diff --git a/desktop/src/features/channels/ui/ChannelIdleAuxiliarySurface.tsx b/desktop/src/features/channels/ui/ChannelIdleAuxiliarySurface.tsx
new file mode 100644
index 0000000000..5263e86e1f
--- /dev/null
+++ b/desktop/src/features/channels/ui/ChannelIdleAuxiliarySurface.tsx
@@ -0,0 +1,86 @@
+import type * as React from "react";
+
+import { FocusThreadDrawer } from "@/features/channels/ui/FocusThreadDrawer";
+import {
+  IdleAuxiliaryPanel,
+  type IdleAuxiliaryHeaderControls,
+} from "@/features/channels/ui/IdleAuxiliaryPanel";
+
+type ChannelIdleAuxiliarySurfaceProps = {
+  canResetWidth: boolean;
+  channelName: string;
+  children: React.ReactNode;
+  headerControls?: IdleAuxiliaryHeaderControls;
+  /** Render the panel inside the cover drawer instead of the split pane. */
+  isCoverDrawer: boolean;
+  isSinglePanelView: boolean;
+  onClose: () => void;
+  onResetWidth: () => void;
+  onResizeStart: React.PointerEventHandler<HTMLButtonElement>;
+  title: string;
+  useSplitAuxiliaryPane: boolean;
+  widthPx: number;
+  /**
+   * Applies the split-pane presentation, including its resize affordances.
+   * Supplied by `ChannelPane` because that pane owns the resize state; the
+   * cover-drawer presentation is applied here.
+   */
+  wrapSplitPane: (panel: React.ReactNode) => React.ReactNode;
+};
+
+/**
+ * The channel's caller-owned idle auxiliary surface, in whichever presentation
+ * was resolved for it.
+ *
+ * Split out of `ChannelPane` alongside `ChannelAgentSessionSurface` so each
+ * auxiliary surface owns its own presentation wiring rather than adding another
+ * pair of closures to that component.
+ *
+ * It reuses `FocusThreadDrawer` rather than `CoverDrawer` directly, so the two
+ * cover presentations stay one surface with one test id; only the accessible
+ * label differs, which is why that label is a prop on the thread drawer.
+ */
+export function ChannelIdleAuxiliarySurface({
+  canResetWidth,
+  channelName,
+  children,
+  headerControls,
+  isCoverDrawer,
+  isSinglePanelView,
+  onClose,
+  onResetWidth,
+  onResizeStart,
+  title,
+  useSplitAuxiliaryPane,
+  widthPx,
+  wrapSplitPane,
+}: ChannelIdleAuxiliarySurfaceProps) {
+  const panel = (
+    <IdleAuxiliaryPanel
+      canResetWidth={canResetWidth}
+      headerControls={headerControls}
+      isFocusDrawer={isCoverDrawer}
+      isSinglePanelView={isSinglePanelView}
+      onClose={onClose}
+      onResetWidth={onResetWidth}
+      onResizeStart={onResizeStart}
+      title={title}
+      useSplitAuxiliaryPane={useSplitAuxiliaryPane}
+      widthPx={widthPx}
+    >
+      {children}
+    </IdleAuxiliaryPanel>
+  );
+
+  return isCoverDrawer ? (
+    <FocusThreadDrawer
+      channelName={channelName}
+      label={title || "Panel"}
+      onClose={onClose}
+    >
+      {panel}
+    </FocusThreadDrawer>
+  ) : (
+    wrapSplitPane(panel)
+  );
+}
diff --git a/desktop/src/features/channels/ui/ChannelPane.tsx b/desktop/src/features/channels/ui/ChannelPane.tsx
index 8b8a3769c1..cf25d9a4e5 100644
--- a/desktop/src/features/channels/ui/ChannelPane.tsx
+++ b/desktop/src/features/channels/ui/ChannelPane.tsx
@@ -27,10 +27,10 @@ import { buildVideoReviewPresentationByMessageId } from "@/features/messages/lib
 import { useComposerHeightPadding } from "@/features/messages/ui/useComposerHeightPadding";
 import { UserProfilePanel } from "@/features/profile/ui/UserProfilePanel";
