dataforth(datasheet): same-day retest faithfulness — exposure sweep + fix proposal

Whole-source sweep (981,716 records / 406,549 serials): 6,515 same-day multi-run
events; DB holds a NON-latest run for 311 (the strictly-greater-date conflict rule
freezes on an arbitrary same-day run). Corrects the verdict doc to flag same-day
retests as a latest-wins faithfulness violation (not benign). Adds the proposed
>= -with-data-differs conflict-rule fix (diagnose-only) and the sweep tool.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

projects/dataforth-dos/PARSING-FIDELITY-VERDICT-2026-06-17.md

@@ -5,7 +5,12 @@
 
 ## Verdict
 
-**Ingestion/parsing is faithful — 0 genuine parse faults across 11,239 comparable records.** Every staged datasheet that has a corresponding DB record and a comparable test run matches on serial, model, date, and the 5 accuracy-test results. The earlier "mismatches" were all explained by retests, reused serials, format variants, or legacy out-of-scope units — not by the parser misreading or mis-segmenting data.
+**Two distinct questions, two answers:**
+
+1. **Is the parser faithful to the `.DAT` record it reads?** YES — 0 genuine parse faults across 11,239 comparable records. Every value the importer stores is byte-exact; no misreads, no mis-segmentation.
+2. **Does each DB row faithfully reproduce the unit's *final* test sheet?** NOT always. The DB is one-row-per-serial, and for units re-tested **on the same calendar date** the conflict rule (strictly-greater date) freezes on an arbitrary same-day run instead of the latest. Whole-source sweep: **311 (serial,date) groups where the DB holds a non-latest same-day run** (see `SAMEDAY-RETEST-EXPOSURE-2026-06-17.txt`). This is a data-model / conflict-rule defect, not a parser fault — fix proposed in `CONFLICT-RULE-FIX-PROPOSAL-2026-06-17.md`.
+
+The remaining staged-sample "mismatches" were explained by legitimate later-date retests (latest-wins working), reused generic serials, VAS format, or legacy out-of-scope units.
 
 ## Method
 
@@ -20,7 +25,7 @@ Compared each staged original `.TXT` (the DOS-station ground truth, written *bef
 |---|---:|---|
 | **Consistent** (SN+model+date+5×error%) | **11,226** | Faithful parse, confirmed |
 | Retest — DB date newer than `.TXT` | 35 | ON-CONFLICT updated DB to a later test (expected) |
-| Retest — same date, stim matches, run differs | 42 | Unit tested twice same day; DB keeps first run (strictly-greater-date rule) |
+| Retest — same date, stim matches, run differs | 42 | **FAITHFULNESS VIOLATION** — unit tested 2+ times same day; DB froze on a non-latest run (strictly-greater-date rule). Staged subset of the 311 whole-source cases. |
 | VAS/single-point format | 5 | No 5-row accuracy block (SCMVAS) — not comparable by this method |
 | Serial collision (generic SN, diff family) | 2 | `1-1`/`1-2` reused across products; unique-on-serial keeps one |
 | **Genuine parse fault** | **0** | — |
@@ -34,7 +39,7 @@ The last 16 suspects were all `SCM5B37K-1530` (K-thermocouple). Their stim value
 ## Two follow-up items (NOT parsing-correctness bugs)
 
 1. **608 staged originals have no DB record** (mostly A-prefix `10xxx` serials, e.g. `A243-1` = `10243-1`, model `5B45-25D`). These exist as staged `.TXT` but are absent from the DB under both decoded and encoded serial. This is an **ingestion-completeness** question (the source `.DAT` for these units appears to be out of the import scan scope, or these are custom `-NND` variants), separate from parsing fidelity. Worth a completeness pass: confirm which `.DAT` paths the importer scans and whether these models' `.DAT` files are present.
-2. **Same-day retests keep the first run.** The `ON CONFLICT` rule updates only when `EXCLUDED.test_date > test_records.test_date` (strictly greater). Two runs on the *same date* leave the DB on the first-imported run, which may differ from the latest staged datasheet. If "latest run wins" is desired, the rule needs a tiebreaker (e.g. `>=` with an import-time or sequence guard). 42 records currently sit on a same-day earlier run.
+2. **Same-day retests don't apply "latest wins" (PRIMARY DEFECT).** The `ON CONFLICT` rule updates only when `EXCLUDED.test_date > test_records.test_date` (strictly greater). For a unit tested 2+ times on one date, the rule freezes on whichever same-day run the import processed first and never advances to the latest — so the DB (and the website cert) can show non-final measured values. Whole-source exposure (981,716 records / 406,549 serials): **6,515 same-day multi-run events across 5,977 serials; the DB holds a non-latest run for 311 of them** (3,803 already on latest, 984 superseded by a later-date retest, 1,417 serial absent). Fix proposed in `CONFLICT-RULE-FIX-PROPOSAL-2026-06-17.md`. Directly audit-relevant: same-day runs are typically trim/re-test iterations and the **last** run is the accepted cert result.
 
 ## How to re-run