What it is
An intentionally minimal pattern for agent handoffs, released by OpenAI as educational rather than production code. Two primitives, routines and handoffs, and very little else. As a teaching artifact it is excellent, because you can read the whole thing in an afternoon and understand exactly what a handoff is.
What goes wrong
Nothing, because you should not be running it in production. OpenAI has been explicit that it is experimental, and has since moved its production recommendation elsewhere. Anyone shipping on it is building on a stated non-commitment.
What the adapter does
Subclasses the client to instrument it, mostly so you can watch handoffs form a causal chain while learning what a handoff is.
client = adapter.create_instrumented_client()
Caveat
The caveat is the page. This is here to learn from, and the concepts transfer to every other framework on this list.