fix: 为图片生成 API 添加超时与 5xx 重试机制

- ImageGenConfig 新增 timeout/max_retries/retry_delay 配置项（默认 120s/2次/5s）
- 替换 http.DefaultClient 为带超时的 imageHTTPClient
- callImageAPI 对 5xx 错误自动重试，避免 504 等瞬时故障直接失败

backend/.env.example

@@ -26,6 +26,9 @@ GEN2D_IMAGE_MODEL=gpt-image-2-token
 GEN2D_IMAGE_WIDTH=1024
 GEN2D_IMAGE_HEIGHT=1024
 GEN2D_IMAGE_QUALITY=low
+GEN2D_IMAGE_TIMEOUT=120
+GEN2D_IMAGE_MAX_RETRIES=2
+GEN2D_IMAGE_RETRY_DELAY=5
 GEN2D_IMAGE_NUM_IMAGES=1
 GEN2D_IMAGE_STEPS=30
 GEN2D_IMAGE_CFG_SCALE=7.0

backend/internal/config/config.go

@@ -52,6 +52,9 @@ type ImageGenConfig struct {
 	Width        int    `mapstructure:"width"`
 	Height       int    `mapstructure:"height"`
 	Quality      string `mapstructure:"quality"`
+	Timeout      int    `mapstructure:"timeout"`       // HTTP 请求超时秒数，默认 120
+	MaxRetries   int    `mapstructure:"max_retries"`   // 5xx 错误重试次数，默认 2
+	RetryDelay   int    `mapstructure:"retry_delay"`   // 重试间隔秒数，默认 5
 }
 
 // QiniuConfig 七牛云对象存储配置。
@@ -117,6 +120,9 @@ func setDefaults(v *viper.Viper) {
 	v.SetDefault("image_gen.width", 1024)
 	v.SetDefault("image_gen.height", 1024)
 	v.SetDefault("image_gen.quality", "low")
+	v.SetDefault("image_gen.timeout", 120)
+	v.SetDefault("image_gen.max_retries", 2)
+	v.SetDefault("image_gen.retry_delay", 5)
 	v.SetDefault("image_gen.num_images", 1)
 	v.SetDefault("image_gen.steps", 30)
 	v.SetDefault("image_gen.cfg_scale", 7.0)
@@ -148,6 +154,9 @@ func bindEnvVars(v *viper.Viper) {
 	v.BindEnv("image_gen.width", "GEN2D_IMAGE_WIDTH")
 	v.BindEnv("image_gen.height", "GEN2D_IMAGE_HEIGHT")
 	v.BindEnv("image_gen.quality", "GEN2D_IMAGE_QUALITY")
+	v.BindEnv("image_gen.timeout", "GEN2D_IMAGE_TIMEOUT")
+	v.BindEnv("image_gen.max_retries", "GEN2D_IMAGE_MAX_RETRIES")
+	v.BindEnv("image_gen.retry_delay", "GEN2D_IMAGE_RETRY_DELAY")
 	v.BindEnv("image_gen.num_images", "GEN2D_IMAGE_NUM_IMAGES")
 	v.BindEnv("image_gen.steps", "GEN2D_IMAGE_STEPS")
 	v.BindEnv("image_gen.cfg_scale", "GEN2D_IMAGE_CFG_SCALE")

backend/internal/service/inference.go

@@ -15,6 +15,7 @@ import (
 	"mime/multipart"
 	"net/http"
 	"strings"
+	"time"
 
 	"gen2d/internal/config"
 )
@@ -22,9 +23,17 @@ import (
 // imgCfg 保存文生图配置，由 main 通过 InitImageGenConfig 注入。
 var imgCfg config.ImageGenConfig
 
+// imageHTTPClient 带超时的 HTTP 客户端，由 InitImageGenConfig 初始化。
+var imageHTTPClient *http.Client
+
 // InitImageGenConfig 注入文生图配置。
 func InitImageGenConfig(cfg config.ImageGenConfig) {
 	imgCfg = cfg
+	timeout := time.Duration(cfg.Timeout) * time.Second
+	if timeout <= 0 {
+		timeout = 120 * time.Second
+	}
+	imageHTTPClient = &http.Client{Timeout: timeout}
 }
 
