Show the Markers layer when a location is created or focused

Points placed with Draw > Point were written to the database but never appeared
on the map. The cause is not in the new workflow: the Markers layer is built
with visible: false so a fresh map is uncluttered, and nothing in the
application ever switched it on — only the LayerSwitcher could. So the record
was saved, the map panned to it, and nothing was drawn.

This predates the workflow change; making Draw > Point the single way to add a
point is what made it obvious, because placing a point is now the common
gesture rather than an occasional one.

MapView.showMarkers() switches the layer on, and the three places that act on a
specific location call it: adding one from the map form, adding one from the
sidebar form, and picking one from the Locations list. The default stays hidden,
so a map with no locations in play still opens clean.

Traced the marker count and layer visibility through the whole sequence — add,
enter Digitise, draw, save, pick Select, leave Digitise. The count was always
right and the layer was false throughout, which is what pinned the cause; it is
now true from the save onward.

Service Worker v20 -> v21.

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

dist/index.html

@@ -1917,7 +1917,7 @@
     }
 
   </style>
-  <script type="module" crossorigin src="/assets/index-CF9fisV-.js"></script>
+  <script type="module" crossorigin src="/assets/index-BQfxXCp7.js"></script>
   <link rel="modulepreload" crossorigin href="/assets/openlayers-J9qS6Th1.js">
   <link rel="modulepreload" crossorigin href="/assets/pako-Xa-UToif.js">
   <link rel="modulepreload" crossorigin href="/assets/geotiff-BaoeLn6q.js">

dist/sw.js

@@ -113,7 +113,12 @@
 //      add/remove pair is kept off the undo stack. Marker details, which used
 //      to need Add Location mode, now open in the neutral mode. The dock keeps
 //      its six remaining buttons and divides them evenly on narrow screens.
-const CACHE_VERSION = 'v20';
+// v21: Location markers were saved but never drawn. The Markers layer is built
+//      hidden and nothing ever switched it on except the LayerSwitcher, so a
+//      point placed with Draw > Point was written to the database and the map
+//      panned to it with nothing to see. Creating a location, or picking one
+//      from the Locations list, now switches the layer on.
+const CACHE_VERSION = 'v21';
 const SHELL_CACHE   = `shell-${CACHE_VERSION}`;
 const MODULES_CACHE = `modules-${CACHE_VERSION}`;
 const API_CACHE     = `api-${CACHE_VERSION}`;

main.js

@@ -397,6 +397,10 @@ async function initApp() {
 
       await loadLocations();
 
+      // The Markers layer starts hidden, so without this the point the officer
+      // just placed is written to the database and never drawn.
+      mapView?.showMarkers();
+
       // Zoom to the new location on the map
       mapView?.zoomTo(data.lon, data.lat, 14);
 
@@ -849,6 +853,9 @@ async function handleAddLocation(event) {
     form.reset();
     await loadLocations();
 
+    // As above: the Markers layer is hidden until something needs it shown.
+    mapView?.showMarkers();
+
     // Zoom to the new location on the map
     mapView?.zoomTo(longitude, latitude, 14);
 
@@ -968,6 +975,7 @@ function renderLocations(locations) {
       const id = parseInt(item.dataset.id);
 
       // Zoom to location on map
+      mapView?.showMarkers();
       mapView?.zoomTo(lon, lat, 14);
 
       // Select the marker

public/sw.js

@@ -113,7 +113,12 @@
 //      add/remove pair is kept off the undo stack. Marker details, which used
 //      to need Add Location mode, now open in the neutral mode. The dock keeps
 //      its six remaining buttons and divides them evenly on narrow screens.
-const CACHE_VERSION = 'v20';
+// v21: Location markers were saved but never drawn. The Markers layer is built
+//      hidden and nothing ever switched it on except the LayerSwitcher, so a
+//      point placed with Draw > Point was written to the database and the map
+//      panned to it with nothing to see. Creating a location, or picking one
+//      from the Locations list, now switches the layer on.
+const CACHE_VERSION = 'v21';
 const SHELL_CACHE   = `shell-${CACHE_VERSION}`;
 const MODULES_CACHE = `modules-${CACHE_VERSION}`;
 const API_CACHE     = `api-${CACHE_VERSION}`;

src/components/MapView.js

@@ -3584,6 +3584,23 @@ export class MapView {
   /**
    * Select a marker (highlights it)
    */
+  /**
+   * Make the Markers layer visible.
+   *
+   * The layer starts hidden so a fresh map is uncluttered, and the LayerSwitcher
+   * is the only thing that ever turned it on. That is fine until the officer
+   * creates or focuses a location, at which point an invisible layer means the
+   * point they just placed is simply not there — the record is written, the map
+   * pans to it, and nothing is drawn. Callers that act on a specific location
+   * call this so the result of the action can actually be seen.
+   */
+  showMarkers() {
+    if (this.markersLayer && !this.markersLayer.getVisible()) {
+      this.markersLayer.setVisible(true);
+      console.log('[MapView] Markers layer switched on to show a location');
+    }
+  }
+
   selectMarker(featureOrId) {
     if (typeof featureOrId === 'object') {
       this.selectedFeature = featureOrId;