contracts

type Cache interface {
	Exists(ctx context.Context, key string) (bool, error)
	Get(ctx context.Context, key string) ([]byte, error) // Err 返回可兼容为“不存在”
	Set(ctx context.Context, key string, val []byte, ttl time.Duration) error
	Delete(ctx context.Context, key string) error
	ScanDeleteByPrefix(ctx context.Context, prefix string) error
	Incr(ctx context.Context, key string) (int64, error) // 原子自增（用于标签版本）
}

type Serializer[T any] interface {
	Encode(v T) ([]byte, error)
	Decode(b []byte) (T, error)
}