fix: hover-route line not drawn in e2e — MapLibre clips queried lines across tiles and quantizes their coordinates (strict single-feature equality never matched)

e2e/hover.spec.ts

@@ -174,22 +174,32 @@ async function airportLonLat(page: Page, icao: string): Promise<[number, number]
   return [f.properties.lon, f.properties.lat];
 }
 
-// ISS-022/025/027: the hover-route layer must hold exactly one LineString whose first and last
-// coordinates are the two airports' exact dataset coords (greatCircleArc returns them verbatim
-// at t=0/t=1, so strict equality is safe). Call fitToAirports([from, to]) first — rendered
-// features are viewport-scoped.
+// ISS-022/025/027: the hover-route layer must hold the great-circle trace from origin to dest.
+// MapLibre stores GeoJSON geometry in per-tile INTEGER grids and clips long lines across tiles, so
+// queryRenderedFeatures returns ONE FEATURE PER TILE the line crosses (the 1420 km EDDF→LEMD leg is
+// 4 segments at z=4 / 5 at z=5) with coordinates quantized to the rendered zoom's grid — up to ~half
+// a grid step off (~0.001° observed at z≥4, ~0.02° worst case at z=0). A strict single-feature +
+// exact-coords comparison can therefore never match even when the line is drawn correctly (CI run #69:
+// all three hover-route timeouts while the trace was visibly rendered), so we accept any number of
+// segments and require some segment to START within EPS of `from` and some to END within EPS of `to`.
+// The true endpoints survive clipping verbatim in whichever tile contains them. Call
+// fitToAirports([from, to]) first — rendered features are viewport-scoped.
+const HOVER_ROUTE_EPS_DEG = 0.05; // ~5 km: above worst-case quantization at any zoom, below the distance between any two EU airports
+
 async function expectHoverRoute(page: Page, fromIcao: string, toIcao: string): Promise<void> {
   const [from, to] = await Promise.all([airportLonLat(page, fromIcao), airportLonLat(page, toIcao)]);
+  const near = (a: [number, number], b: [number, number]) =>
+    Math.abs(a[0] - b[0]) <= HOVER_ROUTE_EPS_DEG && Math.abs(a[1] - b[1]) <= HOVER_ROUTE_EPS_DEG;
   await expect.poll(async () => {
     const feats = (await renderedFeatures(page, ['hover-route'])) as Array<{ geometry: { coordinates: [number, number][] } }>;
-    if (feats.length !== 1) return false;
-    const coords = feats[0].geometry.coordinates;
-    return (
-      coords[0][0] === from[0] &&
-      coords[0][1] === from[1] &&
-      coords[coords.length - 1][0] === to[0] &&
-      coords[coords.length - 1][1] === to[1]
-    );
+    if (!feats.length) return false;
+    // The line may be clipped into several per-tile segments — check the endpoints across all of them.
+    const startsAtFrom = feats.some((f) => near(f.geometry.coordinates[0], from));
+    const endsAtTo = feats.some((f) => {
+      const c = f.geometry.coordinates;
+      return near(c[c.length - 1], to);
+    });
+    return startsAtFrom && endsAtTo;
   }, { timeout: 15_000, message: `waiting for the hover-route line ${fromIcao} → ${toIcao}` }).toBe(true);
 }