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LOOP-5693 Fix CarbMath preconditionFailure when a carb entry predates the ISF window #945

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Merged
ps2 merged 1 commit into from
Aug 13, 2026
+9 −2
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LOOP-5693 Fix CarbMath preconditionFailure when a carb entry predates the ISF window #945

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11 changes: 9 additions & 2 deletions Loop/Managers/LoopDataManager.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -389,8 +389,15 @@ final class LoopDataManager: ObservableObject {
recommendationEffectInterval: recommendationEffectInterval
)

// Carb entries (and a backdated manual-bolus entry) can extend back to carbsStart, and
// CarbMath.map(to:) preconditionFailures if the ISF/carb-ratio timelines don't cover every
// carb entry's start date. timelineIntervalForSensitivity derives its window from dose and
// glucose history only — which can be more recent than carbsStart (e.g. after a CGM gap) —
// so extend the ISF (and override) window back to cover the carb window, matching carbRatio.
let sensitivityStart = min(neededSensitivityTimeline.start, carbsStart)

let sensitivity = try await settingsProvider.getInsulinSensitivityHistory(
startDate: neededSensitivityTimeline.start,
startDate: sensitivityStart,
endDate: neededSensitivityTimeline.end
)

Expand All @@ -404,7 +411,7 @@ final class LoopDataManager: ObservableObject {
throw LoopError.configurationError(.maximumBasalRatePerHour)
}

var overrides = temporaryPresetsManager.presetHistory.getOverrideHistory(startDate: neededSensitivityTimeline.start, endDate: forecastEndTime)
var overrides = temporaryPresetsManager.presetHistory.getOverrideHistory(startDate: sensitivityStart, endDate: forecastEndTime)

// For recommendation, we should consider preMeal override to be ending at time of dose
if presumePresetEndingNow,
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