Paper A v3.18.2: address codex GPT-5.5 round-16 Minor-Revision findings

Codex independent peer review (paper/codex_review_gpt55_v3_18_1.md) audited
empirical claims against scripts/JSON reports rather than rubber-stamping
prior Accept verdicts. Verdict: Minor Revision. This commit addresses every
flagged item.

- Soften mechanism-identification language (Results IV-D.1, Discussion B):
  per-signature cosine "fails to reject unimodality" rather than "reflects a
  single dominant generative mechanism"; framing tied to joint evidence.
- Replace overabsolute "single stored image" with multi-template phrasing
  in Introduction and Methodology III-A.
- Reframe Methodology III-H so practitioner knowledge is non-load-bearing;
  evidentiary basis is the paper's own image evidence.
- Fix stale section cross-references after the v3.18 retitling: IV-F.* ->
  IV-G.* in 11 locations across methodology and results.
- Fix 0.941 / 0.945 / 0.9407 wording in Methodology III-K to use the
  calibration-fold P5 = 0.9407 and the rounded sensitivity cut 0.945.
- Soften "sharp discontinuity" in Results IV-G.3 to "23-28 percentage-point
  gap consistent with firm-wide non-hand-signing practice".
- Soften Conclusion's "directly generalizable" with explicit conditions on
  analogous anchors and artifact-generation physics.
- Add Appendix B: table-to-script provenance map (15 manuscript tables
  mapped to generating scripts and JSON report artifacts).
- New script signature_analysis/28_byte_identity_decomposition.py produces
  reproducible artifacts for two previously-unverified claims:
  (a) 145 / 50 / 180 / 35 Firm A byte-identity decomposition (verified);
  (b) cross-firm dual-descriptor convergence -- corrected from the previous
      manuscript text "non-Firm-A 11.3% vs Firm A 58.7% (5x)" to the
      database-verified "non-Firm-A 42.12% vs Firm A 88.32% (~2.1x)".
- Clarify scripts 19 / 21 docstrings: legacy EER / FRR / Precision / F1
  helpers are retained for diagnostic use only and are NOT cited as
  biometric performance in the paper. Remove "interview evidence" wording.
- Rebuild Paper_A_IEEE_Access_Draft_v3.docx.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

signature_analysis/19_pixel_identity_validation.py

@@ -8,39 +8,40 @@ occurring reference populations instead of manual labels:
   Positive anchor 1:  pixel_identical_to_closest = 1
       Two signature images byte-identical after crop/resize.
       Mathematically impossible to arise from independent hand-signing
-      => absolute ground truth for replication.
+      => pair-level proof of image reuse and a CONSERVATIVE-SUBSET
+      ground truth for non-hand-signing (only those whose nearest
+      same-CPA match happens to be byte-identical).
 
-  Positive anchor 2:  Firm A (Deloitte) signatures
-      Interview evidence from multiple Firm A accountants confirms that
-      MOST use replication (stamping / firm-level e-signing) but a
-      MINORITY may still hand-sign. Firm A is therefore a
-      "replication-dominated" population (not a pure one). We use it as
-      a strong prior positive for the majority regime, while noting that
-      ~7% of Firm A signatures fall below cosine 0.95 consistent with
-      the minority hand-signers. This matches the long left tail
-      observed in the dip test (Script 15) and the Firm A members who
-      land in C2 (middle band) of the accountant-level GMM (Script 18).
+  Positive anchor 2:  Firm A signatures
+      Treated in the manuscript as a REPLICATION-DOMINATED population
+      based on the paper's own image evidence: the byte-level pair
+      analysis, the Firm A per-signature similarity distribution, the
+      partner-ranking concentration, and the intra-report consistency
+      gap. Approximately 7% of Firm A signatures fall below cosine
+      0.95, forming the long left tail observed in the dip test
+      (Script 15).
 
   Negative anchor:    signatures with cosine <= low threshold
       Pairs with very low cosine similarity cannot plausibly be pixel
-      duplicates, so they serve as absolute negatives.
+      duplicates, so they serve as a conservative supplementary
+      negative reference.
 
-Metrics reported:
-  - FAR/FRR/EER using the pixel-identity anchor as the gold positive
-    and low-similarity pairs as the gold negative.
-  - Precision/Recall/F1 at cosine and dHash thresholds from Scripts
-    15/16/17/18.
+Metrics computed (legacy; NOT all reported in the manuscript):
+  - FAR against the inter-CPA negative anchor is the primary metric
+    reported (Table X). The byte-identical positive anchor has cosine
+    ~= 1 by construction, so FRR / EER / Precision / F1 against that
+    subset are arithmetic tautologies (FRR is trivially 0 below
+    threshold 1) and are intentionally OMITTED from Table X. Legacy
+    EER/FRR/precision/F1 helper functions remain in this script for
+    diagnostic use only and their outputs are NOT cited as biometric
+    performance in the paper.
   - Convergence with Firm A anchor (what fraction of Firm A signatures
     are correctly classified at each threshold).
 
-Small visual sanity sample (30 pairs) is exported for spot-check, but
-metrics are derived entirely from pixel and Firm A evidence.
-
 Output:
   reports/pixel_validation/pixel_validation_report.md
   reports/pixel_validation/pixel_validation_results.json
   reports/pixel_validation/roc_cosine.png, roc_dhash.png
-  reports/pixel_validation/sanity_sample.csv
 """
 
 import sqlite3