The BW filename encodes only the serial NUMBER — `<letter><3 digits>` where
letter = chr(ord('B') + serial // 1000), so `L895…` decodes to 10895. The
two-letter family prefix is not in the filename at all, and every offset
scanner synthesized it as f"BE{num}".
Four of the 43 archive units are BA, not BE. Their binaries say so plainly:
BA9229, BA10060, BA10895, BA15957. Brian caught BA10895 by recognising that
no such unit as BE10895 exists.
serial_of() now reads the serial string out of the file body and falls back
to the old synthesis only when no matching string is found. No analysis
changes: grouping was by the numeric part, which was always correct, and no
unit number maps to more than one serial (checked across all 43).
The same assumption is live in two production sites and is NOT touched here,
because fixing ingest renames rows a running store and Terra-View already
reads them:
- sfm/waveform_store.py:870 `return f"BE{serial_num}"` on import
- minimateplus/client.py:2538 `raw_data.find(b"BE")` in the monitor-log
partial-record decode, which yields serial=None on a BA unit
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HgTe8CamXAHcAmaQ6QNcog
offset_scan3.py covers only waveforms (6,577 unique binaries). The archive
also holds 63,535 unique histograms, which the pre-trigger method cannot
touch: a histogram carries no samples, only a per-interval per-channel peak.
scratch/offset_hist_scan.py scans them — 63,505/63,535 decoded (99.95%),
43 units, 77.9M intervals. It emits every candidate floor statistic per
(file, channel) rather than deciding anything, so thresholds get calibrated
against the waveform ground truth instead of guessed.
Journal §8b records the outcome. What survives is a site-quiet-gated
cross-channel differential that independently confirms BE18438|Vert and
BE9558|Tran+Long with a clean 2.5x separation gap and 0.037% day-level false
alarm, threshold-insensitive across a 2.3x span — the first operating point
in this investigation to pass that test cleanly.
What it does not do, recorded just as plainly: it finds 2 of the 5 confirmed
units, not 5. DC leakage into the interval peak is bimodal (0.9 on BE18438,
0.02 on BE12599), so a negative histogram result is not evidence of health.
Per-channel attribution is not established (channel-scramble p = 0.769) and
timing resolves to ~a month, not a day.
Two dead ends buried for good: the absolute floor is retired (66% of its
discrimination is a day/site confound), and zero-fraction is structurally
impossible — the device clamps every interval peak at >= 1 A/D count.
Two findings independent of the histograms:
- offset_scan3's spread<=0.02 gate discards 18.8% of rows with |pre|>=0.025,
concentrated on 41 unit-channels currently labelled clean; 4 would be
sustained positives without it. The fleet label is three-state, not two.
- The waveform corpus observes ~7% of the days a unit was deployed.
BE10895 is reclassified from transient to a genuine Vert fault of a different
subtype: 49.4% single-axis-dominant events, the highest in the fleet, all on
Vert. The other six marginal units are clean.
Not done: the 11 thin-coverage units were not screened, and no completeness
audit was run.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HgTe8CamXAHcAmaQ6QNcog
serversdownandClaude Opus 5