feat: declare generated Node.js version

AGENTS.md

@@ -52,6 +52,6 @@ Plain-JS shape's entry stays at project root, not under `src/`: with no bundler
 
 `styles`/`react` are only settable when frontend is enabled — enforced twice: `CliSchema`'s `.refine()` checks (`schema.ts`) and structurally by `runPromptFlow.ts` (styles/react prompts only run `if (model.frontend)`). Keep both in sync if this changes. So the frontend axis collapses to 5 states — `false`, or enabled × `{none, styles-only, react-only, styles+react}` — not a raw 2×2 sub-cross.
 
-Combined with `language` (2) and `hasBackend` (2): **20** distinct configs. `registry` (default vs. custom URL) is an independent axis, only toggling whether `generateBase` writes `.npmrc`. No package-manager (npm/yarn/pnpm) axis exists.
+Combined with `language` (2) and `hasBackend` (2): **20** distinct configs. `nodeVersion` is an independent string input that only changes `.nvmrc` and `package.json#engines`; `registry` (default vs. custom URL) is another independent axis that only toggles whether `generateBase` writes `.npmrc`. No package-manager (npm/yarn/pnpm) axis exists.
 
 What's actually observable at runtime per combo (browser vs stdout vs nothing), and current e2e coverage gaps: see `e2e/AGENTS.md`.

package.json

@@ -29,6 +29,7 @@
   "dependencies": {
     "@clack/prompts": "^1.6.0",
     "handlebars": "^4.7.9",
+    "semver": "^7.8.5",
     "zod": "^4.4.3"
   },
   "devDependencies": {
@@ -37,6 +38,7 @@
     "@gravity-ui/tsconfig": "^1.0.0",
     "@playwright/test": "^1.61.1",
     "@types/node": "^24.13.3",
+    "@types/semver": "^7.7.1",
     "eslint": "^9.39.4",
     "eslint-plugin-n": "^18.2.1",
     "knip": "^6.23.0",

scripts/readme/readme.hbs

@@ -36,6 +36,7 @@ Three shapes: app-builder layout (frontend and/or backend selected), plain TS en
 ```
 .
 |-- .gitignore
+|-- .nvmrc
 |-- .prettierrc.js
 |-- .stylelintrc.json          # only with styles
 |-- README.md

src/cli/args.test.ts

@@ -4,9 +4,17 @@ import {parseCli} from './args.js';
 
 test.describe('parseCli', () => {
     test('parses string and enum flags', (t: TestContext) => {
-        const result = parseCli(['--out', './my-app', '--language', 'ts']);
+        const result = parseCli([
+            '--out',
+            './my-app',
+            '--language',
+            'ts',
+            '--node-version',
+            '24.1.0',
+        ]);
         t.assert.equal(result.out, './my-app');
         t.assert.equal(result.language, 'ts');
+        t.assert.equal(result['node-version'], '24.1.0');
     });
 
     test('parses boolean flags', (t: TestContext) => {
@@ -52,6 +60,8 @@ test.describe('parseCli', () => {
 
     test('formats a zod error for a flag with --prefix', (t: TestContext) => {
         t.assert.throws(() => parseCli(['--language', 'cobol']), /^Error: --language: /);
+        t.assert.throws(() => parseCli(['--node-version', 'latest']), /^Error: --node-version: /);
+        t.assert.throws(() => parseCli(['--node-version', '21']), /^Error: --node-version: /);
     });
 
     test('formats the out field error without a -- prefix', (t: TestContext) => {

src/cli/introspect.test.ts

@@ -12,6 +12,7 @@ test.describe('listFields', () => {
             [
                 'out',
                 'language',
+                'node-version',
                 'frontend',
                 'styles',
                 'react',
@@ -52,7 +53,7 @@ test.describe('listFields', () => {
 
     test('classifies plain string fields as kind "string"', (t: TestContext) => {
         const fields = listFields();
-        for (const name of ['out', 'registry']) {
+        for (const name of ['out', 'node-version', 'registry']) {
             const field = fields.find((f) => f.name === name);
             t.assert.equal(field?.kind, 'string');
         }