Addon MCP: Make endpoint configurable

.changeset/quiet-rivers-connect.md

@@ -0,0 +1,5 @@
+---
+"@storybook/addon-mcp": minor
+---
+
+Add an optional MCP endpoint setting for the addon dev server.

README.md

@@ -151,7 +151,7 @@ You can start Storybook with:
 pnpm storybook
 ```
 
-This will build everything and start up Storybook with addon-mcp, and you can then connect your coding agent to it at `http://localhost:6006/mcp` and try it out.
+This will build everything and start up Storybook with addon-mcp, and you can then connect your coding agent to it at `http://localhost:6006/mcp` (or your configured addon endpoint) and try it out.
 
 ### Working with the MCP App
 

packages/addon-mcp/README.md

@@ -8,4 +8,24 @@ Storybook addon for MCP-powered UI development workflows.
 
 See [documentation](https://storybook.js.org/docs/next/ai/mcp/overview/?ref=readme) for installation instructions, usage examples, APIs, and more.
 
+## Configuration
+
+By default, the addon exposes its MCP server at `/mcp`. You can configure a
+different literal endpoint path in `.storybook/main.ts`:
+
+```ts
+export default {
+	addons: [
+		{
+			name: '@storybook/addon-mcp',
+			options: {
+				endpoint: '/custom-mcp',
+			},
+		},
+	],
+};
+```
+
+The endpoint must be a URL pathname such as `/custom-mcp` or `/tools/mcp`.
+
 Learn more about Storybook at [storybook.js.org](https://storybook.js.org/?ref=readme).

packages/addon-mcp/src/auth/composition-auth.test.ts

@@ -1,11 +1,15 @@
-import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
 import { CompositionAuth, extractBearerToken } from './composition-auth.ts';
 
 describe('CompositionAuth', () => {
 	beforeEach(() => {
 		vi.restoreAllMocks();
 	});
 
+	afterEach(() => {
+		vi.unstubAllGlobals();
+	});
+
 	describe('extractBearerToken', () => {
 		it('extracts token from valid Bearer header', () => {
 			expect(extractBearerToken('Bearer abc123')).toBe('abc123');