Post Step 4 Completion

test-fixtures/PROVENANCE.md

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+# Reference fixture provenance
+
+The owner selected the `abacusai` set on 2026-09-13. The source is
+`G:/.vibe/SciFi-XZBT/exhibit-test/abacusai/reference-exhibits/`.
+Only the three exhibit directories, shared dependencies,
+and upstream README were copied. The external source is unchanged.
+
+These files are NGN test fixtures, not product code. Their upstream README
+describes upstream verification and is not evidence of NGN verification.
+
+Local compatibility corrections:
+
+- Eight read-only descriptors used `kind: telemetry`, which is not
+  one of Contract 5.2's four kinds. They now use `kind: state` with their
+  existing value types; IDs and backing readings are unchanged.
+- Planetarium's action argument metadata was named `args`; it is now named
+  `arguments` under the owner's 5.2 clarification.
+- The shared fixture invoke path now enforces declared argument types,
+  required fields, allowed keys, enums, and numeric/string constraints.
+- Planetarium's magnitude reader and native dispatch still used the old
+  camelCase ID. They now match its existing canonical `sky.magnitude-limit`
+  descriptor, fixing a null snapshot value and failed native writes.
+
+NGN has no fixture-specific target logic. These corrections apply only to
+the local fixture copies. No upstream fixes or independent conformance
+certification are claimed.