Replace geometric sub-regions with real historical regions (v0.13.0)

Part of #16

CHANGELOG.md

@@ -2,6 +2,13 @@
 
 All notable changes to **History** are listed here, newest first.
 
+## v0.13.0 — 2026-10-12 08:30
+- **Replaced the geometric sub-region grid with real named sub-national administrative regions (#16, PR 2).** The choropleth source `public/regions.geo.json` now contains real named administrative regions — states, provinces, governorates, oblasts, … (Natural Earth admin-1, 1:10m) — instead of the abstract ~100–200 km geometric grid. Each region keeps a stable `id` and a `name`. The map's data contract is **unchanged** (`properties.parent` → the parent country's ISO_A3, `properties.name` → the region name), so no change to the map code or the LLM contract: `WorldMap.tsx`, `App.tsx`, `shared/protocol.ts`, and `server/map.ts` all keep working as-is.
+- **Generator rewritten** — `scripts/generate-regions.mjs` (same path, dependency-free, `npm run generate:regions`) now groups the admin-1 features by their `adm0_a3` (the parent's ISO_A3), keeps only parents in the 177-country set, and id's each region with its ISO 3166-2 code when present (e.g. `US-CA`, `FR-75`, `RU-MOW`) else `<ISO_A3>-<nn>`; within a country, ids are disambiguated with a `-2/-3/…` suffix on collision (ISO 3166-2 codes are not always unique within a country — e.g. all nine of Bosnia's entities report `BA-BIH`). A country with no admin-1 data would collapse to one whole-country region `<ISO_A3>-01` (0 are needed at 1:10m, which covers all 177). Coordinates are rounded to 4 decimal places, and the file is Douglas–Peucker-simplified only if it exceeds the ~8 MB guard. Output is sorted by (parent, id) and fully deterministic.
+- **The dataset is 4,138 regions covering all 177 countries**, 2,831 KB (2.76 MB) after Douglas–Peucker (the 4-dp base is ~23 MB). Per-country region count: min 1 / median 15 / max 232 (United Kingdom). There are **0 whole-country fallbacks** — 1:10m admin-1 covers every one of the 177 (the five single-region countries are SOL, SAH, CYN, PRI, FLK). Samples: `US-CA` California and `US-NY` New York (US); `FR-75` Paris and `FR-13` Bouches-du-Rhône (France); `RU-MOW` Moskovskaya (Russia).
+- **Validation test updated** — `scripts/regions.test.ts` was rewritten for the new dataset: well-formed features, globally unique ids, all 177 countries covered (≥1 region each), sane region areas (median ≥ 100 km², no non-Antarctica region ≥ 5,000,000 km² — Antarctica is exempt because its full-360° wrap ring breaks the planar area model), and each country's region area summing to within [40%, 175%] of its own area (median within [70%, 130%] — the band is wider than a naive [40%, 110%] because Natural Earth's admin-1 polygons are digitized independently of the admin-0 country polygons and are not clipped to them). Runs in O(total vertices).
+- Part of #16.
+
 ## v0.12.0 — 2026-10-12 01:03
 - **Map now renders the sub-national regional dataset (#16, PR 2).** The choropleth source switches from `public/countries.geo.json` (177 countries) to `public/regions.geo.json` (**2,597 sub-regions**): each country is subdivided into ~100–200 km regions, shown as a finer choropleth with thin internal border lines. The MapLibre source/layer ids are renamed `countries`/`countries-fill`/`countries-line` → `regions`/`regions-fill`/`regions-line`, and the border line is thinned to `0.75` (from `1.25`) so the subdivision reads within each country.
 - **Ownership stays at country granularity.** A nation still owns whole countries, so every sub-region of a country shares that country's owning-nation color (the fill is "same colors as the country map, but subdivided"). The owner of a sub-region is resolved from the RegionMap via the feature's `properties.parent` (the parent country's ISO_A3) — never the sub-region id (`FRA-03`) nor the repacked top-level `feature.id`. Clicking a sub-region switches the dossier to its parent country's owning nation (unchanged behavior); the hover tooltip now also shows the sub-region name + its parent country; a small "Selected …" label appears in the dossier after a map click.