One thing I can't tell from this is what you'd actually want back when you leave. If the requirements, the data shape and the agent's memory of the project are the assets, the question is whether any of it is in a format a different platform can read, or whether it only exists as state inside the one you're on. Lock-in that lives in a database you can export is a migration cost, and lock-in that lives in a proprietary context window is a rewrite. Which of those is it, in your case?