Extend predictive low alarm to Trio

LoopFollow/Alarm/AlarmCondition/AlarmCondition.swift

@@ -8,9 +8,15 @@ protocol AlarmCondition {
     init()
     /// pure, per-alarm logic against `AlarmData`
     func evaluate(alarm: Alarm, data: AlarmData, now: Date) -> Bool
+    /// `true` when `belowBG`/`aboveBG` are this condition's own trigger
+    /// threshold, checked in `evaluate`; `false` (the default) treats them
+    /// as activation limits enforced by `passesBGLimits`.
+    var checksOwnBGLimits: Bool { get }
 }
 
 extension AlarmCondition {
+    var checksOwnBGLimits: Bool { false }
+
     /// Returns `true` when the alarm is allowed to continue evaluating
     /// after BG-limit checks; `false` blocks it immediately.
     func passesBGLimits(alarm: Alarm, data: AlarmData) -> Bool {
@@ -24,7 +30,14 @@ extension AlarmCondition {
         if alarm.type.isBGBased && !haveBG { return false }
 
         // ────────────────────────────────────
-        // 2. No limits?  we’re done.
+        // 2. Conditions that check their own threshold in `evaluate`
+        //    skip the limit gate (the data requirement above applies
+        //    regardless).
+        // ────────────────────────────────────
+        if checksOwnBGLimits { return true }
+
+        // ────────────────────────────────────
+        // 3. No limits?  we’re done.
         // ────────────────────────────────────
         if alarm.belowBG == nil && alarm.aboveBG == nil { return true }
 

LoopFollow/Alarm/AlarmCondition/LowBGCondition.swift

@@ -4,17 +4,23 @@
 import Foundation
 
 /// Fires when:
-/// • every BG in `persistentMinutes` (if set) **and** the latest BG are ≤ `threshold`; **or**
-/// • any predicted BG within `predictiveMinutes` is ≤ `threshold`.
+/// • every BG in `persistentMinutes` (if set) **and** the latest BG are ≤ `belowBG`; **or**
+/// • any predicted BG within `predictiveMinutes` is ≤ `belowBG`.
 struct LowBGCondition: AlarmCondition {
     static let type: AlarmType = .low
     init() {}
 
+    /// `belowBG` is this alarm's trigger threshold, not an activation limit:
+    /// the predictive look-ahead must be able to run while the latest BG is
+    /// still above it, so `evaluate` checks the threshold itself.
+    var checksOwnBGLimits: Bool { true }
+
     func evaluate(alarm: Alarm, data: AlarmData, now _: Date) -> Bool {
         // ────────────────────────────────
         // 0. sanity checks
         // ────────────────────────────────
         guard let belowBG = alarm.belowBG else { return false }
+        guard let latest = data.bgReadings.last, latest.sgv > 0 else { return false }
 
         func isLow(_ g: GlucoseValue) -> Bool {
             g.sgv > 0 && Double(g.sgv) <= belowBG
@@ -73,6 +79,6 @@ struct LowBGCondition: AlarmCondition {
         // ────────────────────────────────
         // 4. final decision
         // ────────────────────────────────
-        return persistentOK || predictiveTrigger
+        return (isLow(latest) && persistentOK) || predictiveTrigger
     }
 }

LoopFollow/Alarm/AlarmEditing/Editors/LowBgAlarmEditor.swift

@@ -8,13 +8,13 @@ struct LowBgAlarmEditor: View {
 
     var body: some View {
         Group {
-            InfoBanner(text: "This warns you if the glucose is too low now or might be soon, based on predictions. Note: predictions is currently not available for Trio.")
+            InfoBanner(text: "This warns you if the glucose is too low now or might be soon, based on the forecast.")
 
             AlarmGeneralSection(alarm: $alarm)
 
             AlarmBGSection(
                 header: "Low Limit",
-                footer: "Alert when any reading or prediction is at or below this value.",
+                footer: "Alert when any reading or forecast is at or below this value.",
                 title: "BG",
                 range: 40 ... 150,
                 value: $alarm.belowBG
@@ -33,7 +33,7 @@ struct LowBgAlarmEditor: View {
 
             AlarmStepperSection(
                 header: "PREDICTION",
-                footer: "Look ahead this many minutes in Loop’s prediction; "
+                footer: "Look ahead this many minutes in the forecast; "
                     + "if any future value is at or below the threshold, "
                     + "you’ll be warned early. Set 0 to disable.",
                 title: "Predictive",

LoopFollow/Task/AlarmTask.swift

@@ -33,9 +33,7 @@ extension MainViewController {
                 bgReadings: self.bgData
                     .suffix(24)
                     .map { GlucoseValue(sgv: $0.sgv, date: Date(timeIntervalSince1970: $0.date)) }, /// These are oldest .. newest
-                predictionData: self.predictionData
-                    .prefix(12)
-                    .map { GlucoseValue(sgv: $0.sgv, date: Date(timeIntervalSince1970: $0.date)) }, /// These are oldest .. newest, Predictions not currently available for Trio
+                predictionData: self.alarmPredictionData(), /// These are oldest .. newest
                 expireDate: Storage.shared.expirationDate.value,
                 lastLoopTime: Observable.shared.alertLastLoopTime.value,
                 latestOverrideStart: latestOverrideStart,
@@ -74,6 +72,59 @@ extension MainViewController {
         }
     }
 
