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Report the guard band's actual depth #13

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Merged
ps2 merged 1 commit into from
Oct 25, 2026
Merged

Report the guard band's actual depth #13

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8 changes: 3 additions & 5 deletions Sources/LoopAlgorithm/Experiments/GuardAndRunwayOutput.swift
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Expand Up @@ -13,6 +13,9 @@ public struct GuardAndRunwayOutput: Equatable {
public var volatility: Double
/// False when active carbs kept the volatility band off.
public var bandApplied: Bool
/// The most the band lowered any point of the forecast, mg/dL; 0 when it was off. A forecast with no
/// points near 60 min, where the band is deepest, is lowered less.
public var bandDepth: Double
/// How far the target for automatic dosing was lowered, mg/dL. Manual recommendations keep the target.
public var runwayShift: Double
/// True while the post-low cut scales down the rising side of retrospective correction.
Expand All @@ -23,11 +26,6 @@ public struct GuardAndRunwayOutput: Equatable {
/// The band's depth multiplier, from the volatility baseline.
public var bandGain: Double { band.gain }

/// How far the band lowers the forecast at its deepest point (60 min), mg/dL; 0 when it was off.
public var bandDepth: Double {
bandApplied ? band.gain * volatility * pow(band.horizon.minutes / 5.0, band.exponent) : 0
}

/// `glucose` lowered by the band as this run applied it; unchanged when the band was off.
public func guarded(_ glucose: [PredictedGlucoseValue]) -> [PredictedGlucoseValue] {
bandApplied ? LoopAlgorithm.volatilityBanded(glucose, band: band, volatility: volatility) : glucose
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9 changes: 7 additions & 2 deletions Sources/LoopAlgorithm/LoopAlgorithm.swift
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Expand Up @@ -842,11 +842,16 @@ public struct LoopAlgorithm {
}
if let band = experimentParameters.volatilityBand, let volatility {
let bandApplied = !(band.carbGate && (prediction.activeCarbs ?? 0) > 0)
var bandDepth = 0.0
if bandApplied {
prediction.glucose = volatilityBanded(prediction.glucose, band: band, volatility: volatility)
let banded = volatilityBanded(prediction.glucose, band: band, volatility: volatility)
bandDepth = zip(prediction.glucose, banded).map {
$0.quantity.doubleValue(for: .milligramsPerDeciliter) - $1.quantity.doubleValue(for: .milligramsPerDeciliter)
}.max() ?? 0
prediction.glucose = banded
}
guardAndRunway = GuardAndRunwayOutput(
volatility: volatility, bandApplied: bandApplied, runwayShift: runwayShift,
volatility: volatility, bandApplied: bandApplied, bandDepth: bandDepth, runwayShift: runwayShift,
postLowRiseCutActive: experimentParameters.postLowRiseCut?.isActive(glucoseHistory: input.glucoseHistory) ?? false,
band: band)
}
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3 changes: 1 addition & 2 deletions Tests/LoopAlgorithmTests/AlgorithmExperimentsTests.swift
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Expand Up @@ -248,8 +248,7 @@ final class AlgorithmExperimentsTests: XCTestCase {
XCTAssertFalse(output.postLowRiseCutActive)
XCTAssertEqual(output.guarded(standard.predictedGlucose), runway.predictedGlucose)
let deepest = zip(plain, banded).map { $0 - $1 }.max()!
XCTAssertLessThanOrEqual(deepest, output.bandDepth + 1e-9)
XCTAssertGreaterThan(deepest, 0.9 * output.bandDepth, "forecast points fall near the 60 min horizon")
XCTAssertEqual(output.bandDepth, deepest, accuracy: 1e-9)
if type == .tempBasal {
XCTAssertGreaterThan(runway.recommendation!.automatic!.basalAdjustment.unitsPerHour,
standard.recommendation!.automatic!.basalAdjustment.unitsPerHour)
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