diff --git a/.github/workflows/converter-ontology-ci.yml b/.github/workflows/converter-ontology-ci.yml
index 2abd3de4b..b3fe56a43 100644
--- a/.github/workflows/converter-ontology-ci.yml
+++ b/.github/workflows/converter-ontology-ci.yml
@@ -25,6 +25,7 @@ on:
     paths:
       - 'converters/ontology/**'
       - 'core-spec/**'
+      - 'ontology/**'
       - 'examples/**'
       - '.github/workflows/converter-ontology-ci.yml'
   pull_request:
@@ -32,6 +33,7 @@ on:
     paths:
       - 'converters/ontology/**'
       - 'core-spec/**'
+      - 'ontology/**'
       - 'examples/**'
       - '.github/workflows/converter-ontology-ci.yml'
 
@@ -64,4 +66,4 @@ jobs:
       - name: Unit Tests
         working-directory: converters/ontology
         run: |
-          uv run pytest
\ No newline at end of file
+          uv run pytest
diff --git a/.github/workflows/converter-orionbelt-ci.yml b/.github/workflows/converter-orionbelt-ci.yml
index 0b3aebf67..9c8e95e96 100644
--- a/.github/workflows/converter-orionbelt-ci.yml
+++ b/.github/workflows/converter-orionbelt-ci.yml
@@ -25,6 +25,7 @@ on:
     paths:
       - 'converters/orionbelt/**'
       - 'core-spec/**'
+      - 'ontology/**'
       - 'examples/**'
       - '.github/workflows/converter-orionbelt-ci.yml'    
   pull_request:
@@ -32,6 +33,7 @@ on:
     paths:
       - 'converters/orionbelt/**'
       - 'core-spec/**'
+      - 'ontology/**'
       - 'examples/**'
       - '.github/workflows/converter-orionbelt-ci.yml'    
 
diff --git a/.github/workflows/validation-ci.yml b/.github/workflows/validation-ci.yml
index 00122a068..5c1299232 100644
--- a/.github/workflows/validation-ci.yml
+++ b/.github/workflows/validation-ci.yml
@@ -26,6 +26,8 @@ on:
       - "validation/**"
       - "python/**"
       - "core-spec/**"
+      - "ontology/**"
+      - "examples/flights.yaml"
       - "examples/tpcds_semantic_model.yaml"
       - ".github/workflows/validation-ci.yml"
   pull_request:
@@ -34,6 +36,8 @@ on:
       - "validation/**"
       - "python/**"
       - "core-spec/**"
+      - "ontology/**"
+      - "examples/flights.yaml"
       - "examples/tpcds_semantic_model.yaml"
       - ".github/workflows/validation-ci.yml"
 
diff --git a/converters/ontology/src/ossie_ontology/converter/ossie_to_spec/converter.py b/converters/ontology/src/ossie_ontology/converter/ossie_to_spec/converter.py
index f6841f419..b63bf9a47 100644
--- a/converters/ontology/src/ossie_ontology/converter/ossie_to_spec/converter.py
+++ b/converters/ontology/src/ossie_ontology/converter/ossie_to_spec/converter.py
@@ -144,6 +144,7 @@ def _convert_relationship(rel: Relationship) -> SpecRelationship:
 
 def _convert_semantic_model(semantic_model: SemanticModel) -> SpecSemanticModel:
     return SpecSemanticModel(
+        version=semantic_model.version,
         name=semantic_model.name,
         description=semantic_model.description,
         ai_context=semantic_model.ai_context,
diff --git a/converters/ontology/src/ossie_ontology/converter/palantir_to_ossie/converter.py b/converters/ontology/src/ossie_ontology/converter/palantir_to_ossie/converter.py
index c87ef7ac1..f1b606c77 100644
--- a/converters/ontology/src/ossie_ontology/converter/palantir_to_ossie/converter.py
+++ b/converters/ontology/src/ossie_ontology/converter/palantir_to_ossie/converter.py
@@ -151,7 +151,7 @@ def convert(
         schema_name: str = "palantir",
     ) -> OssieOntology:
         ontology = OntologyComponent()
-        model = OssieOntology(name="Palantir model", ontology=ontology, version="0.1.0")
+        model = OssieOntology(name="Palantir model", ontology=ontology, version="0.2.0.dev0")
 
