fix(hmr): register inlined assets as a dependency of CSS file

packages/vite/src/node/plugins/css.ts

@@ -373,20 +373,20 @@ export function cssPlugin(config: ResolvedConfig): Plugin {
       const resolveUrl = (url: string, importer?: string) =>
         idResolver(environment, url, importer)
 
-      const urlReplacer: CssUrlReplacer = async (url, importer) => {
+      const urlResolver: CssUrlResolver = async (url, importer) => {
         const decodedUrl = decodeURI(url)
         if (checkPublicFile(decodedUrl, config)) {
           if (encodePublicUrlsInCSS(config)) {
-            return publicFileToBuiltUrl(decodedUrl, config)
+            return [publicFileToBuiltUrl(decodedUrl, config), undefined]
           } else {
-            return joinUrlSegments(config.base, decodedUrl)
+            return [joinUrlSegments(config.base, decodedUrl), undefined]
           }
         }
         const [id, fragment] = decodedUrl.split('#')
         let resolved = await resolveUrl(id, importer)
         if (resolved) {
           if (fragment) resolved += '#' + fragment
-          return fileToUrl(this, resolved)
+          return [await fileToUrl(this, resolved), resolved]
         }
         if (config.command === 'build') {
           const isExternal = config.build.rollupOptions.external
@@ -405,7 +405,7 @@ export function cssPlugin(config: ResolvedConfig): Plugin {
             )
           }
         }
-        return url
+        return [url, undefined]
       }
 
       const {
@@ -418,7 +418,7 @@ export function cssPlugin(config: ResolvedConfig): Plugin {
         id,
         raw,
         preprocessorWorkerController!,
-        urlReplacer,
+        urlResolver,
       )
       if (modules) {
         moduleCache.set(id, modules)
@@ -1058,17 +1058,20 @@ export function cssAnalysisPlugin(config: ResolvedConfig): Plugin {
           // main import to hot update
           const depModules = new Set<string | EnvironmentModuleNode>()
           for (const file of pluginImports) {
-            depModules.add(
-              isCSSRequest(file)
-                ? moduleGraph.createFileOnlyEntry(file)
-                : await moduleGraph.ensureEntryFromUrl(
-                    await fileToDevUrl(
-                      this.environment,
-                      file,
-                      /* skipBase */ true,
-                    ),
-                  ),
-            )
+            if (isCSSRequest(file)) {
+              depModules.add(moduleGraph.createFileOnlyEntry(file))
+            } else {
+              const url = await fileToDevUrl(
+                this.environment,
+                file,
+                /* skipBase */ true,
+              )
+              if (url.startsWith('data:')) {
+                depModules.add(moduleGraph.createFileOnlyEntry(file))
+              } else {
+                depModules.add(await moduleGraph.ensureEntryFromUrl(url))
+              }
+            }
           }
           moduleGraph.updateModuleInfo(
             thisModule,
@@ -1267,7 +1270,7 @@ async function compileCSS(
   id: string,
   code: string,
   workerController: PreprocessorWorkerController,
-  urlReplacer?: CssUrlReplacer,
+  urlResolver?: CssUrlResolver,
 ): Promise<{
   code: string
   map?: SourceMapInput
@@ -1277,7 +1280,7 @@ async function compileCSS(
 }> {
   const { config } = environment
   if (config.css.transformer === 'lightningcss') {
-    return compileLightningCSS(id, code, environment, urlReplacer)
+    return compileLightningCSS(id, code, environment, urlResolver)
   }
 
   const { modules: modulesOptions, devSourcemap } = config.css
@@ -1386,10 +1389,11 @@ async function compileCSS(
     )
   }
 
-  if (urlReplacer) {
+  if (urlResolver) {
     postcssPlugins.push(
       UrlRewritePostcssPlugin({
-        replacer: urlReplacer,
+        resolver: urlResolver,
+        deps,
         logger: environment.logger,
       }),
     )
@@ -1723,6 +1727,12 @@ async function resolvePostcssConfig(
   return result
 }
 
+type CssUrlResolver = (
+  url: string,
+  importer?: string,
+) =>
+  | [url: string, id: string | undefined]
+  | Promise<[url: string, id: string | undefined]>
 type CssUrlReplacer = (
   url: string,
   importer?: string,
@@ -1739,7 +1749,8 @@ export const importCssRE =
 const cssImageSetRE = /(?<=image-set\()((?:[\w-]{1,256}\([^)]*\)|[^)])*)(?=\))/
 
