What you are seeing is flow — the state where your child feels their best and is fully engaged. Your child is deep in a passion project and the required work is waiting. The absorption you are seeing is flow. The brain is fully engaged, time has distorted, and genuine learning is happening. The required work is also real. The skill being built in this transition is the child growing ability to hold both: their passion and their responsibility. That skill starts with how this moment is handled. Priming the required work before the project begins, rather than during it, makes the transition significantly smoother.
You are really into this. I can see it. We have some work that needs to happen. Let's find a good stopping point.