         semantic_model = SemanticModel(name="Palantir semantic model")
 
diff --git a/converters/ontology/src/ossie_ontology/converter/spec_to_ossie/converter.py b/converters/ontology/src/ossie_ontology/converter/spec_to_ossie/converter.py
index 0b45ea8a4..75992421b 100644
--- a/converters/ontology/src/ossie_ontology/converter/spec_to_ossie/converter.py
+++ b/converters/ontology/src/ossie_ontology/converter/spec_to_ossie/converter.py
@@ -226,6 +226,7 @@ def _convert_relationship(
 
     def _convert_semantic_model(self, lm_spec: SpecSemanticModel) -> SemanticModel:
         semantic_model = SemanticModel(
+            version=lm_spec.version,
             name=lm_spec.name,
             description=lm_spec.description,
             ai_context=lm_spec.ai_context,
diff --git a/converters/ontology/src/ossie_ontology/model.py b/converters/ontology/src/ossie_ontology/model.py
index 2f9d1e72d..21c722288 100644
--- a/converters/ontology/src/ossie_ontology/model.py
+++ b/converters/ontology/src/ossie_ontology/model.py
@@ -685,8 +685,8 @@ def custom_extensions(self) -> list[CustomExtension]:
 
 
 class SemanticModel:
-    """Bundle of datasets, join paths and metrics. One or more SemanticModels
-    can feed a single OntologyMapping (see spec)."""
+    """Versioned core semantic model embedded in a single OntologyMapping."""
+    _version: str
     _name: str
     _description: str | None
     _ai_context: AiContext | None
@@ -704,7 +704,13 @@ def __init__(
         description: str | None = None,
         ai_context: AiContext | None = None,
         custom_extensions: list[CustomExtension] | None = None,
+        version: str = "0.2.0.dev0",
     ):
+        if version != "0.2.0.dev0":
+            raise ValueError(
+                f"Unsupported semantic model version {version!r}; expected '0.2.0.dev0'"
+            )
+        self._version = version
         self._name = name
         self._description = description
         self._ai_context = ai_context
@@ -716,6 +722,10 @@ def __init__(
         self._join_path_name_map = {}
         self._metric_name_map = {}
 
+    @property
+    def version(self) -> str:
+        return self._version
+
     @property
     def name(self) -> str:
         return self._name
diff --git a/converters/ontology/src/ossie_ontology/spec.py b/converters/ontology/src/ossie_ontology/spec.py
index e61ce52a4..f2a59012f 100644
--- a/converters/ontology/src/ossie_ontology/spec.py
+++ b/converters/ontology/src/ossie_ontology/spec.py
@@ -175,15 +175,12 @@ class Metric(OssieObject):
 
 
 class SemanticModel(OssieObject):
-    """Model contents: datasets plus the join paths and metrics defined over them.
-
-    OntologyMapping embeds these contents under ``semantic_model``; standalone
-    core documents place them at the root alongside document metadata.
-    """
+    """Complete core document embedded under OntologyMapping.semantic_model."""
+    version: Literal["0.2.0.dev0"]
     name: str
     description: str | None = None
     ai_context: AiContext | None = None
-    datasets: list[Dataset] = Field(default_factory=list)
+    datasets: list[Dataset] = Field(min_length=1)
     relationships: list[JoinPath] = Field(default_factory=list)
     metrics: list[Metric] = Field(default_factory=list)
     custom_extensions: list[CustomExtension] = Field(default_factory=list)
diff --git a/converters/ontology/tests/fixtures/flights.yaml b/converters/ontology/tests/fixtures/flights.yaml
index 803ff73d9..b3fb5a136 100644
--- a/converters/ontology/tests/fixtures/flights.yaml
+++ b/converters/ontology/tests/fixtures/flights.yaml
@@ -540,6 +540,7 @@ ontology:
 ontology_mappings:
 - name: flights_mapping
   semantic_model:
+    version: 0.2.0.dev0
     name: Flights semantic model
     datasets:
     - name: RUNWAY
diff --git a/converters/ontology/tests/snapshots/test_flights_snapshot/test_flights_roundtrip_yaml_snapshot/flights_roundtrip.yaml b/converters/ontology/tests/snapshots/test_flights_snapshot/test_flights_roundtrip_yaml_snapshot/flights_roundtrip.yaml
index 805fadef7..4c025815f 100644
--- a/converters/ontology/tests/snapshots/test_flights_snapshot/test_flights_roundtrip_yaml_snapshot/flights_roundtrip.yaml
+++ b/converters/ontology/tests/snapshots/test_flights_snapshot/test_flights_roundtrip_yaml_snapshot/flights_roundtrip.yaml
@@ -610,6 +610,7 @@ ontology:
 ontology_mappings:
 - name: flights_mapping
   semantic_model:
+    version: 0.2.0.dev0
     name: Flights semantic model
     datasets:
     - name: RUNWAY
diff --git a/converters/ontology/tests/test_ossie_parser.py b/converters/ontology/tests/test_ossie_parser.py
index f8e36e03a..d23808a2e 100644
--- a/converters/ontology/tests/test_ossie_parser.py
+++ b/converters/ontology/tests/test_ossie_parser.py
@@ -25,6 +25,7 @@
 
