fix: per-page dialog tracking and per-context focus for parallel agents

Replace singleton dialog handler with per-page Map so parallel agents
can handle dialogs on their own pages independently. Dialog handlers
are attached per-page via #setupPage() when pages are first discovered.

Replace #selectedPage-based defocus with per-context focus tracking
via #focusedPagePerContext Map. This prevents interleaved selectPage()
calls from parallel agents defocusing the wrong page or skipping
defocus entirely.

Both getDialog() and clearDialog() accept an optional page parameter,
defaulting to the selected page for backward compatibility. handle_dialog
now resolves page via pageIdSchema. Entries are cleaned up on page close.

Author: passtas

docs/tool-reference.md

@@ -1,6 +1,6 @@
 <!-- AUTO GENERATED DO NOT EDIT - run 'npm run docs' to update-->
 
-# Chrome DevTools MCP Tool Reference (~7267 cl100k_base tokens)
+# Chrome DevTools MCP Tool Reference (~7294 cl100k_base tokens)
 
 - **[Input automation](#input-automation)** (8 tools)
   - [`click`](#click)
@@ -94,6 +94,7 @@
 **Parameters:**
 
 - **action** (enum: "accept", "dismiss") **(required)**: Whether to dismiss or accept the dialog
+- **pageId** (number) _(optional)_: Targets a specific page by ID.
 - **promptText** (string) _(optional)_: Optional prompt text to enter into the dialog.
 
 ---
@@ -320,12 +321,12 @@ so returned values have to be JSON-serializable.
 **Parameters:**
 
 - **function** (string) **(required)**: A JavaScript function declaration to be executed by the tool in the currently selected page.
-  Example without arguments: `() => {
+Example without arguments: `() => {
   return document.title
 }` or `async () => {
   return await fetch("example.com")
 }`.
-  Example with arguments: `(el) => {
+Example with arguments: `(el) => {
   return el.innerText;
 }`
 

src/McpContext.ts

@@ -141,7 +141,9 @@ export class McpContext implements Context {
   #screenRecorderData: {recorder: ScreenRecorder; filePath: string} | null =
     null;
   #emulationSettingsMap = new WeakMap<Page, EmulationSettings>();
-  #dialog?: Dialog;
+  #pageDialogs = new Map<Page, Dialog>();
+  #pageDialogHandlers = new WeakMap<Page, (dialog: Dialog) => void>();
+  #focusedPagePerContext = new Map<BrowserContext, Page>();
 
   #pageIdMap = new WeakMap<Page, number>();
   #nextPageId = 1;
@@ -307,6 +309,11 @@ export class McpContext implements Context {
       throw new Error(CLOSE_PAGE_ERROR);
     }
     const page = this.getPageById(pageId);
+    this.#pageDialogs.delete(page);
+    const ctx = page.browserContext();
+    if (this.#focusedPagePerContext.get(ctx) === page) {
+      this.#focusedPagePerContext.delete(ctx);
+    }
     await page.close({runBeforeUnload: false});
     this.#pageToIsolatedContextName.delete(page);
   }
@@ -482,12 +489,19 @@ export class McpContext implements Context {
     return this.#options.performanceCrux;
   }
 
-  getDialog(): Dialog | undefined {
-    return this.#dialog;
+  getDialog(page?: Page): Dialog | undefined {
+    const targetPage = page ?? this.#selectedPage;
+    if (!targetPage) {
+      return undefined;
+    }
+    return this.#pageDialogs.get(targetPage);
   }
 
-  clearDialog(): void {
-    this.#dialog = undefined;
+  clearDialog(page?: Page): void {
+    const targetPage = page ?? this.#selectedPage;
+    if (targetPage) {
+      this.#pageDialogs.delete(targetPage);
+    }
   }
 
   getSelectedPage(): Page {
@@ -522,24 +536,34 @@ export class McpContext implements Context {
     return this.#pageIdMap.get(page);
   }
 
-  #dialogHandler = (dialog: Dialog): void => {
-    this.#dialog = dialog;
-  };
+  /**
+   * Attaches a per-page dialog handler.
+   * Called once per page when it is first discovered.
+   */
+  #setupPage(page: Page): void {
+    if (!this.#pageDialogHandlers.has(page)) {
+      const handler = (dialog: Dialog): void => {
+        this.#pageDialogs.set(page, dialog);
+      };
+      page.on('dialog', handler);
+      this.#pageDialogHandlers.set(page, handler);
+    }
+  }
 
   isPageSelected(page: Page): boolean {
     return this.#selectedPage === page;
   }
 
   selectPage(newPage: Page): void {
-    const oldPage = this.#selectedPage;
-    if (oldPage) {
-      oldPage.off('dialog', this.#dialogHandler);
-      void oldPage.emulateFocusedPage(false).catch(error => {
+    const ctx = newPage.browserContext();
+    const oldFocused = this.#focusedPagePerContext.get(ctx);
+    if (oldFocused && oldFocused !== newPage && !oldFocused.isClosed()) {
+      void oldFocused.emulateFocusedPage(false).catch(error => {
         this.logger('Error turning off focused page emulation', error);
       });
     }
+    this.#focusedPagePerContext.set(ctx, newPage);
     this.#selectedPage = newPage;
-    newPage.on('dialog', this.#dialogHandler);
     this.#updateSelectedPageTimeouts();
     void newPage.emulateFocusedPage(true).catch(error => {
       this.logger('Error turning on focused page emulation', error);
@@ -600,6 +624,7 @@ export class McpContext implements Context {
     for (const page of allPages) {
       if (!this.#pageIdMap.has(page)) {
         this.#pageIdMap.set(page, this.#nextPageId++);
+        this.#setupPage(page);
       }
     }
 

src/tools/ToolDefinition.ts

@@ -109,8 +109,8 @@ export type Context = Readonly<{
   storeTraceRecording(result: TraceResult): void;
   getSelectedPage(): Page;
   resolvePageById(pageId?: number): Page;
-  getDialog(): Dialog | undefined;
-  clearDialog(): void;
+  getDialog(page?: Page): Dialog | undefined;
+  clearDialog(page?: Page): void;
   getPageById(pageId: number): Page;
   getPageId(page: Page): number | undefined;
   isPageSelected(page: Page): boolean;

src/tools/pages.ts

@@ -186,7 +186,7 @@ export const navigatePage = defineTool({
           void dialog.dismiss();
         }
         // We are not going to report the dialog like regular dialogs.
-        context.clearDialog();
+        context.clearDialog(page);
       }
     };
 
@@ -325,6 +325,7 @@ export const handleDialog = defineTool({
     readOnlyHint: false,
   },
   schema: {
+    ...pageIdSchema,
     action: zod
       .enum(['accept', 'dismiss'])
       .describe('Whether to dismiss or accept the dialog'),
@@ -334,7 +335,8 @@ export const handleDialog = defineTool({
       .describe('Optional prompt text to enter into the dialog.'),
   },
   handler: async (request, response, context) => {
-    const dialog = context.getDialog();
+    const page = context.resolvePageById(request.params.pageId);
+    const dialog = context.getDialog(page);
     if (!dialog) {
       throw new Error('No open dialog found');
     }
@@ -362,7 +364,7 @@ export const handleDialog = defineTool({
       }
     }
 
-    context.clearDialog();
+    context.clearDialog(page);
     response.setIncludePages(true);
   },
 });