 // ======================== OpenAI 兼容 Images API 类型 ========================
@@ -73,7 +82,7 @@ func GenerateImages(ctx context.Context, prompt string, params AssetParams) ([]G
 	return generateMockImages(size, count)
 }
 
-// callImageAPI 调用 OpenAI 兼容 Images API。
+// callImageAPI 调用 OpenAI 兼容 Images API，5xx 错误自动重试。
 func callImageAPI(ctx context.Context, prompt string, count, width, height int) ([]GeneratedImage, error) {
 	reqBody := imageGenRequest{
 		Model:   imgCfg.Model,
@@ -89,6 +98,26 @@ func callImageAPI(ctx context.Context, prompt string, count, width, height int)
 	}
 
 	url := strings.TrimRight(imgCfg.BaseURL, "/") + "/images/generations"
+	maxRetries := imgCfg.MaxRetries
+	if maxRetries <= 0 {
+		maxRetries = 2
+	}
+	retryDelay := time.Duration(imgCfg.RetryDelay) * time.Second
+	if retryDelay <= 0 {
+		retryDelay = 5 * time.Second
+	}
+
+	var lastErr error
+	for attempt := 0; attempt <= maxRetries; attempt++ {
+		if attempt > 0 {
+			log.Printf("[inference] retrying image API (attempt %d/%d)", attempt, maxRetries)
+			select {
+			case <-ctx.Done():
+				return nil, fmt.Errorf("context cancelled during retry: %w", ctx.Err())
+			case <-time.After(retryDelay):
+			}
+		}
+
 		req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
 		if err != nil {
 			return nil, fmt.Errorf("create request: %w", err)
@@ -96,18 +125,27 @@ func callImageAPI(ctx context.Context, prompt string, count, width, height int)
 		req.Header.Set("Content-Type", "application/json")
 		req.Header.Set("Authorization", "Bearer "+imgCfg.APIKey)
 
-	resp, err := http.DefaultClient.Do(req)
+		resp, err := imageHTTPClient.Do(req)
 		if err != nil {
-		return nil, fmt.Errorf("send request: %w", err)
+			lastErr = fmt.Errorf("send request: %w", err)
+			continue
+		}
+
+		if resp.StatusCode == http.StatusOK {
+			return parseImageResponse(ctx, resp.Body, width, height)
 		}
-	defer resp.Body.Close()
 
-	if resp.StatusCode != http.StatusOK {
 		b, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
+		resp.Body.Close()
+
+		if resp.StatusCode >= 500 {
+			lastErr = fmt.Errorf("image api error %d: %s", resp.StatusCode, string(b))
+			continue
+		}
 		return nil, fmt.Errorf("image api error %d: %s", resp.StatusCode, string(b))
 	}
 
-	return parseImageResponse(ctx, resp.Body, width, height)
+	return nil, lastErr
 }
 
 // parseImageResponse 解析 OpenAI 兼容图片响应（b64_json 或 url）。
@@ -152,7 +190,7 @@ func downloadImage(ctx context.Context, url string) ([]byte, error) {
 	if err != nil {
 		return nil, fmt.Errorf("create download request: %w", err)
 	}
-	resp, err := http.DefaultClient.Do(req)
+	resp, err := imageHTTPClient.Do(req)
 	if err != nil {
 		return nil, fmt.Errorf("download: %w", err)
 	}
@@ -199,7 +237,7 @@ func EditImages(ctx context.Context, imageData []byte, prompt string, count int)
 	req.Header.Set("Content-Type", writer.FormDataContentType())
 	req.Header.Set("Authorization", "Bearer "+imgCfg.APIKey)
 
-	resp, err := http.DefaultClient.Do(req)
+	resp, err := imageHTTPClient.Do(req)
 	if err != nil {
 		return nil, fmt.Errorf("send request: %w", err)
 	}