perf(startup): lazy load task detail surfaces

src/renderer/components/layout/GlobalTaskDetailDialogSlot.test.tsx

@@ -0,0 +1,105 @@
+/* eslint-disable @typescript-eslint/naming-convention -- Component mocks mirror PascalCase exports. */
+import React, { act } from 'react';
+import { createRoot, type Root } from 'react-dom/client';
+
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+const mockState = vi.hoisted(() => ({
+  globalTaskDetail: null as null | { teamName: string; taskId: string },
+  dialogModuleLoads: 0,
+  dialogRenders: 0,
+}));
+
+vi.mock('@renderer/store', () => ({
+  useStore: <T,>(selector: (state: typeof mockState) => T): T => selector(mockState),
+}));
+
+vi.mock('../team/dialogs/GlobalTaskDetailDialog', () => {
+  mockState.dialogModuleLoads += 1;
+  return {
+    GlobalTaskDetailDialog: () => {
+      mockState.dialogRenders += 1;
+      return React.createElement('div', { 'data-testid': 'global-task-dialog' }, 'Task dialog');
+    },
+  };
+});
+
+/* eslint-enable @typescript-eslint/naming-convention -- Re-enable after component mocks. */
+
+import { GlobalTaskDetailDialogSlot } from './GlobalTaskDetailDialogSlot';
+
+const roots: Root[] = [];
+
+const flushReact = async (): Promise<void> => {
+  await Promise.resolve();
+  await Promise.resolve();
+  await new Promise<void>((resolve) => {
+    setTimeout(resolve, 0);
+  });
+};
+
+const createHarness = (): { host: HTMLDivElement; root: Root } => {
+  const host = document.createElement('div');
+  document.body.appendChild(host);
+  const root = createRoot(host);
+  roots.push(root);
+  return { host, root };
+};
+
+const renderSlot = async (root: Root): Promise<void> => {
+  await act(async () => {
+    root.render(<GlobalTaskDetailDialogSlot />);
+    await flushReact();
+  });
+};
+
+const waitForDialog = async (host: HTMLElement): Promise<void> => {
+  for (let attempt = 0; attempt < 10; attempt += 1) {
+    if (host.querySelector('[data-testid="global-task-dialog"]')) {
+      return;
+    }
+
+    await act(async () => {
+      await flushReact();
+    });
+  }
+
+  expect(host.querySelector('[data-testid="global-task-dialog"]')).not.toBeNull();
+};
+
+describe('GlobalTaskDetailDialogSlot', () => {
+  beforeEach(() => {
+    vi.stubGlobal('IS_REACT_ACT_ENVIRONMENT', true);
+    mockState.globalTaskDetail = null;
+    mockState.dialogModuleLoads = 0;
+    mockState.dialogRenders = 0;
+  });
+
+  afterEach(async () => {
+    await act(async () => {
+      for (const root of roots.splice(0)) {
+        root.unmount();
+      }
+      await flushReact();
+    });
+    document.body.innerHTML = '';
+    vi.unstubAllGlobals();
+  });
+
+  it('does not import the heavy task dialog until a global task is opened', async () => {
+    const { host, root } = createHarness();
+
+    await renderSlot(root);
+
+    expect(host.querySelector('[data-testid="global-task-dialog"]')).toBeNull();
+    expect(mockState.dialogModuleLoads).toBe(0);
+    expect(mockState.dialogRenders).toBe(0);
+
+    mockState.globalTaskDetail = { teamName: 'team-a', taskId: 'task-1' };
+    await renderSlot(root);
+    await waitForDialog(host);
+
+    expect(mockState.dialogModuleLoads).toBe(1);
+    expect(mockState.dialogRenders).toBeGreaterThan(0);
+  });
+});

src/renderer/components/layout/GlobalTaskDetailDialogSlot.tsx

@@ -0,0 +1,23 @@
+import { lazy, Suspense } from 'react';
+
+import { useStore } from '@renderer/store';
+
+const GlobalTaskDetailDialog = lazy(() =>
+  import('../team/dialogs/GlobalTaskDetailDialog').then((module) => ({
+    default: module.GlobalTaskDetailDialog,
+  }))
+);
+
+export const GlobalTaskDetailDialogSlot = (): React.JSX.Element | null => {
+  const isOpen = useStore((state) => state.globalTaskDetail !== null);
+
+  if (!isOpen) {
+    return null;
+  }
+
+  return (
+    <Suspense fallback={null}>
+      <GlobalTaskDetailDialog />
+    </Suspense>
+  );
+};

src/renderer/components/layout/Sidebar.test.tsx

@@ -9,6 +9,7 @@ const storeMock = vi.hoisted(() => ({
     sidebarCollapsed: false,
     toggleSidebar: vi.fn(),
   },
+  sessionsModuleLoads: 0,
 }));
 
 vi.mock('@renderer/store', () => ({
@@ -19,10 +20,13 @@ vi.mock('../sidebar/GlobalTaskList', () => ({
   GlobalTaskList: () => React.createElement('div', { 'data-testid': 'tasks-panel' }, 'Tasks panel'),
 }));
 
