Keep sidebar pins visible while reopening (#2210)

* fix(app): keep sidebar pins visible while reopening

Hidden sidebars stop consuming live workspace updates but retain their last rendered entries so the opening animation never exposes an empty list.

* test(app): reuse sidebar pin flow

packages/app/e2e/helpers/sidebar.ts

@@ -39,6 +39,13 @@ export async function clickArchiveWorkspaceMenuItem(
   await archiveItem.click();
 }
 
+export async function pinWorkspaceFromSidebar(page: Page, workspaceId: string): Promise<void> {
+  const serverId = await openWorkspaceSidebarKebab(page, workspaceId);
+  const pinItem = page.getByTestId(`sidebar-workspace-menu-pin-${serverId}:${workspaceId}`);
+  await expect(pinItem).toBeVisible({ timeout: 10_000 });
+  await pinItem.click();
+}
+
 export async function archiveWorkspaceFromSidebar(page: Page, workspaceId: string): Promise<void> {
   // A clean workspace archives with no prompt. Managed worktree backing may raise
   // a browser confirm for unsynced work, so accept it when present.

packages/app/e2e/sidebar-workspace.spec.ts

@@ -6,6 +6,7 @@ import {
   expectMobileAgentSidebarHidden,
   expectMobileAgentSidebarVisible,
   openMobileAgentSidebar,
+  pinWorkspaceFromSidebar,
 } from "./helpers/sidebar";
 import { seedWorkspace } from "./helpers/seed-client";
 import { expectWorkspaceHeader } from "./helpers/workspace-ui";
@@ -168,6 +169,30 @@ test.describe("Mobile sidebar panelState transition", () => {
     await closeMobileAgentSidebar(page);
     await expectMobileAgentSidebarHidden(page);
   });
+
+  test("keeps a pinned workspace rendered while the retained sidebar is closed", async ({
+    page,
+  }) => {
+    const workspace = await seedWorkspace({ repoPrefix: "sidebar-retained-pin-" });
+
+    try {
+      await gotoAppShell(page);
+      await openMobileAgentSidebar(page);
+      await expectMobileAgentSidebarVisible(page);
+
+      const row = page.getByTestId(getWorkspaceRowTestId(workspace.workspaceId));
+      await expect(row).toBeVisible({ timeout: 30_000 });
+      await pinWorkspaceFromSidebar(page, workspace.workspaceId);
+      await expect(page.getByTestId("sidebar-pinned-section")).toBeVisible();
+
+      await closeMobileAgentSidebar(page);
+      await expectMobileAgentSidebarHidden(page);
+
+      await expect(row).toHaveCount(1);
+    } finally {
+      await workspace.cleanup();
+    }
+  });
 });
 
 test.describe("Half-screen desktop layout", () => {

packages/app/src/hooks/use-sidebar-workspace-entries.ts

@@ -38,7 +38,10 @@ export function useSidebarWorkspaceEntries(
   // subscription to structurally shared indexes, never one session-store
   // subscription per mounted row.
   return useMemo(() => {
-    if (!enabled || placements.length === 0 || sessions.length === 0) {
+    if (!enabled) {
+      return previousEntriesRef.current;
+    }
+    if (placements.length === 0 || sessions.length === 0) {
       previousEntriesRef.current = EMPTY_ENTRIES;
       return EMPTY_ENTRIES;
     }