MSW for frontend API mocking in tests

Brittle test suites often come from mocking fetch at every call site. MSW lets me mock at the network layer: components make real HTTP calls, but the test environment intercepts them and returns deterministic responses. That keeps tests closer to reality and makes refactors less painful. I also like that you can reuse the same handlers for Storybook, local development, and tests. The big lesson is centralizing mocks and treating them as ‘fake server behavior’ instead of function stubs. When a component changes its request shape, the test should fail loudly and obviously.