The fork exists to add one line to the system message. If anything else drifts, the
pilot's cheat rate stops being comparable to the baseline measured with the stock task,
and nothing would fail to say so.
Also asserts the scratch line says nothing about agents, sharing, persistence or
messages, since the mechanism being reproduced started as a scratchpad.
92 tests, green with HTTP_PROXY pointed at a closed port.
Claude-Session: https://claude.ai/code/session_01Cq98H7sNoSJdL3W98f18bu
