A twice-daily medication ended up with two rows for one dose slot: the
projector / reminder worker mints a pending row (source REMINDER) at the
slot's `localHmAsUtc` instant, while a "taken" write from the per-med or
bulk intake route inserted a fresh row (source WEB / API). Because
`source` is part of the `(userId, medicationId, scheduledFor, source)`
unique key — and the written instant could drift by a minute from the
projected one — the two rows coexisted: one taken, one still pending and
overdue. The card then read the slot as taken, counted 100%, and
suppressed the "due now" prompt for a dose the user had not taken.
Resolve every scheduled intake write to the slot's canonical instant
before writing and upsert in place, source-agnostic:
- `resolve-slot-instant.ts` snaps an incoming instant to the nearest
scheduled slot for that day (enumerated through the canonical
recurrence engine, so PRN and cyclic off-weeks resolve to no slot) and
anchors it on the same `localHmAsUtc` the projector and worker use.
Off-slot and as-needed writes resolve to null and keep insert semantics.
- The per-med and bulk routes look up the existing row at the canonical
`(userId, medicationId, scheduledFor)` ignoring source and update it in
place — mirroring the status-toggle route — instead of inserting a
sibling. The bulk per-entry response gains an additive `updated` status.
- The reminder worker's missed-dose mint now skips a slot that already
carries an actioned row (taken or skipped) from any source, not only an
existing pending REMINDER row.
PRN / as-needed writes are unaffected. Regression tests pin the collapse
(exact and one-minute drift), the PRN exemption, and the worker guard.