diff --git a/converters/dbt/tests/test_msi_to_ossie.py b/converters/dbt/tests/test_msi_to_ossie.py
index 7ed0aa89..418cff0a 100644
--- a/converters/dbt/tests/test_msi_to_ossie.py
+++ b/converters/dbt/tests/test_msi_to_ossie.py
@@ -75,7 +75,7 @@ def _field_expr(result: OssieDocument, field_idx: int = 0) -> str:
 
 
 def _ossie_metrics(result: OssieDocument) -> list:
-    """Return Ossie metrics for the first semantic model, asserting they exist."""
+    """Return the document's Ossie metrics, asserting they exist."""
     metrics = result.metrics
     assert metrics is not None
     return metrics
diff --git a/converters/sigma/src/ossie_sigma/ossie_to_sigma.py b/converters/sigma/src/ossie_sigma/ossie_to_sigma.py
index 3753aa70..abde620d 100644
--- a/converters/sigma/src/ossie_sigma/ossie_to_sigma.py
+++ b/converters/sigma/src/ossie_sigma/ossie_to_sigma.py
@@ -30,7 +30,6 @@
     OssieField,
     OssieMetric,
     OssieRelationship,
-    OssieSemanticModel,
     OssieVendor,
 )
 
@@ -40,7 +39,7 @@
 from ossie_sigma.spec_keys import MODEL_LEVEL_SPEC_KEYS
 
 # Objects a `SIGMA` custom_extensions vendor entry can be attached to.
-_SigmaExtensionHost = Union[OssieDataset, OssieField, OssieMetric, OssieRelationship, OssieSemanticModel]
+_SigmaExtensionHost = Union[OssieDataset, OssieField, OssieMetric, OssieRelationship, OssieDocument]
 
 _ID_NAMESPACE = uuid5(NAMESPACE_URL, "ossie.apache.org/converters/sigma")
 
diff --git a/converters/sigma/tests/test_ossie_to_sigma.py b/converters/sigma/tests/test_ossie_to_sigma.py
index da6ff383..20e1800a 100644
--- a/converters/sigma/tests/test_ossie_to_sigma.py
+++ b/converters/sigma/tests/test_ossie_to_sigma.py
@@ -17,6 +17,7 @@
 
 from pathlib import Path
 
+import pytest
 import yaml
 from ossie import (
     OssieDataset,
@@ -28,7 +29,6 @@
     OssieMetric,
 )
 
-import pytest
 from ossie import OssieRelationship
 from pydantic import ValidationError
 
@@ -121,7 +121,7 @@ def test_relationship_ids_are_scoped_by_owning_dataset():
             OssieRelationship(
                 name="Parent", **{"from": "shipments"}, to="carriers", from_columns=["x"], to_columns=["y"]
             ),
-        ]
+        ],
     )
 
     spec = OssieToSigmaConverter().convert(document).output
@@ -205,7 +205,7 @@ def test_untranslatable_expression_omits_the_column_instead_of_faking_a_formula(
                     ]
                 ),
             )
-        ]
+        ],
     )
 
     result = OssieToSigmaConverter().convert(document)
@@ -259,7 +259,7 @@ def test_datatypes_only_ever_emit_the_two_documented_format_kinds():
                     )
                 ],
             )
-        ]
+        ],
     )
 
     columns = OssieToSigmaConverter().convert(document).output["pages"][0]["elements"][0]["columns"]
diff --git a/converters/sigma/tests/test_roundtrip.py b/converters/sigma/tests/test_roundtrip.py
index 6c03251d..4e5a0905 100644
--- a/converters/sigma/tests/test_roundtrip.py
+++ b/converters/sigma/tests/test_roundtrip.py
@@ -61,11 +61,14 @@ def test_osi_sigma_osi_roundtrip_preserves_portable_fields(fixture_name):
     document_2 = SigmaToOssieConverter().convert(spec_2).output
 
     def portable(document):
-        model = document
         return {
-            "datasets": [(d.name, d.source, [(f.name, f.datatype) for f in d.fields or []]) for d in model.datasets],
-            "relationships": [(r.name, r.from_dataset, r.to, r.from_columns, r.to_columns) for r in model.relationships or []],
-            "metrics": [(m.name,) for m in model.metrics or []],
+            "datasets": [
+                (d.name, d.source, [(f.name, f.datatype) for f in d.fields or []]) for d in document.datasets
+            ],
+            "relationships": [
+                (r.name, r.from_dataset, r.to, r.from_columns, r.to_columns) for r in document.relationships or []
+            ],
+            "metrics": [(m.name,) for m in document.metrics or []],
         }
 
     assert portable(document_1) == portable(document_2)
diff --git a/converters/wisdom/tests/test_ossie_to_wisdom.py b/converters/wisdom/tests/test_ossie_to_wisdom.py
index f89f5413..bfee1bad 100644
--- a/converters/wisdom/tests/test_ossie_to_wisdom.py
+++ b/converters/wisdom/tests/test_ossie_to_wisdom.py
@@ -190,7 +190,7 @@ def test_one_to_one_note_restores_relationship_type():
                 to_columns=["id"],
                 ai_context="one-to-one relationship",
             )
-        ]
+        ],
     )
     export = OssieToWisdomConverter().convert(document, exported_at="2026-07-10T00:00:00+00:00").output
     edges = export["domain"]["zsheet_json"]["relationshipGraph"]["relationships"]
@@ -203,7 +203,7 @@ def test_unresolved_metric_attaches_to_first_dataset():
     document = OssieDocument(
         name="m",
         datasets=[OssieDataset(name="a", source="db.s.a"), OssieDataset(name="b", source="db.s.b")],
-        metrics=[OssieMetric(name="row_count", expression=_snowflake("COUNT(*)"))]
+        metrics=[OssieMetric(name="row_count", expression=_snowflake("COUNT(*)"))],
     )
     result = OssieToWisdomConverter().convert(document, exported_at="2026-07-10T00:00:00+00:00")
     export = result.output
diff --git a/python/src/ossie/models.py b/python/src/ossie/models.py
index a1825557..9a00b44b 100644
--- a/python/src/ossie/models.py
+++ b/python/src/ossie/models.py
@@ -194,7 +194,7 @@ class OssieMetric(BaseModel):
 
 
 class OssieSemanticModel(BaseModel):
-    """Top-level container representing a complete semantic model."""
+    """Semantic model: the datasets, relationships, and metrics for one business domain."""
 
     model_config = ConfigDict(frozen=True)