fix(map): tighten edge cases in heatmap, info map, and trail color

- Heatmap: filter points with invalid coords or out-of-range intensity
  so malformed rows can't distort the layer.
- InfoMap: validate coords for range (not just NaN) and use an epsilon
  when comparing positions, so float noise doesn't cause needless
  re-renders or accept bogus data.
- TrailManager: getTrailCenter returns null for empty input instead of
  the ambiguous (0, 0) null-island; callers guard accordingly.

assets/js/features/trail_manager.ts

@@ -304,12 +304,13 @@ export class TrailManager {
     return unwrapped;
   }
 
-  // Get the average position of a trail
+  // Get the average position of a trail. Returns null for empty arrays so
+  // callers can't accidentally treat null island (0, 0) as a real center.
   private getTrailCenter(positions: PositionHistory[]): {
     lat: number;
     lng: number;
-  } {
-    if (positions.length === 0) return { lat: 0, lng: 0 };
+  } | null {
+    if (positions.length === 0) return null;
 
     const sum = positions.reduce(
       (acc, pos) => ({
@@ -341,6 +342,8 @@ export class TrailManager {
         return;
 
       const otherCenter = this.getTrailCenter(trailState.positions);
+      if (!otherCenter) return;
+
       const distance = this.calculateDistance(
         center.lat,
         center.lng,
@@ -377,8 +380,8 @@ export class TrailManager {
     }
 
     // All 15 colors in use — pick one not used by nearby trails
-    if (positions.length > 0) {
-      const center = this.getTrailCenter(positions);
+    const center = this.getTrailCenter(positions);
+    if (center) {
       const nearbyColors = this.getNearbyTrailColors(baseCallsign, center);
       for (const color of this.colorPalette) {
         if (!nearbyColors.has(color)) {

assets/js/hooks/info_map.ts

@@ -2,6 +2,23 @@
 
 declare const L: typeof import("leaflet");
 
+// ~1.1 m at the equator — enough to ignore float noise but still notice any
+// real position change from the server.
+const POSITION_EPSILON = 0.00001;
+
+function isValidLatLng(lat: number, lng: number): boolean {
+  return (
+    !isNaN(lat) &&
+    !isNaN(lng) &&
+    isFinite(lat) &&
+    isFinite(lng) &&
+    lat >= -90 &&
+    lat <= 90 &&
+    lng >= -180 &&
+    lng <= 180
+  );
+}
+
 interface InfoMapContext {
   el: HTMLElement;
   map: import("leaflet").Map | null;
@@ -29,7 +46,7 @@ export const InfoMap = {
     const symbolHtml = this.el.dataset.symbolHtml || null;
     const callsign = this.el.dataset.callsign || "unknown";
 
-    if (isNaN(lat) || isNaN(lon)) {
+    if (!isValidLatLng(lat, lon)) {
       console.warn(
         `InfoMap: Invalid coordinates lat=${lat}, lon=${lon} for ${callsign} during update`,
       );
@@ -47,7 +64,10 @@ export const InfoMap = {
 
     if (this.marker) {
       const currentPos = this.marker.getLatLng();
-      if (currentPos.lat !== lat || currentPos.lng !== lon) {
+      if (
+        Math.abs(currentPos.lat - lat) > POSITION_EPSILON ||
+        Math.abs(currentPos.lng - lon) > POSITION_EPSILON
+      ) {
         this.marker.setLatLng([lat, lon]);
 
         this.marker.setPopupContent(
@@ -97,7 +117,7 @@ function initializeMap(this: InfoMapContext) {
   const callsign = this.el.dataset.callsign || "unknown";
   const symbolHtml = this.el.dataset.symbolHtml || null;
 
-  if (isNaN(lat) || isNaN(lon)) {
+  if (!isValidLatLng(lat, lon)) {
     console.warn(
       `InfoMap: Invalid coordinates lat=${lat}, lon=${lon} for ${callsign}`,
     );

assets/js/map.ts

@@ -1575,16 +1575,26 @@ let MapAPRSMap = {
           }
         }
 
-        // Convert heat points to format expected by Leaflet.heat
-        // Intensity is pre-normalized to 0-1 range by the server
-        const heatData = data.heat_points.map(
-          (point) =>
-            [point.lat, point.lng, point.intensity] as [
-              number,
-              number,
-              number,
-            ],
-        );
+        // Convert heat points to format expected by Leaflet.heat.
+        // Server pre-normalizes intensity to [0, 1] but validate defensively
+        // so malformed rows can't distort the whole heat layer.
+        const heatData = data.heat_points
+          .filter(
+            (point) =>
+              isValidCoordinate(point.lat, point.lng) &&
+              typeof point.intensity === "number" &&
+              isFinite(point.intensity) &&
+              point.intensity >= 0 &&
+              point.intensity <= 1,
+          )
+          .map(
+            (point) =>
+              [point.lat, point.lng, point.intensity] as [
+                number,
+                number,
+                number,
+              ],
+          );
 
         // Update heat layer data
         self.heatLayer.setLatLngs(heatData);