Our sales to onboarding handoff currently depends on people remembering stuff

We're small enough that the handoff from sales to onboarding still works because everyone talks to each other, although I'm trying to fix it before that stops scaling.

Someone closes the customer, then onboarding needs to figure out what was promised, who cares about what, whether anything weird came up during the sales process and what needs to happen next. Half the time that means reading through notes or just asking the salesperson.

Then CS eventually inherits the account and does some version of the same archaeology.

For teams that have cleaned this up, how much of the handoff happens without someone manually packaging everything for the next person now?