Covers the oskiewaroll at the title — every Start may open the other door — and pins what each side owes: the climb is a solo run with rising lava; the climb bot and the fight bot both work off a scene graph rebuilt every tick, with their options inside it, and the cube offers no rungs. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01AGbWC1RD3FzZTgbW7S4zDx