Implement reload_extension tool

Author: Natallia Harshunova

src/McpContext.ts

@@ -772,4 +772,8 @@ export class McpContext implements Context {
   listExtensions(): InstalledExtension[] {
     return this.#extensionRegistry.list();
   }
+
+  getExtension(id: string): InstalledExtension | undefined {
+    return this.#extensionRegistry.getById(id);
+  }
 }

src/tools/ToolDefinition.ts

@@ -144,6 +144,7 @@ export type Context = Readonly<{
   installExtension(path: string): Promise<string>;
   uninstallExtension(id: string): Promise<void>;
   listExtensions(): InstalledExtension[];
+  getExtension(id: string): InstalledExtension | undefined;
 }>;
 
 export function defineTool<Schema extends zod.ZodRawShape>(

src/tools/extensions.ts

@@ -63,3 +63,25 @@ export const listExtensions = defineTool({
     response.setListExtensions();
   },
 });
+
+export const reloadExtension = defineTool({
+  name: 'reload_extension',
+  description: 'Reloads an unpacked Chrome extension by its ID.',
+  annotations: {
+    category: ToolCategory.EXTENSIONS,
+    readOnlyHint: false,
+    conditions: [EXTENSIONS_CONDITION],
+  },
+  schema: {
+    id: zod.string().describe('ID of the extension to reload.'),
+  },
+  handler: async (request, response, context) => {
+    const {id} = request.params;
+    const extension = context.getExtension(id);
+    if (!extension) {
+      throw new Error(`Extension with ID ${id} not found.`);
+    }
+    await context.installExtension(extension.path);
+    response.appendResponseLine('Extension reloaded.');
+  },
+});

tests/tools/extensions.test.ts

@@ -10,10 +10,12 @@ import {describe, it} from 'node:test';
 
 import sinon from 'sinon';
 
+import type {McpResponse} from '../../src/McpResponse.js';
 import {
   installExtension,
   uninstallExtension,
   listExtensions,
+  reloadExtension,
 } from '../../src/tools/extensions.js';
 import {withMcpContext} from '../utils.js';
 
@@ -22,6 +24,15 @@ const EXTENSION_PATH = path.join(
   '../../../tests/tools/fixtures/extension',
 );
 
+function extractId(response: McpResponse) {
+  const responseLine = response.responseLines[0];
+  assert.ok(responseLine, 'Response should not be empty');
+  const match = responseLine.match(/Extension installed\. Id: (.+)/);
+  const extensionId = match ? match[1] : null;
+  assert.ok(extensionId, 'Response should contain a valid key');
+  return extensionId;
+}
+
 describe('extension', () => {
   it('installs and uninstalls an extension and verifies it in chrome://extensions', async () => {
     await withMcpContext(async (response, context) => {
@@ -32,12 +43,7 @@ describe('extension', () => {
         context,
       );
 
-      const responseLine = response.responseLines[0];
-      assert.ok(responseLine, 'Response should not be empty');
-      const match = responseLine.match(/Extension installed\. Id: (.+)/);
-      const extensionId = match ? match[1] : null;
-      assert.ok(extensionId, 'Response should contain a valid key');
-
+      const extensionId = extractId(response);
       const page = context.getSelectedPage();
       await page.goto('chrome://extensions');
 
@@ -84,4 +90,38 @@ describe('extension', () => {
       );
     });
   });
+  it('reloads an extension', async () => {
+    await withMcpContext(async (response, context) => {
+      await installExtension.handler(
+        {params: {path: EXTENSION_PATH}},
+        response,
+        context,
+      );
+
+      const extensionId = extractId(response);
+      const installSpy = sinon.spy(context, 'installExtension');
+      response.resetResponseLineForTesting();
+
+      await reloadExtension.handler(
+        {params: {id: extensionId!}},
+        response,
+        context,
+      );
+      assert.ok(
+        installSpy.calledOnceWithExactly(EXTENSION_PATH),
+        'installExtension should be called with the extension path',
+      );
+
+      const reloadResponseLine = response.responseLines[0];
+      assert.ok(
+        reloadResponseLine.includes('Extension reloaded'),
+        'Response should indicate reload',
+      );
+
+      const list = context.listExtensions();
+      assert.ok(list.length === 1, 'List should have only one extension');
+      const reinstalled = list.find(e => e.id === extensionId);
+      assert.ok(reinstalled, 'Extension should be present after reload');
+    });
+  });
 });