feat(@angular/cli): allow Algolia search key override via env var

The MCP `search_documentation` tool currently uses a single bundled
Algolia API key for the public Angular documentation index. This works
out of the box but gives operators no way to:

* substitute a different key for self-hosted documentation indices,
* point an internal CI environment at a separate Algolia application
  to avoid sharing the public rate-limit budget,
* test key rotation without rebuilding the CLI.

This change adds a `NG_DOCS_SEARCH_API_KEY` environment variable that,
when set to a non-empty string, is used verbatim in place of the
bundled key. When the variable is absent or empty, behaviour is
unchanged — the bundled key continues to be used.

The override path is factored into a small `resolveAlgoliaApiKey()`
helper so the env-var precedence rules are unit-testable without
spinning up the full MCP tool runner. Three Jasmine specs cover:
override set, override unset, and override set to empty string.

The previous comment block on `ALGOLIA_API_E` is replaced with a
short note describing the override mechanism and the operator
scenarios it enables.

Author: gn00295120

packages/angular/cli/src/commands/mcp/tools/doc-search.ts

@@ -14,11 +14,32 @@ import { at, iv, k1 } from '../constants';
 import { type McpToolContext, declareTool } from './tool-registry';
 
 const ALGOLIA_APP_ID = 'L1XWT2UJ7F';
-// https://www.algolia.com/doc/guides/security/api-keys/#search-only-api-key
-// This is a search only, rate limited key. It is sent within the URL of the query request.
-// This is not the actual key.
+// Default Algolia API key used when NG_DOCS_SEARCH_API_KEY is not set.
+// Operators (e.g. self-hosted documentation, internal CI, rotation testing)
+// can override this by setting NG_DOCS_SEARCH_API_KEY in the environment.
 const ALGOLIA_API_E = '34738e8ae1a45e58bbce7b0f9810633d8b727b44a6479cf5e14b6a337148bd50';
 
+/**
+ * Resolves the Algolia API key to use for documentation search. If the
+ * `NG_DOCS_SEARCH_API_KEY` environment variable is set to a non-empty value
+ * it is used verbatim; otherwise the bundled default is used.
+ *
+ * Exported for testing.
+ */
+export function resolveAlgoliaApiKey(): string {
+  const override = process.env['NG_DOCS_SEARCH_API_KEY'];
+  if (typeof override === 'string' && override !== '') {
+    return override;
+  }
+  const dcip = createDecipheriv(
+    'aes-256-gcm',
+    (k1 + ALGOLIA_APP_ID).padEnd(32, '^'),
+    iv,
+  ).setAuthTag(Buffer.from(at, 'base64'));
+
+  return dcip.update(ALGOLIA_API_E, 'hex', 'utf-8') + dcip.final('utf-8');
+}
+
 /**
  * The minimum major version of Angular for which a version-specific documentation index is known to exist.
  * Searches for versions older than this will be clamped to this version.
@@ -129,16 +150,8 @@ function createDocSearchHandler({ logger }: McpToolContext) {
 
   return async ({ query, includeTopContent, version }: DocSearchInput) => {
     if (!client) {
-      const dcip = createDecipheriv(
-        'aes-256-gcm',
-        (k1 + ALGOLIA_APP_ID).padEnd(32, '^'),
-        iv,
-      ).setAuthTag(Buffer.from(at, 'base64'));
       const { searchClient } = await import('algoliasearch');
-      client = searchClient(
-        ALGOLIA_APP_ID,
-        dcip.update(ALGOLIA_API_E, 'hex', 'utf-8') + dcip.final('utf-8'),
-      );
+      client = searchClient(ALGOLIA_APP_ID, resolveAlgoliaApiKey());
     }
 
     let finalSearchedVersion = Math.max(

packages/angular/cli/src/commands/mcp/tools/doc-search_spec.ts

@@ -0,0 +1,45 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+import { resolveAlgoliaApiKey } from './doc-search';
+
+describe('resolveAlgoliaApiKey', () => {
+  const ENV_VAR = 'NG_DOCS_SEARCH_API_KEY';
+  let saved: string | undefined;
+
+  beforeEach(() => {
+    saved = process.env[ENV_VAR];
+    delete process.env[ENV_VAR];
+  });
+
+  afterEach(() => {
+    if (saved === undefined) {
+      delete process.env[ENV_VAR];
+    } else {
+      process.env[ENV_VAR] = saved;
+    }
+  });
+
+  it('returns the env var value when set to a non-empty string', () => {
+    process.env[ENV_VAR] = 'override-key-1234';
+
+    expect(resolveAlgoliaApiKey()).toBe('override-key-1234');
+  });
+
+  it('falls back to the bundled default when the env var is unset', () => {
+    delete process.env[ENV_VAR];
+
+    expect(resolveAlgoliaApiKey()).toMatch(/^[0-9a-f]{32}$/);
+  });
+
+  it('falls back to the bundled default when the env var is an empty string', () => {
+    process.env[ENV_VAR] = '';
+
+    expect(resolveAlgoliaApiKey()).toMatch(/^[0-9a-f]{32}$/);
+  });
+});