diff --git a/backend/.gitignore b/backend/.gitignore
new file mode 100644
index 0000000..46c8ed0
--- /dev/null
+++ b/backend/.gitignore
@@ -0,0 +1 @@
+test_output/
diff --git a/backend/internal/service/inference.go b/backend/internal/service/inference.go
index ac9c896..bd55b0c 100644
--- a/backend/internal/service/inference.go
+++ b/backend/internal/service/inference.go
@@ -36,7 +36,6 @@ type imageGenRequest struct {
 	Prompt         string  `json:"prompt"`
 	N              int     `json:"n,omitempty"`
 	Size           string  `json:"size,omitempty"`
-	ResponseFormat string  `json:"response_format,omitempty"`
 	Steps          int     `json:"steps,omitempty"`
 	CFGScale       float64 `json:"cfg_scale,omitempty"`
 }
@@ -57,7 +56,12 @@ func GenerateImages(ctx context.Context, prompt string, params AssetParams) ([]G
 	}
 
 	if imgCfg.APIKey != "" {
-		return callImageGenAPI(ctx, prompt, count)
+		width, height := imgCfg.Width, imgCfg.Height
+		if params.Resolution > 0 {
+			width = params.Resolution
+			height = params.Resolution
+		}
+		return callImageGenAPI(ctx, prompt, count, width, height)
 	}
 
 	size := params.Resolution
@@ -69,13 +73,12 @@ func GenerateImages(ctx context.Context, prompt string, params AssetParams) ([]G
 }
 
 // callImageGenAPI 调用 OpenAI 兼容的 Images API，返回生成的图片。
-func callImageGenAPI(ctx context.Context, prompt string, count int) ([]GeneratedImage, error) {
+func callImageGenAPI(ctx context.Context, prompt string, count, width, height int) ([]GeneratedImage, error) {
 	reqBody := imageGenRequest{
 		Model:          imgCfg.Model,
 		Prompt:         prompt,
 		N:              count,
-		Size:           fmt.Sprintf("%dx%d", imgCfg.Width, imgCfg.Height),
-		ResponseFormat: "b64_json",
+		Size:           fmt.Sprintf("%dx%d", width, height),
 	}
 	if imgCfg.Steps > 0 {
 		reqBody.Steps = imgCfg.Steps
@@ -108,7 +111,7 @@ func callImageGenAPI(ctx context.Context, prompt string, count int) ([]Generated
 		return nil, fmt.Errorf("image gen api error %d: %s", resp.StatusCode, string(b))
 	}
 
-	return parseImageResponse(ctx, resp.Body)
+	return parseImageResponse(ctx, resp.Body, width, height)
 }
 
 // ======================== 图片编辑 API ========================
@@ -138,7 +141,6 @@ func callImageEditAPI(ctx context.Context, imageData []byte, prompt string, coun
 	writer.WriteField("model", imgCfg.Model)
 	writer.WriteField("n", strconv.Itoa(count))
 	writer.WriteField("size", fmt.Sprintf("%dx%d", imgCfg.Width, imgCfg.Height))
-	writer.WriteField("response_format", "b64_json")
 
 	if err := writer.Close(); err != nil {
 		return nil, fmt.Errorf("close multipart writer: %w", err)
@@ -164,11 +166,11 @@ func callImageEditAPI(ctx context.Context, imageData []byte, prompt string, coun
 		return nil, fmt.Errorf("image edit api error %d: %s", resp.StatusCode, string(b))
 	}
 
-	return parseImageResponse(ctx, resp.Body)
+	return parseImageResponse(ctx, resp.Body, imgCfg.Width, imgCfg.Height)
 }
 
 // parseImageResponse 解析 OpenAI 兼容的图片生成/编辑响应体。
-func parseImageResponse(ctx context.Context, r io.Reader) ([]GeneratedImage, error) {
+func parseImageResponse(ctx context.Context, r io.Reader, width, height int) ([]GeneratedImage, error) {
 	var genResp imageGenResponse
 	if err := json.NewDecoder(r).Decode(&genResp); err != nil {
 		return nil, fmt.Errorf("decode response: %w", err)
@@ -195,8 +197,8 @@ func parseImageResponse(ctx context.Context, r io.Reader) ([]GeneratedImage, err
 		}
 		images = append(images, GeneratedImage{
 			Data:   data,
-			Width:  imgCfg.Width,
-			Height: imgCfg.Height,
+			Width:  width,
+			Height: height,
 			Format: "png",
 		})
 	}
diff --git a/backend/tools/gentest.go b/backend/tools/gentest.go
new file mode 100644
index 0000000..d6af462
--- /dev/null
+++ b/backend/tools/gentest.go
@@ -0,0 +1,49 @@
+//go:build ignore
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"gen2d/internal/config"
+	"gen2d/internal/service"
+)
+
+func main() {
+	cfg := config.Load()
+
+	// 清空 API key 强制走 mock
+	cfg.ImageGen.APIKey = ""
+	service.InitImageGenConfig(cfg.ImageGen)
+	service.InitLLMConfig(cfg.LLM)
+
+	in := service.PipelineInput{
+		AssetType: "sprite",
+		Prompt:    "a cute cat warrior with golden armor",
+		Tags:      []string{"pixel art", "fantasy", "16-bit"},
+		Params: service.AssetParams{
+			Resolution: 816,
+			Frames:     service.FrameParams{Directions: 4, FramesPerDirection: 1},
+			Format:     "individual",
+		},
+	}
+
+	output, err := service.RunPipeline(context.Background(), in)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(1)
+	}
+
+	os.MkdirAll("test_output", 0755)
+	for i, a := range output.Assets {
+		fname := fmt.Sprintf("test_output/gen_%d.%s", i, a.Format)
+		if err := os.WriteFile(fname, a.Data, 0644); err != nil {
+			fmt.Fprintf(os.Stderr, "write %s: %v\n", fname, err)
+			os.Exit(1)
+		}
+		fmt.Printf("saved %s (%d bytes)\n", fname, len(a.Data))
+	}
+	fmt.Printf("metadata: %+v\n", output.Metadata)
+}