test: add project name display tests

- Add comprehensive tests for getProjectDisplayName function
- Test various path structures including worktrees, nested projects, and edge cases
- Include regression tests for the reported bug cases
- Create separate utility file for better testability

Fixes session stats display where wrong fragments were shown
Related to: #348 (quota display), #103 (context display)

ui/src/components/analytics/project-name-utils.ts

@@ -0,0 +1,30 @@
+/**
+ * Project Name Utility Functions
+ *
+ * Utility functions for extracting meaningful project names from file paths
+ */
+
+/**
+ * Extracts the leaf folder name from a project path
+ *
+ * This function takes a full project path and returns just the leaf folder name,
+ * which represents the actual project name that the user would recognize.
+ *
+ * Examples:
+ * - '/home/user/projects/my-app' → 'my-app'
+ * - '/Users/joe/Developer/share-pi' → 'share-pi'
+ * - '/Users/joe/Developer/ExaDev/.../worktrees/2026-01-08' → '2026-01-08'
+ *
+ * @param path - The full project path
+ * @returns The leaf folder name (project name)
+ */
+export function getProjectDisplayName(path: string): string {
+  if (!path) return '';
+
+  // Remove leading/trailing slashes and split into segments
+  const cleanPath = path.replace(/^\/|\/$/g, '');
+  const segments = cleanPath.split('/').filter(segment => segment.length > 0);
+
+  // Return the last segment (leaf folder name)
+  return segments[segments.length - 1] || '';
+}

ui/src/components/analytics/session-stats-card.tsx

@@ -13,6 +13,7 @@ import type { PaginatedSessions } from '@/hooks/use-usage';
 import { cn } from '@/lib/utils';
 import { formatDistanceToNow } from 'date-fns';
 import { usePrivacy, PRIVACY_BLUR_CLASS } from '@/contexts/privacy-context';
+import { getProjectDisplayName } from './project-name-utils';
 
 interface SessionStatsCardProps {
   data: PaginatedSessions | undefined;
@@ -152,16 +153,6 @@ export function SessionStatsCard({ data, isLoading, className }: SessionStatsCar
   );
 }
 
-function getProjectDisplayName(path: string): string {
-  if (!path) return '';
-
-  // Remove leading/trailing slashes and split into segments
-  const cleanPath = path.replace(/^\/|\/$/g, '');
-  const segments = cleanPath.split('/').filter(segment => segment.length > 0);
-
-  // Return the last segment (leaf folder name)
-  return segments[segments.length - 1] || '';
-}
 
 function formatCompact(num: number): string {
   if (num >= 1_000_000_000) return `${(num / 1_000_000_000).toFixed(1)}B`;

ui/tests/unit/components/analytics/project-name-display.test.ts

@@ -0,0 +1,127 @@
+/**
+ * Project Name Display Tests
+ * Unit tests for getProjectDisplayName function
+ */
+
+import { describe, it, expect } from 'vitest';
+
+// Import the function from the utility
+import { getProjectDisplayName } from '../../../../../src/components/analytics/project-name-utils';
+
+describe('getProjectDisplayName', () => {
+  describe('Simple project paths', () => {
+    it('returns the leaf folder name for simple paths', () => {
+      expect(getProjectDisplayName('/home/user/projects/my-app')).toBe('my-app');
+      expect(getProjectDisplayName('/Users/joe/Developer/share-pi')).toBe('share-pi');
+      expect(getProjectDisplayName('/var/www/html')).toBe('html');
+    });
+
+    it('handles paths without leading/trailing slashes', () => {
+      expect(getProjectDisplayName('home/user/projects/my-app')).toBe('my-app');
+      expect(getProjectDisplayName('Users/joe/Developer/share-pi')).toBe('share-pi');
+    });
+  });
+
+  describe('Complex project paths', () => {
+    it('returns leaf folder for worktree paths', () => {
+      expect(getProjectDisplayName('/Users/joe/Developer/ExaDev/Clients/Architect/repositories/architect/worktrees/2026-01-08')).toBe('2026-01-08');
+      expect(getProjectDisplayName('/home/user/workspaces/repo-name/worktrees/feature-branch')).toBe('feature-branch');
+      expect(getProjectDisplayName('/project/repo/worktrees/v2.0')).toBe('v2.0');
+    });
+
+    it('handles nested paths', () => {
+      expect(getProjectDisplayName('/home/user/projects/web-dashboard/src/components')).toBe('components');
+      expect(getProjectDisplayName('/opt/apps/my-app/lib/utils')).toBe('utils');
+    });
+  });
+
+  describe('Edge cases', () => {
+    it('handles empty string', () => {
+      expect(getProjectDisplayName('')).toBe('');
+    });
+
+    it('handles only slashes', () => {
+      expect(getProjectDisplayName('///')).toBe('');
+      expect(getProjectDisplayName('/')).toBe('');
+    });
+
+    it('handles single segment paths', () => {
+      expect(getProjectDisplayName('my-app')).toBe('my-app');
+      expect(getProjectDisplayName('project')).toBe('project');
+    });
+
+    it('handles paths with trailing slash', () => {
+      expect(getProjectDisplayName('/home/user/projects/my-app/')).toBe('my-app');
+      expect(getProjectDisplayName('/Users/joe/Developer/share-pi/')).toBe('share-pi');
+    });
+
+    it('handles paths with leading slash only', () => {
+      expect(getProjectDisplayName('/my-app')).toBe('my-app');
+      expect(getProjectDisplayName('/project')).toBe('project');
+    });
+  });
+
+  describe('Real-world examples from the bug report', () => {
+    it('displays correct project name for share-pi project', () => {
+      // Before fix: would show "pi"
+      // After fix: should show "share-pi"
+      const path = '/Users/joe/Developer/share-pi';
+      expect(getProjectDisplayName(path)).toBe('share-pi');
+    });
+
+    it('displays correct project name for worktree project', () => {
+      // Before fix: would show "08"
+      // After fix: should show "2026-01-08"
+      const path = '/Users/joe/Developer/ExaDev/Clients/Architect/repositories/architect.worktrees/2026-01-08';
+      expect(getProjectDisplayName(path)).toBe('2026-01-08');
+    });
+
+    it('displays correct project name for nested project', () => {
+      // Example: a project in a subdirectory
+      const path = '/home/user/dev/company/projects/web-app';
+      expect(getProjectDisplayName(path)).toBe('web-app');
+    });
+
+    it('displays correct project name for repo with worktrees', () => {
+      // Example: main repository
+      const path = '/Users/joe/Developer/my-repo';
+      expect(getProjectDisplayName(path)).toBe('my-repo');
+    });
+
+    it('displays correct project name for feature branch worktree', () => {
+      // Example: feature branch worktree
+      const path = '/Users/joe/Developer/my-repo/.git/worktrees/feature-x';
+      expect(getProjectDisplayName(path)).toBe('feature-x');
+    });
+  });
+
+  describe('Regression tests', () => {
+    it('does not return empty string for valid paths', () => {
+      const testCases = [
+        '/project',
+        '/home/user/app',
+        '/var/log/nginx',
+        '/tmp/test-file',
+      ];
+
+      testCases.forEach(path => {
+        const result = getProjectDisplayName(path);
+        expect(result).not.toBe('');
+        expect(result).not.toBeUndefined();
+        expect(result).not.toBeNull();
+      });
+    });
+
+    it('handles paths with special characters', () => {
+      expect(getProjectDisplayName('/home/user/my-project_v2')).toBe('my-project_v2');
+      expect(getProjectDisplayName('/home/user/project-with-dashes')).toBe('project-with-dashes');
+      expect(getProjectDisplayName('/home/user/project.with.dots')).toBe('project.with.dots');
+    });
+
+    it('handles numeric paths correctly', () => {
+      expect(getProjectDisplayName('/home/user/project123')).toBe('project123');
+      expect(getProjectDisplayName('/home/user/123project')).toBe('123project');
+      expect(getProjectDisplayName('/home/user/v1.2.3')).toBe('v1.2.3');
+    });
+  });
+});

