diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9ab3b03cc..1b71b6b09 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,9 @@
   the five borough cores load and `CCTV_NYC_MAX_SOURCES` changes the cap. The catalog-wide ceiling is
   unchanged; extra cameras share it round-robin with the other packs.
 
+- Street Level counts unique tiles before ranking so overlapping dateline halves
+  in polar views do not waste slots in the 16-tile overview budget.
+
 - Directions no longer shows a truncation notice for a route with exactly 200
   turns, and a roundabout at the 200th turn keeps its exit distance.
 
diff --git a/docs/CURRENT-STATE.md b/docs/CURRENT-STATE.md
index 054aff963..7f9c94ff4 100644
--- a/docs/CURRENT-STATE.md
+++ b/docs/CURRENT-STATE.md
@@ -3132,6 +3132,10 @@ sequence lines below 60 km; the proxy strips the unused `image` layer from z14
 tiles (12 MB → ~80 KB) and shares one upstream fetch between concurrent
 requests for a tile.
 
+Mapillary coverage ranks unique tile addresses before applying the 16-tile
+overview budget. Overlapping dateline halves in a polar view therefore do not
+waste overview slots on the same tile; loading already skips duplicate keys.
+
 On Google 3D (`photoreal`) at street zoom (in below 1,400 m above ground, out
 above 1,800 m) the surface mode switches from `draped` to `terrain`: draped
 lines land on roofs and tree tops, so `groundCast.js` instead places lines,
diff --git a/src/layers/streetLevel/street-level-unique-tiles.test.mjs b/src/layers/streetLevel/street-level-unique-tiles.test.mjs
new file mode 100644
index 000000000..52e7b6aea
--- /dev/null
+++ b/src/layers/streetLevel/street-level-unique-tiles.test.mjs
@@ -0,0 +1,31 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { tilesForBbox } from './tileMath.js';
+
+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);
+});
+
+test('a limit that fits every distinct tile is not spent on repeats', () => {
+  // Before de-duplication this box yielded 27 entries for 24 tiles, so a
+  // 24-slot overview held repeats and still reported itself truncated.
+  const result = tilesForBbox([-10, 60, -20, 85], 3, { limit: 24 });
+  const keys = result.tiles.map((tile) => `${tile.x}/${tile.y}/${tile.z}`);
+  assert.equal(new Set(keys).size, 24);
+  assert.equal(result.truncated, false);
+});
diff --git a/src/layers/streetLevel/tileMath.js b/src/layers/streetLevel/tileMath.js
index fe3c3ec18..350188200 100644
--- a/src/layers/streetLevel/tileMath.js
+++ b/src/layers/streetLevel/tileMath.js
@@ -146,8 +146,16 @@ export function tilesForBbox(bbox, z, { limit = Infinity, focus = null } = {}) {
         const dx = Math.abs(tile.x - centre.x);
         return Math.min(dx, n - dx) ** 2 + (tile.y - centre.y) ** 2;
       };
-  // Each tile's distance is computed once; ties keep their row order.
-  const ranked = tiles
+  // The date-line halves share a column when the gap between east and west is
+  // narrower than a tile; count that column once so a capped overview does not
+  // spend its slots on repeats. Each tile's distance is computed once; ties keep
+  // their row order.
+  const unique = [
+    ...new Map(
+      tiles.map((tile) => [`${tile.x}/${tile.y}/${tile.z}`, tile]),
+    ).values(),
+  ];
+  const ranked = unique
     .map((tile) => ({ tile, d: distance2(tile) }))
     .sort((a, b) => a.d - b.d)
     .map(({ tile }) => tile);