feat: Accept a function for config.manifest

Author: aklinker1

.prettierignore

@@ -1,3 +1,4 @@
 .output
 coverage
 dist
+e2e/project

e2e/tests/user-config.test.ts

@@ -55,4 +55,27 @@ describe('User Config', () => {
       {\\"manifest_version\\":3,\\"name\\":\\"E2E Extension\\",\\"version\\":\\"0.0.0\\",\\"version_name\\":\\"0.0.0-test\\",\\"background\\":{\\"service_worker\\":\\"background.js\\"}}"
     `);
   });
+
+  it('should accept a function for a manifest', async () => {
+    const project = new TestProject();
+
+    await project.build({
+      // @ts-expect-error: Specifically setting an invalid field for the test - it should show up in the snapshot
+      manifest: ({ mode, browser, manifestVersion, command }) => ({
+        example_customization: [
+          mode,
+          browser,
+          String(manifestVersion),
+          command,
+        ],
+      }),
+    });
+
+    const output = await project.serializeOutput();
+    expect(output).toMatchInlineSnapshot(`
+      ".output/chrome-mv3/manifest.json
+      ----------------------------------------
+      {\\"manifest_version\\":3,\\"name\\":\\"E2E Extension\\",\\"version\\":\\"0.0.0\\",\\"version_name\\":\\"0.0.0-test\\",\\"example_customization\\":[\\"production\\",\\"chrome\\",\\"3\\",\\"build\\"]}"
+    `);
+  });
 });

src/core/types/external.ts

@@ -20,7 +20,7 @@ export interface InlineConfig {
   manifestVersion?: TargetManifestVersion;
   logger?: Logger;
   vite?: Omit<vite.UserConfig, 'root' | 'configFile' | 'mode'>;
-  manifest?: UserManifest;
+  manifest?: UserManifest | Promise<UserManifest> | UserManifestFn;
   server?: WxtDevServer;
   runner?: ExtensionRunnerConfig;
 }
@@ -226,6 +226,23 @@ export type UserManifest = Omit<
   | 'version_name'
 >;
 
+export type UserManifestFn = (
+  env: ConfigEnv,
+) => UserManifest | Promise<UserManifest>;
+
+export interface ConfigEnv {
+  mode: string;
+  command: 'build' | 'serve';
+  /**
+   * Browser passed in from the CLI
+   */
+  browser: TargetBrowser;
+  /**
+   * Manifest version passed in from the CLI
+   */
+  manifestVersion: 2 | 3;
+}
+
 /**
  * Configure how the browser starts up.
  */

src/core/utils/getInternalConfig.ts

@@ -3,6 +3,7 @@ import {
   InlineConfig,
   InternalConfig,
   UserConfig,
+  UserManifest,
 } from '../types';
 import path, { resolve } from 'node:path';
 import * as vite from 'vite';
@@ -31,6 +32,15 @@ export async function getInternalConfig(
   const outDir = path.resolve(outBaseDir, `${browser}-mv${manifestVersion}`);
   const logger = config.logger ?? consola;
 
+  const manifest: UserManifest = await (typeof config.manifest === 'function'
+    ? config.manifest({
+        browser,
+        command,
+        manifestVersion,
+        mode,
+      })
+    : config.manifest ?? {});
+
   const baseConfig: InternalConfigNoUserDirs = {
     root,
     outDir,
@@ -42,7 +52,7 @@ export async function getInternalConfig(
     command,
     logger,
     vite: config.vite ?? {},
-    manifest: config.manifest ?? {},
+    manifest,
     imports: config.imports ?? {},
     runnerConfig: await loadConfig<ExtensionRunnerConfig>({
       name: 'web-ext',