Replace the per-popup "Nearby on Wikipedia" link with a live Wikipedia layer

The old link only ever surfaced one nearby article at a time, buried
in whatever POI's popup you happened to open, and only for uploaded
files with a category. Replaced it with a standalone "Wikipedia"
toggle under the renamed "Tracks & Points" panel: enabling it adds a
live map layer that refetches GET /api/kiwix/nearby on every pan/zoom
and plots every nearby article as its own point.

kiwix-serve's own geo search never echoes back a result's coordinates
(confirmed live against the real production ZIM, both its HTML and
?format=xml output) — it only filters by distance from a point. So
Maptool::Kiwix.nearby fetches each matching article's own page too and
reads its <meta name="geo.position"> tag, which every geotagged
Wikipedia article carries. Tried parallelizing those per-article
fetches with threads first; measured no improvement against the real
ZIM (kiwix-serve appears to serialize requests regardless), so it
stayed sequential — ~1.6s for a 30-result page, fine for a
refetch-on-pan-end layer.

Clicking a point opens a small popup linking to the article (proxied
through the existing /kiwix/* passthrough). New WIKI_ICON (NPS's
bookstore-22.svg) marks these, kept out of POI_ICONS since that set
doubles as notes.js's icon-picker option list and this fixed-glyph
layer has no per-feature category to key off of.

public/js/gpx.js

@@ -11,6 +11,7 @@ import {
   MAP_MARKER_ICON,
   POI_ICONS,
   PARK4NIGHT_TAGS,
+  WIKI_ICON,
 } from "/js/icons.js";
 import { notifySidePanelOpen, onlyOneSidePanelOpen, onGpxStoreChanged, notifyGpxStoreChanged } from "/js/panels.js";
 import { formatActivityType } from "/js/track_profile.js";
@@ -27,6 +28,13 @@ const POI_ICON_SIZE = 0.3; // 48 * 0.3 = ~14px, sized to sit inside the marker b
 const MAP_MARKER_SIZE = 0.55;
 const BADGE_IMAGE_PREFIX = "badge-"; // one registered image per distinct badge color actually seen, see _registerBadgeColors
 
+// The "Wikipedia" layer (a live GET /api/kiwix/nearby refetch on every
+// pan/zoom, not a file in the tree — see _enableWikiLayer) — one fixed
+// icon/color for every point on it, unlike a POI file's per-category ones.
+const WIKI_SOURCE_ID = "wiki-points";
+const WIKI_ICON_ID = "wiki-icon";
+const WIKI_BADGE_COLOR = "#795548";
+
 // Custom drag payload MIME type for moving an already-uploaded file between
 // folders, as opposed to an OS file drag (type "Files") for uploading a new
 // one — both land on the same drop targets, told apart by this.
@@ -46,6 +54,9 @@ export class GpxPanelControl {
     this._linesByPath = new Map(); // path -> its lines/polygons FeatureCollection, same reason (a polygon/line note also carries a category)
     this._hiddenCategories = new Set(); // category names toggled off in the legend
     this._openDownloadMenu = null; // the one gpx-tree__download-menu currently open, if any
+    this._wikiEnabled = false; // the "Wikipedia" layer's checkbox state
+    this._wikiMoveHandler = null; // the moveend listener driving its live refetch, while enabled
+    this._wikiRequestSeq = 0; // ignores an in-flight refetch a newer one has already superseded
 
     // setStyle() (switching the Online/Offline base map) tears down all
     // custom sources/layers/images — re-register the category glyphs before
@@ -57,6 +68,7 @@ export class GpxPanelControl {
     map.on("style.load", () => {
       this._iconsReady = this._registerCategoryGlyphs();
       this._visible.forEach((path) => this._addLayers(path));
+      if (this._wikiEnabled) this._addWikiLayers().then(() => this._refreshWikiLayer());
     });
 
     // notes.js writes directly into the same GPX store (a hand-drawn note
@@ -114,10 +126,21 @@ export class GpxPanelControl {
     );
   }
 
