perf(app): limit initial sidebar workspace rendering

Large project, status, and pinned groups now render 20 rows until expanded. Newly discovered workspaces are prepended without disturbing the saved order.

packages/app/src/hooks/sidebar-workspaces-view-model.test.ts

@@ -471,7 +471,7 @@ describe("computeSidebarOrderUpdates", () => {
     expect(updates).toEqual({ projectOrder: null, workspaceOrders: [] });
   });
 
-  it("appends unseen projects and workspaces to the persisted orders", () => {
+  it("appends unseen projects while putting unseen workspaces before the saved order", () => {
     const projects = [
       sidebarProject({ projectKey: "project-a", workspaceKeys: ["ws-1", "ws-2"] }),
       sidebarProject({ projectKey: "project-b", workspaceKeys: ["ws-3"] }),
@@ -485,11 +485,33 @@ describe("computeSidebarOrderUpdates", () => {
 
     expect(updates.projectOrder).toEqual(["project-a", "project-b"]);
     expect(updates.workspaceOrders).toEqual([
-      { projectKey: "project-a", order: ["srv:ws-1", "srv:ws-2"] },
+      { projectKey: "project-a", order: ["srv:ws-2", "srv:ws-1"] },
       { projectKey: "project-b", order: ["srv:ws-3"] },
     ]);
   });
 
+  it("preserves the saved workspace order behind multiple newly discovered workspaces", () => {
+    const projects = [
+      sidebarProject({
+        projectKey: "project-a",
+        workspaceKeys: ["newest", "newer", "old-a", "old-b"],
+      }),
+    ];
+
+    const updates = computeSidebarOrderUpdates({
+      projects,
+      persistedProjectOrder: ["project-a"],
+      getWorkspaceOrder: () => ["srv:old-b", "srv:old-a"],
+    });
+
+    expect(updates.workspaceOrders).toEqual([
+      {
+        projectKey: "project-a",
+        order: ["srv:newest", "srv:newer", "srv:old-b", "srv:old-a"],
+      },
+    ]);
+  });
+
   it("returns no project-order update when persisted order already covers visible keys", () => {
     const projects = [
       sidebarProject({ projectKey: "project-a", workspaceKeys: ["ws-1"] }),

packages/app/src/hooks/sidebar-workspaces-view-model.ts

@@ -477,6 +477,23 @@ export function appendMissingOrderKeys(input: {
   return [...input.currentOrder, ...missingKeys];
 }
 
+export function prependMissingOrderKeys(input: {
+  currentOrder: string[];
+  visibleKeys: string[];
+}): string[] {
+  if (input.visibleKeys.length === 0) {
+    return input.currentOrder;
+  }
+
+  const existingKeys = new Set(input.currentOrder);
+  const missingKeys = input.visibleKeys.filter((key) => !existingKeys.has(key));
+  if (missingKeys.length === 0) {
+    return input.currentOrder;
+  }
+
+  return [...missingKeys, ...input.currentOrder];
+}
+
 export interface SidebarOrderUpdates {
   projectOrder: string[] | null;
   workspaceOrders: Array<{ projectKey: string; order: string[] }>;
@@ -500,7 +517,7 @@ export function computeSidebarOrderUpdates(input: {
   const workspaceOrders: Array<{ projectKey: string; order: string[] }> = [];
   for (const project of input.projects) {
     const persistedWorkspaceOrder = input.getWorkspaceOrder(project.projectKey);
-    const nextWorkspaceOrder = appendMissingOrderKeys({
+    const nextWorkspaceOrder = prependMissingOrderKeys({
       currentOrder: persistedWorkspaceOrder,
       visibleKeys: project.workspaces.map((workspace) => workspace.workspaceKey),
     });