fix(browser): stop a cancelled drag from leaving every browser tab unclickable (#26986)

The webview registry made every webview click-through on dragstart and only
restored it on dragend or drop. A dragstart that something cancels (for
example pressing and moving an agent logo in the tab strip, which the tab drag
sensor cancels) never starts a drag, so neither event fires and every existing
browser tab ignores clicks until a later full drag or a reload.

A live native drag delivers no pointer events to the page, so any pointerdown
or pointermove now ends the native-drag passthrough. Renderer pointer drags
hold their own passthrough tokens and are unaffected.

src/renderer/src/components/browser-pane/host-guest/webview-registry.test.ts

@@ -76,7 +76,13 @@ describe('webview registry drag listeners', () => {
 
     registerPersistentWebview('page-1', createWebview())
 
-    expect(addedListeners.map((entry) => entry.type)).toEqual(['dragstart', 'dragend', 'drop'])
+    expect(addedListeners.map((entry) => entry.type)).toEqual([
+      'dragstart',
+      'dragend',
+      'drop',
+      'pointerdown',
+      'pointermove'
+    ])
   })
 
   it('removes drag listeners after the last webview is destroyed', async () => {
@@ -86,7 +92,7 @@ describe('webview registry drag listeners', () => {
     registerPersistentWebview('page-1', createWebview())
     registerPersistentWebview('page-2', createWebview())
 
-    expect(addedListeners).toHaveLength(3)
+    expect(addedListeners).toHaveLength(5)
 
     destroyPersistentWebview('page-1')
 
@@ -94,7 +100,13 @@ describe('webview registry drag listeners', () => {
 
     destroyPersistentWebview('page-2')
 
-    expect(removedListeners.map((entry) => entry.type)).toEqual(['dragstart', 'dragend', 'drop'])
+    expect(removedListeners.map((entry) => entry.type)).toEqual([
+      'dragstart',
+      'dragend',
+      'drop',
+      'pointerdown',
+      'pointermove'
+    ])
     expect(unregisterGuestMock).toHaveBeenCalledWith({ browserPageId: 'page-1' })
     expect(unregisterGuestMock).toHaveBeenCalledWith({ browserPageId: 'page-2' })
   })
@@ -124,13 +136,35 @@ describe('webview registry drag listeners', () => {
     expect(secondWebview.style.pointerEvents).toBe('auto')
   })
 
+  it('releases native drag passthrough when a cancelled dragstart never starts a drag', async () => {
+    const { registerPersistentWebview } = await import('./webview-registry')
+    const webview = createWebview()
+    webview.style.pointerEvents = 'auto'
+    registerPersistentWebview('page-1', webview)
+    const listener = (type: string): ((event: Event) => void) => {
+      const found = addedListeners.find((entry) => entry.type === type)?.listener
+      if (typeof found !== 'function') {
+        throw new Error(`${type} listener missing`)
+      }
+      return found
+    }
+
+    for (const pointerType of ['pointermove', 'pointerdown']) {
+      listener('dragstart')(new Event('dragstart'))
+      expect(webview.style.pointerEvents).toBe('none')
+      // No dragend or drop follows a cancelled dragstart; the next pointer event proves no drag is live.
+      listener(pointerType)(new Event(pointerType))
+      expect(webview.style.pointerEvents).toBe('auto')
+    }
+  })
+
   it('keeps one listener set across repeated registrations', async () => {
     const { registerPersistentWebview } = await import('./webview-registry')
 
     registerPersistentWebview('page-1', createWebview())
     registerPersistentWebview('page-2', createWebview())
 
-    expect(addedListeners).toHaveLength(3)
+    expect(addedListeners).toHaveLength(5)
   })
 
   it('profiles live webviews and registered browser guests for memory breadcrumbs', async () => {

src/renderer/src/components/browser-pane/host-guest/webview-registry.ts

@@ -44,6 +44,8 @@ type DragListenerRegistry = {
   dragstart: () => void
   dragend: () => void
   drop: () => void
+  pointerdown: () => void
+  pointermove: () => void
 }
 
 function getListenerHost(): (Window & { [DRAG_LISTENER_KEY]?: DragListenerRegistry }) | null {
@@ -62,6 +64,8 @@ function removeDragListeners(): void {
   window.removeEventListener('dragstart', existingListeners.dragstart, true)
   window.removeEventListener('dragend', existingListeners.dragend, true)
   window.removeEventListener('drop', existingListeners.drop, true)
+  window.removeEventListener('pointerdown', existingListeners.pointerdown, true)
+  window.removeEventListener('pointermove', existingListeners.pointermove, true)
   delete listenerHost[DRAG_LISTENER_KEY]
   dragListenersAttached = false
   nativeDragPassthroughRelease?.()
@@ -81,13 +85,19 @@ function ensureDragListeners(): void {
   const dragstart = (): void => setWebviewsDragPassthrough(true)
   const dragend = (): void => setWebviewsDragPassthrough(false)
   const drop = (): void => setWebviewsDragPassthrough(false)
+  // Why: a cancelled dragstart never starts a drag, so no dragend or drop follows and every webview
+  // would stay click-through. A live native drag delivers no pointer events, so one proves it is over.
+  const pointerdown = (): void => setWebviewsDragPassthrough(false)
+  const pointermove = (): void => setWebviewsDragPassthrough(false)
 
   window.addEventListener('dragstart', dragstart, true)
   window.addEventListener('dragend', dragend, true)
   window.addEventListener('drop', drop, true)
+  window.addEventListener('pointerdown', pointerdown, true)
+  window.addEventListener('pointermove', pointermove, true)
   // Why: only live webviews need drag passthrough listeners; removing them
   // when the registry empties keeps browserless sessions free of global hooks.
-  listenerHost[DRAG_LISTENER_KEY] = { dragstart, dragend, drop }
+  listenerHost[DRAG_LISTENER_KEY] = { dragstart, dragend, drop, pointerdown, pointermove }
   dragListenersAttached = true
 }