refactor: 全面集成 slog 日志到 handler、service、middleware

- cmd/main.go: 集成 logger.Init 和日志中间件，替换标准 log 包
- handler 层: 5xx 错误记录完整日志，返回通用消息（防内部信息泄露）
- service 层: LLM/图片生成/存储/认证等关键操作补充结构化日志
- auth 中间件: 记录认证失败原因
- generate.go: 后台管线任务使用带 task_id 的 logger

backend/internal/service/auth.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"gen2d/internal/db"
+	"gen2d/internal/logger"
 	"gen2d/internal/model"
 
 	"github.com/golang-jwt/jwt/v5"
@@ -29,8 +30,11 @@ func NewAuthService(jwtSecret string, jwtExpire int64) *AuthService {
 
 // Register 注册新用户，密码使用 bcrypt 加密存储。
 func (s *AuthService) Register(ctx context.Context, username, password, email string) (*model.User, error) {
+	l := logger.FromCtx(ctx)
+
 	hashed, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
 	if err != nil {
+		l.Error("bcrypt failed", "error", err)
 		return nil, err
 	}
 
@@ -42,25 +46,33 @@ func (s *AuthService) Register(ctx context.Context, username, password, email st
 
 	if err := db.DB.WithContext(ctx).Create(&user).Error; err != nil {
 		if errors.Is(err, gorm.ErrDuplicatedKey) {
+			l.Warn("register failed: duplicate username", "username", username)
 			return nil, errors.New("用户名已存在")
 		}
+		l.Error("register db failed", "username", username, "error", err)
 		return nil, err
 	}
 
+	l.Info("user registered", "username", username, "user_id", user.ID)
 	return &user, nil
 }
 
 // Login 校验用户名密码，成功返回 JWT token 及用户信息。
 func (s *AuthService) Login(ctx context.Context, username, password string) (string, int64, *model.User, error) {
+	l := logger.FromCtx(ctx)
+
 	var user model.User
 	if err := db.DB.WithContext(ctx).Where("username = ?", username).First(&user).Error; err != nil {
 		if errors.Is(err, gorm.ErrRecordNotFound) {
+			l.Warn("login failed: user not found", "username", username)
 			return "", 0, nil, errors.New("用户名或密码错误")
 		}
+		l.Error("login db query failed", "username", username, "error", err)
 		return "", 0, nil, err
 	}
 
 	if err := bcrypt.CompareHashAndPassword([]byte(user.Password), []byte(password)); err != nil {
+		l.Warn("login failed: wrong password", "username", username)
 		return "", 0, nil, errors.New("用户名或密码错误")
 	}
 
@@ -72,8 +84,10 @@ func (s *AuthService) Login(ctx context.Context, username, password string) (str
 	}
 	token, err := jwt.NewWithClaims(jwt.SigningMethodHS256, claims).SignedString(s.jwtSecret)
 	if err != nil {
+		l.Error("jwt sign failed", "error", err)
 		return "", 0, nil, err
 	}
 
+	l.Info("login succeeded", "username", username, "user_id", user.ID)
 	return token, int64(s.jwtExpire.Seconds()), &user, nil
 }

backend/internal/service/inference.go

@@ -11,13 +11,13 @@ import (
 	"image/color"
 	"image/png"
 	"io"
-	"log"
 	"mime/multipart"
 	"net/http"
 	"strings"
 	"time"
 
 	"gen2d/internal/config"
+	"gen2d/internal/logger"
 )
 
 // imgCfg 保存文生图配置，由 main 通过 InitImageGenConfig 注入。
@@ -64,21 +64,33 @@ func GenerateImages(ctx context.Context, prompt string, params AssetParams) ([]G
 		count = params.Frames.Directions * params.Frames.FramesPerDirection
 	}
 
+	l := logger.FromCtx(ctx)
+
 	if imgCfg.APIKey != "" {
 		width, height := imgCfg.Width, imgCfg.Height
 		if params.Resolution > 0 {
 			width = params.Resolution
 			height = params.Resolution
 		}
-		log.Println("[inference] calling image gen API")
-		return callImageAPI(ctx, prompt, count, width, height)
+		l.Info("calling image gen API",
+			"model", imgCfg.Model,
+			"count", count,
+			"size", fmt.Sprintf("%dx%d", width, height),
+		)
+		images, err := callImageAPI(ctx, prompt, count, width, height)
+		if err != nil {
+			l.Error("image gen API failed", "error", err)
+			return nil, err
+		}
+		l.Info("image gen API succeeded", "image_count", len(images))
+		return images, nil
 	}
 
 	size := params.Resolution
 	if size <= 0 {
 		size = 64
 	}
-	log.Println("[inference] image API key not configured, using mock")
+	l.Warn("image API key not configured, using mock")
 	return generateMockImages(size, count)
 }
 