 import pytest
 import yaml
+from pydantic import ValidationError
 
 from ossie_ontology.converter.ossie_to_spec.converter import (
     OssieToSpecConverter,
@@ -49,6 +50,62 @@ def test_parse_returns_model_with_metadata(flights_model):
     assert flights_model.description == "Ontology of flights into and out of airports."
 
 
+def test_embedded_core_document_version_survives_roundtrip(flights_model, tmp_path):
+    assert all(
+        mapping.semantic_model.version == "0.2.0.dev0"
+        for mapping in flights_model.ontology_mappings
+    )
+
+    exported = OssieToSpecConverter.convert(flights_model).dump_yaml()
+    document = yaml.safe_load(exported)
+    assert all(
+        mapping["semantic_model"]["version"] == "0.2.0.dev0"
+        for mapping in document["ontology_mappings"]
+    )
+
+    path = tmp_path / "roundtrip.yaml"
+    path.write_text(exported)
+    reparsed = OssieParser().parse(path)
+    assert all(
+        mapping.semantic_model.version == "0.2.0.dev0"
+        for mapping in reparsed.ontology_mappings
+    )
+
+
+@pytest.mark.parametrize("version", ["missing", "0.1.0", "0.2.0", None, 2])
+def test_parse_rejects_invalid_embedded_version(flights_path, tmp_path, version):
+    document = yaml.safe_load(flights_path.read_text())
+    model = document["ontology_mappings"][0]["semantic_model"]
+    if version == "missing":
+        del model["version"]
+    else:
+        model["version"] = version
+    path = tmp_path / "invalid.yaml"
+    path.write_text(yaml.safe_dump(document))
+
+    with pytest.raises(ValidationError) as exc:
+        OssieParser().parse(path)
+
+    assert exc.value.errors()[0]["loc"] == ("ontology_mappings", 0, "semantic_model", "version")
+
+
+@pytest.mark.parametrize("missing", [True, False], ids=["missing", "empty"])
+def test_parse_rejects_missing_or_empty_datasets(flights_path, tmp_path, missing):
+    document = yaml.safe_load(flights_path.read_text())
+    model = document["ontology_mappings"][0]["semantic_model"]
+    if missing:
+        del model["datasets"]
+    else:
+        model["datasets"] = []
+    path = tmp_path / "invalid.yaml"
+    path.write_text(yaml.safe_dump(document))
+
+    with pytest.raises(ValidationError) as exc:
+        OssieParser().parse(path)
+
+    assert exc.value.errors()[0]["loc"] == ("ontology_mappings", 0, "semantic_model", "datasets")
+
+
 def test_parse_returns_populated_ontology(flights_model):
     ontology = flights_model.ontology
     # Built-in concepts (String, Integer, Decimal, ...) are always present on top
diff --git a/converters/ontology/tests/test_palantir_converter.py b/converters/ontology/tests/test_palantir_converter.py
index 3edd4980a..e7a37f8a5 100644
--- a/converters/ontology/tests/test_palantir_converter.py
+++ b/converters/ontology/tests/test_palantir_converter.py
@@ -277,6 +277,23 @@ def _identifier_columns(model: OssieOntology, concept_name: str) -> list[str]:
     return columns
 