 import { ChannelManagementAuxiliaryPanel } from "@/features/channels/ui/ChannelManagementAuxiliaryPanel";
-import { IdleAuxiliaryPanel } from "@/features/channels/ui/IdleAuxiliaryPanel";
 import { RightAuxiliaryPane } from "@/features/channels/ui/RightAuxiliaryPane";
 import { ThreadViewModeToggle } from "@/features/channels/ui/ThreadViewModeToggle";
 import { ChannelAgentSessionSurface } from "@/features/channels/ui/ChannelAgentSessionSurface";
+import { ChannelIdleAuxiliarySurface } from "@/features/channels/ui/ChannelIdleAuxiliarySurface";
 import { FocusThreadDrawer } from "@/features/channels/ui/FocusThreadDrawer";
 import { AGENT_SESSION_SURFACE_KEY } from "@/features/channels/lib/agentSessionPanelPresentation";
 import {
@@ -540,38 +540,32 @@ export const ChannelPane = React.memo(function ChannelPane({
     ) : (
       wrapAux(panel, "message-thread-panel", { key: THREAD_SURFACE_KEY })
     );
-  const wrapIdlePanel = (panel: React.ReactNode) =>
-    useFocusIdleDrawer && onCloseIdleAuxiliaryPanel ? (
-      <FocusThreadDrawer
-        channelName={activeChannel?.name ?? "channel"}
-        key="idle-auxiliary-surface"
-        label={idleAuxiliaryTitle || "Panel"}
-        onClose={onCloseIdleAuxiliaryPanel}
-      >
-        {panel}
-      </FocusThreadDrawer>
-    ) : (
-      wrapAux(panel, "idle-auxiliary-panel")
-    );
   const idleAuxiliarySurface =
-    idleAuxiliaryPanel && onCloseIdleAuxiliaryPanel
-      ? wrapIdlePanel(
-          <IdleAuxiliaryPanel
-            canResetWidth={canResetThreadPanelWidth}
-            headerControls={idleAuxiliaryHeaderActions}
-            isFocusDrawer={useFocusIdleDrawer}
-            isSinglePanelView={isSinglePanelView}
-            onClose={onCloseIdleAuxiliaryPanel}
-            onResetWidth={onResetThreadPanelWidth}
-            onResizeStart={onThreadPanelResizeStart}
-            title={idleAuxiliaryTitle}
-            useSplitAuxiliaryPane={useSplitAuxiliaryPane}
-            widthPx={threadPanelWidthPx}
-          >
-            {idleAuxiliaryPanel}
-          </IdleAuxiliaryPanel>,
-        )
-      : null;
+    idleAuxiliaryPanel && onCloseIdleAuxiliaryPanel ? (
+      <ChannelIdleAuxiliarySurface
+        // Keyed here, on `AnimatePresence`'s direct child, and deliberately
+        // per-presentation: the cover drawer and the split pane were distinct
+        // keys before this surface was extracted, so a viewport change that
+        // flips the presentation remounts exactly as it did then.
+        key={
+          useFocusIdleDrawer ? "idle-auxiliary-surface" : "idle-auxiliary-panel"
+        }
+        canResetWidth={canResetThreadPanelWidth}
+        channelName={activeChannel?.name ?? "channel"}
+        headerControls={idleAuxiliaryHeaderActions}
+        isCoverDrawer={useFocusIdleDrawer}
+        isSinglePanelView={isSinglePanelView}
+        onClose={onCloseIdleAuxiliaryPanel}
+        onResetWidth={onResetThreadPanelWidth}
+        onResizeStart={onThreadPanelResizeStart}
+        title={idleAuxiliaryTitle}
+        useSplitAuxiliaryPane={useSplitAuxiliaryPane}
+        widthPx={threadPanelWidthPx}
+        wrapSplitPane={(panel) => wrapAux(panel, "idle-auxiliary-panel")}
+      >
+        {idleAuxiliaryPanel}
+      </ChannelIdleAuxiliarySurface>
+    ) : null;
   const wrapAgentSessionSplitPane = (panel: React.ReactNode) =>
     wrapAux(panel, "agent-session-thread-panel", {
       key: AGENT_SESSION_SURFACE_KEY,