ci: gate the parity check against the reference

.github/workflows/main.yml

@@ -75,11 +75,21 @@ jobs:
         run: |
           # oold-schema owns the reference implementation. Comparing against its current main
           # catches drift that the committed fixture snapshot cannot see.
+          #
+          # This gates, as of oold-schema switching its own CI to this validator. Until then the
+          # reference was still what checked that repository, so parity was informative and a
+          # disagreement had a second opinion behind it. Now nothing else validates the
+          # specification's own examples, which makes agreement between the two implementations
+          # the evidence the switch rests on - and evidence that cannot fail is not evidence.
+          #
+          # It stays valuable after the migration rather than becoming scaffolding: validate.mjs
+          # is being extracted to oold-js, so this becomes a standing cross-implementation
+          # conformance check, which is what catches an ambiguity in the specification rather
+          # than a bug in one port.
           git clone --depth 1 https://github.com/OO-LD/oold-schema.git /tmp/oold-schema
           npm --prefix /tmp/oold-schema install --no-audit --no-fund
           OOLD_SCHEMA_DIR=/tmp/oold-schema uv run python -m pytest \
             tests/test_validation/test_parity_live.py -v --no-cov
-        continue-on-error: true
 
   check-docs:
     runs-on: ubuntu-latest