 
+# ----- document metadata ------------------------------------------------
+
+def test_generated_semantic_model_has_core_document_version(tmp_path: Path):
+    model = _convert(
+        tmp_path,
+        [_object_type("widget", "Widget", status="active")],
+        datasets=[_dataset("widget", ["widget_id"])],
+    )
+
+    document = OssieToSpecConverter.convert(model).dump_dict()
+
+    assert document["version"] == "0.2.0.dev0"
+    [mapping] = document["ontology_mappings"]
+    assert mapping["semantic_model"]["version"] == "0.2.0.dev0"
+    assert mapping["semantic_model"]["datasets"]
+
+
 # ----- object type statuses ---------------------------------------------
 
 def test_default_policy_admits_active_endorsed_and_intermediary(tmp_path: Path):
diff --git a/converters/ontology/tests/test_semantic_model.py b/converters/ontology/tests/test_semantic_model.py
new file mode 100644
index 000000000..66f9f05ac
--- /dev/null
+++ b/converters/ontology/tests/test_semantic_model.py
@@ -0,0 +1,62 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+"""Core document constraints at runtime construction and export."""
+
+import pytest
+from pydantic import ValidationError
+
+from ossie_ontology.converter.ossie_to_spec.converter import OssieToSpecConverter
+from ossie_ontology.model import (
+    Dataset,
+    OntologyComponent,
+    OntologyMapping,
+    OssieOntology,
+    SemanticModel,
+)
+
+
+@pytest.mark.parametrize("version", ["0.1.0", "0.2.0", "", None, 2])
+def test_rejects_unsupported_version_at_construction(version):
+    with pytest.raises(ValueError, match="Unsupported semantic model version"):
+        SemanticModel(name="sales", version=version)
+
+
+@pytest.mark.parametrize("version_args", [{}, {"version": "0.2.0.dev0"}])
+def test_requires_datasets_at_export_but_allows_incremental_construction(version_args):
+    model = SemanticModel(name="sales", **version_args)
+    ontology = OssieOntology(
+        name="sales", version="0.2.0.dev0", ontology=OntologyComponent()
+    )
+    ontology.add_ontology_mapping(
+        OntologyMapping(
+            name="sales_mapping", ontology=ontology.ontology, semantic_model=model
+        )
+    )
+
+    with pytest.raises(ValidationError) as exc:
+        OssieToSpecConverter.convert(ontology)
+    assert exc.value.errors()[0]["loc"] == ("datasets",)
+
+    model.add_dataset(Dataset(name="orders", source="sales.public.orders", fields=[]))
+    exported = OssieToSpecConverter.convert(ontology).dump_dict()
+
+    assert exported["ontology_mappings"][0]["semantic_model"] == {
+        "version": "0.2.0.dev0",
+        "name": "sales",
+        "datasets": [{"name": "orders", "source": "sales.public.orders"}],
+    }
diff --git a/converters/orionbelt/ossie_obml_ontology_mapping_analysis.md b/converters/orionbelt/ossie_obml_ontology_mapping_analysis.md
index 8e4ebd0e9..5d39e1828 100644
--- a/converters/orionbelt/ossie_obml_ontology_mapping_analysis.md
+++ b/converters/orionbelt/ossie_obml_ontology_mapping_analysis.md
@@ -68,7 +68,7 @@ ontology_mappings:
 | `join.joinType` | `Relationship.multiplicity` | `many-to-one`→`ManyToOne`, `one-to-one`→`OneToOne` |
 | `column.primaryKey` | entity `object_mappings[].expression` | `<table>.<pk_code>`; identifies the entity |
 | `join.columnsFrom` (FK) | `link_mappings[].object_mapping.expression` | `<table_A>.<fk_code>`; binds the relationship to its far role |
-| whole core model | `ontology_mappings[].semantic_model` | embedded from `OBMLtoOssie.convert()` without standalone document metadata (`version`, `dialects`, `vendors`) |
+| whole core model | `ontology_mappings[].semantic_model` | complete output from `OBMLtoOssie.convert()`|
 
