feat: implement trigger extension action

Author: nroscino

src/McpContext.ts

@@ -939,6 +939,24 @@ export class McpContext implements Context {
     this.#extensionRegistry.remove(id);
   }
 
+  async triggerExtensionAction(id: string): Promise<void> {
+    const page = this.getSelectedPage();
+    // @ts-expect-error internal puppeteer api is needed since we don't have a way to get
+    // a tab id at the moment
+    const theTarget = page._tabId;
+    const session = await this.browser.target().createCDPSession();
+
+    try {
+      // @ts-expect-error triggerAction is not yet available
+      await session.send('Extensions.triggerAction', {
+        id,
+        targetId: theTarget,
+      });
+    } finally {
+      await session.detach();
+    }
+  }
+
   listExtensions(): InstalledExtension[] {
     return this.#extensionRegistry.list();
   }

src/tools/ToolDefinition.ts

@@ -190,6 +190,7 @@ export type Context = Readonly<{
   ): void;
   installExtension(path: string): Promise<string>;
   uninstallExtension(id: string): Promise<void>;
+  triggerExtensionAction(id: string): Promise<void>;
   listExtensions(): InstalledExtension[];
   getExtension(id: string): InstalledExtension | undefined;
   getSelectedMcpPage(): McpPage;

src/tools/extensions.ts

@@ -85,3 +85,21 @@ export const reloadExtension = defineTool({
     response.appendResponseLine('Extension reloaded.');
   },
 });
+
+export const triggerExtensionAction = defineTool({
+  name: 'trigger_extension_action',
+  description: 'Triggers an action in a Chrome extension.',
+  annotations: {
+    category: ToolCategory.EXTENSIONS,
+    readOnlyHint: false,
+    conditions: [EXTENSIONS_CONDITION],
+  },
+  schema: {
+    id: zod.string().describe('ID of the extension.'),
+  },
+  handler: async (request, response, context) => {
+    const {id} = request.params;
+    await context.triggerExtensionAction(id);
+    response.appendResponseLine(`Extension action triggered. Id: ${id}`);
+  },
+});

tests/tools/extensions.test.ts

@@ -16,6 +16,7 @@ import {
   uninstallExtension,
   listExtensions,
   reloadExtension,
+  triggerExtensionAction,
 } from '../../src/tools/extensions.js';
 import {withMcpContext} from '../utils.js';
 
@@ -128,4 +129,39 @@ describe('extension', () => {
       assert.ok(reinstalled, 'Extension should be present after reload');
     });
   });
+
+  it('triggers an extension action', async () => {
+    await withMcpContext(
+      async (response, context) => {
+        const triggerSpy = sinon.spy(context, 'triggerExtensionAction');
+
+        await installExtension.handler(
+          {params: {path: EXTENSION_PATH}},
+          response,
+          context,
+        );
+
+        const extensionId = extractId(response);
+        response.resetResponseLineForTesting();
+
+        await triggerExtensionAction.handler(
+          {params: {id: extensionId}},
+          response,
+          context,
+        );
+
+        assert.ok(
+          triggerSpy.calledOnceWithExactly(extensionId),
+          'triggerExtensionAction should be called with correct params',
+        );
+        assert.ok(
+          response.responseLines[0].includes(
+            `Extension action triggered. Id: ${extensionId}`,
+          ),
+          'Response should indicate action triggered',
+        );
+      },
+      {channel: 'chrome-canary'},
+    );
+  });
 });

tests/utils.ts

@@ -47,10 +47,11 @@ let context: McpContext | undefined;
 
 export async function withBrowser(
   cb: (browser: Browser, page: Page) => Promise<void>,
-  options: {debug?: boolean; autoOpenDevTools?: boolean} = {},
+  options: {debug?: boolean; autoOpenDevTools?: boolean; channel?: string} = {},
 ) {
   const launchOptions: LaunchOptions = {
     executablePath: process.env.PUPPETEER_EXECUTABLE_PATH,
+    channel: options.channel as any,
     headless: !options.debug,
     defaultViewport: null,
     devtools: options.autoOpenDevTools ?? false,
@@ -85,6 +86,7 @@ export async function withMcpContext(
     debug?: boolean;
     autoOpenDevTools?: boolean;
     performanceCrux?: boolean;
+    channel?: string;
   } = {},
   args: ParsedArguments = {} as ParsedArguments,
 ) {