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

@@ -0,0 +1,273 @@
+/**
+ * Session Stats Card Tests
+ * Unit tests for SessionStatsCard component with project name formatting
+ */
+
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { SessionStatsCard } from '../../../../../src/components/analytics/session-stats-card';
+import { AllProviders } from '../../../setup/test-utils';
+import type { PaginatedSessions } from '../../../../../src/hooks/use-usage';
+
+// Mock date-fns to return consistent dates
+const mockFormatDistanceToNow = vi.fn();
+vi.mock('date-fns', async () => {
+  const actual = await vi.importActual('date-fns');
+  return {
+    ...actual,
+    formatDistanceToNow: mockFormatDistanceToNow,
+  };
+});
+
+describe('SessionStatsCard', () => {
+  beforeEach(() => {
+    // Reset all mocks
+    vi.clearAllMocks();
+
+    // Mock formatDistanceToNow to return consistent values
+    mockFormatDistanceToNow.mockReturnValue('27 minutes ago');
+  });
+
+  describe('Loading and Empty States', () => {
+    it('renders loading skeleton when isLoading is true', () => {
+      render(<SessionStatsCard data={undefined} isLoading={true} />, { wrapper: AllProviders });
+
+      // Should have card structure with skeleton loading state
+      expect(screen.getByRole('generic')).toBeInTheDocument();
+    });
+
+    it('shows empty state when no data available', () => {
+      render(<SessionStatsCard data={undefined} />, { wrapper: AllProviders });
+
+      expect(screen.getByText('Session Stats')).toBeInTheDocument();
+      expect(screen.getByText('No session data available')).toBeInTheDocument();
+    });
+
+    it('shows empty state when sessions array is empty', () => {
+      const emptyData: PaginatedSessions = {
+        sessions: [],
+        total: 0,
+        page: 1,
+        pageSize: 10,
+      };
+
+      render(<SessionStatsCard data={emptyData} />, { wrapper: AllProviders });
+
+      expect(screen.getByText('Session Stats')).toBeInTheDocument();
+      expect(screen.getByText('No session data available')).toBeInTheDocument();
+    });
+  });
+
+  describe('Session Stats Display', () => {
+    const createMockSession = (projectPath: string, inputTokens: number, outputTokens: number, cost: number) => ({
+      sessionId: `session-${Math.random()}`,
+      projectPath,
+      inputTokens,
+      outputTokens,
+      cost,
+      lastActivity: new Date().toISOString(),
+    });
+
+    const mockData: PaginatedSessions = {
+      sessions: [
+        createMockSession('/home/user/projects/my-app', 1500, 2500, 0.08),
+        createMockSession('/home/user/workspaces/repo-name/worktrees/feature-branch', 2000, 3000, 0.12),
+        createMockSession('/Users/joe/Developer/share-pi', 1000, 2000, 0.05),
+      ],
+      total: 3,
+      page: 1,
+      pageSize: 10,
+    };
+
+    beforeEach(() => {
+      mockData.sessions = [
+        createMockSession('/home/user/projects/my-app', 1500, 2500, 0.08),
+        createMockSession('/home/user/workspaces/repo-name/worktrees/feature-branch', 2000, 3000, 0.12),
+        createMockSession('/Users/joe/Developer/share-pi', 1000, 2000, 0.05),
+      ];
+    });
+
+    it('displays session stats header', () => {
+      render(<SessionStatsCard data={mockData} />, { wrapper: AllProviders });
+
+      expect(screen.getByText('Session Stats')).toBeInTheDocument();
+    });
+
+    it('shows total sessions count', () => {
+      render(<SessionStatsCard data={mockData} />, { wrapper: AllProviders });
+
+      expect(screen.getByText('3')).toBeInTheDocument();
+      expect(screen.getByText('Total Sessions')).toBeInTheDocument();
+    });
+
+    it('calculates and displays average cost per session', () => {
+      render(<SessionStatsCard data={mockData} />, { wrapper: AllProviders });
+
+      // Average cost: (0.08 + 0.12 + 0.05) / 3 = 0.0833 → $0.08
+      expect(screen.getByText('$0.08')).toBeInTheDocument();
+      expect(screen.getByText('Avg Cost/Session')).toBeInTheDocument();
+    });
+
+    it('shows recent activity section', () => {
+      render(<SessionStatsCard data={mockData} />, { wrapper: AllProviders });
+
+      expect(screen.getByText('Recent Activity')).toBeInTheDocument();
+    });
+  });
+
+  describe('Project Name Formatting', () => {
+    it('displays correct project name for simple path', () => {
+      const mockData: PaginatedSessions = {
+        sessions: [
+          {
+            sessionId: '1',
+            projectPath: '/home/user/projects/my-app',