 `<table>` is the final identifier of the dataset `source` (e.g. `db.schema.t` → `t`),
 falling back to the dataset name when `source` has no dotted physical table.
diff --git a/converters/orionbelt/src/ossie_orionbelt/ontology.py b/converters/orionbelt/src/ossie_orionbelt/ontology.py
index 0dfac93c8..e5ee6897b 100644
--- a/converters/orionbelt/src/ossie_orionbelt/ontology.py
+++ b/converters/orionbelt/src/ossie_orionbelt/ontology.py
@@ -106,7 +106,6 @@ def convert(self) -> dict:
             ai_instructions=self.ai_instructions,
         )
         sem_model = core_conv.convert()
-        sem_model.pop("version", None)
         self.warnings.extend(core_conv.warnings)
 
         data_objects = self.obml.get("dataObjects", {}) or {}
diff --git a/converters/orionbelt/tests/test_ossie_converter_ontology.py b/converters/orionbelt/tests/test_ossie_converter_ontology.py
index 64933665d..930688951 100644
--- a/converters/orionbelt/tests/test_ossie_converter_ontology.py
+++ b/converters/orionbelt/tests/test_ossie_converter_ontology.py
@@ -101,13 +101,17 @@ def test_embeds_core_semantic_model(self) -> None:
         omap = doc["ontology_mappings"][0]
         assert omap["name"] == "sales_map"
         assert "semantic_model" in omap
-        assert not {"version", "dialects", "vendors"} & set(omap["semantic_model"])
+        assert omap["semantic_model"]["version"] == "0.2.0.dev0"
+        assert not {"dialects", "vendors"} & set(omap["semantic_model"])
         assert omap["semantic_model"]["name"] == "sales"
         assert {d["name"] for d in omap["semantic_model"]["datasets"]} == {
             "Customers",
             "Products",
             "Orders",
         }
+        result = conv.validate_ossie(omap["semantic_model"])
+        assert result.valid, result.schema_errors + result.semantic_errors
+        assert not result.semantic_warnings
 
     def test_concept_mappings_bind_keys_and_fks(self) -> None:
         doc = conv.OBMLtoOssieOntology(_OBML, model_name="sales").convert()
diff --git a/core-spec/spec.md b/core-spec/spec.md
index dce683616..c1bc8e578 100644
--- a/core-spec/spec.md
+++ b/core-spec/spec.md
@@ -150,10 +150,8 @@ model array cannot produce a valid model document. Preserve model contents and
 custom extensions; never silently select only the first model or overwrite a file
 when splitting a document.
 
-The reusable `$defs/SemanticModel` schema still describes model contents without
-standalone document metadata. In particular, an ontology map continues to embed
-those contents under its `semantic_model` property. This standalone document
-change does not rename or flatten that ontology property.
+For [ontology maps](../ontology/ontology.md#ontology-mappings), each embedded
+model must be a complete core document.
 
 ---
 
diff --git a/examples/flights.yaml b/examples/flights.yaml
index 803ff73d9..b3fb5a136 100644
--- a/examples/flights.yaml
+++ b/examples/flights.yaml
@@ -540,6 +540,7 @@ ontology:
 ontology_mappings:
 - name: flights_mapping
   semantic_model:
+    version: 0.2.0.dev0
     name: Flights semantic model
     datasets:
     - name: RUNWAY
diff --git a/ontology/ontology.json b/ontology/ontology.json
index 47a00e03f..60a316def 100644
--- a/ontology/ontology.json
+++ b/ontology/ontology.json
@@ -297,7 +297,7 @@
           "description": "Human-readable description of this ontology map"
         },
         "semantic_model": {
-          "$ref": "https://raw.githubusercontent.com/apache/ossie/main/core-spec/ossie-schema.json#/$defs/SemanticModel"
+          "$ref": "https://raw.githubusercontent.com/apache/ossie/main/core-spec/ossie-schema.json"
         },
         "concept_mappings": {
           "type": "array",
diff --git a/ontology/ontology.md b/ontology/ontology.md
index 94002a5c1..fc2775bed 100644
--- a/ontology/ontology.md
+++ b/ontology/ontology.md
@@ -385,6 +385,22 @@ Ontology mappings declare how to map the values of fields at the logical level t
 in the ontology. Just as ontologies are partitioned by concept, ontology maps partition into concept
 mappings that group by some concept.
 
