An undeclared-rate accumulated scalar is served by packetBurst until
HrtRateFit is ready, then by the hrt branch. The two place a burst
differently -- packetBurst ends it at wallNow, the hrt branch at
wallNow - (nElems-1)*hrtDt -- and the warm-up left no state behind, so
the handover packet skipped the monotonic clamp and stepped the signal
backwards by up to a burst width (-6.5 ms at 10 samples per 2.5 ms
packet, -0.99 s at 1000 samples per 10 ms).
Seeding lastEmitted* alone would only restore ordering. Without
lastAccHrt/prevAccCount the first hrt packet also has no tick delta to
measure, falls back to kDefaultDt and latches ClockOffset against a
burst width that is wrong whenever the cadence is not 1 kHz -- 89 ms of
permanent displacement at 100 samples per 10 ms, below the
recalibration threshold that would otherwise heal it. Seed both.
Also close the wallElapsed <= 0 bypass in both branches: skipping the
bleed cap when the wall has not moved hands back the full proportional
advance, letting a run of same-tick arrivals gain lead while no wall
time passes at all.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
