fix(common): 新增文件类型检测工具并更新 Redis 依赖

utils/detect_file.go

@@ -0,0 +1,49 @@
+package utils
+
+import (
+	"net/http"
+	"strings"
+)
+
+// DetectFileType 根据二进制内容推断 contentType + 扩展名（尽量稳定）。
+// 纯 stdlib 实现（http.DetectContentType + 常见类型映射），不依赖模型网关。
+// 本函数是统一实现；model-gateway/common/util/files.go 的本地副本后续委托到此处。
+func DetectFileType(data []byte) (contentType string, ext string) {
+	if len(data) == 0 {
+		return "application/octet-stream", ""
+	}
+	ct := http.DetectContentType(data)
+	// DetectContentType 可能带 charset 等参数：text/plain; charset=utf-8
+	if idx := strings.Index(ct, ";"); idx > 0 {
+		ct = strings.TrimSpace(ct[:idx])
+	}
+	switch ct {
+	case "audio/mpeg":
+		return ct, ".mp3"
+	case "audio/wave", "audio/wav", "audio/x-wav":
+		return ct, ".wav"
+	case "video/mp4":
+		return ct, ".mp4"
+	case "image/png":
+		return ct, ".png"
+	case "image/jpeg":
+		return ct, ".jpg"
+	case "application/pdf":
+		return ct, ".pdf"
+	case "text/plain":
+		return ct, ".txt"
+	case "application/json":
+		return ct, ".json"
+	default:
+		// 兜底：尝试从 ct 截取 subtype 作为后缀（例如 application/json）
+		if parts := strings.Split(ct, "/"); len(parts) == 2 {
+			sub := parts[1]
+			// 避免出现 "plain; charset=utf-8" 之类的后缀
+			if idx := strings.Index(sub, ";"); idx > 0 {
+				sub = strings.TrimSpace(sub[:idx])
+			}
+			return ct, "." + sub
+		}
+		return ct, ""
+	}
+}