Writes the UI-layer tests of a use case (UC-XXX) for an Angular client with Vitest and Angular's own testing idioms: TestBed component tests for the routed page, HttpTestingController for the API boundary, DI overrides for non-HTTP services, and plain service tests — in UC-XXX-<slug>.spec.ts files with a describe('UC-XXX: …') block. Use when the user asks to "write frontend tests", "test the Angular component", "write a Vitest test", "unit test an Angular page", "test the UI of UC-001", or mentions TestBed, ComponentFixture, or HttpTestingController. Normally run by /use-case-test as the UI test layer of a project whose docs/architecture/stack.md names Angular; it can also be run directly. Browser tests against the running application are /playwright-e2e-test.