diff --git a/apps/desktop/src/components/pane-shell/pane-visibility.ts b/apps/desktop/src/components/pane-shell/pane-visibility.ts
new file mode 100644
index 000000000000..e16975b5224e
--- /dev/null
+++ b/apps/desktop/src/components/pane-shell/pane-visibility.ts
@@ -0,0 +1,27 @@
+/**
+ * Keep-alive visibility — the one policy every document-wide lookup must obey.
+ *
+ * A tab group keeps each ever-active pane MOUNTED and hides the inactive ones
+ * with `visibility: hidden` (see `tree/renderer/tree-group.tsx`), deliberately
+ * preserving their layout box so scroll positions survive a tab round-trip. The
+ * cost is that an inactive tab's rect is IDENTICAL to the visible tab's, so
+ * neither selector order nor a rect hit-test can tell them apart. A lookup that
+ * resolves "the chat surface / composer / viewport" from the document therefore
+ * has to skip hidden panes, or it silently answers with the wrong tab.
+ */
+
+/** Marks a mounted-but-hidden pane layer (an inactive tab in a stack). */
+export const PANE_HIDDEN_ATTR = 'data-pane-hidden'
+
+const HIDDEN_PANE = `[${PANE_HIDDEN_ATTR}]`
+
+/** Spread onto a kept pane layer so the lookups below can skip it. */
+export const hiddenPaneProps = (hidden: boolean): Record<string, string> => (hidden ? { [PANE_HIDDEN_ATTR]: '' } : {})
+
+/** `querySelectorAll` minus anything inside an inactive tab. */
+export const queryAllVisible = <T extends HTMLElement>(selector: string, root: ParentNode = document): T[] =>
+  [...root.querySelectorAll<T>(selector)].filter(el => !el.closest(HIDDEN_PANE))
+
+/** `querySelector` minus anything inside an inactive tab. */
+export const queryVisible = <T extends HTMLElement>(selector: string, root: ParentNode = document): null | T =>
+  queryAllVisible<T>(selector, root)[0] ?? null
diff --git a/apps/desktop/src/components/pane-shell/tree/renderer/tree-group.tsx b/apps/desktop/src/components/pane-shell/tree/renderer/tree-group.tsx
index 0d14929b4210..6df3e2163dfc 100644
--- a/apps/desktop/src/components/pane-shell/tree/renderer/tree-group.tsx
+++ b/apps/desktop/src/components/pane-shell/tree/renderer/tree-group.tsx
@@ -30,6 +30,7 @@ import { cn } from '@/lib/utils'
 
 import { $layoutEditMode } from '../../edit-mode'
 import { useWindowControlsOverlap } from '../../geometry'
+import { hiddenPaneProps } from '../../pane-visibility'
 import type { DropPosition, GroupNode, RootEdge } from '../model'
 import { adjacentGroup } from '../model'
 import {
@@ -520,7 +521,9 @@ export function TreeGroup({
       {/* Body: the zone's pane content — every kept (ever-active) pane stays
           mounted in an absolute layer; only the active one is visible.
           `visibility` (not display) keeps the hidden pane's layout box, so
-          scroll positions and measurements survive the round-trip. */}
+          scroll positions and measurements survive the round-trip — which also
+          makes a hidden layer's rect identical to the visible one's, hence the
+          marker document-wide lookups filter on (see pane-visibility.ts). */}
       {!node.minimized && (
         <div className="relative min-h-0 min-w-0 flex-1 overflow-hidden">
           {isEmpty ? (
@@ -538,6 +541,7 @@ export function TreeGroup({
                   aria-hidden={!isActive || undefined}
                   className={cn('absolute inset-0 overflow-auto', !isActive && 'pointer-events-none invisible')}
                   key={paneId}
+                  {...hiddenPaneProps(!isActive)}
                 >
                   {pane?.render ? (
                     <ContribBoundary id={pane.id}>{pane.render()}</ContribBoundary>