fix(ui): align activity heading count with sidebar

src/App.test.tsx

@@ -2,7 +2,10 @@ import { describe, expect, it, vi, beforeEach } from "vitest";
 import { act, render, screen } from "@testing-library/react";
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
 import App from "./App";
+import { useGitHubData } from "./hooks/useGitHubData";
 import { useDashboardStore } from "./stores/dashboard";
+import type { Activity } from "./lib/types/github";
+import type { DashboardData, DashboardStats } from "./lib/types/dashboard";
 
 vi.mock("./lib/open", () => ({
   openUrl: vi.fn(),
@@ -18,16 +21,55 @@ vi.mock("./lib/tauri", async (importOriginal) => {
 });
 
 vi.mock("./hooks/useGitHubData", () => ({
-  useGitHubData: vi.fn().mockReturnValue({
-    dashboard: { syncedAt: "2026-03-28T10:00:00Z", reviewRequests: [], myPullRequests: [], assignedIssues: [], recentActivity: [], workspaces: [] },
-    stats: { pendingReviews: 3, openPrs: 5, openIssues: 2, totalWorkspaces: 1, unreadActivity: 0 },
+  useGitHubData: vi.fn(),
+}));
+
+function makeActivity(id: string): Activity {
+  return {
+    id,
+    activityType: "comment_added",
+    actor: "alice",
+    repoId: "repo-1",
+    pullRequestId: "pr-1",
+    issueId: null,
+    message: "Some comment",
+    isRead: false,
+    createdAt: "2026-03-28T10:00:00Z",
+  };
+}
+
+function makeGitHubDataMock(overrides?: {
+  readonly dashboard?: Partial<DashboardData>;
+  readonly stats?: Partial<DashboardStats>;
+}): ReturnType<typeof useGitHubData> {
+  return {
+    dashboard: {
+      syncedAt: "2026-03-28T10:00:00Z",
+      reviewRequests: [],
+      myPullRequests: [],
+      assignedIssues: [],
+      recentActivity: [],
+      workspaces: [],
+      ...overrides?.dashboard,
+    },
+    stats: {
+      pendingReviews: 3,
+      openPrs: 5,
+      openIssues: 2,
+      totalWorkspaces: 1,
+      unreadActivity: 0,
+      ...overrides?.stats,
+    },
     isLoading: false,
     error: null,
     authExpired: false,
+    syncError: null,
     forceSync: vi.fn(),
     isSyncing: false,
-  }),
-}));
+  };
+}
+
+const mockedUseGitHubData = vi.mocked(useGitHubData);
 
 function renderApp() {
   const queryClient = new QueryClient({
@@ -42,6 +84,7 @@ function renderApp() {
 
 describe("App layout", () => {
   beforeEach(() => {
+    mockedUseGitHubData.mockReturnValue(makeGitHubDataMock());
     useDashboardStore.setState({
       currentView: "overview",
       activeFilters: {},
@@ -104,6 +147,21 @@ describe("App layout", () => {
     expect(await screen.findByTestId("activity-feed")).toBeInTheDocument();
   });
 
+  it("should use unread activity stats for the activity heading", async () => {
+    mockedUseGitHubData.mockReturnValue(
+      makeGitHubDataMock({
+        dashboard: { recentActivity: [makeActivity("act-1")] },
+        stats: { unreadActivity: 149 },
+      }),
+    );
+    useDashboardStore.setState({ currentView: "feed" });
+
+    renderApp();
+
+    expect(await screen.findByTestId("activity-feed")).toBeInTheDocument();
+    expect(screen.getByRole("heading", { name: "Activity 149" })).toBeInTheDocument();
+  });
+
   it("should render settings view", async () => {
     useDashboardStore.setState({ currentView: "settings" });
     renderApp();
@@ -153,6 +211,7 @@ describe("App keyboard shortcuts", () => {
   let mockedOpenUrl: ReturnType<typeof vi.fn>;
 
   beforeEach(async () => {
+    mockedUseGitHubData.mockReturnValue(makeGitHubDataMock());
     // Use "feed" view — it has no useRegisterNavigableItems hook,
     // so pre-seeded navigableItems are preserved for keyboard tests.
     useDashboardStore.setState({

src/App.tsx

@@ -107,7 +107,7 @@ interface MainContentProps {
 }
 
 function MainContent({ view, onBackToDashboard }: MainContentProps): ReactElement {
-  const { dashboard } = useGitHubData();
+  const { dashboard, stats } = useGitHubData();
   const queryClient = useQueryClient();
 
   const markAllRead = useMutation({
@@ -184,6 +184,7 @@ function MainContent({ view, onBackToDashboard }: MainContentProps): ReactElemen
       return (
         <ActivityFeed
           activities={dashboard?.recentActivity ?? []}
+          headerCount={stats?.unreadActivity}
           onMarkAllRead={() => markAllRead.mutate()}
         />
       );

src/components/ActivityFeed/ActivityFeed.test.tsx

@@ -200,6 +200,19 @@ describe("ActivityFeed", () => {
     expect(screen.getByText("6")).toBeInTheDocument();
   });
 
+  it("should prefer an explicit header count over the visible activity count", () => {
+    render(
+      <ActivityFeed
+        activities={[commentActivity]}
+        headerCount={149}
+        onMarkAllRead={onMarkAllRead}
+      />,
+    );
+
+    expect(screen.getByRole("heading", { name: "Activity 149" })).toBeInTheDocument();
+    expect(screen.queryByRole("heading", { name: "Activity 1" })).not.toBeInTheDocument();
+  });
+
   it("should hide section header when hideHeader is true", () => {
     render(<ActivityFeed activities={allActivities} onMarkAllRead={onMarkAllRead} hideHeader />);
 

src/components/ActivityFeed/ActivityFeed.tsx

@@ -12,6 +12,7 @@ import { ActivityItem } from "./ActivityItem";
 
 interface ActivityFeedProps {
   readonly activities: readonly Activity[];
+  readonly headerCount?: number;
   readonly isLoading?: boolean;
   readonly onMarkAllRead: () => void;
   readonly hideHeader?: boolean;
@@ -56,6 +57,7 @@ function matchesFilter(activity: Activity, filter: FilterType): boolean {
 
 export function ActivityFeed({
   activities,
+  headerCount,
   isLoading = false,
   onMarkAllRead,
   hideHeader = false,
@@ -79,14 +81,15 @@ export function ActivityFeed({
       value.toLowerCase().includes(normalizedQuery),
     );
   });
+  const sectionCount = isLoading ? undefined : headerCount ?? visible.length;
 
   return (
     <section
       data-testid="activity-feed"
       aria-busy={isLoading ? "true" : undefined}
       className="flex flex-col gap-2"
     >
-      {!hideHeader && <SectionHead title="Activity" count={isLoading ? undefined : visible.length} />}
+      {!hideHeader && <SectionHead title="Activity" count={sectionCount} />}
 
       {isLoading ? (
         <>