@@ -107,10 +119,15 @@ func callImageAPI(ctx context.Context, prompt string, count, width, height int)
 		retryDelay = 5 * time.Second
 	}
 
+	l := logger.FromCtx(ctx)
+
 	var lastErr error
 	for attempt := 0; attempt <= maxRetries; attempt++ {
 		if attempt > 0 {
-			log.Printf("[inference] retrying image API (attempt %d/%d)", attempt, maxRetries)
+			l.Warn("retrying image API",
+				"attempt", attempt,
+				"max_retries", maxRetries,
+			)
 			select {
 			case <-ctx.Done():
 				return nil, fmt.Errorf("context cancelled during retry: %w", ctx.Err())
@@ -128,6 +145,7 @@ func callImageAPI(ctx context.Context, prompt string, count, width, height int)
 		resp, err := imageHTTPClient.Do(req)
 		if err != nil {
 			lastErr = fmt.Errorf("send request: %w", err)
+			l.Warn("image API request failed", "error", lastErr)
 			continue
 		}
 
@@ -140,8 +158,18 @@ func callImageAPI(ctx context.Context, prompt string, count, width, height int)
 
 		if resp.StatusCode >= 500 {
 			lastErr = fmt.Errorf("image api error %d: %s", resp.StatusCode, string(b))
+			l.Error("image API server error",
+				"status", resp.StatusCode,
+				"body", string(b),
+				"attempt", attempt,
+			)
 			continue
 		}
+		// 4xx 不重试
+		l.Error("image API client error",
+			"status", resp.StatusCode,
+			"body", string(b),
+		)
 		return nil, fmt.Errorf("image api error %d: %s", resp.StatusCode, string(b))
 	}
 
@@ -205,10 +233,17 @@ func downloadImage(ctx context.Context, url string) ([]byte, error) {
 
 // EditImages 图片编辑接口，调用 OpenAI 兼容 Images Edits API（multipart/form-data）。
 func EditImages(ctx context.Context, imageData []byte, prompt string, count int) ([]GeneratedImage, error) {
+	l := logger.FromCtx(ctx)
+
 	if imgCfg.APIKey == "" {
 		return nil, fmt.Errorf("image API key not configured")
 	}
 
+	l.Info("calling image edit API",
+		"model", imgCfg.Model,
+		"count", count,
+	)
+
 	var buf bytes.Buffer
 	writer := multipart.NewWriter(&buf)
 
@@ -239,16 +274,25 @@ func EditImages(ctx context.Context, imageData []byte, prompt string, count int)
 
 	resp, err := imageHTTPClient.Do(req)
 	if err != nil {
+		l.Error("image edit API request failed", "error", err)
 		return nil, fmt.Errorf("send request: %w", err)
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
 		b, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
+		l.Error("image edit API error", "status", resp.StatusCode, "body", string(b))
 		return nil, fmt.Errorf("image edit api error %d: %s", resp.StatusCode, string(b))
 	}
 
-	return parseImageResponse(ctx, resp.Body, imgCfg.Width, imgCfg.Height)
+	images, err := parseImageResponse(ctx, resp.Body, imgCfg.Width, imgCfg.Height)
+	if err != nil {
+		l.Error("image edit response parse failed", "error", err)
+		return nil, err
+	}
+
+	l.Info("image edit API succeeded", "image_count", len(images))
+	return images, nil
 }
 
 // ======================== 质检 ========================

backend/internal/service/pipeline.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"fmt"
 
+	"gen2d/internal/logger"
+
 	"github.com/cloudwego/eino/compose"
 )
 
@@ -82,20 +84,32 @@ func NewGenerateGraph() (*compose.Graph[PipelineInput, PipelineOutput], error) {
 
 // RunPipeline 编译并执行生成管线。
 func RunPipeline(ctx context.Context, in PipelineInput) (*PipelineOutput, error) {
+	l := logger.FromCtx(ctx)
+
+	l.Info("pipeline started",
+		"asset_type", in.AssetType,
+		"tags", in.Tags,
+		"resolution", in.Params.Resolution,
+	)
+
 	g, err := NewGenerateGraph()
 	if err != nil {
+		l.Error("pipeline create graph failed", "error", err)
 		return nil, fmt.Errorf("create graph: %w", err)
 	}
 
 	r, err := g.Compile(ctx, compose.WithMaxRunSteps(20))
 	if err != nil {
+		l.Error("pipeline compile failed", "error", err)
 		return nil, fmt.Errorf("compile graph: %w", err)
 	}
 
 	output, err := r.Invoke(ctx, in)
 	if err != nil {
+		l.Error("pipeline invoke failed", "error", err)
 		return nil, fmt.Errorf("invoke pipeline: %w", err)
 	}
 