+Each mapping's `semantic_model` is a complete
+[core document](../core-spec/spec.md#semantic-model), with its own `version`,
+`name`, and at least one dataset. For example:
+
+```yaml
+ontology_mappings:
+  - name: sales_mapping
+    semantic_model:
+      version: 0.2.0.dev0
+      name: sales_analytics
+      datasets:
+        - name: orders
+          source: sales.public.orders
+    concept_mappings: []
+```
+
 ### Concept mappings
 
 Each concept mapping declares how to populate a concept with objects and how to populate the relationships
@@ -588,6 +604,7 @@ though `Store` plays a role in three of the relationships.
 ## Version History
 
 - **0.2.0.dev0** (2026-05-29): Basic support for ontologies and logical schema mappings
+  - Breaking: each ontology map's `semantic_model` now requires its own `version`.
   - Core ontology structure: Concepts, relationships, and business rules (requires and derived_by)
   - Schema mappings from one or more logical models into an ontology
 
diff --git a/python/README.md b/python/README.md
index 43f9e73b3..88a3b7f4e 100644
--- a/python/README.md
+++ b/python/README.md
@@ -29,8 +29,7 @@ flat shape. The former `semantic_model` wrapper is rejected. Unwrap old
 single-model documents and split multi-model documents into separate files,
 preserving model contents and setting `version` in each file before loading them.
 
-`OssieSemanticModel` remains available for embedded models, such as ontology
-components, which do not include document metadata.
+Use `OssieDocument` for models embedded in ontology maps.
 
 ## Development
 
diff --git a/validation/tests/test_ontology.py b/validation/tests/test_ontology.py
new file mode 100644
index 000000000..00aee8cc3
--- /dev/null
+++ b/validation/tests/test_ontology.py
@@ -0,0 +1,129 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+"""Validate ontology mappings against the local core document schema."""
+
+import json
+from pathlib import Path
+
+import pytest
+import yaml
+from jsonschema import Draft202012Validator
+from referencing import Registry, Resource
+
+_REPO = Path(__file__).parents[2]
+
+
+@pytest.fixture
+def ontology_validator() -> Draft202012Validator:
+    core = json.loads((_REPO / "core-spec/ossie-schema.json").read_text())
+    ontology = json.loads((_REPO / "ontology/ontology.json").read_text())
+    Draft202012Validator.check_schema(core)
+    Draft202012Validator.check_schema(ontology)
+    resource = Resource.from_contents(core)
+    # Resolve both the core schema's canonical ID and the retrieval URL used by
+    # ontology references locally. Registry never fetches over HTTP.
+    registry = Registry().with_resources(
+        [
+            (core["$id"], resource),
+            (
+                "https://raw.githubusercontent.com/apache/ossie/main/core-spec/ossie-schema.json",
+                resource,
+            ),
+        ]
+    )
+    return Draft202012Validator(ontology, registry=registry)
+
+
+def _ontology(semantic_model: object) -> dict:
+    return {
+        "version": "0.2.0.dev0",
+        "name": "sales",
+        "ai_context": {"instructions": "Use for sales analysis"},
+        "ontology": [{"concept": "Order", "type": "EntityType"}],
+        "ontology_mappings": [
+            {
+                "name": "sales_mapping",
+                "semantic_model": semantic_model,
+                "concept_mappings": [],
+            }
+        ],
+    }
+
+
+def _semantic_model() -> dict:
+    return {
+        "version": "0.2.0.dev0",
+        "name": "sales_model",
+        "datasets": [{"name": "orders", "source": "sales.public.orders"}],
+    }
+
+
+def test_ontology_accepts_complete_core_document(ontology_validator):
+    ontology_validator.validate(_ontology(_semantic_model()))
+
+
+@pytest.mark.parametrize("required_property", ["version", "name", "datasets"])
+def test_embedded_model_requires_core_document_properties(
+    ontology_validator, required_property
+):
+    model = _semantic_model()
+    del model[required_property]
+
+    errors = list(ontology_validator.iter_errors(_ontology(model)))
+
+    assert len(errors) == 1
+    assert errors[0].validator == "required"
+    assert required_property in errors[0].message
+    assert list(errors[0].absolute_path) == ["ontology_mappings", 0, "semantic_model"]
+
+
+@pytest.mark.parametrize("version", ["0.1.0", "0.2.0", "", None, 2])
+def test_embedded_model_rejects_invalid_version(ontology_validator, version):
+    model = _semantic_model()
+    model["version"] = version
+
+    errors = list(ontology_validator.iter_errors(_ontology(model)))
+
+    assert errors
+    assert all(
+        list(error.absolute_path) == ["ontology_mappings", 0, "semantic_model", "version"]
+        for error in errors
+    )
+
+
+@pytest.mark.parametrize(
+    "model",
+    [
+        {**_semantic_model(), "datasets": []},
+        {**_semantic_model(), "unexpected": True},
+        {"semantic_model": _semantic_model()},
+        [_semantic_model()],
+    ],
+)
+def test_embedded_model_rejects_invalid_document_shapes(ontology_validator, model):
+    assert not ontology_validator.is_valid(_ontology(model))
+
+
+def test_flights_embedded_models_validate_as_core_documents(ontology_validator):
+    flights = yaml.safe_load((_REPO / "examples/flights.yaml").read_text())
+
+    assert flights["ontology_mappings"]
+    for mapping in flights["ontology_mappings"]:
+        # Validate the embedded core documents without expanding this test to
+        # unrelated ontology concept and relationship constraints.
+        ontology_validator.validate(_ontology(mapping["semantic_model"]))
diff --git a/validation/tests/test_validate.py b/validation/tests/test_validate.py
index 8583c53c7..94dac610d 100644
--- a/validation/tests/test_validate.py
+++ b/validation/tests/test_validate.py
@@ -16,6 +16,7 @@
 # under the License.
 
