sort popup features by configurable field

Add popupSortField and popupSortOrder to PopupConfig and PopupOverride.
When set, features within the same layer are sorted by that field after
deduplication. Defaults to descending (newest first). Enables PlowPHL
treatments to display most recent first instead of arbitrary order.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ajrothwell

src/components/MapPanel.vue

@@ -692,6 +692,8 @@ interface PopupFeature {
     title: string;
     fields: PopupField[];
     showTime?: boolean;
+    popupSortField?: string;
+    popupSortOrder?: "asc" | "desc";
   } | null;
 }
 
@@ -891,6 +893,20 @@ function handleLayerClick(e: { lngLat: { lng: number; lat: number } }) {
 
   if (newFeatures.length === 0) return;
 
+  // Sort features within the same layer by popupSortField if configured
+  // (e.g., PlowPHL treatments sorted newest-first by time_visited_utc)
+  newFeatures.sort((a, b) => {
+    // Only sort features from the same layer
+    if (a.layerId !== b.layerId) return 0;
+    const sortField = a.popupConfig?.popupSortField;
+    if (!sortField) return 0;
+    const valA = a.properties[sortField];
+    const valB = b.properties[sortField];
+    if (valA == null || valB == null) return 0;
+    const order = a.popupConfig?.popupSortOrder === "asc" ? 1 : -1;
+    return valA < valB ? order : valA > valB ? -order : 0;
+  });
+
   popupFeatures.value = newFeatures;
   currentFeatureIndex.value = 0;
   popupLngLat.value = [e.lngLat.lng, e.lngLat.lat];

src/types/layer.ts

@@ -26,6 +26,10 @@ export interface PopupConfig {
   title: string;
   fields: PopupField[];
   showTime?: boolean;
+  /** Sort popup features by this field when multiple features are at the click point */
+  popupSortField?: string;
+  /** Sort order: "desc" for newest-first, "asc" for oldest-first (default: "desc") */
+  popupSortOrder?: "asc" | "desc";
 }
 
 /**
@@ -65,6 +69,8 @@ export interface LayerConfig {
  */
 export interface PopupOverride {
   showTime?: boolean;
+  popupSortField?: string;
+  popupSortOrder?: "asc" | "desc";
 }
 
 /**