diff --git a/converters/dbt/pyproject.toml b/converters/dbt/pyproject.toml
index f1bb3b0..abc40a8 100644
--- a/converters/dbt/pyproject.toml
+++ b/converters/dbt/pyproject.toml
@@ -26,6 +26,7 @@ packages = ["src/osi_dbt"]
 
 [tool.uv]
 dev-dependencies = [
+    "jsonschema>=4.0",
     "pytest>=8.0",
     "syrupy>=4.0",
 ]
diff --git a/converters/dbt/src/osi_dbt/msi_to_osi.py b/converters/dbt/src/osi_dbt/msi_to_osi.py
index 6a7dbec..f0f4cf9 100644
--- a/converters/dbt/src/osi_dbt/msi_to_osi.py
+++ b/converters/dbt/src/osi_dbt/msi_to_osi.py
@@ -105,7 +105,6 @@ def convert(
         return ConverterResult(
             output=OSIDocument(
                 version="0.2.0.dev0",
-                dialects=[self._dialect],
                 semantic_model=[
                     OSISemanticModel(
                         name=osi_model_name,
diff --git a/converters/dbt/tests/test_msi_to_osi.py b/converters/dbt/tests/test_msi_to_osi.py
index 686106b..4a082fc 100644
--- a/converters/dbt/tests/test_msi_to_osi.py
+++ b/converters/dbt/tests/test_msi_to_osi.py
@@ -285,7 +285,6 @@ def test_default_dialect_is_ansi_sql(self) -> None:
         )
         result = MSIToOSIConverter().convert(_manifest(semantic_models=[sm])).output
 
-        assert result.dialects == [OSIDialect.ANSI_SQL]
         assert _fields(result)[0].expression.dialects[0].dialect == OSIDialect.ANSI_SQL
 
     def test_configurable_dialect(self) -> None:
@@ -295,7 +294,6 @@ def test_configurable_dialect(self) -> None:
         )
         result = MSIToOSIConverter(dialect=OSIDialect.SNOWFLAKE).convert(_manifest(semantic_models=[sm])).output
 
-        assert result.dialects == [OSIDialect.SNOWFLAKE]
         assert _fields(result)[0].expression.dialects[0].dialect == OSIDialect.SNOWFLAKE
 
 
diff --git a/converters/dbt/tests/test_schema_conformance.py b/converters/dbt/tests/test_schema_conformance.py
new file mode 100644
index 0000000..ce898a5
--- /dev/null
+++ b/converters/dbt/tests/test_schema_conformance.py
@@ -0,0 +1,90 @@
+"""Regression guard: converter output must validate against the core OSI schema."""
+
+import json
+import sys
+from pathlib import Path
+
+import pytest
+import yaml
+
+from osi import OSIDialect
+from osi_dbt.msi_to_osi import MSIToOSIConverter
+
+from metricflow_semantic_interfaces.implementations.semantic_model import PydanticNodeRelation
+from metricflow_semantic_interfaces.test_utils import semantic_model_with_guaranteed_meta
+from metricflow_semantic_interfaces.type_enums import (
+    AggregationType,
+    DimensionType,
+    EntityType,
+    TimeGranularity,
+)
+
+from tests.helpers import _dimension, _entity, _manifest, _measure, _simple_metric
+
+REPO_ROOT = Path(__file__).resolve().parents[3]
+# Reuse the repository's canonical validator instead of reimplementing schema checks.
+sys.path.insert(0, str(REPO_ROOT / "validation"))
+from validate import validate_schema  # noqa: E402
+
+SCHEMA_PATH = REPO_ROOT / "core-spec" / "osi-schema.json"
+
+
+def _representative_manifest():
+    """A manifest that exercises datasets, keys, dimensions, measures, relationships
+    and metrics, so the emitted document covers most of the core schema."""
+    orders = semantic_model_with_guaranteed_meta(
+        name="orders",
+        description="Order facts",
+        node_relation=PydanticNodeRelation(schema_name="analytics", alias="orders"),
+        entities=[
+            _entity("order_id", entity_type=EntityType.PRIMARY),
+            _entity("customer", entity_type=EntityType.FOREIGN, expr="customer_id"),
+        ],
+        dimensions=[
+            _dimension("ds", dim_type=DimensionType.TIME, granularity=TimeGranularity.DAY),
+            _dimension("status", description="Order status", label="Status"),
+        ],
+        measures=[
+            _measure("revenue", agg=AggregationType.SUM, expr="amount"),
+            _measure("order_count", agg=AggregationType.COUNT, expr="order_id"),
+        ],
+    )
+    customers = semantic_model_with_guaranteed_meta(
+        name="customers",
+        description="Customer dimension",
+        node_relation=PydanticNodeRelation(schema_name="analytics", alias="customers"),
+        entities=[
+            _entity("customer", entity_type=EntityType.PRIMARY, expr="customer_id"),
+            _entity("email", entity_type=EntityType.UNIQUE),
+        ],
+        dimensions=[_dimension("country")],
+    )
+    return _manifest(
+        semantic_models=[orders, customers],
+        metrics=[_simple_metric("revenue", "revenue"), _simple_metric("order_count", "order_count")],
+    )
+
+
+def _load_schema() -> dict:
+    return json.loads(SCHEMA_PATH.read_text())
+
+
+@pytest.mark.parametrize("dialect", [OSIDialect.ANSI_SQL, OSIDialect.SNOWFLAKE])
+def test_converter_output_conforms_to_core_schema(dialect: OSIDialect) -> None:
+    document = (
+        MSIToOSIConverter(dialect=dialect)
+        .convert(_representative_manifest(), osi_model_name="conformance")
+        .output
+    )
+    schema = _load_schema()
+
+    # Both public serializations (CLI uses to_osi_yaml) must be schema-conformant.
+    for serialization, data in (
+        ("yaml", yaml.safe_load(document.to_osi_yaml())),
+        ("json", json.loads(document.to_osi_json())),
+    ):
+        errors = validate_schema(data, schema)
+        assert errors == [], (
+            f"{dialect.value} converter output ({serialization}) is not schema-conformant:\n"
+            + "\n".join(errors)
+        )
diff --git a/python/src/osi/models.py b/python/src/osi/models.py
index 766b6e0..703e058 100644
--- a/python/src/osi/models.py
+++ b/python/src/osi/models.py
@@ -149,8 +149,6 @@ class OSIDocument(BaseModel):
     model_config = ConfigDict(frozen=True)
 
     version: str = "0.2.0.dev0"
-    dialects: Optional[list[OSIDialect]] = None
-    vendors: Optional[list[OSIVendor]] = None
     semantic_model: list[OSISemanticModel]
 
     def to_osi_yaml(self, **kwargs: Any) -> str: