A good handover is written, not a meeting

The usual end-of-project ritual is a series of recorded walkthroughs. Six months later nobody has watched them, the one person who might have has left, and the codebase is full of decisions that look random because the reasons are gone.

Write it while people still disagree

A written record of a technical decision is worth almost nothing if you write it after the argument is settled. By then the alternatives have been forgotten, and the document turns into a description of the code. Written during the argument, it captures the part that actually matters: what else was considered, and why it lost.

1. State the decision in one sentence.
2. List the options that were genuinely considered, including the one you rejected fastest.
3. Record what decided it — usually a deadline, a missing skill or a cost limit. These are the parts people feel awkward writing down, and the parts future readers need most.
4. Note what would make you change your mind. That turns the document into a trigger instead of an archive.

The test

Every project longer than six months ends with the client's own engineers explaining the system back to us, without help, while we take notes on the gaps. Whatever they cannot explain, we document properly in the time we have left. It is a slightly uncomfortable exercise, and it is the only handover check we trust.

You have not handed over a system until someone else can defend its decisions in a design review.