, caret, textDecoration

[abhakat]

Adds shorthand expansion autofixers to stylex-valid-shorthands for 15+ CSS shorthand properties that were previously unsupported. Each shorthand follows the same createSpecificTransformer pattern used by existing handlers (border, gap, flex, animation, etc.).

What changed / motivation ?

The stylex-valid-shorthands rule already auto-fixed border, borderTop/Right/Bottom/Left, margin, padding, flex, gap, animation, font, outline, background, and grid properties. This PR extends coverage to the remaining common shorthands:

Logical border shorthands:

• borderInlineEnd, borderInlineStart, borderBlockEnd, borderBlockStart → Width/Style/Color longhands
• borderInline, borderBlock → Width/Style/Color longhands
• borderInlineColor/Style/Width, borderBlockColor/Style/Width → Start/End longhands

Layout shorthands:

• overflow: 'hidden scroll' → overflowX: 'hidden' + overflowY: 'scroll'
• overscrollBehavior: 'contain auto' → overscrollBehaviorX + overscrollBehaviorY
• inset: '0 10px' → insetBlock + insetInline (2-value); top/right/bottom/left (3-4 value)
• insetBlock/insetInline → Start/End longhands
• placeContent: 'center space-between' → alignContent + justifyContent
• placeItems/placeSelf → align/justify longhands
• flexFlow: 'row wrap' → flexDirection + flexWrap (with token validation)

Other shorthands:

• columnRule: '1px solid red' → columnRuleWidth + columnRuleStyle + columnRuleColor
• columns: '200px 3' → columnWidth + columnCount (with integer/length disambiguation)
• listStyle: 'disc inside url(bullet.png)' → listStyleType + listStylePosition + listStyleImage
• caret: 'red bar' → caretColor + caretShape
• textDecoration: 'underline solid red 2px' → textDecorationLine + textDecorationStyle + textDecorationColor + textDecorationThickness

All handlers:

• Pass through single-value properties unchanged (no false positives)
• Return CANNOT_FIX for ambiguous/unparseable values (commas, slashes, too many tokens)
• Propagate !important when allowImportant is enabled
• Are fully tested with valid (passthrough) and invalid (expansion + CANNOT_FIX) cases

Linked PR/Issues

Follow-up to #1553, #1552, #1538, #1537

Additional Context

Tests: npx jest --watchman=false stylex-valid-shorthands-test.js — all 569 tests pass.

Files changed: 3

• src/stylex-valid-shorthands.js — register new shorthands in shorthandAliases
• src/utils/splitShorthands.js — expansion logic for each shorthand
• __tests__/stylex-valid-shorthands-test.js — ~1250 new lines of test coverage

Pre-flight checklist

• I have read the contributing guidelines
  Contribution Guidelines
• Performed a self-review of my code

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
stylex	Skipped		Apr 6, 2026 6:06pm

[github-actions]

workflow: benchmarks/perf

Comparison of performance test results, measured in operations per second. Larger is better.
yarn workspace v1.22.22
yarn run v1.22.22
$ node ./compare.js /tmp/tmp.iBxnw0oXCh /tmp/tmp.ydGnTQKfHM

Results	Base	Patch	Ratio
babel-plugin: stylex.create
· basic create	539	552	1.02	+
· complex create	63	66	1.05	+
babel-plugin: stylex.createTheme
· basic themes	428	435	1.02	+
· complex themes	34	34	1.00
Done in 0.08s.
Done in 0.32s.

[github-actions]

workflow: benchmarks/size

Comparison of minified (terser) and compressed (brotli) size results, measured in bytes. Smaller is better.
yarn workspace v1.22.22
yarn run v1.22.22
$ node ./compare.js /tmp/tmp.vaxbEBXnRV /tmp/tmp.zujWEiYE7I

Results	Base	Patch	Ratio
@stylexjs/stylex/lib/cjs/stylex.js
· compressed	1,441	1,441	1.00
· minified	4,386	4,386	1.00
@stylexjs/stylex/lib/cjs/inject.js
· compressed	1,793	1,793	1.00
· minified	4,915	4,915	1.00
benchmarks/size/.build/bundle.js
· compressed	496,650	496,650	1.00
· minified	4,847,840	4,847,840	1.00
benchmarks/size/.build/stylex.css
· compressed	99,653	99,653	1.00
· minified	747,850	747,850	1.00
Done in 0.08s.
Done in 0.35s.