+  // Same registration as _registerCategoryGlyphs above, for the one fixed
+  // glyph the "Wikipedia" layer uses — kept separate from POI_ICONS since
+  // that set is keyed by OSM/p4n2gpx category and doubles as notes.js's
+  // icon-picker option list, neither of which applies to this layer.
+  async _registerWikiIcon() {
+    if (this._map.hasImage(WIKI_ICON_ID)) return;
+    const whiteSvg = WIKI_ICON.replace(/currentColor/g, "#fff");
+    const imageData = await svgToImageData(whiteSvg, POI_ICON_IMAGE_SIZE);
+    if (!this._map.hasImage(WIKI_ICON_ID)) this._map.addImage(WIKI_ICON_ID, imageData);
+  }
+
   mount(sidebar) {
     this._container = document.createElement("div");
     this._container.className = "sidebar-item";
-    this._container.innerHTML = `<button type="button" class="sidebar-icon" title="Tracks" aria-label="Tracks">${GPX_ICON}</button>`;
+    this._container.innerHTML = `<button type="button" class="sidebar-icon" title="Tracks &amp; Points" aria-label="Tracks &amp; Points">${GPX_ICON}</button>`;
     this._icon = this._container.querySelector(".sidebar-icon");
     this._icon.addEventListener("click", () => this._togglePanel());
 
@@ -125,6 +148,12 @@ export class GpxPanelControl {
     this._treeContainer = this._panel.querySelector(".gpx-tree");
     this._legendContainer = this._panel.querySelector(".gpx-legend");
     this._uploadStatus = this._panel.querySelector(".gpx-upload__status");
+    wikiToggleLabel = this._panel.querySelector(".gpx-panel__wiki");
+    wikiToggleLabel.hidden = !kiwixConfig.available;
+    wikiToggleLabel.querySelector(".gpx-panel__wiki-toggle").addEventListener("change", (event) => {
+      if (event.target.checked) this._enableWikiLayer();
+      else this._disableWikiLayer();
+    });
     this._panel.querySelector('[data-action="new-folder"]').innerHTML = NEW_FOLDER_ICON;
     this._panel.querySelector('[data-action="upload"]').innerHTML = UPLOAD_ICON;
     if (!isLoggedIn()) {
@@ -713,7 +742,7 @@ export class GpxPanelControl {
       const editable = feature.properties.category === "Note" && !!feature.properties.id && isLoggedIn();
       const popup = new Popup({ closeButton: true, maxWidth: "260px" })
         .setLngLat(event.lngLat)
-        .setHTML(popupHtml(feature.properties, { editable, lngLat: event.lngLat }))
+        .setHTML(popupHtml(feature.properties, { editable }))
         .addTo(this._map);
       if (editable) this._wireNoteActions(popup, path, feature);
     });
@@ -765,7 +794,7 @@ export class GpxPanelControl {
       const bodyInput = content.querySelector(".gpx-popup__edit-body");
       titleInput.focus();
       content.querySelector(".gpx-popup__edit-cancel").addEventListener("click", () => {
-        content.innerHTML = popupHtml(feature.properties, { editable: true, lngLat: popup.getLngLat() });
+        content.innerHTML = popupHtml(feature.properties, { editable: true });
         this._wireNoteActions(popup, path, feature);
       });
       content.querySelector(".gpx-popup__edit-save").addEventListener("click", async () => {
@@ -924,6 +953,110 @@ export class GpxPanelControl {
     }
   }
 
