Discovered while dry-running the backfill on the prod store: ~10,000
of ~10,059 events are histogram-mode (filename extension `*H`), and
the waveform-body codec wired in via the previous commit doesn't
handle histogram-mode bodies — only the waveform-mode codec at
§7.6.1 is implemented; the histogram-mode codec at §7.6.2 of the
protocol reference is documented but no Python implementation
exists yet.
Without this guard, every histogram event's .h5 file would be
*replaced* with an empty one — strictly worse than today's
broken-int16-LE .h5 because any downstream viewer expecting
non-empty sample arrays would now error out instead of just
rendering wrong values.
Fix: after the decoder runs, check whether any channel has samples.
If not, skip the .h5 write entirely. The sidecar still regenerates
(refreshing the tool_version stamp and any peaks/project info from
the DB row), but the existing .h5 is left untouched.
This is a *temporary* gate. When the histogram codec lands (next
branch: `feat/wire-histogram-codec`), the has_samples check can be
removed and the backfill will then correctly regenerate all .h5
files, histogram and waveform alike.
Observed effect (dry-run on prod store, 10,059 events):
- waveform events (~5%): "[DRY ] would write … + .h5 (would (re)write)"
- histogram events (~95%): "[DRY ] would write … + .h5 (skipped-empty-samples)"
- sidecar tool_version bump succeeds for both
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
serversdown
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