Follow the TDD workflow from CLAUDE.md strictly. Do not skip or reorder steps.

1. Ask the user: what feature should be implemented? (one sentence)
2. Check the current test suite passes before touching anything: run npm test. If it fails, stop and report — do not continue until the user confirms.
3. Write the Gherkin scenario in tests/features/<name>.feature. Use existing .feature files in that directory as style reference.
4. STOP — show the feature file to the user and wait for explicit approval before continuing.
5. Only after approval: write the failing Playwright test in tests/e2e/<name>.spec.js. Import helpers from tests/support/helpers.js. Follow the patterns in tests/CLAUDE.md.
6. Run npm test. Confirm the new test fails. If it passes already, the test is wrong — stop and report to the user.
7. Implement the feature in src/app.js following the patterns in src/CLAUDE.md:
   • Pure functions near related utilities at the top
   • Stateful behaviour inside boot() as closures
   • Route dataset data through StateManager
   • Update renderAll() or a render helper if the UI changes
   • Add read-only accessors to window.__wheel if tests need to inspect state
8. Run npm test. Confirm all tests pass, including the new ones.
9. Run npm run check (lint + format + audit). Fix any violations.
10. Report done: summarise what was added, which tests cover it, and confirm the full suite is green.