fix: time out stalled devtools probes

Author: bertrand319

src/McpContext.ts

@@ -707,10 +707,26 @@ export class McpContext implements Context {
         // Some Electron apps still use older version
         // Fall back to not exposing DevTools at all.
         try {
-          if (await page.hasDevTools()) {
-            mcpPage.devToolsPage = await page.openDevTools();
-          } else {
+          const hasDevTools = await resolveWithTimeout(
+            page.hasDevTools(),
+            DEFAULT_TIMEOUT,
+          );
+          if (!hasDevTools) {
+            if (hasDevTools === undefined) {
+              this.logger(`Timed out detecting DevTools for ${page.url()}`);
+            }
             mcpPage.devToolsPage = undefined;
+            return;
+          }
+          const devToolsPage = await resolveWithTimeout(
+            page.openDevTools(),
+            DEFAULT_TIMEOUT,
+          );
+          if (devToolsPage === undefined) {
+            this.logger(`Timed out opening DevTools for ${page.url()}`);
+            mcpPage.devToolsPage = undefined;
+          } else {
+            mcpPage.devToolsPage = devToolsPage;
           }
         } catch {
           mcpPage.devToolsPage = undefined;

tests/McpContext.test.ts

@@ -171,6 +171,38 @@ describe('McpContext', () => {
     });
   });
 
+  it('skips pages whose DevTools state does not resolve', async () => {
+    await withMcpContext(async (_response, context) => {
+      const page = context.getSelectedPptrPage();
+      const target = context.browser.targets().find(target => {
+        return target.type() === 'page';
+      });
+      assert.ok(target);
+      sinon.stub(target, 'page').resolves(page);
+      sinon.stub(context.browser, 'targets').returns([target]);
+      const hasDevTools = sinon.stub(page, 'hasDevTools').returns(
+        new Promise<boolean>(() => {
+          // Intentionally never resolves to mimic a stalled DevTools probe.
+        }),
+      );
+      const clock = sinon.useFakeTimers();
+
+      const detectionPromise = context.detectOpenDevToolsWindows();
+      for (let attempt = 0; attempt < 10 && !hasDevTools.called; attempt++) {
+        await clock.tickAsync(0);
+      }
+      assert.ok(hasDevTools.called);
+      let resolved = false;
+      void detectionPromise.then(() => {
+        resolved = true;
+      });
+      await clock.tickAsync(5_000);
+      await clock.tickAsync(0);
+
+      assert.strictEqual(resolved, true);
+    });
+  });
+
   it('resolves uid from a non-selected page snapshot', async () => {
     await withMcpContext(async (_response, context) => {
       // Page 1: set content and snapshot