fix(@angular/build): allow .json file replacements with application builds

packages/angular/build/src/builders/application/tests/options/file-replacements_spec.ts

@@ -0,0 +1,37 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+import { buildApplication } from '../../index';
+import { APPLICATION_BUILDER_INFO, BASE_OPTIONS, describeBuilder } from '../setup';
+
+describeBuilder(buildApplication, APPLICATION_BUILDER_INFO, (harness) => {
+  describe('Option: "fileReplacements"', () => {
+    it('should replace JSON files', async () => {
+      harness.useTarget('build', {
+        ...BASE_OPTIONS,
+        fileReplacements: [{ replace: './src/one.json', with: './src/two.json' }],
+      });
+
+      await harness.modifyFile('tsconfig.json', (content) => {
+        const tsconfig = JSON.parse(content);
+        tsconfig.compilerOptions.resolveJsonModule = true;
+
+        return JSON.stringify(tsconfig);
+      });
+
+      await harness.writeFile('./src/one.json', '{ "x": 12345 }');
+      await harness.writeFile('./src/two.json', '{ "x": 67890 }');
+      await harness.writeFile('src/main.ts', 'import { x } from "./one.json";\n console.log(x);');
+
+      const { result } = await harness.executeOnce();
+      expect(result?.success).toBe(true);
+      harness.expectFile('dist/browser/main.js').content.not.toContain('12345');
+      harness.expectFile('dist/browser/main.js').content.toContain('67890');
+    });
+  });
+});

packages/angular/build/src/tools/esbuild/angular/compiler-plugin.ts

@@ -512,6 +512,31 @@ export function createCompilerPlugin(
         }),
       );
 
+      // Add a load handler if there are file replacement option entries for JSON files
+      if (
+        pluginOptions.fileReplacements &&
+        Object.keys(pluginOptions.fileReplacements).some((value) => value.endsWith('.json'))
+      ) {
+        build.onLoad(
+          { filter: /\.json$/ },
+          createCachedLoad(pluginOptions.loadResultCache, async (args) => {
+            const replacement = pluginOptions.fileReplacements?.[path.normalize(args.path)];
+            if (replacement) {
+              return {
+                contents: await import('fs/promises').then(({ readFile }) =>
+                  readFile(path.normalize(replacement)),
+                ),
+                loader: 'json' as const,
+                watchFiles: [replacement],
+              };
+            }
+
+            // If no replacement defined, let esbuild handle it directly
+            return null;
+          }),
+        );
+      }
+
       // Setup bundling of component templates and stylesheets when in JIT mode
       if (pluginOptions.jit) {
         setupJitPluginCallbacks(