Record that 2-BM's start_date is the previous scan's end_date - #653
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Operations said `start_date` is the acquisition timestamp and stopped there, which is how a reader ends up trusting it. Measured across the six files in the pilot experiment folder: every `end_date` falls within five seconds of its own file close, and in three consecutive cases the `start_date` is the previous file's `end_date` to the second. One file does look correct, which is part of why the defect survives casual inspection. The page now separates what was measured from what was inferred. The six-file pattern and the live PV read are measurements; the explanation (the areaDetector timestamp attribute refreshing only while frames flow) is a reading of them, and staff own the IOC configuration that would confirm or replace it. New DATA-11 asks whether the file contract can be repaired at the source, and says plainly that this is upstream of CORA: every consumer of a 2-BM scan file inherits it, silently. DATA-8 gains its first real data point and, more usefully, becomes askable at all. Until 2026-08-12 the reader could not read the commanded counts, because 2-BM writes them as one-element arrays and the reader understood only plain scalars, so every shortfall check compared against nothing. The first production scan CORA read end to end dropped no frames. The host section's interim file-access answer is corrected from what was proposed to what was done: a staged copy, exercised on a 24.5 GB file, with the two costs a durable answer should weigh (the copy duplicates the file, and digesting it takes 82 seconds). Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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Folds today's beamline findings into the 2-BM pages. Docs only; no code.
start_dateis the previous scan'send_dateOperations said
start_dateis the acquisition timestamp and stopped there, which is how a reader ends up trusting it. Measured across the six files in the pilot experiment folder: everyend_datefalls within five seconds of its own file close, and in three consecutive cases thestart_dateis the previous file'send_dateto the second.test_005ran on the morning of Aug 12 and claims a start on the evening of Aug 11.One file,
test_002, does look correct. It is included rather than omitted, because leaving it out would overstate the pattern and anyone checking their own files will find it.The page separates measurement from inference. The six-file table and the live PV read are measured; the explanation (the areaDetector timestamp attribute refreshing only while frames flow) is a reading of them, and staff own the IOC configuration that would confirm or replace it.
New DATA-11 asks whether the file contract can be repaired at the source, and states plainly that this is upstream of CORA: every consumer of a 2-BM scan file inherits the wrong start time, silently.
DATA-8 becomes answerable
Until 2026-08-12 the question could not be asked at all. The reader could not read the commanded counts, because 2-BM writes them as one-element arrays and the reader understood only plain scalars, so every shortfall check silently compared against nothing. Fixed in #651. The first production scan CORA read end to end dropped no frames: 1501 commanded, 1501 captured.
Host section
The interim file-access answer is corrected from what was proposed to what was done: a staged copy, exercised on a 24.5 GB file, with the two costs a durable answer should weigh (the copy duplicates the file; digesting it takes 82 seconds, which is why the deployment raises the digest walk budget from #652).
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