fix(css): track dependencies from addWatchFile for HMR (#15608)

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

@@ -237,7 +237,6 @@ const cssUrlAssetRE = /__VITE_CSS_URL__([\da-f]+)__/g
  */
 export function cssPlugin(config: ResolvedConfig): Plugin {
   const isBuild = config.command === 'build'
-  let server: ViteDevServer
   let moduleCache: Map<string, Record<string, string>>
 
   const resolveUrl = config.createResolver({
@@ -254,10 +253,6 @@ export function cssPlugin(config: ResolvedConfig): Plugin {
   return {
     name: 'vite:css',
 
-    configureServer(_server) {
-      server = _server
-    },
-
     buildStart() {
       // Ensure a new cache for every build (i.e. rebuilding in watch mode)
       moduleCache = new Map<string, Record<string, string>>()
@@ -292,16 +287,14 @@ export function cssPlugin(config: ResolvedConfig): Plugin {
       }
     },
 
-    async transform(raw, id, options) {
+    async transform(raw, id) {
       if (
         !isCSSRequest(id) ||
         commonjsProxyRE.test(id) ||
         SPECIAL_QUERY_RE.test(id)
       ) {
         return
       }
-      const ssr = options?.ssr === true
-
       const urlReplacer: CssUrlReplacer = async (url, importer) => {
         const decodedUrl = decodeURI(url)
         if (checkPublicFile(decodedUrl, config)) {
@@ -345,60 +338,12 @@ export function cssPlugin(config: ResolvedConfig): Plugin {
         moduleCache.set(id, modules)
       }
 
-      // track deps for build watch mode
-      if (config.command === 'build' && config.build.watch && deps) {
+      if (deps) {
         for (const file of deps) {
           this.addWatchFile(file)
         }
       }
 
-      // dev
-      if (server) {
-        // server only logic for handling CSS @import dependency hmr
-        const { moduleGraph } = server
-        const thisModule = moduleGraph.getModuleById(id)
-        if (thisModule) {
-          // CSS modules cannot self-accept since it exports values
-          const isSelfAccepting =
-            !modules && !inlineRE.test(id) && !htmlProxyRE.test(id)
-          if (deps) {
-            // record deps in the module graph so edits to @import css can trigger
-            // main import to hot update
-            const depModules = new Set<string | ModuleNode>()
-            const devBase = config.base
-            for (const file of deps) {
-              depModules.add(
-                isCSSRequest(file)
-                  ? moduleGraph.createFileOnlyEntry(file)
-                  : await moduleGraph.ensureEntryFromUrl(
-                      stripBase(
-                        await fileToUrl(file, config, this),
-                        (config.server?.origin ?? '') + devBase,
-                      ),
-                      ssr,
-                    ),
-              )
-            }
-            moduleGraph.updateModuleInfo(
-              thisModule,
-              depModules,
-              null,
-              // The root CSS proxy module is self-accepting and should not
-              // have an explicit accept list
-              new Set(),
-              null,
-              isSelfAccepting,
-              ssr,
-            )
-            for (const file of deps) {
-              this.addWatchFile(file)
-            }
-          } else {
-            thisModule.isSelfAccepting = isSelfAccepting
-          }
-        }
-      }
-
       return {
         code: css,
         map,
@@ -945,6 +890,78 @@ export function cssPostPlugin(config: ResolvedConfig): Plugin {
   }
 }
 
+export function cssAnalysisPlugin(config: ResolvedConfig): Plugin {
+  let server: ViteDevServer
+
+  return {
+    name: 'vite:css-analysis',
+
+    configureServer(_server) {
+      server = _server
+    },
+
+    async transform(_, id, options) {
+      if (
+        !isCSSRequest(id) ||
+        commonjsProxyRE.test(id) ||
+        SPECIAL_QUERY_RE.test(id)
+      ) {
+        return
+      }
+
+      const ssr = options?.ssr === true
+      const { moduleGraph } = server
+      const thisModule = moduleGraph.getModuleById(id)
+
+      // Handle CSS @import dependency HMR and other added modules via this.addWatchFile.
+      // JS-related HMR is handled in the import-analysis plugin.
+      if (thisModule) {
+        // CSS modules cannot self-accept since it exports values
+        const isSelfAccepting =
+          !cssModulesCache.get(config)?.get(id) &&
+          !inlineRE.test(id) &&
+          !htmlProxyRE.test(id)
+        // attached by pluginContainer.addWatchFile
+        const pluginImports = (this as any)._addedImports as
+          | Set<string>
+          | undefined
+        if (pluginImports) {
+          // record deps in the module graph so edits to @import css can trigger
+          // main import to hot update
+          const depModules = new Set<string | ModuleNode>()
+          const devBase = config.base
+          for (const file of pluginImports) {
+            depModules.add(
+              isCSSRequest(file)
+                ? moduleGraph.createFileOnlyEntry(file)
+                : await moduleGraph.ensureEntryFromUrl(
+                    stripBase(
+                      await fileToUrl(file, config, this),
+                      (config.server?.origin ?? '') + devBase,
+                    ),
+                    ssr,
+                  ),
+            )
+          }
+          moduleGraph.updateModuleInfo(
+            thisModule,
+            depModules,
+            null,
+            // The root CSS proxy module is self-accepting and should not
+            // have an explicit accept list
+            new Set(),
+            null,
+            isSelfAccepting,
+            ssr,
+          )
+        } else {
+          thisModule.isSelfAccepting = isSelfAccepting
+        }
+      }
+    },
+  }
+}
+
 /**
  * Create a replacer function that takes code and replaces given pure CSS chunk imports
  * @param pureCssChunkNames The chunks that only contain pure CSS and should be replaced

