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Lull app icon

Lull

Everyday apps · iOS · Working prototype

How much caffeine might be left at bedtime?

Screens

Lull — See beyond the next cup.
See beyond the next cup.
Lull — Start with what you drank.
Start with what you drank.
Lull — Keep the day in view.
Keep the day in view.
Lull — Let the evening feel quieter.
Let the evening feel quieter.

Captured from the development build

What it does

Make the relationship between logged caffeine and a chosen bedtime easier to understand through a simple estimate.

How it works

  1. Step 1Log a drink

    Choose a preset or enter an amount and consumption time.

  2. Step 2Keep the record

    The drink remains a local record that can be reviewed in the ledger.

  3. Step 3Estimate the remainder

    The model sums a decay estimate for each drink at the requested time.

  4. Step 4See the evening

    Sampled points become a curve with current and bedtime estimates.

Coffee logDose · time

Enter the drink, caffeine amount and time.

Daily viewSwiftUI

Keep logging and the evening estimate in one quiet surface.

Decay modelCaffeineMath

Add the estimated remainder from each past drink.

Evening targetBedtime · threshold

Compare the estimate against the selected target time.

Drink historySwiftData

Retain logs across app launches.

Caffeine curveTime sampling

Sample the model to draw a curve through the day.

Stack

SwiftUI · SwiftSwiftDataFoundation Date mathExponential decay modelCustom curve drawingUserDefaults settings

A configurable estimate with a default five-hour half-life, not a personal medical measurement.