Keep large sidebars responsive (#1966)

* perf(app): keep large sidebars responsive

Sidebar rows rescanned every agent for each session update, multiplying work with both workspace and agent count. Build workspace activity once and share the derived sidebar model so updates scale with the underlying collections.

* test(app): use valid agent fixture for workspace restore

* refactor(app): keep sidebar model surface focused

packages/app/src/components/sidebar/sidebar-status-list.tsx

@@ -9,11 +9,7 @@ import {
   type SidebarStatusWorkspacePlacement,
   type SidebarWorkspaceEntry,
 } from "@/hooks/use-sidebar-workspaces-list";
-import {
-  buildStatusGroups,
-  buildStatusShortcutIndex,
-  type StatusGroup,
-} from "@/hooks/sidebar-status-view-model";
+import type { StatusGroup } from "@/hooks/sidebar-status-view-model";
 import { isWeb as platformIsWeb, isNative as platformIsNative } from "@/constants/platform";
 import { StyleSheet } from "react-native-unistyles";
 import type { Theme } from "@/styles/theme";
@@ -90,7 +86,7 @@ const archiveLeadingIcon = <ThemedArchive size={14} uniProps={foregroundMutedCol
 const renameLeadingIcon = <ThemedPencil size={14} uniProps={foregroundMutedColorMapping} />;
 
 interface StatusWorkspaceListProps {
-  workspaces: SidebarStatusWorkspacePlacement[];
+  groups: StatusGroup[];
   projectNamesByKey: Map<string, string>;
   shortcutIndexByWorkspaceKey: Map<string, number>;
   showShortcutBadges: boolean;
@@ -100,31 +96,19 @@ interface StatusWorkspaceListProps {
 }
 
 export function SidebarStatusWorkspaceList({
-  workspaces,
+  groups,
   projectNamesByKey,
-  shortcutIndexByWorkspaceKey: _projectShortcutIndex,
+  shortcutIndexByWorkspaceKey,
   showShortcutBadges,
   onWorkspacePress,
   hostLabelByServerId,
   showHostLabels,
 }: StatusWorkspaceListProps) {
-  const groups = useMemo(
-    () => buildStatusGroups(workspaces, projectNamesByKey),
-    [workspaces, projectNamesByKey],
-  );
   const collapsedStatusGroupKeys = useSidebarCollapsedSectionsStore(
     (state) => state.collapsedStatusGroupKeys,
   );
 
-  const statusShortcutIndex = useMemo(
-    () =>
-      showShortcutBadges
-        ? buildStatusShortcutIndex(
-            groups.filter((group) => !collapsedStatusGroupKeys.has(group.bucket)),
-          )
-        : new Map<string, number>(),
-    [collapsedStatusGroupKeys, groups, showShortcutBadges],
-  );
+  const statusShortcutIndex = showShortcutBadges ? shortcutIndexByWorkspaceKey : new Map();
 
   return (
     <View style={styles.container}>