feat(tickets map): fan out co-located pins so faded-closed is visible

Cluster-centroid tickets share an exact coordinate, so the open layer sat on
top of the faded closed pins (23 of 25 closed points were occluded) — the new
closed colouring was correct but invisible. Now pins sharing a coordinate are
fanned into a small deterministic sunflower spiral around it, computed across
BOTH layers so an open and a closed ticket at the same centroid separate.
Active (vivid) and closed (faded) now both show. Also default the Closed layer
on. Offsets are cosmetic (cluster centroids are already approximate).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/index.html

@@ -951,7 +951,7 @@ function vehState(p) {
 
 let tkMap = null, tkPopup = null, tkLivePoll = null, tkClosureChart = null;
 const tkMarkers = new Map();                            // imei → maplibregl.Marker
-const tkLayerState = { open: true, closed: false, vehicles: true };
+const tkLayerState = { open: true, closed: true, vehicles: true };
 let incData = null, incDropdownsInit = false, vehCount = 0;
 
 // ── INC helpers ───────────────────────────────────────────────────────────
@@ -1007,6 +1007,51 @@ function addPinImages() {
     if (!tkMap.hasImage(id)) tkMap.addImage(id, pinImageData(fill), { pixelRatio: 2 });
 }
 
+// Co-located declutter ("fan-out"). Cluster-centroid tickets share an EXACT coordinate,
+// so the open layer would sit on top of (hide) the faded closed pins at the same point.
+// Pins that share a coordinate are fanned into a small deterministic sunflower spiral
+// around it — computed across BOTH layers so an open and a closed ticket separate — so
+// active (vivid) and closed (faded) are both visible. Offsets are cosmetic (a few tens
+// to ~hundreds of m around the cluster centroid; popups already flag 'approx').
+const JITTER_BASE_DEG = 0.00035;                  // innermost step (~38 m); grows ~sqrt(i)
+const GOLDEN_ANGLE = Math.PI * (3 - Math.sqrt(5));
+function fanOutColocated(openFC, closedFC) {
+  const groups = new Map();
+  const add = (f, layer) => {
+    const c = f && f.geometry && f.geometry.coordinates; if (!c) return;
+    const key = c[0].toFixed(6) + ',' + c[1].toFixed(6);
+    let arr = groups.get(key); if (!arr) { arr = []; groups.set(key, arr); }
+    arr.push({ f, layer });
+  };
+  ((openFC && openFC.features) || []).forEach((f) => add(f, 'open'));
+  ((closedFC && closedFC.features) || []).forEach((f) => add(f, 'closed'));
+  const outOpen = [], outClosed = [];
+  for (const items of groups.values()) {
+    if (items.length > 1)   // stable order so pins don't jump between refreshes
+      items.sort((a, b) => String((a.f.properties || {}).ticket_id || '')
+        .localeCompare(String((b.f.properties || {}).ticket_id || '')));
+    items.forEach((it, i) => {
+      const c = it.f.geometry.coordinates;
+      let coords = c;
+      if (items.length > 1 && i > 0) {            // i=0 stays on the true centroid
+        const r = JITTER_BASE_DEG * Math.sqrt(i), a = i * GOLDEN_ANGLE;
+        const latRad = c[1] * Math.PI / 180;
+        coords = [c[0] + (r * Math.cos(a)) / Math.max(Math.cos(latRad), 0.2), c[1] + r * Math.sin(a)];
+      }
+      (it.layer === 'open' ? outOpen : outClosed).push(
+        { type: 'Feature', properties: it.f.properties, geometry: { type: 'Point', coordinates: coords } });
+    });
+  }
+  return { open: { type: 'FeatureCollection', features: outOpen },
+           closed: { type: 'FeatureCollection', features: outClosed } };
+}
+function renderIncMap() {
+  if (!tkMap || !incData) return;
+  const { open, closed } = fanOutColocated(incData.open, incData.closed);
+  if (tkMap.getSource('inc-open'))   tkMap.getSource('inc-open').setData(open);
+  if (tkMap.getSource('inc-closed')) tkMap.getSource('inc-closed').setData(closed);
+}
+
 function initIncMap() {
   if (tkMap) { tkMap.resize(); return; }               // already built — just fix sizing
 
@@ -1062,10 +1107,7 @@ function initIncMap() {
       tkMap.on('mousemove', id, (e) => showIncPopup(e.features[0], id === 'inc-closed'));
     }
     tkMap.on('zoom', updateVehScale); updateVehScale();
-    if (incData) {   // INC data may have arrived before the basemap finished loading
-      tkMap.getSource('inc-open').setData(incData.open || EMPTY_FC);
-      tkMap.getSource('inc-closed').setData(incData.closed || EMPTY_FC);
-    }
+    if (incData) renderIncMap();   // INC data may have arrived before the basemap loaded
     loadLive();
     tkLivePoll = setInterval(loadLive, LIVE_POLL_MS);
   });
@@ -1154,8 +1196,7 @@ async function loadInc() {
     renderIncMetrics(j.metrics, j.freshness);
     renderIncTables(j.metrics);
     renderClosureChart(j.metrics && j.metrics.closure_rate);
-    if (tkMap && tkMap.getSource('inc-open'))   tkMap.getSource('inc-open').setData(j.open || EMPTY_FC);
-    if (tkMap && tkMap.getSource('inc-closed')) tkMap.getSource('inc-closed').setData(j.closed || EMPTY_FC);
+    renderIncMap();   // fan out co-located pins so open (vivid) + closed (faded) both show
     buildIncLayers();
   } catch (e) {
     console.error(e);