fix: pass define through to the Angular target and exposed modules

src/builders/build/builder.ts

@@ -11,7 +11,6 @@ import {
   buildApplication,
 } from "@angular/build";
 import {
-  buildApplicationInternal,
   normalizeDevServerOptions,
   serveWithVite,
   SourceFileCache,
@@ -46,7 +45,7 @@ import {
   sharedMappingDirs,
   syncNfFileWatcher,
 } from "@softarc/native-federation/internal";
-import { type Plugin, type PluginBuild } from "esbuild";
+import { type PluginBuild } from "esbuild";
 import { devHostInstancesPlugin } from "../../plugin/dev-host-instances-plugin.js";
 import { withDiskCaseWorkspaceRoot } from "./../../utils/disk-case.js";
 import { checkForInvalidImports } from "./../../utils/check-for-invalid-imports.js";
@@ -63,6 +62,7 @@ import { createAngularBuildAdapter } from "../../tools/esbuild/angular-esbuild-a
 import { createSharedMappingsPlugin } from "../../tools/esbuild/shared-mappings-plugin.js";
 import { getI18nConfig, translateFederationArtifacts } from "./i18n.js";
 import { updateScriptTags } from "./update-index-html.js";
+import { createInternalAngularBuilder } from "./internal-angular-builder.js";
 
 const originalWrite = process.stderr.write.bind(process.stderr);
 
@@ -87,47 +87,6 @@ process.stderr.write = function (
   return originalWrite(chunk, encodingOrCallback as BufferEncoding, callback);
 };
 
-const createInternalAngularBuilder =
-  (
-    externals: string[],
-    opts?: { instrumentForCoverage?: (filename: string) => boolean },
-  ) =>
-  (
-    options: Parameters<typeof buildApplicationInternal>[0],
-    context: BuilderContext,
-    pluginsOrExtensions?:
-      | Plugin[]
-      | Parameters<typeof buildApplicationInternal>[2],
-  ) => {
-    let extensions: Parameters<typeof buildApplicationInternal>[2];
-    if (pluginsOrExtensions && Array.isArray(pluginsOrExtensions)) {
-      extensions = {
-        codePlugins: pluginsOrExtensions,
-      };
-    } else {
-      extensions = pluginsOrExtensions as Parameters<
-        typeof buildApplicationInternal
-      >[2];
-    }
-
-    // serveWithVite fetches its own browserOptions independently, so ngBuilderOptions
-    // modifications don't reach here. Add NF externals to externalDependencies so
-    // Angular routes them to optimizeDeps.exclude, preventing Vite from trying to
-    // pre-bundle packages that include native .node binaries.
-    options.externalDependencies = [
-      ...(options.externalDependencies ?? []),
-      ...externals,
-    ];
-
-    if (opts?.instrumentForCoverage) {
-      options.instrumentForCoverage = opts.instrumentForCoverage;
-    }
-
-    // Todo: share cache with Angular builder: https://github.com/angular/angular-cli/pull/32527
-    // options.codeBundleCache = nfOptions.federationCache.bundlerCache;
-    return buildApplicationInternal(options, context, extensions);
-  };
-
 export async function* runBuilder(
   nfBuilderOptions: NfBuilderSchema & NfInternalOptions,
   builderContext: BuilderContext,
@@ -218,6 +177,13 @@ export async function* runBuilder(
     ngBuilderOptions.outputPath = nfBuilderOptions.outputPath;
   }
 
+  if (nfBuilderOptions.define) {
+    ngBuilderOptions.define = {
+      ...ngBuilderOptions.define,
+      ...nfBuilderOptions.define,
+    };
+  }
+
   const declaresTsConfig =
     !!nfBuilderOptions.tsConfig && nfBuilderOptions.tsConfig.length > 0;
 
@@ -557,6 +523,7 @@ export async function* runBuilder(
         appBuilderName,
         createInternalAngularBuilder(externals, {
           instrumentForCoverage: nfBuilderOptions.instrumentForCoverage,
+          define: nfBuilderOptions.define,
         }),
         context,
         nfBuilderOptions.skipHtmlTransform

src/builders/build/internal-angular-builder.spec.ts

@@ -0,0 +1,47 @@
+import { buildApplicationInternal } from "@angular/build/private";
+import type { BuilderContext } from "@angular-devkit/architect";
+
+import { createInternalAngularBuilder } from "./internal-angular-builder.js";
+
+vi.mock("@angular/build/private", () => ({
+  buildApplicationInternal: vi.fn(),
+}));
+
+type Options = Parameters<typeof buildApplicationInternal>[0];
+
+function run(
+  options: Partial<Options>,
+  opts?: Parameters<typeof createInternalAngularBuilder>[1],
+) {
+  createInternalAngularBuilder(["@angular/core"], opts)(
+    options as Options,
+    {} as BuilderContext,
+  );
+  return vi.mocked(buildApplicationInternal).mock.calls.at(-1)![0];
+}
+
+describe("createInternalAngularBuilder", () => {
+  beforeEach(() => vi.mocked(buildApplicationInternal).mockClear());
+
+  it("appends the federation externals", () => {
+    expect(run({ externalDependencies: ["fs"] }).externalDependencies).toEqual([
+      "fs",
+      "@angular/core",
+    ]);
+  });
+
+  // #129: serveWithVite reads the build target's options itself, so the builder's define
+  // must be merged here or `serve --define` never reaches the main bundle.
+  it("merges the builder define over the target define", () => {
+    const options = run(
+      { define: { BUILD_ID: "'target'", KEEP: "true" } },
+      { define: { BUILD_ID: "'cli'" } },
+    );
+
+    expect(options.define).toEqual({ BUILD_ID: "'cli'", KEEP: "true" });
+  });
+
+  it("leaves the target define alone when the builder sets none", () => {
+    expect(run({ define: { KEEP: "true" } }).define).toEqual({ KEEP: "true" });
+  });
+});

