feat: support extra field in chatcompletion tool_calls for gemini openai compat

crates/goose/src/providers/formats/databricks.rs

@@ -167,11 +167,24 @@ fn format_messages(messages: &[Message], image_format: &ImageFormat) -> Vec<Data
                                 })
                                 .unwrap_or_else(|| "{}".to_string());
 
-                            converted.tool_calls.get_or_insert_default().push(json!({
+                            let tool_calls = converted.tool_calls.get_or_insert_default();
+                            let mut tool_call_json = json!({
                                 "id": request.id,
                                 "type": "function",
-                                "function": {"name": sanitized_name, "arguments": arguments_str}
-                            }));
+                                "function": {
+                                    "name": sanitized_name,
+                                    "arguments": arguments_str,
+                                }
+                            });
+
+                            // Include all metadata fields in the tool call (e.g., thoughtSignature, extra_content)
+                            if let Some(metadata) = &request.metadata {
+                                for (key, value) in metadata {
+                                    tool_call_json[key] = value.clone();
+                                }
+                            }
+
+                            tool_calls.push(tool_call_json);
                         }
                         Err(e) => {
                             content_array
@@ -1347,6 +1360,39 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn test_format_messages_with_thought_signature_metadata() -> anyhow::Result<()> {
+        // Test that thoughtSignature in metadata is included in formatted tool calls
+        let mut metadata = serde_json::Map::new();
+        metadata.insert(
+            "thoughtSignature".to_string(),
+            json!("sig_abc123_test_signature"),
+        );
+
+        let message = Message::assistant().with_tool_request_with_metadata(
+            "tool1",
+            Ok(CallToolRequestParam {
+                name: "test_tool".into(),
+                arguments: Some(object!({"param": "value"})),
+            }),
+            Some(&metadata),
+            None,
+        );
+
+        let spec = format_messages(&[message], &ImageFormat::OpenAi);
+        let as_value = serde_json::to_value(spec)?;
+        let spec_array = as_value.as_array().unwrap();
+
+        assert_eq!(spec_array.len(), 1);
+        let tool_call = &spec_array[0]["tool_calls"][0];
+        assert_eq!(tool_call["id"], "tool1");
+        assert_eq!(tool_call["function"]["name"], "test_tool");
+        // Verify thoughtSignature is included at top level of tool_call
+        assert_eq!(tool_call["thoughtSignature"], "sig_abc123_test_signature");
+
+        Ok(())
+    }
+
     #[test]
     fn test_create_request_claude_has_cache_control() -> anyhow::Result<()> {
         let model_config = ModelConfig {
@@ -1440,4 +1486,45 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn test_format_messages_with_multiple_metadata_fields() -> anyhow::Result<()> {
+        // Test that multiple metadata fields are all preserved
+        let mut metadata = serde_json::Map::new();
+        metadata.insert("thoughtSignature".to_string(), json!("sig_top_level"));
+        metadata.insert(
+            "extra_content".to_string(),
+            json!({
+                "google": {
+                    "thought_signature": "sig_nested"
+                }
+            }),
+        );
+        metadata.insert("custom_field".to_string(), json!("custom_value"));
+
+        let message = Message::assistant().with_tool_request_with_metadata(
+            "tool1",
+            Ok(CallToolRequestParam {
+                name: "test_tool".into(),
+                arguments: None,
+            }),
+            Some(&metadata),
+            None,
+        );
+
+        let spec = format_messages(&[message], &ImageFormat::OpenAi);
+        let as_value = serde_json::to_value(spec)?;
+        let spec_array = as_value.as_array().unwrap();
+
+        let tool_call = &spec_array[0]["tool_calls"][0];
+        // All metadata fields should be present
+        assert_eq!(tool_call["thoughtSignature"], "sig_top_level");
+        assert_eq!(
+            tool_call["extra_content"]["google"]["thought_signature"],
+            "sig_nested"
+        );
+        assert_eq!(tool_call["custom_field"], "custom_value");
+
+        Ok(())
+    }
 }