CycleStart with derived cycle day #10

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GKaszewski · 2026-08-26T09:14:04Z

GKaszewski commented

2026-08-26 09:14:04 +00:00

What to build

A CycleStart is a Date on which a User's menstrual period began. Recorded once per cycle, never per day. Cycle day for any Date is derived from the most recent preceding CycleStart and is never stored.

Storing cycle day as an integer — the original proposal — fails the same way storing moon phase would. It needs input every single day, which is the least consistently-trackable shape possible; a missed day is an unfillable hole; correcting a mis-remembered start date fixes nothing retroactively; and health providers export period records with dates, not cycle-day integers, so an import could never populate it.

Deriving it means one tap a month, no gaps, and a correction to a CycleStart repairs every Date that depends on it at once.

The feature is entirely optional and invisible unless the User turns it on.

Acceptance criteria

A User can record, edit, and delete a CycleStart on a Date
Cycle day is derived on read and never persisted
Correcting a CycleStart changes the derived cycle day for every affected Date
Dates before the first recorded CycleStart have no cycle day, and that renders sensibly
The feature is off by default and absent from the UI until enabled
Date resolution uses the rule from #2

Blocked by

Date and Timezone become load-bearing (#2)

## What to build A `CycleStart` is a `Date` on which a User's menstrual period began. Recorded once per cycle, never per day. Cycle day for any `Date` is derived from the most recent preceding `CycleStart` and is never stored. Storing cycle day as an integer — the original proposal — fails the same way storing moon phase would. It needs input every single day, which is the least consistently-trackable shape possible; a missed day is an unfillable hole; correcting a mis-remembered start date fixes nothing retroactively; and health providers export period records with dates, not cycle-day integers, so an import could never populate it. Deriving it means one tap a month, no gaps, and a correction to a `CycleStart` repairs every `Date` that depends on it at once. The feature is entirely optional and invisible unless the User turns it on. ## Acceptance criteria - [ ] A User can record, edit, and delete a `CycleStart` on a `Date` - [ ] Cycle day is derived on read and never persisted - [ ] Correcting a `CycleStart` changes the derived cycle day for every affected `Date` - [ ] Dates before the first recorded `CycleStart` have no cycle day, and that renders sensibly - [ ] The feature is off by default and absent from the UI until enabled - [ ] `Date` resolution uses the rule from #2 ## Blocked by - #2

GKaszewski added the ready-for-agent label 2026-08-26 09:14:04 +00:00

GKaszewski referenced this issue

2026-08-26 09:15:23 +00:00

Split export into a complete backup and a shareable extract #16

GKaszewski closed this issue

2026-08-26 19:06:21 +00:00

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Reference: GKaszewski/k-mood#10