+    /// Builds the forward glucose series the low alarm looks ahead in,
+    /// oldest .. newest at 5-minute spacing.
+    ///
+    /// Loop reports a single forecast, already stored in `predictionData`. Trio
+    /// reports four forecasts, collapsed into the lowest value per point in time
+    /// by `lowestForecast(forecasts:start:cap:)`.
+    func alarmPredictionData() -> [GlucoseValue] {
+        if Storage.shared.device.value == "Loop" {
+            return predictionData
+                .prefix(MainViewController.alarmForecastPointCap)
+                .map { GlucoseValue(sgv: $0.sgv, date: Date(timeIntervalSince1970: $0.date)) }
+        }
+
+        guard let predBGs = openAPSPredBGs else { return [] }
+
+        let forecasts = ["ZT", "IOB", "COB", "UAM"].compactMap { predBGs[$0] }
+        return MainViewController.lowestForecast(
+            forecasts: forecasts,
+            start: openAPSPredUpdatedTime ?? Date().timeIntervalSince1970
+        )
+    }
+
+    /// Maximum number of forward points (5-minute spacing) the low alarm looks at:
+    /// 12 points = 60 minutes, matching the predictive look-ahead's upper bound.
+    static let alarmForecastPointCap = 12
+
+    /// Collapses several forecasts into a single series by taking the **lowest**
+    /// value at each point in time, oldest .. newest at 5-minute spacing.
+    ///
+    /// Trio/OpenAPS reports four forecasts (ZT, IOB, COB, UAM) rather than the
+    /// single one Loop provides, so this lets the predictive-low alarm fire if
+    /// *any* forecast dips to or below the threshold. Empty forecasts are ignored,
+    /// and each point uses whichever forecasts still extend that far.
+    static func lowestForecast(
+        forecasts: [[Double]],
+        start: TimeInterval,
+        cap: Int = alarmForecastPointCap
+    ) -> [GlucoseValue] {
+        let nonEmpty = forecasts.filter { !$0.isEmpty }
+        guard !nonEmpty.isEmpty else { return [] }
+
+        let count = min(nonEmpty.map { $0.count }.max() ?? 0, cap)
+
+        return (0 ..< count).compactMap { i in
+            let valuesAtIndex = nonEmpty.compactMap { i < $0.count ? $0[i] : nil }
+            guard let lowest = valuesAtIndex.min() else { return nil }
+            return GlucoseValue(
+                sgv: Int(lowest.rounded()),
+                date: Date(timeIntervalSince1970: start + Double(i) * 300)
+            )
+        }
+    }
+
     func saveLatestAlarmDataToFile(_ alarmData: AlarmData) {
         let encoder = JSONEncoder()
         encoder.dateEncodingStrategy = .iso8601

Tests/AlarmConditions/Helpers.swift

@@ -29,6 +29,14 @@ extension Alarm {
         return alarm
     }
 
+    static func low(belowBG: Double?, predictiveMinutes: Int? = nil, persistentMinutes: Int? = nil) -> Self {
+        var alarm = Alarm(type: .low)
+        alarm.belowBG = belowBG
+        alarm.predictiveMinutes = predictiveMinutes
+        alarm.persistentMinutes = persistentMinutes
+        return alarm
+    }
+
     static func fastDrop(delta: Double?, window: Int?) -> Self {
         var alarm = Alarm(type: .fastDrop)
         alarm.delta = delta
@@ -61,7 +69,8 @@ extension AlarmData {
             latestBatteryIsCharging: nil,
             latestPumpBattery: nil,
             batteryHistory: [],
-            recentCarbs: []
+            recentCarbs: [],
+            dbSizePercentage: nil
         )
     }
 
@@ -86,7 +95,8 @@ extension AlarmData {
             latestBatteryIsCharging: nil,
             latestPumpBattery: nil,
             batteryHistory: [],
-            recentCarbs: []
+            recentCarbs: [],
+            dbSizePercentage: nil
         )
     }
 
@@ -116,9 +126,37 @@ extension AlarmData {
             IOB: nil,
             recentBoluses: [],
             latestBattery: nil,
+            latestBatteryIsCharging: nil,
+            latestPumpBattery: nil,
+            batteryHistory: [],
+            recentCarbs: [],
+            dbSizePercentage: nil
+        )
+    }
+
+    static func withGlucose(readings: [GlucoseValue] = [], prediction: [GlucoseValue] = []) -> Self {
+        AlarmData(
+            bgReadings: readings,
+            predictionData: prediction,
+            expireDate: nil,
+            lastLoopTime: nil,
+            latestOverrideStart: nil,
+            latestOverrideEnd: nil,
+            latestTempTargetStart: nil,
+            latestTempTargetEnd: nil,
+            recBolus: nil,
+            COB: nil,
+            sageInsertTime: nil,
+            pumpInsertTime: nil,
+            latestPumpVolume: nil,
+            IOB: nil,
+            recentBoluses: [],
+            latestBattery: nil,
+            latestBatteryIsCharging: nil,
             latestPumpBattery: nil,
             batteryHistory: [],
-            recentCarbs: []
+            recentCarbs: [],
+            dbSizePercentage: nil
         )
     }
 
@@ -143,7 +181,8 @@ extension AlarmData {
             latestBatteryIsCharging: nil,
             latestPumpBattery: nil,
             batteryHistory: [],
-            recentCarbs: carbs
+            recentCarbs: carbs,
+            dbSizePercentage: nil
         )
     }
 }