# Project notes for Claude

US County Climate Explorer: a static Leaflet app (`index.html`, `app.js`,
`styles.css`) over `data/climate-data.csv`, built by the Python scripts in
`scripts/`. The 12 filters are being reviewed one at a time before the CSV is
restructured; see [docs/pipeline-plan.md](docs/pipeline-plan.md).

## Guardrails

- Never rerun `scripts/build_county_climate_data.py` over
  `data/climate-data.csv`. It drops live columns and overwrites `koppenZone`
  (pipeline plan §7).
- Change one filter at a time. After every apply step, run the checker and
  compare changed counties against expectations.
- Run scripts from the project root with the virtual environment:
  - `.venv\Scripts\python.exe scripts\check_climate_data.py`
  - `.venv\Scripts\python.exe -m unittest discover -s tests`
- When `app.js` or the data files change, bump `APP_ASSET_VERSION` in `app.js`
  (it also versions the CSV and GeoJSON URLs) and the matching `app.js?v=`
  query in `index.html`. `styles.css` has its own query in `index.html`.
- The map and every filter cover the 50 states and DC. Puerto Rico rows stay in
  the data files but are never shown.
- Do not start the Phase 3 CSV restructure until all 12 filters are reviewed.

## Writing

- Write "Köppen" with the umlaut in prose, UI text, help text, and messages.
  Use ASCII `koppen` only in identifiers, file names, and data paths.

## Documentation layout

Each fact has one home:

- `docs/pipeline-plan.md`: current pipeline, target design, phases, the
  per-filter checklist (§5), the filter tracker (§6), and guardrails (§7).
  Keep it about 200 lines.
- `docs/reviews/`: one file per filter with its findings, decision links, and
  tasks; `00-cross-filter.md` for findings that affect several filters.
  `docs/reviews/README.md` has the numbering conventions and the finding index.
- `docs/decisions.md`: open decisions and a dated log of decided ones. An item
  leaves "Open decisions" only when the project owner decides it.
- `docs/filter-calculations.md`: what each calculation is. No review status.
- `scripts/common/README.md`: rules for shared helpers.

Keep the tracker status in the plan and the review-file checkboxes in sync.