The engagement ends and the client keeps the server

The build is done. The client wants to own it and never call you again. Good.

Their stack has lived in a server pool since kickoff. Handover is membership surgery: you invite their ops lead to the pool with the senior role, they accept, you snapshot everything as handover-final, and your team removes itself. The containers don't move. The URLs don't change. Nothing is exported, re-imported, or "migrated to the client's AWS account" over three painful weeks.

If they hire you back for a month next year, the same process runs in reverse.

Handover used to be a zip and a wiki page. Now it's a change of who's in the pool.