Normalize null metadata handling in tool entities (#26890)

api/tests/unit_tests/core/tools/test_tool_entities.py

@@ -0,0 +1,29 @@
+from core.tools.entities.common_entities import I18nObject
+from core.tools.entities.tool_entities import ToolEntity, ToolIdentity, ToolInvokeMessage
+
+
+def _make_identity() -> ToolIdentity:
+    return ToolIdentity(
+        author="author",
+        name="tool",
+        label=I18nObject(en_US="Label"),
+        provider="builtin",
+    )
+
+
+def test_log_message_metadata_none_defaults_to_empty_dict():
+    log_message = ToolInvokeMessage.LogMessage(
+        id="log-1",
+        label="Log entry",
+        status=ToolInvokeMessage.LogMessage.LogStatus.START,
+        data={},
+        metadata=None,
+    )
+
+    assert log_message.metadata == {}
+
+
+def test_tool_entity_output_schema_none_defaults_to_empty_dict():
+    entity = ToolEntity(identity=_make_identity(), output_schema=None)
+
+    assert entity.output_schema == {}