+  // The "Wikipedia" layer's checkbox toggle (see mount()) — not a file in
+  // _visible/the tree, so it gets its own small add/remove pair rather than
+  // going through _addLayers/_removeLayers, which are built around a
+  // GpxStore path. Refetches on every pan/zoom instead of once for a fixed
+  // area (contrast the import plugins' "Run for this area" button): cheap
+  // to do since GET /api/kiwix/nearby only ever talks to kiwix-serve's own
+  // local ZIM, none of the plugins' shared/rate-limited API concerns apply.
+  async _enableWikiLayer() {
+    this._wikiEnabled = true;
+    await this._addWikiLayers();
+    this._wikiMoveHandler = () => this._refreshWikiLayer();
+    this._map.on("moveend", this._wikiMoveHandler);
+    this._refreshWikiLayer();
+  }
+
+  _disableWikiLayer() {
+    this._wikiEnabled = false;
+    if (this._wikiMoveHandler) {
+      this._map.off("moveend", this._wikiMoveHandler);
+      this._wikiMoveHandler = null;
+    }
+    this._removeWikiLayers();
+  }
+
+  async _addWikiLayers() {
+    if (this._map.getSource(WIKI_SOURCE_ID)) return;
+    await Promise.all([this._registerWikiIcon(), this._registerBadgeColors([WIKI_BADGE_COLOR])]);
+    if (this._map.getSource(WIKI_SOURCE_ID)) return; // style.load raced this while awaiting
+
+    this._map.addSource(WIKI_SOURCE_ID, { type: "geojson", data: { type: "FeatureCollection", features: [] } });
+    this._map.addLayer({
+      id: `${WIKI_SOURCE_ID}-badge`,
+      type: "symbol",
+      source: WIKI_SOURCE_ID,
+      layout: {
+        "icon-image": badgeImageId(WIKI_BADGE_COLOR),
+        "icon-size": MAP_MARKER_SIZE,
+        "icon-allow-overlap": true,
+        "icon-ignore-placement": true,
+      },
+    });
+    this._map.addLayer({
+      id: `${WIKI_SOURCE_ID}-icon`,
+      type: "symbol",
+      source: WIKI_SOURCE_ID,
+      layout: { "icon-image": WIKI_ICON_ID, "icon-size": POI_ICON_SIZE, "icon-allow-overlap": true, "icon-ignore-placement": true },
+    });
+    this._registerWikiInteractivity(`${WIKI_SOURCE_ID}-badge`);
+  }
+
+  _removeWikiLayers() {
+    [`${WIKI_SOURCE_ID}-badge`, `${WIKI_SOURCE_ID}-icon`].forEach((layerId) => {
+      if (this._map.getLayer(layerId)) this._map.removeLayer(layerId);
+    });
+    if (this._map.getSource(WIKI_SOURCE_ID)) this._map.removeSource(WIKI_SOURCE_ID);
+  }
+
+  // Not _registerPointInteractivity: that one's built around a GpxStore
+  // path for Note edit/delete, neither of which a wiki article has —
+  // simpler to keep this layer's own small click/hover pair separate than
+  // to bend the shared one around a case it was never meant to cover.
+  _registerWikiInteractivity(layerId) {
+    if (this._interactiveLayers.has(layerId)) return;
+    this._interactiveLayers.add(layerId);
+
+    this._map.on("click", layerId, (event) => {
+      const feature = event.features[0];
+      if (!feature) return;
+      new Popup({ closeButton: true, maxWidth: "260px" }).setLngLat(event.lngLat).setHTML(wikiPopupHtml(feature.properties)).addTo(this._map);
+    });
+    this._map.on("mouseenter", layerId, () => {
+      this._map.getCanvas().style.cursor = "pointer";
+    });
+    this._map.on("mouseleave", layerId, () => {
+      this._map.getCanvas().style.cursor = "";
+    });
+  }
+
+  // seq guards against an out-of-order response — a fast second pan's
+  // fetch resolving before a slower first one's — overwriting newer data
+  // with stale data; not a full abort-in-flight setup, just the ordering
+  // guarantee this actually needs.
+  async _refreshWikiLayer() {
+    const seq = ++this._wikiRequestSeq;
+    const bounds = this._map.getBounds();
+    const params = new URLSearchParams({
+      south: bounds.getSouth(),
+      west: bounds.getWest(),
+      north: bounds.getNorth(),
+      east: bounds.getEast(),
+    });
+
+    let geojson;
+    try {
+      geojson = await (await fetch(`/api/kiwix/nearby?${params}`)).json();
+    } catch {
+      return;
+    }
+    if (seq !== this._wikiRequestSeq) return;
+
+    const source = this._map.getSource(WIKI_SOURCE_ID);
+    if (source) source.setData(geojson);
+  }
+
   async _uploadFiles(fileList, folder) {
     // .zip: Garmin's bulk/FIT export format — the server expands it into
     // its .gpx/.fit/.geojson entries, so it's accepted here even though the
@@ -1104,9 +1237,14 @@ function gpxFileUrl(path) {
 // module-level rather than threaded through every popupHtml call, since
 // it's the same answer for the whole page's lifetime.
 let kiwixConfig = { available: false, url: "" };
+// Set once GpxPanelControl#mount runs — updated here too since map.js's
+// GET /api/kiwix check resolves after mount() already ran, so the panel
+// markup exists but its availability isn't known yet at that point.
+let wikiToggleLabel = null;
 
