Parents starting out with a shared co-parenting app tend to do one of two things. Most write down nothing, because the idea of keeping track of everything is exhausting before it begins. A few take it literally and end up with a running commentary on their own life.
Neither helps. The useful version is much narrower than "everything" and much lighter than it sounds.
Why less is genuinely better
It stops you finding things. If eight months of notes contain four hundred entries, the handful you actually want — the term dates, the medication change, the weekend you swapped — are buried under the rest.
It changes how it feels. Writing down every small irritation keeps you thinking about every small irritation. The point of getting the admin out of your head is to stop carrying it, not to carry it somewhere more organised.
It does not survive contact with a busy week. Anything that takes twenty minutes a day gets abandoned inside a fortnight, usually right before the term you would have liked to look back on.
The four things worth keeping
Handovers that did not go to plan. Not the ones that went fine — that is almost all of them, and they tell you nothing. Note the ones that shifted: running late, a changed pickup point, a swap agreed at the school gate. It takes a second at the time and saves the "wasn't that the week you had them?" conversation later.
If you can, note it as it happens rather than that evening. A check-in at the pickup point is a tap; a note written after dinner is a chore you will skip.
Money. Every shared cost, with the receipt, when it happens. Every payment, and every confirmation it arrived. This is the least emotionally loaded thing you will keep and by far the most useful, because money questions are specific and answerable — as long as you are both looking at the same list.
What you agreed. Every schedule change: who asked, what was asked for, what the answer was. Agreements matter as much as refusals. A surprising amount of friction is just one parent remembering something was settled and the other remembering it was floated, and a two-line entry ends that permanently.
Health and school. Diagnoses, medication changes, referrals, anything the school raised. Mostly for the practical reason that you will want it at 2am in an after-hours clinic, and because "was the other parent told" has an easy answer when it is written down.
What to leave out
How you felt. Your feelings are real and they belong somewhere — a friend, a diary, a counsellor. A shared app is not that place, and putting them there turns a logistics tool into somewhere you go to feel bad.
Commentary on the other parent. Opinions about their parenting, their new partner, their spending. Even where you are entirely right, writing it down does nothing for you and it makes the shared space worse to be in.
Things you did not see yourself. Anything a child reported is a child's account of their day, filtered through a six-year-old. If it is worth noting, note what was said and when, without your reading of it.
The trivial. A message answered two hours late is not an event. Logging it costs you the habit.
Write it down as it happens
If you take one thing from this: a two-line note made at the time beats a detailed reconstruction later, every time.
Partly it is accuracy — nobody remembers the specifics of a Tuesday six weeks on. Mostly it is that reconstruction is work, and work you have to do in one sitting is work that does not happen. The whole point is to spend less time on this, not more.
This is why Halven timestamps things itself rather than asking you to, and why check-ins and handover notes are one tap. The less it asks of you in the moment, the more likely it is to be there when you want it.
And then leave it alone
The last thing, and the one worth sitting with.
Most of what you write down will never be read by anyone, including you. That is the point. You keep it so that when a question comes up — which weekend, how much, did we agree that — it is already answered and you can both move on to something else.
Keeping notes in order to make a point about someone tends to be visible as exactly that, and it makes the whole thing heavier for everyone, yourself very much included.
Keep the four things. Keep them briefly, at the time, without adjectives. Then close the app and get on with your evening.