[Bug Fix] [Bug]: New Databricks Foundation Models databricks-gpt-oss-20b and databricks-gpt-oss-120b failed with error: litellm.APIConnectionError: 'signature' (#13318)

* test_transform_choices_without_signature

* fix ChatCompletionThinkingBlock

* extract_reasoning_content

litellm/llms/databricks/chat/transformation.py

@@ -371,8 +371,8 @@ class DatabricksConfig(DatabricksBase, OpenAILikeChatConfig, AnthropicConfig):
                         reasoning_content += sum["text"]
                         thinking_block = ChatCompletionThinkingBlock(
                             type="thinking",
-                            thinking=sum["text"],
-                            signature=sum["signature"],
+                            thinking=sum.get("text", ""),
+                            signature=sum.get("signature", ""),
                         )
                         if thinking_blocks is None:
                             thinking_blocks = []

litellm/proxy/proxy_config.yaml

@@ -1,6 +1,6 @@
 model_list:
-  - model_name: vertex_ai/*
+  - model_name: anthropic/*
     litellm_params:
-      model: vertex_ai/*
+      model: anthropic/*
 
 

tests/test_litellm/llms/databricks/chat/test_databricks_chat_transformation.py

@@ -45,3 +45,48 @@ def test_transform_choices():
     assert choices[0].message.reasoning_content == "i'm thinking."
     assert choices[0].message.thinking_blocks is not None
     assert choices[0].message.tool_calls is None
+
+
+def test_transform_choices_without_signature():
+    """
+    Test that the transformation works correctly when the signature field is missing
+    from the summary, which occurs with new Databricks Foundation Models like
+    databricks-gpt-oss-20b and databricks-gpt-oss-120b.
+    """
+    config = DatabricksConfig()
+    databricks_choices = [
+        {
+            "message": {
+                "role": "assistant",
+                "content": [
+                    {
+                        "type": "reasoning",
+                        "summary": [
+                            {
+                                "type": "summary_text",
+                                "text": "i'm thinking without signature.",
+                                # Note: no signature field here
+                            }
+                        ],
+                    },
+                    {"type": "text", "text": "Response without signature"},
+                ],
+            },
+            "index": 0,
+            "finish_reason": "stop",
+        }
+    ]
+
+    # This should not raise a KeyError for missing signature
+    choices = config._transform_dbrx_choices(choices=databricks_choices)
+
+    assert len(choices) == 1
+    assert choices[0].message.content == "Response without signature"
+    assert choices[0].message.reasoning_content == "i'm thinking without signature."
+    assert choices[0].message.thinking_blocks is not None
+    assert len(choices[0].message.thinking_blocks) == 1
+    
+    # Verify the thinking block was created successfully without signature
+    thinking_block = choices[0].message.thinking_blocks[0]
+    assert thinking_block["type"] == "thinking"
+    assert thinking_block["thinking"] == "i'm thinking without signature."