 export function setKiwixConfig(config) {
   kiwixConfig = config;
+  if (wikiToggleLabel) wikiToggleLabel.hidden = !config.available;
 }
 
 // properties come straight from an uploaded GPX file — untrusted input —
@@ -1114,11 +1252,8 @@ export function setKiwixConfig(config) {
 // editable (only ever true for a "Note" feature the viewer is logged in
 // for — see _registerPointInteractivity) adds Edit/Delete buttons; the
 // click handling for them lives in _wireNoteActions, not here, since this
-// only builds markup, it has no map/store access of its own. lngLat (the
-// popup's own anchor point) drives the "Nearby on Wikipedia" link — kiwix-
-// serve's own geo search, linked to directly rather than proxied/embedded
-// (it already has a full search UI of its own, see docs/development.adoc).
-function popupHtml({ name, description, time, category, photos, icon }, { editable = false, lngLat = null } = {}) {
+// only builds markup, it has no map/store access of its own.
+function popupHtml({ name, description, time, category, photos, icon }, { editable = false } = {}) {
   const parts = [];
   if (name) {
     const glyph = icon && POI_ICONS[icon] ? `<span class="gpx-popup__header-icon">${POI_ICONS[icon]}</span>` : "";
@@ -1139,10 +1274,6 @@ function popupHtml({ name, description, time, category, photos, icon }, { editab
       parts.push(`<p class="gpx-popup__time">${escapeHtml(parsed.toLocaleString())}</p>`);
     }
   }
-  if (kiwixConfig.available && lngLat) {
-    const wikiUrl = `${kiwixConfig.url}/search?pattern=&latitude=${lngLat.lat}&longitude=${lngLat.lng}&distance=2000`;
-    parts.push(`<p class="gpx-popup__wiki"><a href="${escapeHtml(wikiUrl)}" target="_blank" rel="noopener noreferrer">Nearby on Wikipedia →</a></p>`);
-  }
   if (editable) {
     parts.push(
       `<div class="gpx-popup__note-actions"><button type="button" class="gpx-popup__edit">Edit</button><button type="button" class="gpx-popup__delete">Delete</button></div>`,
@@ -1151,6 +1282,16 @@ function popupHtml({ name, description, time, category, photos, icon }, { editab
   return parts.length > 0 ? parts.join("") : "<em>No details</em>";
 }
 
+// properties come from GET /api/kiwix/nearby — kiwix-serve's own ZIM
+// content, not an uploaded file, but still untrusted-by-convention like
+// every other popup builder here (escaped all the same). link already
+// carries the /kiwix prefix this app proxies (see lib/maptool/kiwix.rb).
+function wikiPopupHtml({ name, link }) {
+  const parts = [`<div class="gpx-popup__header"><strong>${escapeHtml(name)}</strong></div>`];
+  parts.push(`<p class="gpx-popup__wiki"><a href="${escapeHtml(link)}" target="_blank" rel="noopener noreferrer">Read on Wikipedia →</a></p>`);
+  return parts.join("");
+}
+
 // properties come straight from an uploaded GPX/FIT file — untrusted input.
 function trackPopupHtml({ name, activity_type, distance_meters, elevation_gain_meters, duration_secs }) {
   const parts = [];