 import json
+import urllib.request
 from importlib.util import module_from_spec, spec_from_file_location
 from pathlib import Path
 
@@ -67,14 +68,43 @@ def test_accepts_a_single_root_model(core_schema: dict) -> None:
     assert _VALIDATE.validate_schema(document, core_schema) == []
 
 
+@pytest.fixture
+def offline(monkeypatch):
+    def reject_request(*args, **kwargs):
+        pytest.fail("Schema validation must not make HTTP requests")
+
+    monkeypatch.setattr(urllib.request, "urlopen", reject_request)
+    monkeypatch.setattr("jsonschema.validators.urlopen", reject_request, raising=False)
+
+
+@pytest.mark.parametrize("uri", [
+    "https://github.com/apache/ossie/core-spec/ossie-schema.json",
+    "https://raw.githubusercontent.com/apache/ossie/main/core-spec/ossie-schema.json",
+])
+@pytest.mark.parametrize("fragment, document", [
+    ("", _document([_ORDERS], [])),
+    ("#/$defs/AIContext", {"instructions": "Use for sales analysis"}),
+])
+def test_core_schema_references_resolve_offline(offline, uri, fragment, document):
+    assert _VALIDATE.validate_schema(document, {"$ref": uri + fragment}) == []
+
+
+def test_unresolvable_reference_is_a_validation_error(offline):
+    uri = "https://example.invalid/unknown-schema.json"
+
+    errors = _VALIDATE.validate_schema({}, {"$ref": uri})
+
+    assert errors == [f"[Schema] Cannot resolve schema reference: {uri}"]
+
+
 def test_rejects_empty_root_datasets(core_schema: dict) -> None:
     errors = _VALIDATE.validate_schema(_document([], []), core_schema)
 
     assert errors == ["[Schema] datasets: [] should be non-empty"]
 
