tddlisted

# TDD bug fix When fixing a bug with a clear, cheap test path, make the broken behavior executable before changing production code. The goal is a focused regression test that fails before the fix and passes after it. ## Workflow 1. **Understand the bug.** Identify the intended behavior, current behavior, affected path, and smallest observable reproduction. 2. **Choose the narrowest executable check.** Prefer the closest unit, component, integration, or regression test already used for that codepath. If none is practical, follow the rule below instead of building one from scratch. 3. **Write the failing test first.** Add the smallest focused test that would have caught the bug. The test should encode intended behavior, not mirror the current implementation. 4. **Run the new test before fixing.** Confirm it fails for the intended reason. If it passes or fails for an unrelated reason, correct the test or reproduction before editing the implementation. 5. **Fix the bug.** Make the smallest production change that satisfies the intended behavior while preserving nearby contracts. 6. **Rerun the regression test.** Confirm the test now passes. 7. **Run nearby validation.** Run relevant adjacent tests, type checks, lint, or scenario checks when the change has broader risk. ## If a failing test is impractical A test is impractical when it would require broad harness setup, brittle mocks, slow end-to-end infrastructure, production-only state, vague reproduction steps, or large unre