Context

PR #874 added the Agent Profiles list and detail pages with thorough store/utility/property tests (78 new tests). However, the data composition hooks and page components have no unit tests.

Missing test files

Critical (established precedent in Dashboard page)

1. web/src/__tests__/hooks/useAgentsData.test.ts -- follow useDashboardData.test.ts pattern: mock useWebSocket, mock usePolling, verify mount fetch, verify channel bindings, verify return shape
2. web/src/__tests__/hooks/useAgentDetailData.test.ts -- verify mount/unmount lifecycle (clearDetail on unmount), derived data memoization, fetchMoreActivity offset calculation
3. web/src/__tests__/pages/AgentsPage.test.tsx -- follow DashboardPage.test.tsx pattern: mock the hook, test loading/error/normal rendering states
4. web/src/__tests__/pages/AgentDetailPage.test.tsx -- test skeleton/not-found/full-render states, verify useParams integration

Important

5. ActivityLog.test.tsx -- verify load-more button visibility and click handler
6. AgentGridView.test.tsx -- verify empty state and link URL encoding
7. AgentFilters.test.tsx -- verify store integration and empty-to-null mapping

Acceptance criteria

• All 4 critical test files created following existing patterns
• At least 3 important test files created
• All tests pass with npm --prefix web run test

Found during PR #874 review (pr-test-analyzer agent).