Harden GPS mode updates with callback reattach and status polling fallback

static/js/modes/gps.js

@@ -9,6 +9,7 @@ const GPS = (function() {
     let lastPosition = null;
     let lastSky = null;
     let skyPollTimer = null;
+    let statusPollTimer = null;
     let themeObserver = null;
     let skyRenderer = null;
     let skyRendererInitAttempted = false;
@@ -413,10 +414,10 @@ const GPS = (function() {
     }
 
     function connect() {
-        updateConnectionUI(false, false, 'connecting');
-        fetch('/gps/auto-connect', { method: 'POST' })
-            .then(r => r.json())
-            .then(data => {
+        updateConnectionUI(false, false, 'connecting');
+        fetch('/gps/auto-connect', { method: 'POST' })
+            .then(r => r.json())
+            .then(data => {
                 if (data.status === 'connected') {
                     connected = true;
                     updateConnectionUI(true, data.has_fix);
@@ -427,16 +428,18 @@ const GPS = (function() {
                     if (data.sky) {
                         lastSky = data.sky;
                         updateSkyUI(data.sky);
-                    }
-                    subscribeToStream();
-                    startSkyPolling();
-                    // Ensure the global GPS stream is running
-                    if (typeof startGpsStream === 'function' && !gpsEventSource) {
-                        startGpsStream();
-                    }
-                } else {
-                    connected = false;
-                    updateConnectionUI(false, false, 'error', data.message || 'gpsd not available');
+                    }
+                    subscribeToStream();
+                    startSkyPolling();
+                    startStatusPolling();
+                    // Ensure the global GPS stream is running
+                    const hasGlobalGpsStream = typeof gpsEventSource !== 'undefined' && !!gpsEventSource;
+                    if (typeof startGpsStream === 'function' && !hasGlobalGpsStream) {
+                        startGpsStream();
+                    }
+                } else {
+                    connected = false;
+                    updateConnectionUI(false, false, 'error', data.message || 'gpsd not available');
                 }
             })
             .catch(() => {
@@ -445,14 +448,15 @@ const GPS = (function() {
             });
     }
 
-    function disconnect() {
-        unsubscribeFromStream();
-        stopSkyPolling();
-        fetch('/gps/stop', { method: 'POST' })
-            .then(() => {
-                connected = false;
-                updateConnectionUI(false);
-            });
+    function disconnect() {
+        unsubscribeFromStream();
+        stopSkyPolling();
+        stopStatusPolling();
+        fetch('/gps/stop', { method: 'POST' })
+            .then(() => {
+                connected = false;
+                updateConnectionUI(false);
+            });
     }
 
     function onGpsStreamData(data) {
@@ -470,14 +474,14 @@ const GPS = (function() {
         }
     }
 
-    function startSkyPolling() {
-        stopSkyPolling();
-        // Poll satellite data every 5 seconds as a reliable fallback
-        // SSE stream may miss sky updates due to queue contention with position messages
-        pollSatellites();
-        skyPollTimer = setInterval(pollSatellites, 5000);
-    }
-
+    function startSkyPolling() {
+        stopSkyPolling();
+        // Poll satellite data every 5 seconds as a reliable fallback
+        // SSE stream may miss sky updates due to queue contention with position messages
+        pollSatellites();
+        skyPollTimer = setInterval(pollSatellites, 5000);
+    }
+
     function stopSkyPolling() {
         if (skyPollTimer) {
             clearInterval(skyPollTimer);
@@ -485,18 +489,55 @@ const GPS = (function() {
         }
     }
 
-    function pollSatellites() {
-        if (!connected) return;
-        fetch('/gps/satellites')
-            .then(r => r.json())
-            .then(data => {
+    function pollSatellites() {
+        if (!connected) return;
+        fetch('/gps/satellites')
+            .then(r => r.json())
+            .then(data => {
                 if (data.status === 'ok' && data.sky) {
                     lastSky = data.sky;
                     updateSkyUI(data.sky);
                 }
-            })
-            .catch(() => {});
-    }
+            })
+            .catch(() => {});
+    }
+
+    function startStatusPolling() {
+        stopStatusPolling();
+        // Poll full status as a fallback when SSE is unavailable or blocked.
+        pollStatus();
+        statusPollTimer = setInterval(pollStatus, 2000);
+    }
+
+    function stopStatusPolling() {
+        if (statusPollTimer) {
+            clearInterval(statusPollTimer);
+            statusPollTimer = null;
+        }
+    }
+
+    function pollStatus() {
+        if (!connected) return;
+        fetch('/gps/status')
+            .then(r => r.json())
+            .then(data => {
+                if (!connected || !data || data.running !== true) return;
+
+                if (data.position) {
+                    lastPosition = data.position;
+                    updatePositionUI(data.position);
+                    updateConnectionUI(true, true);
+                } else {
+                    updateConnectionUI(true, false);
+                }
+
+                if (data.sky) {
+                    lastSky = data.sky;
+                    updateSkyUI(data.sky);
+                }
+            })
+            .catch(() => {});
+    }
 
     function subscribeToStream() {
         // Subscribe to the global GPS stream instead of opening a separate SSE connection
@@ -1443,6 +1484,7 @@ const GPS = (function() {
     function destroy() {
         unsubscribeFromStream();
         stopSkyPolling();
+        stopStatusPolling();
         if (themeObserver) {
             themeObserver.disconnect();
             themeObserver = null;