The /db/events/{id}/waveform.json endpoint returns `time_axis` as a
metadata object — {sample_rate, pretrig_samples, t0_ms, dt_ms,
n_samples, total_samples, rectime_seconds} — not a per-sample times
array. Both viewers (sfm_webapp.html sidecar modal + event_browser.html)
were treating it as an array, silently falling back to a derived path
that ignored pretrig entirely and started the time axis at 0.
Symptom: trigger line drawn at the very left edge of every chart, no
visible "leading up to the event" samples even though they're in the
decoded data.
Fix: read time_axis.t0_ms (negative when pretrig samples exist),
time_axis.dt_ms, build per-sample times as `t0_ms + i * dt_ms`. Trigger
line lands at sample where t crosses 0; pretrig samples render at
negative t to the left of it.
Confirmed on a K558 event with 208 pretrig samples + 2 sec rectime at
1024 sps — time axis now spans -203 ms to +2046 ms, trigger line at
~9% from the left edge as expected.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
serversdown
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