src/builders/build/internal-angular-builder.ts

@@ -0,0 +1,50 @@
+import { buildApplicationInternal } from "@angular/build/private";
+import { type BuilderContext } from "@angular-devkit/architect";
+import { type Plugin } from "esbuild";
+
+export const createInternalAngularBuilder =
+  (
+    externals: string[],
+    opts?: {
+      instrumentForCoverage?: (filename: string) => boolean;
+      define?: Record<string, string>;
+    },
+  ) =>
+  (
+    options: Parameters<typeof buildApplicationInternal>[0],
+    context: BuilderContext,
+    pluginsOrExtensions?:
+      Plugin[] | Parameters<typeof buildApplicationInternal>[2],
+  ) => {
+    let extensions: Parameters<typeof buildApplicationInternal>[2];
+    if (pluginsOrExtensions && Array.isArray(pluginsOrExtensions)) {
+      extensions = {
+        codePlugins: pluginsOrExtensions,
+      };
+    } else {
+      extensions = pluginsOrExtensions as Parameters<
+        typeof buildApplicationInternal
+      >[2];
+    }
+
+    // serveWithVite fetches its own browserOptions independently, so ngBuilderOptions
+    // modifications don't reach here. Add NF externals to externalDependencies so
+    // Angular routes them to optimizeDeps.exclude, preventing Vite from trying to
+    // pre-bundle packages that include native .node binaries.
+    options.externalDependencies = [
+      ...(options.externalDependencies ?? []),
+      ...externals,
+    ];
+
+    if (opts?.instrumentForCoverage) {
+      options.instrumentForCoverage = opts.instrumentForCoverage;
+    }
+
+    if (opts?.define) {
+      options.define = { ...options.define, ...opts.define };
+    }
+
+    // Todo: share cache with Angular builder: https://github.com/angular/angular-cli/pull/32527
+    // options.codeBundleCache = nfOptions.federationCache.bundlerCache;
+    return buildApplicationInternal(options, context, extensions);
+  };

src/builders/build/schema.d.ts

@@ -16,6 +16,7 @@ export interface NfBuilderSchema extends JsonObject {
   esmsInitOptions: ESMSInitOptions;
   baseHref?: string;
   outputPath?: string;
+  define?: Record<string, string>;
   projectName?: string;
   ssr: boolean;
   tsConfig?: string;

src/builders/build/schema.json

@@ -50,6 +50,11 @@
     "outputPath": {
       "type": "string"
     },
+    "define": {
+      "type": "object",
+      "additionalProperties": { "type": "string" },
+      "description": "Global identifiers to replace at build time, merged over the Angular target's own 'define'. String values must be put in quotes."
+    },
     "esmsInitOptions": {
       "type": "object",
       "description": "Options for esms-module-shims https://github.com/guybedford/es-module-shims?tab=readme-ov-file#init-options",

src/tools/esbuild/angular-bundler.spec.ts

@@ -145,4 +145,25 @@ describe('createAngularEsbuildContext', () => {
 
     expect(lastBuildOptions().entryPoints).toEqual([{ in: absolute, out: 'ui' }]);
   });
+
+  // #129: exposed modules left user defines unreplaced, throwing a ReferenceError in the host.
+  // Angular's own flags win over user defines, mirroring the application builder.
+  it('applies the builder define, keeping the Angular flags on top', async () => {
+    await createAngularEsbuildContext(
+      makeOptions({
+        builderOptions: {
+          optimization: false,
+          sourceMap: false,
+          define: { BUILD_ID: "'abc'", ngJitMode: 'true' },
+        },
+      } as unknown as Partial<NormalizedContextOptions>),
+      'mapping-or-exposed'
+    );
+
+    expect(lastBuildOptions().define).toEqual({
+      BUILD_ID: "'abc'",
+      ngDevMode: 'false',
+      ngJitMode: 'false',
+    });
+  });
 });

src/tools/esbuild/angular-bundler.ts

@@ -174,6 +174,7 @@ export async function createAngularEsbuildContext(
     logLimit: 0,
     plugins: [compilerPlugin, commonjsPlugin(), ...customPlugins],
     define: {
+      ...builderOptions.define,
       ...(dev ? {} : { ngDevMode: 'false' }),
       ngJitMode: 'false',
     },