fix(clustermap): stop EventSource reload from hijacking navigation in Firefox

static/js/clustermaps/live.js

@@ -1,4 +1,14 @@
 function initClustermaps() {
+	// Track whether the page is unloading. Firefox tears down the EventSource
+	// while navigating away and dispatches an `error` event during unload.
+	// Without this guard the error handler below calls window.location.reload(),
+	// which cancels the navigation and snaps the user back to the clustermap
+	// (and makes external links like CONTRIBUTE appear to "just refresh").
+	let isUnloading = false;
+	const markUnloading = function() { isUnloading = true; };
+	window.addEventListener('pagehide', markUnloading);
+	window.addEventListener('beforeunload', markUnloading);
+
 	// Open a Server Side Events stream for all live locations
 	const eventSource = new EventSource('/clustermap/locations/live');
 	// Listen for new locations
@@ -8,13 +18,22 @@ function initClustermaps() {
 		updateClustermap(data);
 	});
 	eventSource.addEventListener('error', function(event) {
+		// Don't react while navigating away, and let EventSource handle its own
+		// automatic reconnection (readyState CONNECTING). Only reload when the
+		// connection has permanently failed (readyState CLOSED).
+		if (isUnloading || eventSource.readyState !== EventSource.CLOSED) {
+			return;
+		}
 		console.error('EventSource failed:', event);
 		window.location.reload();
 	});
 	eventSource.addEventListener('open', function(event) {
 		console.log('EventSource opened');
 	});
 	eventSource.addEventListener('close', function(event) {
+		if (isUnloading) {
+			return;
+		}
 		console.warn('EventSource closed:', event);
 		window.location.reload();
 	});