fix(chrome): sample geometry after instant scroll, cap artifact pageT…

…itle - mouse_click and element screenshot now scroll with behavior:'instant': the default 'auto' follows the page's scroll-behavior CSS, so on smooth-scroll pages the geometry was sampled while the scroll animation was still in flight and clicks landed at stale coordinates while still reporting success - save_as_pdf caps page-controlled pageTitle at 1 KiB: document.title is uncapped page input riding the unchunked metadata frame and could exceed the daemon's WS maxPayload, dropping the bridge for every session - regression tests pin the instant-scroll declaration and the title cap
yiliang114 · Aug 7, 2026 · Aug 8, 2026 · Aug 8, 2026 · Aug 8, 2026 · Aug 9, 2026
commit 736eb9a68960b0955ede1bacb8200f752dac6269
diff --git a/packages/chrome-extension/src/background/web-bridge-actions.test.ts b/packages/chrome-extension/src/background/web-bridge-actions.test.ts
@@ -866,6 +866,14 @@ describe('WebBridge actions', () => {
       'Input.dispatchMouseEvent',
       expect.objectContaining({ type: 'mousePressed', x: 20, y: 30 }),
     );
+    // Coordinates are sampled after the scroll: it must not be a smooth
+    // animation still in flight when getBoxModel measures the box.
+    expect(cdp.send).toHaveBeenCalledWith(
+      'Runtime.callFunctionOn',
+      expect.objectContaining({
+        functionDeclaration: expect.stringContaining("behavior: 'instant'"),
+      }),
+    );
   });
 
   it('keeps a delivered mouse click successful if navigation clears metadata', async () => {
@@ -1703,6 +1711,22 @@ describe('WebBridge actions', () => {
     );
   });
 
+  it('caps page-controlled pageTitle in the PDF metadata frame', async () => {
+    // document.title is page-controlled and rides the unchunked metadata
+    // frame; an uncapped multi-MiB title would exceed the daemon's WS
+    // maxPayload and drop the bridge for every session.
+    cdp.send
+      .mockResolvedValueOnce({ data: 'cGRm' })
+      .mockResolvedValueOnce({ result: { value: 't'.repeat(4096) } });
+    const { executeWebBridgeAction } = await loadActions();
+
+    const result = (await executeWebBridgeAction('save_as_pdf', {
+      _tabId: 17,
+    })) as { pageTitle: string };
+
+    expect(result.pageTitle).toHaveLength(1024);
+  });
+
   it('captures element screenshots in document coordinates', async () => {
     cdp.send
       .mockResolvedValueOnce({ result: { objectId: 'button-1' } })

diff --git a/packages/chrome-extension/src/background/web-bridge-actions.ts b/packages/chrome-extension/src/background/web-bridge-actions.ts
@@ -525,7 +525,7 @@ async function mouseClick(args: Args): Promise<unknown> {
     await send('Runtime.callFunctionOn', {
       objectId,
       functionDeclaration:
-        "function() { this.scrollIntoView({ block: 'center', inline: 'center' }); }",
+        "function() { this.scrollIntoView({ block: 'center', inline: 'center', behavior: 'instant' }); }",
     });
     const box = record(await send('DOM.getBoxModel', { objectId }));
     const content = record(box['model'])['content'];
@@ -804,7 +804,7 @@ async function screenshot(args: Args): Promise<unknown> {
       await send('Runtime.callFunctionOn', {
         objectId,
         functionDeclaration:
-          "function() { this.scrollIntoView({ block: 'center', inline: 'center' }); }",
+          "function() { this.scrollIntoView({ block: 'center', inline: 'center', behavior: 'instant' }); }",
       });
       const box = record(await send('DOM.getBoxModel', { objectId }));
       const border = record(box['model'])['border'];
@@ -879,7 +879,13 @@ async function saveAsPdf(args: Args): Promise<unknown> {
           returnByValue: true,
         }),
       );
-      pageTitle = string(record(titleResult['result'])['value']) ?? '';
+      // document.title is page-controlled and rides the unchunked metadata
+      // frame — cap it so a multi-MiB title cannot exceed the daemon's WS
+      // maxPayload and take down the bridge for every session.
+      pageTitle = (string(record(titleResult['result'])['value']) ?? '').slice(
+        0,
+        1024,
+      );
     } catch {
       // Metadata is optional.
     }