- the dose is expanded to its component antigens first, so one Tdap
entry settles a tetanus booster and a pertussis booster at once;
matching the preparation's own slug would leave both standing
- it runs inside the create transaction and nowhere else: no cron, no
ingest hook, and an edit never re-runs it, so correcting a typo in a
date cannot move a reminder
- forward-only, which is what makes transcribing an old record safe: a
page from decades ago never clears a booster that is due now
- a free-text-only dose matches nothing; a name string is not evidence
about what was in the syringe
- an ordinary preventive-care reminder carries no antigen key and is
structurally out of reach