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

@@ -744,7 +744,7 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
       }
 
       // update the module graph for HMR analysis.
-      // node CSS imports does its own graph update in the css plugin so we
+      // node CSS imports does its own graph update in the css-analysis plugin so we
       // only handle js graph updates here.
       if (!isCSSRequest(importer)) {
         // attached by pluginContainer.addWatchFile

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

@@ -12,7 +12,7 @@ import { resolvePlugin } from './resolve'
 import { optimizedDepsPlugin } from './optimizedDeps'
 import { esbuildPlugin } from './esbuild'
 import { importAnalysisPlugin } from './importAnalysis'
-import { cssPlugin, cssPostPlugin } from './css'
+import { cssAnalysisPlugin, cssPlugin, cssPostPlugin } from './css'
 import { assetPlugin } from './asset'
 import { clientInjectionsPlugin } from './clientInjections'
 import { buildHtmlPlugin, htmlInlineProxyPlugin } from './html'
@@ -101,7 +101,11 @@ export async function resolvePlugins(
     // internal server-only plugins are always applied after everything else
     ...(isBuild
       ? []
-      : [clientInjectionsPlugin(config), importAnalysisPlugin(config)]),
+      : [
+          clientInjectionsPlugin(config),
+          cssAnalysisPlugin(config),
+          importAnalysisPlugin(config),
+        ]),
   ].filter(Boolean) as Plugin[]
 }
 

playground/hmr/__tests__/hmr.spec.ts

@@ -5,6 +5,7 @@ import {
   browserLogs,
   editFile,
   getBg,
+  getColor,
   isBuild,
   page,
   removeFile,
@@ -919,4 +920,11 @@ if (import.meta.hot) {
     )
     await untilUpdated(() => el.evaluate((it) => `${it.clientHeight}`), '40')
   })
+
+  test('CSS HMR with this.addWatchFile', async () => {
+    await page.goto(viteTestUrl + '/css-deps/index.html')
+    expect(await getColor('.css-deps')).toMatch('red')
+    editFile('css-deps/dep.js', (code) => code.replace(`red`, `green`))
+    await untilUpdated(() => getColor('.css-deps'), 'green')
+  })
 }

playground/hmr/css-deps/dep.js

@@ -0,0 +1,8 @@
+// This file is depended by main.css via this.addWatchFile
+export const color = 'red'
+
+// Self-accept so that updating this file would not trigger a page reload.
+// We only want to observe main.css updating itself.
+if (import.meta.hot) {
+  import.meta.hot.accept()
+}

playground/hmr/css-deps/index.html

@@ -0,0 +1,8 @@
+<div class="css-deps">should be red</div>
+
+<script type="module">
+  import './main.css'
+  // Import dep.js so that not only the CSS depends on dep.js, as Vite will do
+  // a full page reload if the only importers are CSS files.
+  import './dep.js'
+</script>

playground/hmr/css-deps/main.css

@@ -0,0 +1,3 @@
+.css-deps {
+  color: replaced;
+}

playground/hmr/vite.config.ts

@@ -1,3 +1,5 @@
+import fs from 'node:fs/promises'
+import path from 'node:path'
 import { defineConfig } from 'vite'
 import type { Plugin } from 'vite'
 
@@ -24,6 +26,7 @@ export default defineConfig({
     },
     virtualPlugin(),
     transformCountPlugin(),
+    watchCssDepsPlugin(),
   ],
 })
 
@@ -66,3 +69,20 @@ function transformCountPlugin(): Plugin {
     },
   }
 }
+
+function watchCssDepsPlugin(): Plugin {
+  return {
+    name: 'watch-css-deps',
+    async transform(code, id) {
+      // replace the `replaced` identifier in the CSS file with the adjacent
+      // `dep.js` file's `color` variable.
+      if (id.includes('css-deps/main.css')) {
+        const depPath = path.resolve(__dirname, './css-deps/dep.js')
+        const dep = await fs.readFile(depPath, 'utf-8')
+        const color = dep.match(/color = '(.+?)'/)[1]
+        this.addWatchFile(depPath)
+        return code.replace('replaced', color)
+      }
+    },
+  }
+}