Compare Qwen cache snapshots at matching stages

docs/issue109-verify-gate/README.md

@@ -84,3 +84,13 @@ MTPLX_QWEN4_VERIFY_SDPA_HEAD_CHUNK=0 \
   tools/issue109-model-reference.py /path/to/pinned/mtplx \
   "$DS4_QWEN38_ARTIFACTS" "$DS4_ISSUE109_DIR" /tmp/issue109-model-oracle
 ```
+
+## Snapshot comparison correction (#114)
+
+The historical zero-sign receipt above measured an extra deep oracle snapshot
+against a lazy native bank entry. The deep clone adds zero; this alone creates
+the reported bit change. The raw/live and matching lazy snapshots agree exactly.
+The corrected shared oracle now compares the server's actual snapshot stages,
+requires every raw cache bit to match, and has no signed-zero exception. See
+[the isolated trace and regression](../issue114-snapshot-zero/README.md). The
+original receipts remain unchanged as evidence of the measurement error.