Only clear the forecast when the data source changes

LoopFollow/Controllers/Graphs.swift

@@ -967,6 +967,30 @@ extension MainViewController {
         BGChart.notifyDataSetChanged()
     }
 
+    // Removes the Loop forecast line. Used when the active system switches away from Loop.
+    func clearLoopPredictionGraph() {
+        guard !predictionData.isEmpty else { return }
+        predictionData.removeAll()
+        updatePredictionGraph()
+    }
+
+    // Removes the Trio/OpenAPS forecast lines (ZT/IOB/COB/UAM). Used when the active system switches away from Trio/OpenAPS.
+    func clearOpenAPSPredictionGraph() {
+        let openAPSDataIndices = [12, 13, 14, 15]
+        for dataIndex in openAPSDataIndices {
+            let mainChart = BGChart.lineData!.dataSets[dataIndex] as! LineChartDataSet
+            let smallChart = BGChartFull.lineData!.dataSets[dataIndex] as! LineChartDataSet
+            if !mainChart.entries.isEmpty || !smallChart.entries.isEmpty {
+                updatePredictionGraphGeneric(
+                    dataIndex: dataIndex,
+                    predictionData: [],
+                    chartLabel: "",
+                    color: UIColor.systemGray
+                )
+            }
+        }
+    }
+
     func updatePredictionGraph(color: UIColor? = nil) {
         let dataIndex = 1
         var mainChart = BGChart.lineData!.dataSets[dataIndex] as! LineChartDataSet

LoopFollow/Controllers/Nightscout/DeviceStatus.swift

@@ -66,6 +66,7 @@ extension MainViewController {
     // NS Device Status Response Processor
     func updateDeviceStatusDisplay(jsonDeviceStatus: [[String: AnyObject]]) {
         let previousIOBText = Observable.shared.iobText.value
+        let previousDeviceWasLoop = Storage.shared.device.value == "Loop"
         infoManager.clearInfoData(types: [.iob, .cob, .battery, .pump, .pumpBattery, .target, .isf, .carbRatio, .updated, .recBolus, .tdd])
 
         // For Loop, clear the current override here - For Trio, it is handled using treatments
@@ -155,6 +156,17 @@ extension MainViewController {
 
         // Loop - handle new data
         if let lastLoopRecord = lastDeviceStatus?["loop"] as! [String: AnyObject]? {
+            // Some pumps report no `pump.clock`; without it alertLastLoopTime stays 0
+            // and the forecast anchors to epoch 0. Fall back to the loop cycle timestamp.
+            if (lastDeviceStatus?["pump"] as? [String: AnyObject])?["clock"] == nil,
+               let loopTimestampString = lastLoopRecord["timestamp"] as? String,
+               let loopTimestamp = formatter.date(from: loopTimestampString)?.timeIntervalSince1970,
+               loopTimestamp > (Observable.shared.alertLastLoopTime.value ?? 0)
+            {
+                Observable.shared.alertLastLoopTime.value = loopTimestamp
+                Storage.shared.lastLoopTime.value = loopTimestamp
+            }
+
             DeviceStatusLoop(formatter: formatter, lastLoopRecord: lastLoopRecord)
 
             var oText = ""
@@ -188,6 +200,17 @@ extension MainViewController {
             DeviceStatusOpenAPS(formatter: formatter, lastDeviceStatus: lastDeviceStatus, lastLoopRecord: lastLoopRecord)
         }
 
+        // If the active looping system flipped (Loop ⇄ Trio/OpenAPS), drop the previous
+        // system's forecast so it doesn't linger next to the one just drawn above.
+        let currentDeviceIsLoop = Storage.shared.device.value == "Loop"
+        if currentDeviceIsLoop != previousDeviceWasLoop {
+            if currentDeviceIsLoop {
+                clearOpenAPSPredictionGraph()
+            } else {
+                clearLoopPredictionGraph()
+            }
+        }
+
         // Start the timer based on the timestamp
         let now = dateTimeUtils.getNowTimeIntervalUTC()
         let secondsAgo = now - (Observable.shared.alertLastLoopTime.value ?? 0)

LoopFollow/Controllers/Nightscout/DeviceStatusLoop.swift

@@ -68,7 +68,7 @@ extension MainViewController {
                 let prediction = predictdata["values"] as! [Double]
                 Observable.shared.predictionText.value = Localizer.toDisplayUnits(String(Int(round(prediction.last!))))
                 Observable.shared.predictionColor.value = .purple
-                if Storage.shared.downloadPrediction.value, previousLastLoopTime < lastLoopTime {
+                if Storage.shared.downloadPrediction.value, previousLastLoopTime < lastLoopTime || predictionData.isEmpty {
                     predictionData.removeAll()
                     var predictionTime = lastLoopTime
                     let toLoad = Int(Storage.shared.predictionToLoad.value * 12)

LoopFollow/Task/DeviceStatusTask.swift

@@ -15,6 +15,10 @@ extension MainViewController {
     func deviceStatusAction() {
         // If no NS config, we wait 60s before trying again:
         guard IsNightscoutEnabled() else {
+            // No device-status source (e.g. Dexcom-only): drop any forecast left over
+            // from a previous Loop/Trio source so it doesn't linger on the chart.
+            clearLoopPredictionGraph()
+            clearOpenAPSPredictionGraph()
             TaskScheduler.shared.rescheduleTask(id: .deviceStatus, to: Date().addingTimeInterval(60))
             return
         }

LoopFollow/ViewControllers/MainViewController.swift

@@ -565,29 +565,6 @@ class MainViewController: UIViewController, ChartViewDelegate, UNUserNotificatio
     @objc func refresh() {
         LogManager.shared.log(category: .general, message: "Refreshing")
 
-        // Clear prediction for both Loop or OpenAPS
-
-        // Check if Loop prediction data exists and clear it if necessary
-        if !predictionData.isEmpty {
-            predictionData.removeAll()
-            updatePredictionGraph()
-        }
-
-        // Check if OpenAPS prediction data exists and clear it if necessary
-        let openAPSDataIndices = [12, 13, 14, 15]
-        for dataIndex in openAPSDataIndices {
-            let mainChart = BGChart.lineData!.dataSets[dataIndex] as! LineChartDataSet
-            let smallChart = BGChartFull.lineData!.dataSets[dataIndex] as! LineChartDataSet
-            if !mainChart.entries.isEmpty || !smallChart.entries.isEmpty {
-                updatePredictionGraphGeneric(
-                    dataIndex: dataIndex,
-                    predictionData: [],
-                    chartLabel: "",
-                    color: UIColor.systemGray
-                )
-            }
-        }
-
         Observable.shared.minAgoText.value = "Refreshing"
         scheduleAllTasks()
         NightscoutSocketManager.shared.connectIfNeeded()