The duplicate-open mistake is one of the quietly common ones — you think you've finished a pen, you open the next one, and three days later you find the old one with two doses still in it at the back of the fridge or the kitchen counter. Sometimes it's a few days' worth of medication you can't use; sometimes it's a refill request submitted earlier than it needed to be, which throws the prescription rhythm out of sync with the calendar. The fix is a single column in the journal — a pen-lifecycle ledger.
One row per pen, in order. Each row holds two dates: the day you broke the seal on the pen, and the day you finished it. Both dates get logged the moment they happen, not later.
Three things that ledger gives you. One. You can never double-open, because the active pen is the one with an open-date and no depleted-date — one tap to confirm.
Two. You know exactly when the next refill needs ordering, because the average pen-lifespan across the last four entries tells you the rhythm — most weekly users land between 28 and 32 days per pen, but it varies by dose and stays surprisingly consistent per person. Three.
The ledger is the cleanest record to share at a refill conversation with the pharmacist, who occasionally asks 'how long does a pen typically last you' and otherwise gets a vague answer. Titra has a one-line entry slot per pen — you can sit the ledger inside the journal without creating a separate tracking app. Organisational note: the medication itself is your prescriber's call, and the storage rules are on the leaflet.
The ledger is just the calendar of when each pen lived and died.