docs: address review scope and feature placement for #1032

src/layers/streetLevel/street-level-unique-tiles.test.mjs

@@ -1,15 +1,22 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
 import { tilesForBbox } from './tileMath.js';
-test('coarse dateline coverage counts each tile exactly once', () => {
-  for (const z of [0, 1, 2]) {
-    const result = tilesForBbox([170, -1, -170, 1], z);
-    const keys = result.tiles.map((t) => `${t.x}/${t.y}/${t.z}`);
-    assert.equal(new Set(keys).size, keys.length);
-    assert.equal(result.total, keys.length);
-    const limited = tilesForBbox([170, -1, -170, 1], z, { limit: 1 });
-    assert.equal(limited.total, keys.length);
-    assert.equal(limited.truncated, keys.length > 1);
-    assert.equal(limited.tiles.length, 1);
-  }
+
+test('reachable polar dateline coverage ranks 24 distinct tiles before overview truncation', () => {
+  // coverage uses the actual view bbox above zoom 1; polar views can wrap.
+  const bbox = [-10, 60, -20, 85];
+  const result = tilesForBbox(bbox, 3);
+  const keys = result.tiles.map((tile) => `${tile.x}/${tile.y}/${tile.z}`);
+  assert.equal(keys.length, 24);
+  assert.equal(new Set(keys).size, 24);
+  assert.equal(result.total, 24);
+  assert.equal(result.truncated, false);
+  const overview = tilesForBbox(bbox, 3, { limit: 16 });
+  assert.equal(overview.total, 24);
+  assert.equal(overview.tiles.length, 16);
+  assert.equal(
+    new Set(overview.tiles.map((tile) => `${tile.x}/${tile.y}/${tile.z}`)).size,
+    16,
+  );
+  assert.equal(overview.truncated, true);
 });