fix: avoid deprecated Rollup asset name access (#2453)

packages/wxt/e2e/tests/output-structure.test.ts

@@ -84,6 +84,51 @@ describe('Output Directory Structure', () => {
     `);
   });
 
+  it('should route content script CSS with Rollup strict deprecations enabled', async () => {
+    const project = new TestProject();
+    project.addFile(
+      'entrypoints/content.content/index.ts',
+      `import './style.css';
+      export default defineContentScript({
+        matches: ["*://*/*"],
+        main: () => {},
+      })`,
+    );
+    project.addFile(
+      'entrypoints/content.content/style.css',
+      `body { color: purple }`,
+    );
+
+    await project.build({
+      vite: () => ({
+        build: {
+          rollupOptions: {
+            strictDeprecations: true,
+          },
+        },
+      }),
+    });
+
+    expect(
+      await project.serializeOutput([
+        '.output/chrome-mv3/content-scripts/content.js',
+      ]),
+    ).toMatchInlineSnapshot(`
+      ".output/chrome-mv3/content-scripts/content.css
+      ----------------------------------------
+      body{color:purple}
+
+      ================================================================================
+      .output/chrome-mv3/content-scripts/content.js
+      ----------------------------------------
+      <contents-ignored>
+      ================================================================================
+      .output/chrome-mv3/manifest.json
+      ----------------------------------------
+      {"manifest_version":3,"name":"E2E Extension","description":"Example description","version":"0.0.0","content_scripts":[{"matches":["*://*/*"],"css":["content-scripts/content.css"],"js":["content-scripts/content.js"]}]}"
+    `);
+  });
+
   it('should allow inputs with invalid JS variable names, like dashes', async () => {
     const project = new TestProject();
     project.addFile(

packages/wxt/src/core/builders/vite/index.ts

@@ -29,6 +29,11 @@ import {
 } from '../../utils/virtual-modules';
 import * as wxtPlugins from './plugins';
 
+interface RollupAssetNameInfo {
+  name?: string;
+  names?: string[];
+}
+
 export async function createViteBuilder(
   wxtConfig: ResolvedConfig,
   hooks: Hookable<WxtHooks>,
@@ -166,10 +171,12 @@ export async function createViteBuilder(
             ),
             // Output content script CSS to `content-scripts/`, but all other scripts are written to
             // `assets/`.
-            assetFileNames: ({ name }) => {
+            assetFileNames: (assetInfo) => {
               if (
                 entrypoint.type === 'content-script' &&
-                name?.endsWith('css')
+                getRollupAssetNames(assetInfo).some((name) =>
+                  name.endsWith('css'),
+                )
               ) {
                 return `content-scripts/${entrypoint.name}.[ext]`;
               } else {
@@ -392,6 +399,11 @@ export async function createViteBuilder(
   };
 }
 
+function getRollupAssetNames(assetInfo: RollupAssetNameInfo): string[] {
+  if (Array.isArray(assetInfo.names)) return assetInfo.names;
+  return assetInfo.name ? [assetInfo.name] : [];
+}
+
 function getBuildOutputChunks(
   result: Awaited<ReturnType<typeof vite.build>>,
 ): BuildStepOutput['chunks'] {