 
-def test_embedded_semantic_model_does_not_require_document_version(core_schema: dict) -> None:
-    # Ontology components reference this definition without a document envelope.
+def test_semantic_model_definition_does_not_require_document_version(core_schema: dict) -> None:
+    # The reusable contents definition remains independent of document metadata.
     embedded_schema = {
         "$ref": "#/$defs/SemanticModel",
         "$defs": core_schema["$defs"],
@@ -294,10 +324,13 @@ def test_skips_malformed_flat_unique_keys() -> None:
 
 @pytest.fixture
 def run_validator(tmp_path, monkeypatch, capsys):
-    def run(document):
+    def run(document, schema_path=None):
         model_path = tmp_path / "model.json"
         model_path.write_text(json.dumps(document))
-        monkeypatch.setattr(_VALIDATE.sys, "argv", [str(_VALIDATE_PATH), str(model_path)])
+        args = [str(_VALIDATE_PATH), str(model_path)]
+        if schema_path is not None:
+            args.extend(["--schema", str(schema_path)])
+        monkeypatch.setattr(_VALIDATE.sys, "argv", args)
         with pytest.raises(SystemExit) as caught:
             _VALIDATE.main()
         return caught.value.code, capsys.readouterr().out
@@ -305,6 +338,31 @@ def run(document):
     return run
 
 
+@pytest.mark.parametrize("version, expected_exit", [("0.2.0.dev0", 0), ("0.1.0", 1)])
+def test_ontology_cli_validates_embedded_documents_offline(
+    run_validator, offline, version, expected_exit
+):
+    model = _document([_ORDERS], [])
+    model["version"] = version
+    document = {
+        "version": "0.2.0.dev0",
+        "name": "sales",
+        "ai_context": {"instructions": "Use for sales analysis"},
+        "ontology": [{"concept": "Order", "type": "EntityType"}],
+        "ontology_mappings": [{"semantic_model": model, "concept_mappings": []}],
+    }
+
+    exit_code, output = run_validator(
+        document, Path(__file__).parents[2] / "ontology/ontology.json"
+    )
+
+    assert exit_code == expected_exit
+    if expected_exit == 0:
+        assert "Validation PASSED" in output
+    else:
+        assert "ontology_mappings -> 0 -> semantic_model -> version" in output
+
+
 @pytest.mark.parametrize("target", [
     "missing_customers",
     "Warning: missing_customers",
diff --git a/validation/validate.py b/validation/validate.py
index 99b390c6f..8e7af189c 100644
--- a/validation/validate.py
+++ b/validation/validate.py
@@ -50,6 +50,8 @@
 try:
     import yaml
     from jsonschema import Draft202012Validator
+    from referencing import Registry, Resource
+    from referencing.exceptions import Unresolvable
     from yaml.constructor import ConstructorError
 except ImportError:
     print("Missing dependencies. Install with:")
@@ -146,12 +148,26 @@ def _check_unique_keys(self, node: yaml.Node, visited: set) -> None:
 
 
 def validate_schema(data: dict, schema: dict) -> list[str]:
-    """Validate against JSON Schema."""
-    validator = Draft202012Validator(schema)
+    """Validate against JSON Schema, resolving core references locally."""
+    core_path = Path(__file__).parent.parent / "core-spec" / "ossie-schema.json"
+    core = json.loads(core_path.read_text())
+    resource = Resource.from_contents(core)
+    # Ontology references use the raw URL; also register the canonical schema ID.
+    registry = Registry().with_resources([
+        (core["$id"], resource),
+        (
+            "https://raw.githubusercontent.com/apache/ossie/main/core-spec/ossie-schema.json",
+            resource,
+        ),
+    ])
+    validator = Draft202012Validator(schema, registry=registry)
     errors = []
-    for error in validator.iter_errors(data):
-        path = " -> ".join(str(p) for p in error.absolute_path) if error.absolute_path else "(root)"
-        errors.append(f"[Schema] {path}: {error.message}")
+    try:
+        for error in validator.iter_errors(data):
+            path = " -> ".join(str(p) for p in error.absolute_path) if error.absolute_path else "(root)"
+            errors.append(f"[Schema] {path}: {error.message}")
+    except Unresolvable as error:
+        errors.append(f"[Schema] Cannot resolve schema reference: {error.ref}")
     return errors