Every item names code and tests that exist at 1be71d9, with links to their lines at that commit. For each test, the guide says what it measures. The guide drops the removed MotionDriver, SetFrameDriver, SetFrameSpin, SetFrameOrbit, PlaceOnOrbit and ApplySpin (also ter-iq0w). It describes rails components, motion intents, step records and following frames in their place. Section 7 now covers the rotation terms of a turning frame, the air rule of a character's up, numeric frames and following frames inside turning frames, with their tests and the measured numbers of spin-gravity.md and ARCHITECTURE.md. Section 4 gives the measured thresholds of numeric-frames.md. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>