+            inputTokens: 1000,
+            outputTokens: 2000,
+            cost: 0.05,
+            lastActivity: new Date().toISOString(),
+          }
+        ],
+        total: 1,
+        page: 1,
+        pageSize: 10,
+      };
+
+      render(<SessionStatsCard data={mockData} />, { wrapper: AllProviders });
+
+      // Should show "my-app" instead of just "app"
+      expect(screen.getByTitle('/home/user/projects/my-app')).toHaveTextContent('my-app');
+    });
+
+    it('displays correct project name for worktree path', () => {
+      const mockData: PaginatedSessions = {
+        sessions: [
+          {
+            sessionId: '1',
+            projectPath: '/Users/joe/Developer/ExaDev/Clients/Architect/repositories/architect/worktrees/2026-01-08',
+            inputTokens: 1000,
+            outputTokens: 2000,
+            cost: 0.05,
+            lastActivity: new Date().toISOString(),
+          }
+        ],
+        total: 1,
+        page: 1,
+        pageSize: 10,
+      };
+
+      render(<SessionStatsCard data={mockData} />, { wrapper: AllProviders });
+
+      // Should show "2026-01-08" instead of just "08"
+      expect(screen.getByTitle('/Users/joe/Developer/ExaDev/Clients/Architect/repositories/architect/worktrees/2026-01-08'))
+        .toHaveTextContent('2026-01-08');
+    });
+
+    it('displays correct project name for shared project', () => {
+      const mockData: PaginatedSessions = {
+        sessions: [
+          {
+            sessionId: '1',
+            projectPath: '/Users/joe/Developer/share-pi',
+            inputTokens: 1000,
+            outputTokens: 2000,
+            cost: 0.05,
+            lastActivity: new Date().toISOString(),
+          }
+        ],
+        total: 1,
+        page: 1,
+        pageSize: 10,
+      };
+
+      render(<SessionStatsCard data={mockData} />, { wrapper: AllProviders });
+
+      // Should show "share-pi" instead of just "pi"
+      expect(screen.getByTitle('/Users/joe/Developer/share-pi')).toHaveTextContent('share-pi');
+    });
+
+    it('handles empty project path gracefully', () => {
+      const mockData: PaginatedSessions = {
+        sessions: [
+          {
+            sessionId: '1',
+            projectPath: '',
+            inputTokens: 1000,
+            outputTokens: 2000,
+            cost: 0.05,
+            lastActivity: new Date().toISOString(),
+          }
+        ],
+        total: 1,
+        page: 1,
+        pageSize: 10,
+      };
+
+      render(<SessionStatsCard data={mockData} />, { wrapper: AllProviders });
+
+      // Should not crash and show empty string
+      expect(screen.getByTitle('')).toHaveTextContent('');
+    });
+
+    it('handles project path with only slashes', () => {
+      const mockData: PaginatedSessions = {
+        sessions: [
+          {
+            sessionId: '1',
+            projectPath: '///',
+            inputTokens: 1000,
+            outputTokens: 2000,
+            cost: 0.05,
+            lastActivity: new Date().toISOString(),
+          }
+        ],
+        total: 1,
+        page: 1,
+        pageSize: 10,
+      };
+
+      render(<SessionStatsCard data={mockData} />, { wrapper: AllProviders });
+
+      // Should handle gracefully and show empty string
+      expect(screen.getByTitle('///')).toHaveTextContent('');
+    });
+  });
+
+  describe('Token Count Display', () => {
+    it('displays token counts in compact format', () => {
+      const mockData: PaginatedSessions = {
+        sessions: [
+          {
+            sessionId: '1',
+            projectPath: '/project/test',
+            inputTokens: 1500000, // 1.5M
+            outputTokens: 500000,  // 500K
+            cost: 0.10,
+            lastActivity: new Date().toISOString(),
+          }
+        ],
+        total: 1,
+        page: 1,
+        pageSize: 10,
+      };
+
+      render(<SessionStatsCard data={mockData} />, { wrapper: AllProviders });
+
+      expect(screen.getByText('2.0M toks')).toBeInTheDocument();
+    });
+  });
+
+  describe('Privacy Mode', () => {
+    it('blurs cost information when privacy mode is enabled', () => {
+      // This would require mocking the privacy context
+      // For now, just ensure the component renders with privacy mode
+      const { container } = render(
+        <SessionStatsCard data={mockData} />,
+        { wrapper: AllProviders }
+      );
+
+      // Component should render without errors
+      expect(container).toBeInTheDocument();
+    });
+  });
+});