The residual RANDOM peer shakiness on accel/decel was proven (BT_RXJIT record
inter-arrival probe) to be TEST-RIG packet jitter, not the game: two Debug btl4
nodes on one box contend for CPU, so Windows batches their TCP delivery -- records
arrive in bursts (max 56-226ms gaps, burstiness 3-7x) instead of even ~17ms. The
peer dead-reckons across the gaps then snaps -> random shake. Pinning the nodes to
disjoint cores restored even ~17ms delivery (burstiness ~1.0) and the shakiness
vanished (user-confirmed 'that was it'). Real pods = dedicated machines, no
contention -> never see it. So NO un-authentic jitter buffer -- the coupled
body-channel peer (96a896a/f094d78/23f1532) is the authentic + correct finish.
- mech.cpp: BT_RXJIT record-arrival-jitter probe (env-gated).
- tools/mp_launch.sh: 2-node launcher that pins nodes to disjoint cores (bakes in
the fair-delivery condition; documents why).
- context/multiplayer.md: the finding, so it is not re-litigated.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
