fix(@angular/build): anchor debug ID comment matching and make injection idempotent

packages/angular/build/src/builders/application/inject-debug-ids.ts

@@ -11,6 +11,7 @@ import {
   generateDebugId,
   injectDebugIdIntoJs,
   injectDebugIdIntoSourceMap,
+  stripDebugIdFromSourceMap,
 } from '../../utils/debug-id';
 
 /**
@@ -42,8 +43,10 @@ export function injectDebugIds(outputFiles: BuildOutputFile[]): void {
       continue;
     }
 
-    const id = generateDebugId(map.contents);
+    const mapText = map.text;
+    const mapTextForHash = stripDebugIdFromSourceMap(mapText);
+    const id = generateDebugId(mapTextForHash);
     file.contents = encoder.encode(injectDebugIdIntoJs(file.text, id));
-    map.contents = encoder.encode(injectDebugIdIntoSourceMap(map.text, id));
+    map.contents = encoder.encode(injectDebugIdIntoSourceMap(mapText, id));
   }
 }

packages/angular/build/src/utils/debug-id.ts

@@ -40,8 +40,8 @@ export function generateDebugId(name: string | Uint8Array): string {
   return `${h.slice(0, 8)}-${h.slice(8, 12)}-${h.slice(12, 16)}-${h.slice(16, 20)}-${h.slice(20, 32)}`;
 }
 
-/** Pattern matching an existing `//# debugId=<uuid>` comment anywhere in the file. */
-const DEBUG_ID_COMMENT = /\n\/\/# debugId=[^\r\n]*\n?/;
+/** Pattern matching an existing `//# debugId=<uuid>` comment at the end of the file. */
+const DEBUG_ID_COMMENT = /(\n\/\/# debugId=[^\r\n]*)(\n\/\/# sourceMappingURL=[^\r\n]*)?(\s*)$/;
 
 /** Pattern matching the `//# sourceMappingURL=` comment, used to position the debug-id line. */
 const SOURCE_MAPPING_URL_COMMENT = /\n\/\/# sourceMappingURL=[^\r\n]*\s*$/;
@@ -58,7 +58,7 @@ export function injectDebugIdIntoJs(text: string, id: string): string {
 
   // Replace any existing debugId comment to keep the operation idempotent.
   if (DEBUG_ID_COMMENT.test(text)) {
-    return text.replace(DEBUG_ID_COMMENT, `\n${comment}\n`);
+    return text.replace(DEBUG_ID_COMMENT, (_, p1, p2, p3) => `\n${comment}${p2 || ''}${p3 || ''}`);
   }
 
   if (SOURCE_MAPPING_URL_COMMENT.test(text)) {
@@ -96,3 +96,11 @@ export function injectDebugIdIntoSourceMap(json: string, id: string): string {
 
   return JSON.stringify(parsed, null, indent);
 }
+
+/**
+ * Strips any existing `debugId` field from the source map JSON string to restore
+ * the original JSON contents for deterministic/idempotent hashing.
+ */
+export function stripDebugIdFromSourceMap(json: string): string {
+  return json.replace(/,\s*"debugId"\s*:\s*"[^"]*"|\s*"debugId"\s*:\s*"[^"]*"\s*,?/g, '');
+}

packages/angular/build/src/utils/debug-id_spec.ts

@@ -6,7 +6,12 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
-import { generateDebugId, injectDebugIdIntoJs, injectDebugIdIntoSourceMap } from './debug-id';
+import {
+  generateDebugId,
+  injectDebugIdIntoJs,
+  injectDebugIdIntoSourceMap,
+  stripDebugIdFromSourceMap,
+} from './debug-id';
 
 const UUID = /^[0-9a-f]{8}-[0-9a-f]{4}-5[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/;
 
@@ -59,6 +64,17 @@ describe('debug-id', () => {
       // Re-running with the same id is a no-op.
       expect(injectDebugIdIntoJs(result, id)).toBe(result);
     });
+
+    it('does not replace a debugId comment that is inside a string or template literal', () => {
+      const text =
+        'const t = `\n//# debugId=00000000-0000-5000-8000-000000000000\n`;\n//# sourceMappingURL=foo.js.map\n';
+      const result = injectDebugIdIntoJs(text, id);
+      expect(result).toBe(
+        'const t = `\n//# debugId=00000000-0000-5000-8000-000000000000\n`;\n' +
+          `//# debugId=${id}\n` +
+          '//# sourceMappingURL=foo.js.map\n',
+      );
+    });
   });
 
   describe('injectDebugIdIntoSourceMap', () => {
@@ -95,4 +111,27 @@ describe('debug-id', () => {
       expect(injectDebugIdIntoSourceMap(malformed, id)).toBe(malformed);
     });
   });
+
+  describe('stripDebugIdFromSourceMap', () => {
+    it('removes the debugId field from pretty-printed source maps', () => {
+      const original = '{\n\t"version": 3,\n\t"mappings": ""\n}';
+      const updated =
+        '{\n\t"version": 3,\n\t"mappings": "",\n\t"debugId": "11111111-2222-5333-9444-555555555555"\n}';
+      expect(stripDebugIdFromSourceMap(updated)).toBe(original);
+    });
+
+    it('removes the debugId field from minified source maps', () => {
+      const original = '{"version":3,"mappings":""}';
+      const updated =
+        '{"version":3,"mappings":"","debugId":"11111111-2222-5333-9444-555555555555"}';
+      expect(stripDebugIdFromSourceMap(updated)).toBe(original);
+    });
+
+    it('removes the debugId field when it is the first property', () => {
+      const original = '{\n\t"version": 3,\n\t"mappings": ""\n}';
+      const updated =
+        '{\n\t"debugId": "11111111-2222-5333-9444-555555555555",\n\t"version": 3,\n\t"mappings": ""\n}';
+      expect(stripDebugIdFromSourceMap(updated)).toBe(original);
+    });
+  });
 });