diff --git a/converters/gooddata/src/ossie_gooddata/osi_to_gooddata.py b/converters/gooddata/src/ossie_gooddata/osi_to_gooddata.py
index a8dbac1c..ee1bd232 100644
--- a/converters/gooddata/src/ossie_gooddata/osi_to_gooddata.py
+++ b/converters/gooddata/src/ossie_gooddata/osi_to_gooddata.py
@@ -329,6 +329,12 @@ def _convert_relationship(
     to_ds = rel["to"]
     from_columns: list[str] = rel.get("from_columns", [])
     to_columns: list[str] = rel.get("to_columns", from_columns)
+    if len(from_columns) != len(to_columns):
+        raise ValueError(
+            f"Relationship '{rel.get('name', '<unnamed>')}': from_columns and "
+            f"to_columns must have the same length (got {len(from_columns)} and "
+            f"{len(to_columns)})"
+        )
 
     target_meta = target_info.get(to_ds, {"is_date": False, "col_to_attr": {}})
     sources: list[GdReferenceSource] = []
diff --git a/converters/gooddata/tests/test_osi_to_gooddata.py b/converters/gooddata/tests/test_osi_to_gooddata.py
index 7848eec4..e45adccd 100644
--- a/converters/gooddata/tests/test_osi_to_gooddata.py
+++ b/converters/gooddata/tests/test_osi_to_gooddata.py
@@ -352,6 +352,44 @@ def test_relationships_become_references(osi_tpcds_dict: dict):
     assert "store" in ref_targets
 
 
+def test_relationship_column_count_mismatch_raises():
+    """Verify incomplete Ossie relationship pairs do not get silently truncated."""
+    model = {
+        "semantic_model": [
+            {
+                "name": "orders",
+                "datasets": [
+                    {
+                        "name": "orders",
+                        "source": "analytics.orders",
+                        "fields": [
+                            _direct_field("customer_id", dimension={}),
+                            _direct_field("region_id", dimension={}),
+                        ],
+                    },
+                    {
+                        "name": "customers",
+                        "source": "analytics.customers",
+                        "fields": [_direct_field("id", dimension={})],
+                    },
+                ],
+                "relationships": [
+                    {
+                        "name": "orders_to_customers",
+                        "from": "orders",
+                        "to": "customers",
+                        "from_columns": ["customer_id", "region_id"],
+                        "to_columns": ["id"],
+                    }
+                ],
+            }
+        ]
+    }
+
+    with pytest.raises(ValueError, match="from_columns.*to_columns.*same length"):
+        osi_to_gooddata(model)
+
+
 def test_source_column_from_ansi_sql(osi_tpcds_dict: dict):
     """Verify source columns are extracted from ANSI_SQL expressions."""
     result = osi_to_gooddata(osi_tpcds_dict)
diff --git a/converters/wisdom/src/ossie_wisdom/osi_to_wisdom.py b/converters/wisdom/src/ossie_wisdom/osi_to_wisdom.py
index 0ae111fa..dc441271 100644
--- a/converters/wisdom/src/ossie_wisdom/osi_to_wisdom.py
+++ b/converters/wisdom/src/ossie_wisdom/osi_to_wisdom.py
@@ -366,6 +366,13 @@ def _convert_relationships(
                     ConverterIssue(issue_type=ConverterIssueType.AI_CONTEXT_DROPPED, element_name=relationship.name)
                 )
 
+            if len(relationship.from_columns) != len(relationship.to_columns):
+                raise ValueError(
+                    f"Relationship '{relationship.name}': from_columns and to_columns "
+                    f"must have the same length (got {len(relationship.from_columns)} "
+                    f"and {len(relationship.to_columns)})"
+                )
+
             left_ref = {"uuid": zsheet_refs[left]["uuid"], "name": left}
             right_ref = {"uuid": zsheet_refs[right]["uuid"], "name": right}
             conditions = [
diff --git a/converters/wisdom/tests/test_osi_to_wisdom.py b/converters/wisdom/tests/test_osi_to_wisdom.py
index 1ee17173..233ab2d9 100644
--- a/converters/wisdom/tests/test_osi_to_wisdom.py
+++ b/converters/wisdom/tests/test_osi_to_wisdom.py
@@ -209,6 +209,32 @@ def test_one_to_one_note_restores_relationship_type():
     assert edges[0]["properties"]["relationshipType"] == "ONE_TO_ONE"
 
 
+def test_relationship_column_count_mismatch_raises():
+    document = OSIDocument(
+        semantic_model=[
+            OSISemanticModel(
+                name="m",
+                datasets=[
+                    OSIDataset(name="orders", source="db.s.orders"),
+                    OSIDataset(name="customers", source="db.s.customers"),
+                ],
+                relationships=[
+                    OSIRelationship(
+                        name="orders_to_customers",
+                        from_dataset="orders",
+                        to="customers",
+                        from_columns=["customer_id", "region_id"],
+                        to_columns=["id"],
+                    )
+                ],
+            )
+        ]
+    )
+
+    with pytest.raises(ValueError, match="from_columns.*to_columns.*same length"):
+        OSIToWisdomConverter().convert(document, exported_at="2026-07-10T00:00:00+00:00")
+
+
 def test_unresolved_metric_attaches_to_first_dataset():
     from ossie import OSIMetric