fix(ui): tighten analytics session and query contracts

ui/tests/setup/vitest-setup.ts

@@ -11,6 +11,8 @@ import { afterEach, vi } from 'vitest';
 // Cleanup after each test
 afterEach(() => {
   cleanup();
+  vi.restoreAllMocks();
+  vi.unstubAllGlobals();
 });
 
 // Mock matchMedia for components that use media queries

ui/tests/unit/components/analytics/session-stats-card.test.tsx

@@ -58,7 +58,7 @@ describe('SessionStatsCard', () => {
     expect(screen.getByText('No session data available')).toBeInTheDocument();
   });
 
-  it('uses the API total for overall session count while labeling subset averages as recent', () => {
+  it('keeps subset session metrics explicitly sample-scoped when pagination truncates the result set', () => {
     const data = buildPaginatedSessions({
       sessions: [
         buildSession({ sessionId: 'session-1', cost: 0.08 }),
@@ -84,8 +84,9 @@ describe('SessionStatsCard', () => {
 
     render(<SessionStatsCard data={data} />, { wrapper: AllProviders });
 
-    expect(screen.getByText('Total Sessions')).toBeInTheDocument();
-    expect(screen.getByText('9')).toBeInTheDocument();
+    expect(screen.getByText('Sampled Sessions')).toBeInTheDocument();
+    expect(screen.getByText('3')).toBeInTheDocument();
+    expect(screen.getByText('9 total')).toBeInTheDocument();
     expect(screen.getByText('Recent Avg Cost')).toBeInTheDocument();
     expect(screen.getAllByText('$0.08').length).toBeGreaterThan(0);
     expect(screen.getByText('codex')).toBeInTheDocument();

ui/tests/unit/ui/pages/analytics/usage-api-contract.test.ts

@@ -10,21 +10,22 @@ function jsonResponse(body: unknown) {
 
 describe('analytics usage API contract', () => {
   beforeEach(() => {
-    global.fetch = vi
-      .fn()
-      .mockImplementation(() => Promise.resolve(jsonResponse({ data: {} }))) as typeof fetch;
+    vi.stubGlobal(
+      'fetch',
+      vi.fn().mockImplementation(() => Promise.resolve(jsonResponse({ data: {} }))) as typeof fetch
+    );
   });
 
-  it('omits unsupported profile and months query params while keeping supported filters', async () => {
+  it('serializes only the supported analytics query params', async () => {
     const startDate = new Date(2026, 3, 1);
     const endDate = new Date(2026, 3, 30);
 
-    await usageApi.summary({ startDate, endDate, profile: 'work' });
-    await usageApi.trends({ startDate, endDate, profile: 'work' });
-    await usageApi.models({ startDate, endDate, profile: 'work' });
-    await usageApi.sessions({ startDate, endDate, profile: 'work', limit: 50, offset: 10 });
-    await usageApi.insights({ startDate, endDate, profile: 'work' });
-    await usageApi.monthly({ startDate, endDate, profile: 'work' });
+    await usageApi.summary({ startDate, endDate });
+    await usageApi.trends({ startDate, endDate });
+    await usageApi.models({ startDate, endDate });
+    await usageApi.sessions({ startDate, endDate, limit: 50, offset: 10 });
+    await usageApi.insights({ startDate, endDate });
+    await usageApi.monthly({ startDate, endDate });
 
     const urls = vi.mocked(global.fetch).mock.calls.map(([url]) => String(url));
 
@@ -34,7 +35,6 @@ describe('analytics usage API contract', () => {
     expect(urls).toContain('/api/usage/sessions?since=20260401&until=20260430&limit=50&offset=10');
     expect(urls).toContain('/api/usage/insights?since=20260401&until=20260430');
     expect(urls).toContain('/api/usage/monthly?since=20260401&until=20260430');
-    expect(urls.every((url) => !url.includes('profile='))).toBe(true);
     expect(urls.every((url) => !url.includes('months='))).toBe(true);
   });
 });