openai: allow for content _and_ tool calls in the same message

Previously our OpenAI chat completions compat layer assumed that tool
calls and content would never be provided together, but this is not a
correct assumption. Content is only optional when tool calls are
present, but tool calls and content can be provided together

Fixes: https://github.com/ollama/ollama/issues/11704

openai/openai.go

@@ -403,7 +403,11 @@ func fromChatRequest(r ChatCompletionRequest) (*api.ChatRequest, error) {
 	for _, msg := range r.Messages {
 		switch content := msg.Content.(type) {
 		case string:
-			messages = append(messages, api.Message{Role: msg.Role, Content: content, Thinking: msg.Reasoning})
+			toolCalls, err := fromCompletionToolCall(msg.ToolCalls)
+			if err != nil {
+				return nil, err
+			}
+			messages = append(messages, api.Message{Role: msg.Role, Content: content, Thinking: msg.Reasoning, ToolCalls: toolCalls})
 		case []any:
 			for _, c := range content {
 				data, ok := c.(map[string]any)
@@ -454,7 +458,17 @@ func fromChatRequest(r ChatCompletionRequest) (*api.ChatRequest, error) {
 					return nil, errors.New("invalid message format")
 				}
 			}
+			// since we might have added multiple messages above, if we have tools
+			// calls we'll add them to the last message
+			if len(messages) > 0 && len(msg.ToolCalls) > 0 {
+				toolCalls, err := fromCompletionToolCall(msg.ToolCalls)
+				if err != nil {
+					return nil, err
+				}
+				messages[len(messages)-1].ToolCalls = toolCalls
+			}
 		default:
+			// content is only optional if tool calls are present
 			if msg.ToolCalls == nil {
 				return nil, fmt.Errorf("invalid message content type: %T", content)
 			}
@@ -549,6 +563,19 @@ func fromChatRequest(r ChatCompletionRequest) (*api.ChatRequest, error) {
 	}, nil
 }
 
+func fromCompletionToolCall(toolCalls []ToolCall) ([]api.ToolCall, error) {
+	apiToolCalls := make([]api.ToolCall, len(toolCalls))
+	for i, tc := range toolCalls {
+		apiToolCalls[i].Function.Name = tc.Function.Name
+		err := json.Unmarshal([]byte(tc.Function.Arguments), &apiToolCalls[i].Function.Arguments)
+		if err != nil {
+			return nil, errors.New("invalid tool call arguments")
+		}
+	}
+
+	return apiToolCalls, nil
+}
+
 func fromCompleteRequest(r CompletionRequest) (api.GenerateRequest, error) {
 	options := make(map[string]any)
 

openai/openai_test.go

@@ -235,6 +235,45 @@ func TestChatMiddleware(t *testing.T) {
 				Stream: &False,
 			},
 		},
+		{
+			name: "chat handler with tools and content",
+			body: `{
+				"model": "test-model",
+				"messages": [
+					{"role": "user", "content": "What's the weather like in Paris Today?"},
+					{"role": "assistant", "content": "Let's see what the weather is like in Paris", "tool_calls": [{"id": "id", "type": "function", "function": {"name": "get_current_weather", "arguments": "{\"location\": \"Paris, France\", \"format\": \"celsius\"}"}}]}
+				]
+			}`,
+			req: api.ChatRequest{
+				Model: "test-model",
+				Messages: []api.Message{
+					{
+						Role:    "user",
+						Content: "What's the weather like in Paris Today?",
+					},
+					{
+						Role:    "assistant",
+						Content: "Let's see what the weather is like in Paris",
+						ToolCalls: []api.ToolCall{
+							{
+								Function: api.ToolCallFunction{
+									Name: "get_current_weather",
+									Arguments: map[string]any{
+										"location": "Paris, France",
+										"format":   "celsius",
+									},
+								},
+							},
+						},
+					},
+				},
+				Options: map[string]any{
+					"temperature": 1.0,
+					"top_p":       1.0,
+				},
+				Stream: &False,
+			},
+		},
 		{
 			name: "chat handler with streaming tools",
 			body: `{