feat(release): ship esbuild bundle in npm package

The npm registry publish path ships unbundled dist/ plus full
node_modules/ (44,835 files), causing ~1-2 minute cold starts on
Windows due to Defender real-time scanning. The GitHub registry
path already ships a single-file bundle with zero dependencies.

Apply the same bundle transformation to the npm publish path:
- Add scripts/prepare-npm-release.js that rewrites the CLI
  package.json to ship bundle/ instead of dist/, removes all
  dependencies, and adds optionalDependencies for native modules
  (node-pty, keytar) so platform-specific features keep working.
- Add a "Prepare bundled CLI for npm release" step in the publish
  action, conditioned on non-GitHub registry URLs.

Result: npm package drops from 44,835 files to ~129 files (6.8 MB).

Closes #19169

.github/actions/publish-release/action.yml

@@ -181,6 +181,13 @@ runs:
         --workspace="${{ inputs.a2a-package-name }}" \
         --save-exact
 
+    - name: '📦 Prepare bundled CLI for npm release'
+      if: "inputs.npm-registry-url != 'https://npm.pkg.github.com/'"
+      working-directory: '${{ inputs.working-directory }}'
+      shell: 'bash'
+      run: |
+        node ${{ github.workspace }}/scripts/prepare-npm-release.js
+
     - name: 'Get CLI Token'
       uses: './.github/actions/npm-auth-token'
       id: 'cli-token'

scripts/prepare-npm-release.js

@@ -0,0 +1,84 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import fs from 'node:fs';
+import path from 'node:path';
+
+const rootDir = process.cwd();
+
+function readJson(filePath) {
+  return JSON.parse(fs.readFileSync(path.resolve(rootDir, filePath), 'utf-8'));
+}
+
+function writeJson(filePath, data) {
+  fs.writeFileSync(
+    path.resolve(rootDir, filePath),
+    JSON.stringify(data, null, 2),
+  );
+}
+
+// Copy bundle directory into packages/cli
+const sourceBundleDir = path.resolve(rootDir, 'bundle');
+const destBundleDir = path.resolve(rootDir, 'packages/cli/bundle');
+
+if (fs.existsSync(sourceBundleDir)) {
+  fs.rmSync(destBundleDir, { recursive: true, force: true });
+  fs.cpSync(sourceBundleDir, destBundleDir, { recursive: true });
+  console.log('Copied bundle/ directory to packages/cli/');
+} else {
+  console.error(
+    'Error: bundle/ directory not found at project root. Please run `npm run bundle` first.',
+  );
+  process.exit(1);
+}
+
+// Read native module versions from root package.json
+const rootPkg = readJson('package.json');
+const rootOptional = rootPkg.optionalDependencies || {};
+
+const nativeModules = [
+  '@lydell/node-pty',
+  '@lydell/node-pty-darwin-arm64',
+  '@lydell/node-pty-darwin-x64',
+  '@lydell/node-pty-linux-x64',
+  '@lydell/node-pty-win32-arm64',
+  '@lydell/node-pty-win32-x64',
+  'keytar',
+  'node-pty',
+];
+
+const optionalDependencies = {};
+for (const mod of nativeModules) {
+  if (rootOptional[mod]) {
+    optionalDependencies[mod] = rootOptional[mod];
+  }
+}
+
+// Update @google/gemini-cli package.json for bundled npm release
+const cliPkgPath = 'packages/cli/package.json';
+const cliPkg = readJson(cliPkgPath);
+
+cliPkg.files = ['bundle/'];
+cliPkg.bin = {
+  gemini: 'bundle/gemini.js',
+};
+
+delete cliPkg.dependencies;
+delete cliPkg.devDependencies;
+delete cliPkg.scripts;
+delete cliPkg.main;
+delete cliPkg.config;
+
+cliPkg.optionalDependencies = optionalDependencies;
+
+writeJson(cliPkgPath, cliPkg);
+
+console.log('Updated packages/cli/package.json for bundled npm release.');
+console.log(
+  'optionalDependencies:',
+  JSON.stringify(optionalDependencies, null, 2),
+);
+console.log('Successfully prepared packages for npm release.');