 const UrlRewritePostcssPlugin: PostCSS.PluginCreator<{
-  replacer: CssUrlReplacer
+  resolver: CssUrlResolver
+  deps: Set<string>
   logger: Logger
 }> = (opts) => {
   if (!opts) {
@@ -1763,8 +1774,13 @@ const UrlRewritePostcssPlugin: PostCSS.PluginCreator<{
         const isCssUrl = cssUrlRE.test(declaration.value)
         const isCssImageSet = cssImageSetRE.test(declaration.value)
         if (isCssUrl || isCssImageSet) {
-          const replacerForDeclaration = (rawUrl: string) => {
-            return opts.replacer(rawUrl, importer)
+          const replacerForDeclaration = async (rawUrl: string) => {
+            const [newUrl, resolvedId] = await opts.resolver(rawUrl, importer)
+            // only register inlined assets to avoid frequent full refresh (#18979)
+            if (newUrl.startsWith('data:') && resolvedId) {
+              opts.deps.add(resolvedId)
+            }
+            return newUrl
           }
           if (isCssUrl && isCssImageSet) {
             promises.push(
@@ -3135,7 +3151,7 @@ async function compileLightningCSS(
   id: string,
   src: string,
   environment: PartialEnvironment,
-  urlReplacer?: CssUrlReplacer,
+  urlResolver?: CssUrlResolver,
 ): ReturnType<typeof compileCSS> {
   const { config } = environment
   const deps = new Set<string>()
@@ -3221,11 +3237,15 @@ async function compileLightningCSS(
           css = css.replace(dep.placeholder, () => dep.url)
           break
         }
-        if (urlReplacer) {
-          const replaceUrl = await urlReplacer(
+        if (urlResolver) {
+          const [replaceUrl, resolvedId] = await urlResolver(
             dep.url,
             toAbsolute(dep.loc.filePath),
           )
+          // only register inlined assets to avoid frequent full refresh (#18979)
+          if (replaceUrl.startsWith('data:') && resolvedId) {
+            deps.add(resolvedId)
+          }
           css = css.replace(dep.placeholder, () => replaceUrl)
         } else {
           css = css.replace(dep.placeholder, () => dep.url)

packages/vite/src/node/server/hmr.ts

@@ -789,6 +789,9 @@ function propagateUpdate(
     // PostCSS plugins) it should be considered a dead end and force full reload.
     if (
       !isCSSRequest(node.url) &&
+      // we assume .svg is never an entrypoint and does not need a full reload
+      // to avoid frequent full reloads when an SVG file is referenced in CSS files (#18979)
+      !node.file?.endsWith('.svg') &&
       [...node.importers].every((i) => isCSSRequest(i.url))
     ) {
       return true

playground/assets/__tests__/assets.spec.ts

@@ -287,12 +287,36 @@ describe('css url() references', () => {
   })
 
   test('url() with svg', async () => {
-    expect(await getBg('.css-url-svg')).toMatch(/data:image\/svg\+xml,.+/)
+    const bg = await getBg('.css-url-svg')
+    expect(bg).toMatch(/data:image\/svg\+xml,.+/)
+    expect(bg).toContain('blue')
+    expect(bg).not.toContain('red')
+
+    if (isServe) {
+      editFile('nested/fragment-bg-hmr.svg', (code) =>
+        code.replace('fill="blue"', 'fill="red"'),
+      )
+      await untilUpdated(() => getBg('.css-url-svg'), 'red')
+    }
   })
 
   test('image-set() with svg', async () => {
     expect(await getBg('.css-image-set-svg')).toMatch(/data:image\/svg\+xml,.+/)
   })
+
+  test('url() with svg in .css?url', async () => {
+    const bg = await getBg('.css-url-svg-in-url')
+    expect(bg).toMatch(/data:image\/svg\+xml,.+/)
+    expect(bg).toContain('blue')
+    expect(bg).not.toContain('red')
+
+    if (isServe) {
+      editFile('nested/fragment-bg-hmr2.svg', (code) =>
+        code.replace('fill="blue"', 'fill="red"'),
+      )
+      await untilUpdated(() => getBg('.css-url-svg'), 'red')
+    }
+  })
 })
 
 describe('image', () => {
@@ -546,8 +570,8 @@ test.runIf(isBuild)('manifest', async () => {
 
   for (const file of listAssets('foo')) {
     if (file.endsWith('.css')) {
-      // ignore icons-*.css as it's imported with ?url
-      if (file.includes('icons-')) continue
+      // ignore icons-*.css and css-url-url-*.css as it's imported with ?url
+      if (file.includes('icons-') || file.includes('css-url-url-')) continue
       expect(entry.css).toContain(`assets/${file}`)
     } else if (!file.endsWith('.js')) {
       expect(entry.assets).toContain(`assets/${file}`)

playground/assets/css/css-url-url.css

@@ -0,0 +1,4 @@
+.css-url-svg-in-url {
+  background: url(../nested/fragment-bg-hmr2.svg);
+  background-size: 10px;
+}

playground/assets/index.html

@@ -148,6 +148,9 @@ <h2>CSS url references</h2>
 <div class="css-url-svg">
   <span style="background: #fff">CSS SVG background</span>
 </div>
+<div class="css-url-svg-in-url">
+  <span style="background: #fff">CSS (?url) SVG background</span>
+</div>
 
 <div class="css-image-set-svg">
   <span style="background: #fff">CSS SVG background with image-set</span>
@@ -528,6 +531,12 @@ <h3>assets in template</h3>
   import cssUrl from './css/icons.css?url'
   text('.url-css', cssUrl)
 
+  import cssUrlUrl from './css/css-url-url.css?url'
+  const linkTag = document.createElement('link')
+  linkTag.href = cssUrlUrl
+  linkTag.rel = 'stylesheet'
+  document.body.appendChild(linkTag)
+
   // const url = new URL('non_existent_file.png', import.meta.url)
   const metaUrl = new URL('./nested/asset.png', import.meta.url)
   text('.import-meta-url', metaUrl)