feat: make "View Estimated Nodes on Map" a shareable/bookmarkable URL

dborup: clicking the link just landed on a bare "#/map" with no way to
share it -- state lived in sessionStorage, gone after the click and
never in the URL to begin with.

Switched to a deep link, #/map?estimatedNodes=1, same convention as the
existing packet-path deep link (#/map?packet=<hash>&obs=<id>,
loadRouteFromDeepLink). map.js's new loadEstimatedNodesFromDeepLink
fetches /api/analytics/areas fresh and draws the result -- no
sessionStorage involved, since this list isn't per-request state, just
the deployment's current estimate, so the URL alone reproduces it.
Copy/share/reload all just work now. Also converted the trigger from a
JS-click <button> to a real <a href> so "Copy Link Address" works
without even clicking through.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

public/analytics.js

@@ -6783,7 +6783,7 @@ function destroy() { _stopRolesRefresh(); _stopScopesRefresh(); _stopForeignTraf
         '<div class="analytics-card" style="margin-top:16px">' +
           '<h3 style="display:flex;align-items:center;justify-content:space-between;gap:8px;flex-wrap:wrap">' +
             '<span>Position-Fix Coverage Gaps by Area</span>' +
-            (estimatedNodes.length ? '<button type="button" id="areasViewEstimatedNodes" class="btn-link" style="font-size:12px;font-weight:400;cursor:pointer;background:none;border:1px solid var(--border);border-radius:4px;padding:4px 10px;color:var(--link-color)">View Estimated Nodes on Map (' + estimatedNodes.length.toLocaleString() + ')</button>' : '') +
+            (estimatedNodes.length ? '<a href="#/map?estimatedNodes=1" id="areasViewEstimatedNodes" class="btn-link" style="font-size:12px;font-weight:400;text-decoration:none;background:none;border:1px solid var(--border);border-radius:4px;padding:4px 10px;color:var(--link-color)">View Estimated Nodes on Map (' + estimatedNodes.length.toLocaleString() + ')</a>' : '') +
           '</h3>' +
           '<p class="text-muted" style="margin:0 0 8px;font-size:0.85em">How many of each area\'s nodes have an actual reported GPS position vs. how many were only placeable via a neighbor-based estimate (same technique used for View Path\'s approximate markers). Click a column header to sort by it.</p>' +
           '<div id="areasPositionGaps">' + gapsSection.tableHtml() + '</div>' +
@@ -6793,14 +6793,6 @@ function destroy() { _stopRolesRefresh(); _stopScopesRefresh(); _stopForeignTraf
       densitySection.attach();
       bridgeSection.attach();
       gapsSection.attach();
-
-      var viewEstimatedBtn = document.getElementById('areasViewEstimatedNodes');
-      if (viewEstimatedBtn) {
-        viewEstimatedBtn.addEventListener('click', function () {
-          sessionStorage.setItem('map-estimated-nodes', JSON.stringify({ points: estimatedNodes }));
-          window.location.hash = '#/map';
-        });
-      }
     } catch (e) {
       el.innerHTML = '<div class="text-center" style="color:var(--status-red);padding:20px">Failed to load area analytics: ' + esc(String(e)) + '</div>';
     }

public/map.js

@@ -679,19 +679,15 @@
         } catch {}
         return;
       }
-      // Check for an estimated-nodes view from the Areas tab (via
-      // sessionStorage) — see drawEstimatedNodes. Checked before
-      // map-route-hops since both use similar payload shapes but mean
-      // different things (a resolved hop route vs. a flat point list).
-      const estimatedNodesJson = sessionStorage.getItem('map-estimated-nodes');
-      if (estimatedNodesJson) {
-        sessionStorage.removeItem('map-estimated-nodes');
-        try {
-          const parsed = JSON.parse(estimatedNodesJson);
-          if (parsed && Array.isArray(parsed.points)) {
-            drawEstimatedNodes(parsed.points);
-          }
-        } catch {}
+      // Estimated-nodes deep link: #/map?estimatedNodes=1 -- the Areas
+      // tab's "View Estimated Nodes on Map" button links straight here
+      // instead of stashing state in sessionStorage (like the old
+      // map-estimated-nodes key did), so dborup can copy/share/bookmark
+      // the URL and it still works after a reload -- same shareable-URL
+      // convention as loadRouteFromDeepLink below (#1418/#1419).
+      const hashQs = (location.hash || '').split('?')[1];
+      if (new URLSearchParams(hashQs || '').get('estimatedNodes')) {
+        loadEstimatedNodesFromDeepLink();
         return;
       }
       // Check for route from packet detail (via sessionStorage)
@@ -1097,7 +1093,15 @@
     closeBtn.addTo(map);
 
