feat: split RU-ARK into mainland + New Earth + Severnaya Zemlya — idempotent stage, manifests 1,798 (v0.25.0, #31)

scripts/regions.test.ts

@@ -530,16 +530,20 @@ describe('regions.geo.json', () => {
     );
   });
 
-  it('is at the v0.17 fixed point: 1,796 regions, 11,794 parts, 11,795 rings, 164,801 vertices, 1 hole (KZ-KZY)', () => {
+  it('is at the v0.25 fixed point: 1,798 regions, 11,794 parts, 11,795 rings, 164,801 vertices, 1 hole (KZ-KZY)', () => {
     // v0.17 (scripts/fill-gaps.mjs) APPENDED cleaned gap pieces to the v0.16
     // fixed point: it never moves an existing border, merges a part, or
     // removes a ring — it only adds new parts (+6,768: 5,026 → 11,794) and
-    // keeps the single KZ-KZY hole. The region count (1,796), the
-    // per-feature ids/names/parents and their order are unchanged; only the
-    // part/ring/vertex totals and the hole's part structure moved. Pinning
-    // the signature guards against a non-idempotent or destructive re-run.
-    // The fill is byte-deterministic per input and idempotent (a second run
-    // on the filled file changes nothing).
+    // keeps the single KZ-KZY hole. The v0.25 Arkhangel'sk split (#31,
+    // scripts/split-arkhangel.mjs) then repartitioned the 78 RU-ARK parts
+    // across three features (RU-ARK + RU-ARK-NE + RU-ARK-SZ) — a pure
+    // re-grouping: no part/ring/vertex moves, so only the region count
+    // changed (1,796 → 1,798); the part/ring/vertex totals, the per-feature
+    // ids/names/parents, and the feature order (the two new features sit
+    // immediately after RU-ARK) are as pinned below. Pinning the signature
+    // guards against a non-idempotent or destructive re-run; both stages are
+    // byte-deterministic per input and idempotent (a second run changes
+    // nothing).
     const polysOf = (g: Geometry) => (g.type === 'Polygon' ? [g.coordinates] : g.coordinates);
     let verts = 0,
       rings = 0,
@@ -556,15 +560,53 @@ describe('regions.geo.json', () => {
         for (const ring of poly) verts += ring.length;
       }
     }
-    expect(regions.features.length, 'region count').toBe(1796); // unchanged by the fill
-    expect(parts, 'parts').toBe(11_794); // v0.16: 5,026 → +6,768 appended gap pieces
+    expect(regions.features.length, 'region count').toBe(1798); // v0.17: 1,796 → +2 by the #31 split
+    expect(parts, 'parts').toBe(11_794); // v0.16: 5,026 → +6,768 appended gap pieces; unchanged by the split
     expect(rings, 'rings').toBe(11_795); // every appended part is a single-ring polygon (+1 hole = KZ-KZY, pre-existing)
     expect(holes, 'holes').toBe(1); // the single KZ-KZY hole, unchanged
     expect(holeIds, 'the one remaining hole is KZ-KZY').toEqual(['KZ-KZY']);
-    expect(verts, 'total vertices (incl. ring closure)').toBe(164_801); // v0.16: 111,175
+    expect(verts, 'total vertices (incl. ring closure)').toBe(164_801); // v0.16: 111,175; unchanged by the split
     console.log(
-      `\n  v0.17 gap fill: ${regions.features.length} regions, ${parts} parts, ${rings} rings, ` +
-        `${holes} hole (KZ-KZY), ${verts} vertices — v0.16 topology preserved, 6,768 gap pieces appended`,
+      `\n  v0.25 fixed point: ${regions.features.length} regions (1,796 + the #31 split's two islands), ` +
+        `${parts} parts, ${rings} rings, ${holes} hole (KZ-KZY), ${verts} vertices — v0.17 topology preserved`,
+    );
+  });
+
+  it('has the three Arkhangel\'sk features split per #31 (RU-ARK main + New Earth + Severnaya Zemlya)', () => {
+    // v0.25 (#31): the ~411,500 km² RU-ARK mega-region (a 78-part MultiPolygon
+    // mixing mainland and far-north islands) was repartitioned by part
+    // centroid into the mainland (RU-ARK, keeps its id/name/key), the Franz
+    // Josef Land islets (RU-ARK-NE "New Earth", centroid lat ≥ 79.5) and the
+    // Severnaya Zemlya islets (RU-ARK-SZ, centroid 76–79.5° N, lon ≥ 55°E).
+    // Pure re-grouping: all three keep parent RUS and all 78 original parts.
+    const byId = new Map(regions.features.map((f) => [f.id, f]));
+    const ark = byId.get('RU-ARK');
+    const ne = byId.get('RU-ARK-NE');
+    const sz = byId.get('RU-ARK-SZ');
+    expect(ark, 'RU-ARK (the main feature) exists').toBeDefined();
+    expect(ne, 'RU-ARK-NE (New Earth) exists').toBeDefined();
+    expect(sz, 'RU-ARK-SZ (Severnaya Zemlya) exists').toBeDefined();
+    for (const f of [ark!, ne!, sz!]) {
+      expect(f.properties.parent, `${f.id} parent`).toBe('RUS');
+      expect(f.geometry.type, `${f.id} geometry`).toBe('MultiPolygon');
+    }
+    expect(ark!.properties.name, 'RU-ARK keeps its name').toBe("Arkhangel'sk");
+    expect(ne!.properties.name, 'RU-ARK-NE name').toBe('New Earth');
+    expect(sz!.properties.name, 'RU-ARK-SZ name').toBe('Severnaya Zemlya');
+    // the 78 parts of the pre-split feature are all accounted for, verbatim
+    const countParts = (f: (typeof regions.features)[number]) =>
+      f.geometry.type === 'MultiPolygon' ? f.geometry.coordinates.length : 1;
+    expect(
+      countParts(ark!) + countParts(ne!) + countParts(sz!),
+      'total parts across the three features',
+    ).toBe(78);
+    // stable file order: the two new features sit immediately after RU-ARK
+    const idx = regions.features.findIndex((f) => f.id === 'RU-ARK');
+    expect(regions.features[idx + 1]?.id).toBe('RU-ARK-NE');
+    expect(regions.features[idx + 2]?.id).toBe('RU-ARK-SZ');
+    console.log(
+      `\n  #31 split: RU-ARK ${countParts(ark!)} parts (mainland), RU-ARK-NE ${countParts(ne!)} parts (New Earth), ` +
+        `RU-ARK-SZ ${countParts(sz!)} parts (Severnaya Zemlya)`,
     );
   });
 });