feat(bundler): post-process turbopack output to fix import.meta.url

tools/egg-bundler/src/lib/Bundler.ts

@@ -90,6 +90,12 @@ export class Bundler {
     const packResult = await wrapStep('pack build', () => packRunner.run());
     debug('pack produced %d files', packResult.files.length);
 
+    // turbopack wraps `import.meta` in a throwing getter for bundled ESM
+    // chunks.  Patch the output so `createRequire(import.meta.url)` and
+    // other `import.meta.url` usages work at runtime.
+    const patchCount = await wrapStep('patch import.meta.url', () => this.#patchImportMetaUrl(absOutputDir));
+    debug('patched %d import.meta.url occurrences', patchCount);
+
     // Merge project name into output package.json so the framework's
     // getAppname() finds it (it reads baseDir/package.json).
     const outputPkgPath = path.join(absOutputDir, 'package.json');
@@ -130,4 +136,60 @@ export class Bundler {
       manifestPath: manifestPathAbs,
     };
   }
+
+  /**
+   * Turbopack replaces `import.meta` in bundled ESM chunks with an object
+   * that only defines a throwing `url` getter and omits `dirname`/`filename`.
+   *
+   * We post-process the output .js files in two passes:
+   * 1. Replace the throwing `url` IIFE with a working `file://` URL.
+   * 2. Inject `dirname` and `filename` getters so code like
+   *    `path.join(import.meta.dirname, '../lib/asset.html')` works.
+   */
+  async #patchImportMetaUrl(outputDir: string): Promise<number> {
+    // Pass 1 — fix the throwing url getter.
+    const THROWING_IIFE =
+      /\(\(\)\s*=>\s*\{\s*throw\s+new\s+Error\(\s*['"]could not convert import\.meta\.url to filepath['"]\s*\)\s*;?\s*\}\)\s*\(\)/g;
+    // Avoid require() in the replacement — turbopack modules may declare
+    // `const require = createRequire(import.meta.url)` which would be in
+    // the TDZ when our getter runs.  Use globals only.
+    const URL_EXPR = 'new URL("file:///" + encodeURI(process.argv[1])).href';
+
+    // Pass 2 — add dirname/filename after patching url.
+    // Match the url-only meta object that results from pass 1.
+    const META_URL_ONLY =
+      /var __TURBOPACK__import\$2e\$meta__ = \{\s*get url \(\) \{\s*return new URL\("file:\/\/\/" \+ encodeURI\(process\.argv\[1\]\)\)\.href;\s*\}\s*\};/g;
+    const META_FULL = `var __TURBOPACK__import$2e$meta__ = {
+    get url () {
+        return new URL("file:///" + encodeURI(process.argv[1])).href;
+    },
+    get dirname () {
+        return process.argv[1].replace(/[\\\\/][^\\\\/]*$/, "");
+    },
+    get filename () {
+        return process.argv[1];
+    }
+};`;
+
+    let totalPatches = 0;
+    const entries = await fs.readdir(outputDir);
+    for (const name of entries) {
+      if (!name.endsWith('.js')) continue;
+      const filepath = path.join(outputDir, name);
+      const content = await fs.readFile(filepath, 'utf8');
+
+      // Pass 1
+      const urlMatches = content.match(THROWING_IIFE);
+      if (!urlMatches) continue;
+      let patched = content.replace(THROWING_IIFE, URL_EXPR);
+
+      // Pass 2
+      patched = patched.replace(META_URL_ONLY, META_FULL);
+
+      await fs.writeFile(filepath, patched);
+      totalPatches += urlMatches.length;
+      debug('patched %d import.meta in %s', urlMatches.length, name);
+    }
+    return totalPatches;
+  }
 }