fix(@angular/cli): handle modern yarn registry error output and 404 detection

packages/angular/cli/src/package-managers/package-manager-descriptor.ts

@@ -30,6 +30,7 @@ import {
   parseYarnClassicManifest,
   parseYarnClassicMetadata,
   parseYarnModernDependencies,
+  parseYarnModernError,
   parseYarnReleaseAge,
 } from './parsers';
 
@@ -231,7 +232,7 @@ export const SUPPORTED_PACKAGE_MANAGERS = {
       listDependencies: parseYarnModernDependencies,
       getRegistryManifest: parseNpmLikeManifest,
       getRegistryMetadata: parseNpmLikeMetadata,
-      getError: parseNpmLikeError,
+      getError: parseYarnModernError,
       getReleaseAge: parseYarnReleaseAge,
     },
     isNotFound: isKnownNotFound,

packages/angular/cli/src/package-managers/package-manager_spec.ts

@@ -422,6 +422,23 @@ describe('PackageManager', () => {
 
       expect(await pm.getRegistryMetadata('non-existent')).toBeNull();
     });
+
+    it('should return null when yarn npm info fails with a missing package', async () => {
+      const pm = new PackageManager(host, '/tmp', SUPPORTED_PACKAGE_MANAGERS['yarn']);
+      runCommandSpy.and.rejectWith(
+        new PackageManagerError(
+          'Process exited with code 1.',
+          [
+            '{"type":"error","name":35,"displayName":"YN0035","indent":"","data":"Package not found"}',
+            '{"type":"error","name":35,"displayName":"YN0035","indent":"","data":"  Response Code: 404 (Not Found)"}',
+          ].join('\n'),
+          '',
+          1,
+        ),
+      );
+
+      expect(await pm.getRegistryMetadata('non-existent')).toBeNull();
+    });
   });
 
   describe('getCurrentPackageName', () => {

packages/angular/cli/src/package-managers/parsers.ts

@@ -636,6 +636,62 @@ export function parseYarnClassicError(output: string, logger?: Logger): ErrorInf
   return null;
 }
 
+/**
+ * Parses the `stdout` or `stderr` output of modern yarn (v2+) to extract structured error information.
+ *
+ * Modern yarn reports errors as JSON lines, one per message line. The first line holds the summary,
+ * and registry errors include the HTTP status, which is returned as a standardized error code
+ * (`E${statusCode}`). Other output is delegated to `parseNpmLikeError`.
+ *
+ * Example output (`yarn npm info <missing-package> --json`):
+ * ```json
+ * {"type":"error","name":35,"displayName":"YN0035","indent":"","data":"Package not found"}
+ * {"type":"error","name":35,"displayName":"YN0035","indent":"","data":"  Response Code: 404 (Not Found)"}
+ * ```
+ *
+ * @param output The standard output or standard error of the command.
+ * @param logger An optional logger instance.
+ * @returns An `ErrorInfo` object if parsing is successful, otherwise `null`.
+ */
+export function parseYarnModernError(output: string, logger?: Logger): ErrorInfo | null {
+  logger?.debug(`Parsing modern yarn error output...`);
+  logStdout(output, logger); // Log output for debugging purposes
+
+  if (!output) {
+    logger?.debug('  output is empty. No error found.');
+
+    return null;
+  }
+
+  const messages: { code: string; data: string }[] = [];
+  for (const json of parseJsonLines(output, logger)) {
+    if (json?.type === 'error' && typeof json.data === 'string') {
+      messages.push({ code: String(json.displayName ?? 'UNKNOWN_ERROR'), data: json.data });
+    }
+  }
+
+  if (messages.length === 0) {
+    return parseNpmLikeError(output, logger);
+  }
+
+  const [first, ...rest] = messages;
+  const statusCodeMatch = messages
+    .map(({ data }) => data.match(/Response Code: (\d{3})/))
+    .find((match) => match !== null);
+  const code = statusCodeMatch ? `E${statusCodeMatch[1]}` : first.code;
+  logger?.debug(`  Successfully parsed modern yarn error with code '${code}'.`);
+
+  return {
+    code,
+    summary: first.data.trim(),
+    detail:
+      rest
+        .map(({ data }) => data.trim())
+        .filter(Boolean)
+        .join('\n') || undefined,
+  };
+}
+
 /**
  * Known Bun JSON error messages that indicate a requested version or dist-tag does not exist.
  */

packages/angular/cli/src/package-managers/parsers_spec.ts

@@ -19,6 +19,7 @@ import {
   parseYarnClassicError,
   parseYarnClassicManifest,
   parseYarnModernDependencies,
+  parseYarnModernError,
   parseYarnReleaseAge,
 } from './parsers';
 
@@ -641,6 +642,33 @@ project node_modules
     });
   });
 
+  describe('parseYarnModernError', () => {
+    it('should parse a missing package from yarn npm info as E404', () => {
+      const stdout = [
+        '{"type":"error","name":35,"displayName":"YN0035","indent":"","data":"Package not found"}',
+        '{"type":"error","name":35,"displayName":"YN0035","indent":"","data":"  Response Code: 404 (Not Found)"}',
+        '{"type":"error","name":35,"displayName":"YN0035","indent":"","data":"  Request Method: GET"}',
+        '{"type":"error","name":35,"displayName":"YN0035","indent":"","data":"  Request URL: https://registry.yarnpkg.com/@angular%2fnon-existent"}',
+      ].join('\n');
+      expect(parseYarnModernError(stdout)).toEqual(
+        jasmine.objectContaining({ code: 'E404', summary: 'Package not found' }),
+      );
+    });
+
+    it('should use the yarn error code when there is no HTTP status', () => {
+      const stdout =
+        '{"type":"error","name":35,"displayName":"YN0035","indent":"","data":"Request timed out"}';
+      expect(parseYarnModernError(stdout)).toEqual(
+        jasmine.objectContaining({ code: 'YN0035', summary: 'Request timed out' }),
+      );
+    });
+
+    it('should return null for successful or empty output', () => {
+      expect(parseYarnModernError('{"name":"@angular/core","version":"22.2.4"}')).toBeNull();
+      expect(parseYarnModernError('')).toBeNull();
+    });
+  });
+
   describe('parseYarnModernDependencies', () => {
     it('should parse yarn info --name-only --json output', () => {
       const stdout = `