     const valid = (points || []).filter(function (p) { return p && p.lat != null && p.lon != null; });
-    if (valid.length === 0) return;
+    if (valid.length === 0) {
+      const container = map.getContainer();
+      const label = document.createElement('div');
+      label.className = 'mc-estimated-nodes-label';
+      label.style.cssText = 'position:absolute;top:10px;left:50px;z-index:1000;background:var(--input-bg,#1e293b);color:var(--text,#e2e8f0);padding:4px 10px;border-radius:4px;font-size:12px';
+      label.textContent = 'No nodes currently have an estimated position.';
+      container.appendChild(label);
+      return;
+    }
 
     const color = '#f59e0b';
     valid.forEach(function (p) {
@@ -1552,6 +1556,28 @@
     }
   }
 
+  // Deep link for #/map?estimatedNodes=1 -- fetches the current
+  // network-wide estimated-position list fresh from the same endpoint
+  // the Areas tab uses (/api/analytics/areas) and draws it, rather than
+  // relying on a sessionStorage snapshot from whenever the link was
+  // clicked. Since this list isn't per-user/per-request state (it's the
+  // deployment's current estimate), the URL alone is enough to
+  // reproduce the view -- share/bookmark/reload all just work.
+  async function loadEstimatedNodesFromDeepLink() {
+    try {
+      const resp = await fetch('/api/analytics/areas');
+      if (!resp.ok) {
+        console.warn('[deep-link] /api/analytics/areas returned ' + resp.status);
+        return;
+      }
+      const data = await resp.json();
+      const points = (data && Array.isArray(data.estimatedNodes)) ? data.estimatedNodes : [];
+      drawEstimatedNodes(points);
+    } catch (e) {
+      console.warn('[deep-link] estimated-nodes load failed', e);
+    }
+  }
+
   async function loadNodes() {
     try {
       // Load regions from config + observed IATAs

test-analytics-areas-tab.js

@@ -331,19 +331,24 @@ function makeApiStub(resp) {
     assert.ok(!el.innerHTML.includes('Show all'), 'no toggle should render with only 1 area in positionGaps');
   });
 
-  await testAsync('renders a "View Estimated Nodes on Map" button with the estimated-node count when estimatedNodes is non-empty', async () => {
+  await testAsync('renders a "View Estimated Nodes on Map" LINK (not a JS-click button) with the estimated-node count, pointing at a shareable/bookmarkable URL', async () => {
     const ctx = makeAnalyticsSandbox(makeApiStub(makeAreasResponse()));
     const el = fakeEl();
     await ctx.window._analyticsRenderAreasTab(el);
-    assert.ok(el.innerHTML.includes('id="areasViewEstimatedNodes"'), 'the View Estimated Nodes button should render');
-    assert.ok(el.innerHTML.includes('View Estimated Nodes on Map (1)'), 'the button label should show the estimated-node count');
+    assert.ok(el.innerHTML.includes('id="areasViewEstimatedNodes"'), 'the View Estimated Nodes link should render');
+    assert.ok(el.innerHTML.includes('View Estimated Nodes on Map (1)'), 'the link label should show the estimated-node count');
+    // Must be a real <a href> so right-click "Copy Link Address" works and
+    // the URL survives a reload -- dborup asked for this after the first
+    // version (sessionStorage + a plain button) only ever led to a bare
+    // "#/map" with no shareable state.
+    assert.ok(el.innerHTML.includes('<a href="#/map?estimatedNodes=1" id="areasViewEstimatedNodes"'), 'expected a real anchor with the estimatedNodes=1 deep-link query param');
   });
 
-  await testAsync('does not render the "View Estimated Nodes on Map" button when estimatedNodes is empty', async () => {
+  await testAsync('does not render the "View Estimated Nodes on Map" link when estimatedNodes is empty', async () => {
     const ctx = makeAnalyticsSandbox(makeApiStub(makeAreasResponse({ estimatedNodes: [] })));
     const el = fakeEl();
     await ctx.window._analyticsRenderAreasTab(el);
-    assert.ok(!el.innerHTML.includes('id="areasViewEstimatedNodes"'), 'the button should not render when there are no estimated nodes to show');
+    assert.ok(!el.innerHTML.includes('id="areasViewEstimatedNodes"'), 'the link should not render when there are no estimated nodes to show');
   });
 
   await testAsync('renders the unpositioned-nodes summary note including the no-neighbor-fix subset', async () => {