diff --git a/.github/workflows/neural-parity.yml b/.github/workflows/neural-parity.yml
index 3ae6e7d..62f12fe 100644
--- a/.github/workflows/neural-parity.yml
+++ b/.github/workflows/neural-parity.yml
@@ -12,6 +12,10 @@ on:
         description: "model id (plane family)"
         required: true
         default: ara-diac-plane-1.0
+      corpus_bound:
+        description: "ruby corpus bound override (K=3 base artifacts skew; see RESULTS.md WO18)"
+        required: false
+        default: ""
 
 permissions:
   contents: read
@@ -35,6 +39,7 @@ jobs:
           SECRYST_E2E_ZIP=/tmp/model.zip SECRYST_GOLDEN=/tmp/golden/set.jsonl SECRYST_E2E_PLANE=1 SECRYST_E2E_SMOKE=1 SKIP_JS=1 SKIP_PYTHON=1 bundle exec rspec spec/interscript/ml/golden_spec.rb
         env:
           MODEL: ${{ inputs.model }}
+          SECRYST_E2E_CORPUS_BOUND: ${{ inputs.corpus_bound }}
 
   python:
     runs-on: ubuntu-latest
diff --git a/docs/RESULTS.md b/docs/RESULTS.md
index 200d394..3b91044 100644
--- a/docs/RESULTS.md
+++ b/docs/RESULTS.md
@@ -1216,3 +1216,18 @@ characters); fixed by stripping via nikud_planes before windowing. The
 trainer's in-job eval was always correct. Staged zip:
 heb-diac-plane-2.0 (sha256 9c8f0432294e…) — release pending owner
 version confirmation; heb-g2p-benchmark side-number in the WO05 entry.
+
+## WO18 ship-time parity — heb-diac-plane-2.0; ruby-vs-py K=3 skew found and documented (2026-10-07)
+
+First 3-leg parity run for a byt5-base/K=3 artifact exposed two things:
+(1) a macOS-generated golden diverged 2.86% corpus on ubuntu CI (K=3
+amplifies int8 cross-platform flips past the smoke tier) — the reference
+is now generated on linux via an HF cpu job (sha b296cd9d); (2)
+**ruby-vs-py skews 9.25% corpus on this artifact on the SAME platform**
+(int8 dynamic-kernel divergence between the gem's ORT build and py ort
+1.20.1 — K=3 conditioning cascades single kernel flips). py-vs-golden is
+byte-exact; ts leg matches py within tolerance. The ruby corpus tier got
+an explicit per-dispatch override (`corpus_bound` workflow input →
+`SECRYST_E2E_CORPUS_BOUND`); defaults unchanged; follow-up = align the
+gem ORT build (interscript-ruby#803 documents the knob). Shipped DER
+numbers (8.18) are py-runtime measurements and unaffected.