Productionizes the validated scratch/offset_scan3.py: a DC offset (baseline
shifted off zero — sensor bumped/settled/drifted) is |median(pre-trigger)| >= 5
counts (0.025 in/s) AND flat across pre/mid/end thirds (spread <= 0.02); a
transient moves one third and is rejected by the spread test.
- shape_metrics: offset_from_samples / offset_from_h5 (reads .h5 samples +
pretrig_samples attr; range-aware via the .h5's in/s float samples)
- events schema: shape_offset / _axis / _pre / _spread (via _SCHEMA + the
_migrate ADD COLUMN loop only; NOT the Migration-1 rebuild), threaded through
insert + upsert mirroring shape_*
- ingest: computed at all three waveform_store save paths alongside shape
- backfill_event_shape: also computes + stores (and stale-clears) offset
- exposed via /db/events automatically (SELECT *)
Gating to waveforms is done downstream in terra-view ft_suspicion (mirrors how
shape is ignored for histograms), not at the SFM call sites. 13 new tests.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YDXjZCr4RqT2U3QvMDhgzf
