build!: specify a minimum TypeScript version using typesVersions

.changeset/cuddly-apes-check.md

@@ -0,0 +1,6 @@
+---
+'@firebase/app': minor
+'firebase': minor
+---
+
+Specify a minimum TypeScript version using the `typesVersions` field. Shows an error message if below.

packages/app-check/test/util.ts

@@ -35,7 +35,6 @@ import {
 } from '@firebase/component';
 import { AppCheckService } from '../src/factory';
 import { AppCheck, CustomProvider } from '../src';
-import { HeartbeatService } from '@firebase/app/dist/app/src/types';
 
 export const FAKE_SITE_KEY = 'fake-site-key';
 
@@ -112,7 +111,7 @@ export function getFakeHeartbeatServiceProvider(
       () =>
         ({
           getHeartbeatsHeader: () => Promise.resolve(fakeLogString)
-        } as HeartbeatService),
+        } as any),
       ComponentType.PRIVATE
     )
   );

packages/app/package.json

@@ -7,6 +7,10 @@
   "browser": "dist/esm/index.esm2017.js",
   "module": "dist/esm/index.esm2017.js",
   "react-native": "dist/index.cjs.js",
+  "typesVersions": {
+    ">=4.5.0": { "*": ["./dist/app/src/index.d.ts"] },
+    "<4.5.0": { "*": ["./dist/typescript-not-supported.d.ts"] }
+  },
   "exports": {
     ".": {
       "types": "./dist/app-public.d.ts",
@@ -49,6 +53,7 @@
   "devDependencies": {
     "@rollup/plugin-json": "6.1.0",
     "rollup": "2.79.2",
+    "rollup-plugin-copy": "3.5.0",
     "rollup-plugin-replace": "2.2.0",
     "rollup-plugin-typescript2": "0.36.0",
     "rollup-plugin-dts": "5.3.1",

packages/app/rollup.config.js

@@ -15,6 +15,7 @@
  * limitations under the License.
  */
 
+import copy from 'rollup-plugin-copy';
 import typescriptPlugin from 'rollup-plugin-typescript2';
 import replace from 'rollup-plugin-replace';
 import typescript from 'typescript';
@@ -53,6 +54,14 @@ const esmBuilds = [
     external: id => deps.some(dep => id === dep || id.startsWith(`${dep}/`)),
     plugins: [
       ...buildPlugins,
+      copy({
+        targets: [
+          {
+            src: './typescript-not-supported.d.ts',
+            dest: 'dist/'
+          }
+        ]
+      }),
       replace({
         ...generateBuildTargetReplaceConfig('esm', 2017),
         '__RUNTIME_ENV__': ''

packages/app/typescript-not-supported.d.ts

@@ -0,0 +1,20 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Empty typings file to log an error message for unsupported TS versions
+
+'Typescript must be version 4.5 or greater.';

scripts/docgen/docgen.ts

@@ -65,6 +65,7 @@ const PREFERRED_PARAMS = [
 
 let authApiReportOriginal: string;
 let authApiConfigOriginal: string;
+let appPkgOriginal: string;
 
 yargs
   .command(
@@ -119,6 +120,14 @@ function cleanup() {
         authApiReportOriginal
       );
     }
+    // Restore original app/package.json
+    if (authApiConfigOriginal) {
+      console.log(`Restoring original app/package.json contents.`);
+      fs.writeFileSync(
+        `${projectRoot}/packages/app/package.json`,
+        appPkgOriginal
+      );
+    }
     for (const excludedPackage of EXCLUDED_PACKAGES) {
       if (fs.existsSync(`${projectRoot}/temp/${excludedPackage}.skip`)) {
         console.log(
@@ -198,11 +207,26 @@ async function generateDocs(
     `"mainEntryPointFilePath": "<projectFolder>/dist/esm2017/index.doc.d.ts"`
   );
 
+  console.log(`Temporarily modifying packages/app/package.json for docgen.`);
+  // Remove typesVersions restriction just for docgen
+  appPkgOriginal = fs.readFileSync(
+    `${projectRoot}/packages/app/package.json`,
+    'utf8'
+  );
+  const appPkgModified = appPkgOriginal.replace(
+    `./dist/typescript-not-supported.d.ts`,
+    `./dist/app/src/index.d.ts`
+  );
+
   try {
     fs.writeFileSync(
       `${projectRoot}/packages/auth/api-extractor.json`,
       authApiConfigModified
     );
+    fs.writeFileSync(
+      `${projectRoot}/packages/app/package.json`,
+      appPkgModified
+    );
 
     if (skipBuild) {
       await spawn('yarn', ['api-report'], {