diff --git a/internal/cache/cache.go b/internal/cache/cache.go
deleted file mode 100644
index 08bf029d..00000000
--- a/internal/cache/cache.go
+++ /dev/null
@@ -1 +0,0 @@
-package cache
diff --git a/internal/message/message.go b/internal/message/message.go
new file mode 100644
index 00000000..ede1b098
--- /dev/null
+++ b/internal/message/message.go
@@ -0,0 +1 @@
+package message
diff --git a/internal/task/task.go b/internal/task/task.go
index b028dfdf..6e5003f1 100644
--- a/internal/task/task.go
+++ b/internal/task/task.go
@@ -1 +1,12 @@
+// manage task, such as file upload, file copy between accounts, offline download, etc.
 package task
+
+import "context"
+
+type Task struct {
+	Name     string
+	Func     func(context.Context) error
+	Status   string
+	Error    error
+	Progress int
+}