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wp-build: Hash transformed CSS for data-wp-hash dedupe key #76743

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Merged
mirka merged 3 commits into from
Mar 23, 2026
Merged

wp-build: Hash transformed CSS for data-wp-hash dedupe key #76743

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2432daf
wp-build: Salt data-wp-hash to avoid cross-pipeline CSS module collis…
mirka Mar 20, 2026
bc51e9f
Add changelog
mirka Mar 21, 2026
8e9abfb
Hash the transformed CSS instead of using a salt
mirka Mar 23, 2026
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4 changes: 4 additions & 0 deletions packages/wp-build/CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,10 @@

## Unreleased

### Bug Fixes

- Derive `data-wp-hash` from the transformed CSS instead of the raw source to prevent style mismatches when multiple build pipelines process the same source file ([#76743](https://github.com/WordPress/gutenberg/pull/76743)).

## 0.10.0 (2026-03-18)

### Breaking Changes
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13 changes: 7 additions & 6 deletions packages/wp-build/lib/build.mjs
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Expand Up @@ -182,12 +182,6 @@ function getSassOptions( workingDir ) {

function compileInlineStyle( { cssModules = false, minify = true } = {} ) {
return async function styleType( cssText, _dirname, filePath ) {
// Always hash the untransformed code.
const hash = createHash( 'sha1' )
.update( cssText )
.digest( 'hex' )
.slice( 0, 10 );

let moduleExports = null;

// Transform the code: token fallbacks, CSS modules and minification.
Expand All @@ -214,6 +208,13 @@ function compileInlineStyle( { cssModules = false, minify = true } = {} ) {
map: false,
} );

// Hash the transformed CSS so that the dedup key reflects the actual
// injected content, including mangled CSS module class names.
const hash = createHash( 'sha1' )
.update( css )
.digest( 'hex' )
.slice( 0, 10 );

let cssModule = `if (typeof document !== 'undefined' && process.env.NODE_ENV !== 'test' && !document.head.querySelector("style[data-wp-hash='${ hash }']")) {
const style = document.createElement("style");
style.setAttribute("data-wp-hash", "${ hash }");
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