feat(deepseek): add support for Responses API and Chat Prefix Completion

internal/providers/deepseek.go

@@ -257,9 +257,70 @@ func (p *DeepSeekProvider) ImageGeneration(ctx context.Context, req *models.Imag
 }
 
 func (p *DeepSeekProvider) Responses(ctx context.Context, req *models.ResponsesRequest) (*models.ResponsesResponse, error) {
-	return nil, fmt.Errorf("responses API not supported by deepseek")
+	stream := req.Stream != nil && *req.Stream
+	body := BuildOpenAIResponsesBody(req, stream)
+
+	resp, err := p.client.R().
+		SetContext(ctx).
+		SetHeader("Authorization", "Bearer "+p.apiKey).
+		SetBody(body).
+		Post(fmt.Sprintf("%s/responses", p.config.BaseURL))
+
+	if err != nil {
+		return nil, fmt.Errorf("responses request failed: %w", err)
+	}
+
+	if !resp.IsSuccess() {
+		msg := resp.String()
+		if msg == "" && resp.RawBody() != nil {
+			if bodyBytes, err := io.ReadAll(resp.RawBody()); err == nil {
+				msg = string(bodyBytes)
+			}
+		}
+		return nil, fmt.Errorf("DeepSeek Responses API error (%d): %s", resp.StatusCode(), msg)
+	}
+
+	var respJSON map[string]interface{}
+	if err := json.Unmarshal(resp.Body(), &respJSON); err != nil {
+		return nil, fmt.Errorf("failed to parse responses response: %w", err)
+	}
+
+	return ParseOpenAIResponsesResponse(respJSON, req.Model)
 }
 
 func (p *DeepSeekProvider) ResponsesStream(ctx context.Context, req *models.ResponsesRequest) (<-chan *models.ResponsesStreamChunk, error) {
-	return nil, fmt.Errorf("responses API not supported by deepseek")
+	body := BuildOpenAIResponsesBody(req, true)
+
+	resp, err := p.client.R().
+		SetContext(ctx).
+		SetHeader("Authorization", "Bearer "+p.apiKey).
+		SetBody(body).
+		SetDoNotParseResponse(true).
+		Post(fmt.Sprintf("%s/responses", p.config.BaseURL))
+
+	if err != nil {
+		return nil, fmt.Errorf("responses stream request failed: %w", err)
+	}
+
+	if !resp.IsSuccess() {
+		msg := resp.String()
+		if msg == "" && resp.RawBody() != nil {
+			if bodyBytes, err := io.ReadAll(resp.RawBody()); err == nil {
+				msg = string(bodyBytes)
+			}
+		}
+		return nil, fmt.Errorf("DeepSeek Responses API error (%d): %s", resp.StatusCode(), msg)
+	}
+
+	ch := make(chan *models.ResponsesStreamChunk)
+
+	go func() {
+		defer close(ch)
+		err := StreamOpenAIResponses(resp.RawBody(), ch)
+		if err != nil {
+			fmt.Printf("DeepSeek Responses stream error: %v\n", err)
+		}
+	}()
+
+	return ch, nil
 }

internal/providers/helpers.go

@@ -158,6 +158,9 @@ func MessagesToOpenAIJSON(messages []models.UnifiedMessage) ([]interface{}, erro
 		if m.Name != nil {
 			msg["name"] = *m.Name
 		}
+		if m.Prefix != nil {
+			msg["prefix"] = *m.Prefix
+		}
 		result = append(result, msg)
 	}
 	return result, nil