What if we want to bring it in-house later?

That should be possible on any given Tuesday, without a negotiation and without my goodwill being a factor.

What makes it possible

Everything is already yours and already in your accounts, so there is nothing to transfer. That is the whole trick — there is no handover event because there was never a hostage.

What I would do is a proper walkthrough with whoever is taking it on: architecture, decisions and why they were made, the things that look odd but are deliberate, and the two or three areas where I would tread carefully.

The bit most handovers miss

Written documentation aimed at a stranger, not at me. The test is whether a developer who has never met you could run it from the written material alone. That is a higher bar than most documentation clears, including some of mine early on.

Why I am relaxed about it

Because clients who bring things in-house have generally had a good experience, and they talk. And because if a business grows to the point of having its own development team, I would rather be the supplier who made that easy than the one who made it a fight.

It has also, more than once, come back around. The in-house team handles the day to day and calls me for the next new thing, which is a better arrangement for everyone than pretending they need me for everything.