fix(search): normalize geocoder bias across the antimeridian (#1272)

Keep geocoder viewport bias near the antimeridian and omit misleading wrapped viewboxes.

Contribution by @asturksever.

changelog.d/1272-search-issue-fix.md

@@ -0,0 +1 @@
+- Normalize geocoder bias across the antimeridian (asturksever, #1272).

docs/CURRENT-STATE.md

@@ -5197,9 +5197,14 @@ HTTP refusals and outages remain retryable. Searches share a 12-second total
 deadline, with Photon requests capped at six seconds each. Caller/application
 cancellation stops retries and late cache writes. Replacing a location search
 cancels the previous lookup; disposing its controls cancels the active lookup. Photon uses a soft proximity bias, up to five
-candidates, and an unbiased retry for name mismatches. Invalid/wrapped bounds
+candidates, and an unbiased retry for name mismatches. Invalid or wrapped bounds returned by providers
 are omitted rather than framing the wrong part of the globe.
 
+For request viewport bias, Photon unwraps antimeridian-crossing longitude bounds
+before computing their midpoint, then wraps that midpoint back into ±180 degrees.
+Malformed viewport bounds add no proximity bias. Nominatim omits a crossing
+request viewbox and continues searching without that geographic preference.
+
 ### Map Stack Switcher (June 2026)
 
 - `src/mapStackController.js` switches between Google Photorealistic 3D (`photoreal`, the default when a Google or ion key is present), keyless Esri World Imagery (the zero-key default landing, with keyless terrain), Bing Aerial / Aerial-with-Labels via Cesium ion world imagery (require `CESIUM_ION_TOKEN`), and OSM tile fallback. Bing Road is **retired**: it is gone from `MAP_STACKS`, from the `set_map_stack` enum, and from the voice aliases (road phrasings now resolve to OSM, the one shipped road basemap). An old `map=bing-road` link is simply an unknown id and takes `setStack()`'s existing photoreal fallback with the Google 3D tile lit — pinned live in `scripts/qa-map-source-tray.mjs`.

src/keylessGeocoder.js

@@ -206,12 +206,27 @@ export function photonSearchUrl(
   url.searchParams.set('limit', String(limit));
 
   const corners = String(bias ?? '').split('|');
-  if (corners.length === 2) {
-    const [swLat, swLng] = corners[0].split(',').map(Number);
-    const [neLat, neLng] = corners[1].split(',').map(Number);
-    if ([swLat, swLng, neLat, neLng].every(Number.isFinite)) {
+  const tokens = corners.flatMap((corner) => corner.split(','));
+  if (
+    corners.length === 2 &&
+    corners.every((corner) => corner.split(',').length === 2) &&
+    tokens.every((token) => token.trim() !== '')
+  ) {
+    const [swLat, swLng, neLat, neLng] = tokens.map(Number);
+    if (
+      [swLat, swLng, neLat, neLng].every(Number.isFinite) &&
+      Math.abs(swLat) <= 90 &&
+      Math.abs(neLat) <= 90 &&
+      swLat <= neLat &&
+      Math.abs(swLng) <= 180 &&
+      Math.abs(neLng) <= 180
+    ) {
+      const midpoint = (swLng + neLng + (swLng > neLng ? 360 : 0)) / 2;
       url.searchParams.set('lat', String((swLat + neLat) / 2));
-      url.searchParams.set('lon', String((swLng + neLng) / 2));
+      url.searchParams.set(
+        'lon',
+        String(midpoint > 180 ? midpoint - 360 : midpoint),
+      );
     }
   }
   return url.toString();

src/keylessGeocoder.test.mjs

@@ -452,3 +452,14 @@ function readGeocodingConsumer(file) {
     ? [file, 'annotations/resolver.js'] : [file];
   return files.map((name) => fs.readFileSync(path.join(ROOT, 'src', name), 'utf8')).join('\n');
 }
+
+
+test('wrapped view bias stays near the antimeridian and malformed coordinates are omitted', () => {
+  for (const [bias, expected] of [['-20,170|-10,-171', 179.5], ['50,175|60,-165', -175], ['0,180|10,-180', 180], ['0,-180|10,180', 0]]) {
+    const params = new URL(photonSearchUrl('island', { bias })).searchParams;
+    assert.equal(Number(params.get('lon')), expected);
+  }
+  for (const bias of ['-91,0|0,1', '0,181|1,0', '10,0|0,1', ',|,', '0,1,2|3,4', '0,1|Infinity,2']) {
+    assert.equal(new URL(photonSearchUrl('island', { bias })).searchParams.has('lon'), false);
+  }
+});

src/nominatimGeocode.js

@@ -166,6 +166,8 @@ export function nominatimViewboxFromBounds(bounds) {
   const neLat = nominatimLatitude(match[3]);
   const neLng = nominatimLongitude(match[4]);
   if ([swLat, swLng, neLat, neLng].some((value) => value === null)) return null;
-  if (swLat >= neLat) return null;
+  // One Nominatim viewbox cannot express a wrapped interval. Omit this soft
+  // preference rather than biasing the search toward the opposite hemisphere.
+  if (swLat >= neLat || swLng > neLng) return null;
   return `${swLng},${neLat},${neLng},${swLat}`;
 }

src/nominatimGeocode.test.mjs

@@ -173,3 +173,12 @@ test('a viewport hint is sent only when every edge is a real coordinate', () =>
       `${JSON.stringify(bounds)} must not become a viewbox`,
     );
 });
+
+test('wrapped viewports omit the Nominatim bias without rejecting the search', () => {
+  assert.equal(nominatimViewboxFromBounds('-20,170|-10,-171'), null);
+  assert.equal(nominatimViewboxFromBounds('50,175|60,-165'), null);
+  assert.equal(
+    nominatimViewboxFromBounds('-20,170|-10,180'),
+    '170,-10,180,-20',
+  );
+});