add derived_gt/derived_gt.jsonl: peer-consensus derived payload truth for 6580 images (qr-decode-bench); card section appended

README.md

@@ -90,3 +90,15 @@ Original source:
 
 Licence: CC BY 4.0 — <https://creativecommons.org/licenses/by/4.0/>
 Please cite the authors above, not this mirror.
+
+## Derived ground truth (qr-decode-bench)
+
+`derived_gt/derived_gt.jsonl` was ADDED to this repository on 2026-09-01; no existing file was modified (this section was appended to the card). It records, for each image whose payload this dataset does not publish and on which at least two independent QR decoders agreed, what every decoder of a panel decoded on that image — as sha256 digests of the payload bytes, with the payload text beside them only where no identifier detector fires on it — so that a benchmark can score a decoder against what the OTHER decoders established (per-image leave-one-out, quorum 2), never against its own output.
+
+This is truth DERIVED by decoder consensus, not published by the dataset's authors; the benchmark that uses it marks it with †. Agreement between independent implementations is strong evidence, not proof of what a symbol encodes.
+
+* derived at revision `b85ce5ce82d34f4515bf5c90b60d2b680defd401` from the data files' recorded inventory (sha256 `fa6cf1fdb7d7c8d9d91962eb9b9fd02b8206c57c1c405ea26b893053bc2a2ac8`); the data files are unchanged by this commit
+* panel: apple-vision (apple-vision macOS 14.3.1 VNDetectBarcodesRequest rev4), boofcv (boofcv 0.43.1 (PyBoof jar; java 22.0.1)), opencv (opencv 4.12.0 (QRCodeDetector)), opencv-aruco (opencv 4.12.0 (QRCodeDetectorAruco)), quirc (quirc 1.0 (vendored 927d680904dc)), wechat (wechat_qrcode (opencv-contrib 4.12.0; models 8ae41acb,cc49b8c9,e5d36889,e8acfc39)), zxing-cpp (zxing-cpp 3.1.1)
+* images with derived truth: 6580 of 10098 examined (3518 without a quorum, 0 voided)
+* payloads: 6516 established, 0 carried as text, 0 as digest only because an identifier detector fired, 6516 as digest only because the payload is the image's own id (image records are keyed by `sha256` of the id)
+* format `qrb-derived-gt-peer/1`: JSON lines — one header (rule, quorum, panel versions, yield, corroboration, privacy scan), one line per payload, one line per image