feat: add internal thinking field to capture model's reasoning output (#498)

* feat: add multimodal message support with image data URI handling

* feat: enhance ensureDataURIPrefix to detect MIME types and trim whitespace

* feat: add internal thinking field to capture model's reasoning output

Author: ilopezluna

pkg/ollama/api.go

@@ -66,6 +66,7 @@ type Message struct {
 	Images     []string   `json:"images,omitempty"`       // For multimodal support
 	ToolCalls  []ToolCall `json:"tool_calls,omitempty"`   // For function calling
 	ToolCallID string     `json:"tool_call_id,omitempty"` // For tool results
+	Thinking   string     `json:"thinking,omitempty"`     // Internal field for model's thinking output
 }
 
 // ToolCall represents a function call made by the model

pkg/ollama/http_handler.go

@@ -1056,11 +1056,13 @@ func (s *streamingChatResponseWriter) Write(data []byte) (int, error) {
 			continue
 		}
 
-		// Extract content and tool calls from structured response
+		// Extract content, tool calls, and thinking from structured response
 		var content string
+		var thinking string
 		var toolCalls []ToolCall
 		if len(chunk.Choices) > 0 {
 			content = chunk.Choices[0].Delta.Content
+			thinking = chunk.Choices[0].Delta.ReasoningContent
 			if len(chunk.Choices[0].Delta.ToolCalls) > 0 {
 				// Convert tool calls to Ollama format
 				toolCalls = convertToolCallsToOllamaFormat(chunk.Choices[0].Delta.ToolCalls)
@@ -1075,6 +1077,9 @@ func (s *streamingChatResponseWriter) Write(data []byte) (int, error) {
 		if len(toolCalls) > 0 {
 			message.ToolCalls = toolCalls
 		}
+		if thinking != "" {
+			message.Thinking = thinking
+		}
 
 		ollamaChunk := ChatResponse{
 			Model:     s.modelName,
@@ -1242,6 +1247,10 @@ func (h *HTTPHandler) convertChatResponse(w http.ResponseWriter, respRecorder *r
 		if len(openAIResp.Choices[0].Message.ToolCalls) > 0 {
 			message.ToolCalls = convertToolCallsToOllamaFormat(openAIResp.Choices[0].Message.ToolCalls)
 		}
+		// Include thinking content if present
+		if openAIResp.Choices[0].Message.ReasoningContent != "" {
+			message.Thinking = openAIResp.Choices[0].Message.ReasoningContent
+		}
 	}
 
 	// Build Ollama response