feat: add URL hash routing for RADAR tabs (#newsfeed, #govtracker)

js/radar.js

@@ -359,28 +359,48 @@
             govtracker: '> .GOV domain intelligence — tracking U.S. government infrastructure registry'
         };
 
+        function switchToView(view) {
+            // Toggle button states
+            document.querySelectorAll('.radar-view-btn').forEach(function(b) { b.classList.remove('active'); });
+            var activeBtn = document.querySelector('.radar-view-btn[data-view="' + view + '"]');
+            if (activeBtn) activeBtn.classList.add('active');
+
+            // Toggle views
+            document.getElementById('viewNewsfeed').classList.toggle('hidden', view !== 'newsfeed');
+            document.getElementById('viewGovtracker').classList.toggle('hidden', view !== 'govtracker');
+
+            // Update subtitle
+            document.getElementById('radarSubtitle').innerHTML = subtitles[view] || '';
+
+            // Update URL hash without scrolling
+            history.replaceState(null, '', '#' + view);
+
+            // Lazy-load gov tracker data on first switch
+            if (view === 'govtracker' && !GovTracker.loaded) {
+                GovTracker.loadAll();
+            }
+        }
+
         document.querySelectorAll('.radar-view-btn').forEach(function(btn) {
             btn.addEventListener('click', function(e) {
                 e.preventDefault();
-                var view = this.dataset.view;
+                switchToView(this.dataset.view);
-
-                // Toggle button states
-                document.querySelectorAll('.radar-view-btn').forEach(function(b) { b.classList.remove('active'); });
-                this.classList.add('active');
-
-                // Toggle views
-                document.getElementById('viewNewsfeed').classList.toggle('hidden', view !== 'newsfeed');
-                document.getElementById('viewGovtracker').classList.toggle('hidden', view !== 'govtracker');
-
-                // Update subtitle
-                document.getElementById('radarSubtitle').innerHTML = subtitles[view] || '';
-
-                // Lazy-load gov tracker data on first switch
-                if (view === 'govtracker' && !GovTracker.loaded) {
-                    GovTracker.loadAll();
-                }
             });
         });
+
+        // Check URL hash on load
+        var hash = window.location.hash.replace('#', '');
+        if (hash === 'govtracker' || hash === 'newsfeed') {
+            switchToView(hash);
+        }
+
+        // Handle browser back/forward
+        window.addEventListener('hashchange', function() {
+            var h = window.location.hash.replace('#', '');
+            if (h === 'govtracker' || h === 'newsfeed') {
+                switchToView(h);
+            }
+        });
     }
 
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