Nobody owns it
The deal closes. There is a message in a channel, possibly a gong. Then a gap of somewhere between a day and a fortnight, during which the customer has bought something and nothing is happening.
Eventually somebody in delivery opens the proposal, reads it, and builds a project from their understanding of it. That reading is the most consequential hour in the whole engagement and it is not in anybody's calendar.
What gets lost is never the price
The commercials survive. The value is on the order and finance has it.
What does not survive is the reasoning. The exclusion that was negotiated in the third call. The assumption that the client provides the data in a usable format. The thing the buyer said they were nervous about, which the rep handled well and never wrote down.
Those are the things the argument in month two will be about, and they existed only in a conversation.
Two half-fixes
The usual responses each solve half of it. A handover template captures the facts and misses the context, because the useful part does not fit in fields. A handover meeting captures the context and, without a record, leaves delivery retyping the facts anyway — and being in the meeting is not the same as having the terms.
You need both halves, and they fail in opposite directions, which is why doing one well feels like progress and does not help much.
Automate the copying, keep the conversation
The mechanical half should be automatic: the project opens from the won deal, carrying its lines, rates and milestone dates, because those are facts that already exist and copying them by hand only introduces error.
The conversation should still happen. Twenty minutes, recorded as a note on the project, covering what the rep knows and did not write down. That paragraph is usually worth more than the proposal.
The test of whether your handover works is not whether delivery has the terms. It is whether, in month two, anyone has to go back and read the proposal to settle an argument. If they do, the reasoning never made it across — only the paperwork did.