-vi.mock('../sidebar/DateGroupedSessions', () => ({
-  DateGroupedSessions: () =>
-    React.createElement('div', { 'data-testid': 'sessions-panel' }, 'Sessions panel'),
-}));
+vi.mock('../sidebar/DateGroupedSessions', () => {
+  storeMock.sessionsModuleLoads += 1;
+  return {
+    DateGroupedSessions: () =>
+      React.createElement('div', { 'data-testid': 'sessions-panel' }, 'Sessions panel'),
+  };
+});
 
 /* eslint-enable @typescript-eslint/naming-convention -- Re-enable after component mocks. */
 
@@ -33,6 +37,9 @@ const roots: Root[] = [];
 const flushReact = async (): Promise<void> => {
   await Promise.resolve();
   await Promise.resolve();
+  await new Promise<void>((resolve) => {
+    setTimeout(resolve, 0);
+  });
 };
 
 const createHarness = (): { host: HTMLDivElement; root: Root } => {
@@ -65,6 +72,7 @@ describe('Sidebar', () => {
     vi.stubGlobal('IS_REACT_ACT_ENVIRONMENT', true);
     storeMock.state.sidebarCollapsed = false;
     storeMock.state.toggleSidebar.mockClear();
+    storeMock.sessionsModuleLoads = 0;
   });
 
   afterEach(async () => {
@@ -85,6 +93,7 @@ describe('Sidebar', () => {
 
     expect(host.querySelector('[data-testid="tasks-panel"]')).not.toBeNull();
     expect(host.querySelector('[data-testid="sessions-panel"]')).toBeNull();
+    expect(storeMock.sessionsModuleLoads).toBe(0);
   });
 
   it('mounts the sessions panel on first activation and keeps it mounted when hidden', async () => {

src/renderer/components/layout/Sidebar.tsx

@@ -8,14 +8,13 @@
  * - Collapsible: Cmd+B to toggle (Notion-style)
  */
 
-import { useCallback, useEffect, useRef, useState } from 'react';
+import { lazy, Suspense, useCallback, useEffect, useRef, useState } from 'react';
 
 import { useStore } from '@renderer/store';
 import { formatShortcut } from '@renderer/utils/stringUtils';
 import { PanelLeft } from 'lucide-react';
 import { useShallow } from 'zustand/react/shallow';
 
-import { DateGroupedSessions } from '../sidebar/DateGroupedSessions';
 import { GlobalTaskList } from '../sidebar/GlobalTaskList';
 import { defaultTaskFiltersState } from '../sidebar/taskFiltersState';
 
@@ -23,6 +22,12 @@ import type { TaskFiltersState } from '../sidebar/taskFiltersState';
 
 type SidebarTab = 'tasks' | 'sessions';
 
+const DateGroupedSessions = lazy(() =>
+  import('../sidebar/DateGroupedSessions').then((module) => ({
+    default: module.DateGroupedSessions,
+  }))
+);
+
 const MIN_WIDTH = 200;
 const MAX_WIDTH = 500;
 const DEFAULT_WIDTH = 280;
@@ -202,7 +207,11 @@ export const Sidebar = (): React.JSX.Element => {
           hidden={sidebarTab !== 'sessions'}
           className="min-w-0 flex-1 overflow-hidden"
         >
-          {hasOpenedSessionsTab && <DateGroupedSessions />}
+          {hasOpenedSessionsTab && (
+            <Suspense fallback={null}>
+              <DateGroupedSessions />
+            </Suspense>
+          )}
         </div>
       </div>
 

src/renderer/components/layout/TabbedLayout.tsx

@@ -34,9 +34,9 @@ import { UpdateBanner } from '../common/UpdateBanner';
 import { UpdateDialog } from '../common/UpdateDialog';
 import { WorkspaceIndicator } from '../common/WorkspaceIndicator';
 import { CommandPalette } from '../search/CommandPalette';
-import { GlobalTaskDetailDialog } from '../team/dialogs/GlobalTaskDetailDialog';
 
 import { CustomTitleBar } from './CustomTitleBar';
+import { GlobalTaskDetailDialogSlot } from './GlobalTaskDetailDialogSlot';
 import { PaneContainer } from './PaneContainer';
 import { Sidebar } from './Sidebar';
 import { DragOverlayTab } from './SortableTab';
@@ -186,7 +186,7 @@ export const TabbedLayout = (): React.JSX.Element => {
           {activeTab ? <DragOverlayTab tab={activeTab} /> : null}
         </DragOverlay>
       </DndContext>
-      <GlobalTaskDetailDialog />
+      <GlobalTaskDetailDialogSlot />
       <UpdateDialog />
       <WorkspaceIndicator />
     </div>