+	l.Info("pipeline completed", "asset_count", len(output.Assets))
 	return &output, nil
 }

backend/internal/service/prompt_agent.go

@@ -7,11 +7,11 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"log"
 	"net/http"
 	"strings"
 
 	"gen2d/internal/config"
+	"gen2d/internal/logger"
 
 	"github.com/cloudwego/eino/compose"
 )
@@ -130,8 +130,10 @@ type chatResponse struct {
 
 // callLLMRefine 调用 LLM 生成规范化提示词。未配置 API key 时回退到模板生成。
 func callLLMRefine(ctx context.Context, metaPrompt string) (PromptAgentOutput, error) {
+	l := logger.FromCtx(ctx)
+
 	if llmCfg.APIKey == "" {
-		log.Println("[prompt_agent] LLM API key not configured, using template fallback")
+		l.Warn("LLM API key not configured, using template fallback")
 		return fallbackRefine(metaPrompt), nil
 	}
 
@@ -140,12 +142,14 @@ func callLLMRefine(ctx context.Context, metaPrompt string) (PromptAgentOutput, e
 		{Role: "user", Content: metaPrompt},
 	}
 
+	l.Info("calling LLM API", "model", llmCfg.Model)
 	result, err := chatCompletion(ctx, messages)
 	if err != nil {
-		log.Printf("[prompt_agent] LLM API call failed: %v, using template fallback", err)
+		l.Error("LLM API call failed, using template fallback", "error", err)
 		return fallbackRefine(metaPrompt), nil
 	}
 
+	l.Info("LLM API succeeded", "response_length", len(result))
 	return PromptAgentOutput{
 		Prompt:  result,
 		RawText: result,
@@ -175,6 +179,8 @@ func chatCompletion(ctx context.Context, messages []chatMessage) (string, error)
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Authorization", "Bearer "+llmCfg.APIKey)
 
+	l := logger.FromCtx(ctx)
+
 	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return "", fmt.Errorf("send request: %w", err)
@@ -183,6 +189,7 @@ func chatCompletion(ctx context.Context, messages []chatMessage) (string, error)
 
 	if resp.StatusCode != http.StatusOK {
 		b, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
+		l.Error("LLM API error", "status", resp.StatusCode, "body", string(b))
 		return "", fmt.Errorf("llm api error %d: %s", resp.StatusCode, string(b))
 	}
 

backend/internal/service/storage.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"gen2d/internal/config"
+	"gen2d/internal/logger"
 
 	"github.com/qiniu/go-sdk/v7/storagev2/credentials"
 	"github.com/qiniu/go-sdk/v7/storagev2/objects"
@@ -39,8 +40,11 @@ func NewStorageService(cfg config.QiniuConfig) *StorageService {
 
 // Upload 上传图片字节到七牛云，返回 CDN 访问 URL。
 func (s *StorageService) Upload(ctx context.Context, key string, data []byte) (string, error) {
+	l := logger.FromCtx(ctx)
+
 	putPolicy, err := uptoken.NewPutPolicy(s.bucket, time.Now().Add(1*time.Hour))
 	if err != nil {
+		l.Error("qiniu put policy failed", "key", key, "error", err)
 		return "", fmt.Errorf("qiniu put policy: %w", err)
 	}
 	upToken := uptoken.NewSigner(putPolicy, s.creds)
@@ -49,14 +53,19 @@ func (s *StorageService) Upload(ctx context.Context, key string, data []byte) (s
 		UpTokenProvider: upToken,
 	})
 
+	l.Info("uploading to qiniu", "key", key, "size", len(data))
 	err = uploadMgr.UploadReader(ctx, bytes.NewReader(data), &uploader.ObjectOptions{
 		BucketName: s.bucket,
 		ObjectName: &key,
 	}, nil)
 	if err != nil {
+		l.Error("qiniu upload failed", "key", key, "error", err)
 		return "", fmt.Errorf("qiniu upload: %w", err)
 	}
-	return s.buildURL(key), nil
+
+	cdnURL := s.buildURL(key)
+	l.Info("upload succeeded", "key", key, "url", cdnURL)
+	return cdnURL, nil
 }
 
 // GetDownloadURL 生成素材的下载 URL。
@@ -67,8 +76,17 @@ func (s *StorageService) GetDownloadURL(_ context.Context, key string) (string,
 
 // Delete 从七牛云删除指定对象。
 func (s *StorageService) Delete(ctx context.Context, key string) error {
+	l := logger.FromCtx(ctx)
+
 	bucket := s.objectsMgr.Bucket(s.bucket)
-	return bucket.Object(key).Delete().Call(ctx)
+	err := bucket.Object(key).Delete().Call(ctx)
+	if err != nil {
+		l.Error("qiniu delete failed", "key", key, "error", err)
+		return err
+	}
+
+	l.Info("delete succeeded", "key", key)
+	return nil
 }
 
 // buildURL 根据配置构建完整的 CDN URL。