Without this the schedule would be device-local, which is the failure this
whole feature has to avoid: the phone sets five meals, the PC still derives
four, and the PC's gate nags for a 12:00 checkpoint the phone never offered
and can never satisfy. So sync lands before either edit surface, not after.
The history rides the existing `budget` CRDT record as one
`sched:<YYYY-MM-DD>` field per entry, exactly like the budget's own `hist:`
fields. merge_record is per-field LWW over the *union* of field names and both
devices push the merged record, so a device that predates the feature relays
the fields untouched -- no coordinated release. There is a test for precisely
that: merging our push with a budget-only peer keeps both schedule entries.
Verified the two languages agree on the wire, not just in their own suites --
Python and Dart both emit
{"sched:1970-01-01":{"f":8,"l":20,"n":4},"sched:2026-08-16":{"f":8,"l":20,"n":5}}
The Hlc is derived from the *parsed* timestamp on both sides, which matters
because the epoch fallback formats differently in each language
(1970-01-01T00:00:00+00:00 vs ...000Z) and a string comparison would diverge.
Two guards worth naming:
- A device with no history contributes no `sched:` fields at all, so an unset
default can never outrank a peer's real schedule; and an empty merge result
is never written back, so a pre-feature peer cannot erase a real history.
- Dart's `_syncBudget` synthesises a local record when the schedule has been
edited but the budget never has -- `budgetToLog(null, ...)` returns an empty
Log and would otherwise drop the schedule fields too. Its budget value
carries an epoch stamp, so it loses every LWW race against a real edit.
sync_merge/_schedule.py and sync_merge_schedule.dart are separate modules
rather than additions to the budget adapters, which were at 186 and 170 lines
against the 250 cap. Each declares its own record-id constant so the Dart
pair does not import each other.
772 Python tests at 100% branch coverage, 619 Dart.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159b4E5hh512jYUeaJVNxfM
Krzysztof kuhy Rudnicki
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