fix: make RelationResponse.from_id optional to handle null permalinks

When entities are imported from environments where permalinks were not
enabled, the from_entity.permalink can be None. This causes Pydantic
validation to fail because from_id was typed as non-optional Permalink.

This fix:
- Changes from_id to Optional[Permalink] with default=None
- Matches the existing pattern for to_id field
- Adds test case for null permalink validation
- Maintains backwards compatibility

Fixes #483

Co-authored-by: Paul Hernandez <[email protected]>

Author: github-actions[bot]

src/basic_memory/schemas/response.py

@@ -64,13 +64,14 @@ class RelationResponse(Relation, SQLAlchemyModel):
 
     permalink: Permalink
 
-    from_id: Permalink = Field(
+    from_id: Optional[Permalink] = Field(
         # use the permalink from the associated Entity
         # or the from_id value
         validation_alias=AliasChoices(
             AliasPath("from_entity", "permalink"),
             "from_id",
-        )
+        ),
+        default=None,
     )
     to_id: Optional[Permalink] = Field(  # pyright: ignore
         # use the permalink from the associated Entity

tests/schemas/test_schemas.py

@@ -91,6 +91,27 @@ def test_relation_response():
     assert relation.context is None
 
 
+def test_relation_response_with_null_permalink():
+    """Test RelationResponse handles null permalinks (fixes issue #483).
+
+    When entities are imported from environments without permalinks enabled,
+    the from_entity.permalink and to_entity.permalink can be None.
+    This should not cause validation errors.
+    """
+    data = {
+        "permalink": "test/relation/123",
+        "from_id": None,  # Can be None when from_entity.permalink is None
+        "to_id": None,  # Can be None when to_entity.permalink is None
+        "relation_type": "relates_to",
+        "from_entity": {"permalink": None},  # Null permalink
+        "to_entity": {"permalink": None},  # Null permalink
+    }
+    relation = RelationResponse.model_validate(data)
+    assert relation.from_id is None
+    assert relation.to_id is None
+    assert relation.relation_type == "relates_to"
+
+
 def test_entity_out_from_attributes():
     """Test EntityOut creation from database model attributes."""
     # Simulate database model attributes