fix(validation): count a scoped @context term only where it is a property

src/oold/validation/frame.py

@@ -76,11 +76,17 @@ def embedded_properties(schema: dict[str, Any]) -> list[str]:
 
     Shape is the primary signal; a scoped context is a strong hint but not mandatory, since an
     embed can also be mapped by the ambient top-level context.
+
+    A scoped term only counts where the schema declares a property of that name. A schema must
+    reflect every ``$ref`` in its ``@context`` (``OOLD-CMP-b926``), including the ones reached
+    from ``$defs``, so the context carries terms for properties this schema's instances never
+    hold; treating those as embeds puts a property into the derived frame that no instance can
+    match, and framing then returns nothing.
     """
     properties = collect_composed_properties(schema)
     structural = [name for name, prop in properties.items() if is_embed(prop)]
     terms = context_terms(schema.get("@context"))
-    scoped = [term for term, definition in terms.items() if "@context" in definition]
+    scoped = [term for term, definition in terms.items() if "@context" in definition and term in properties]
     # dict.fromkeys dedupes while preserving order, matching the JS Set spread.
     return list(dict.fromkeys([*structural, *scoped]))
 

tests/test_validation/test_jsonld.py

@@ -122,6 +122,28 @@ def test_embedded_properties_follows_allof_composition():
     assert embedded_properties(schema) == ["inherited"]
 
 
+def test_embedded_properties_ignores_a_scoped_term_that_is_not_a_property_here():
+    """A $defs subschema's $ref is reflected in the root @context (OOLD-CMP-b926).
+
+    Its term carries a scoped @context, but the root object has no such property, so an instance
+    can never hold one. Counting it would put an unmatchable property into the derived frame.
+    """
+    schema = {
+        "properties": {"type": {"type": "array", "items": {"type": "string"}}},
+        "$defs": {"Component": {"properties": {"amount": {"$ref": "https://oo-ld.test/x/MassFraction.schema.json"}}}},
+        "@context": {
+            "type": {"@id": "@type", "@container": "@set"},
+            "amount": {
+                "@id": "https://example.org/amount",
+                "@type": "@id",
+                "@context": "https://oo-ld.test/x/MassFraction.schema.json",
+            },
+        },
+    }
+    assert embedded_properties(schema) == []
+    assert "amount" not in schema_to_frame(schema, "https://oo-ld.test/x/C.schema.json")
+
+
 # ------------------------------------------------------------------ loader