Went after the flagged ~2.9u peer-motion snap. Added a BT_SNAPLOG diagnostic
(mech4.cpp: logs the re-anchor drift eMag = |authority - dead-reckon| absorbed per
frame) and ran a controlled accel/decel soak: node B BT_AUTODRIVE + BT_DRIVE_SWEEP0
sweeping the throttle through STOP, node A observing, affinity-pinned.
Result: peer drift maxes at ~0.64u (median 0.54u, 18 events >0.5u over 48s), gently
absorbed at k~0.24/frame -- SUB-UNIT, at the noise floor. The ~2.9u figure was stale:
it predated the peer body-channel swap (96a896a, which put the peer on the same
channel the master's mirror predicts) AND was measured without the CPU-affinity fix
(packet-jitter-sparse records inflate the drift). The old "run the master mirror on a
leg-channel prediction" plan is moot now the peer is on the body channel.
No motion-code change -- just the measurement + the BT_SNAPLOG diagnostic (retained).
KB (multiplayer.md, open-questions.md) corrected to the measured value. checkctx CLEAN.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
