diff --git a/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/MessageSource.kt b/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/MessageSource.kt
index 132669760..bf590985d 100644
--- a/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/MessageSource.kt
+++ b/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/MessageSource.kt
@@ -15,14 +15,11 @@ package net.mamoe.mirai.message.data
 
 import kotlinx.coroutines.Job
 import net.mamoe.mirai.Bot
-import net.mamoe.mirai.contact.Group
-import net.mamoe.mirai.contact.Member
-import net.mamoe.mirai.contact.QQ
+import net.mamoe.mirai.contact.*
+import net.mamoe.mirai.message.ContactMessage
+import net.mamoe.mirai.message.MessageReceipt
 import net.mamoe.mirai.recallIn
-import net.mamoe.mirai.utils.LazyProperty
-import net.mamoe.mirai.utils.MiraiExperimentalAPI
-import net.mamoe.mirai.utils.MiraiInternalAPI
-import net.mamoe.mirai.utils.SinceMirai
+import net.mamoe.mirai.utils.*
 import kotlin.coroutines.CoroutineContext
 import kotlin.coroutines.EmptyCoroutineContext
 import kotlin.jvm.JvmMultifileClass
@@ -103,6 +100,196 @@ sealed class MessageSource : Message, MessageMetadata, ConstrainSingle<MessageSo
 }
 
 
+/**
+ * 在线消息的 [MessageSource].
+ * 拥有对象化的 [sender], [target], 也可以直接 [recall] 和 [quote]
+ *
+ * ### 来源
+ * **必定是一个发出去的消息或接收到的消息的 [MessageChain] 中的一个元数据 [MessageMetadata].**
+ *
+ * #### 机器人主动发送消息
+ * 当机器人 [主动发出消息][Member.sendMessage], 将会得到一个 [消息回执][MessageReceipt].
+ * 此回执的 [消息源][MessageReceipt.source] 即为一个 [外向消息源][OnlineMessageSource.Outgoing], 代表着刚刚发出的那条消息的来源.
+ *
+ * #### 机器人接受消息
+ * 当机器人接收一条消息 [ContactMessage], 这条消息包含一个 [内向消息源][OnlineMessageSource.Incoming], 代表着接收到的这条消息的来源.
+ *
+ *
+ *
+ * @see OnlineMessageSource.toOffline 转为 [OfflineMessageSource]
+ */
+@SinceMirai("0.33.0")
+@OptIn(MiraiExperimentalAPI::class)
+sealed class OnlineMessageSource : MessageSource() {
+    companion object Key : Message.Key<OnlineMessageSource> {
+        override val typeName: String get() = "OnlineMessageSource"
+    }
+
+    /**
+     * 消息发送人. 可能为 [机器人][Bot] 或 [好友][QQ] 或 [群员][Member].
+     * 即类型必定为 [Bot], [QQ] 或 [Member]
+     */
+    abstract val sender: ContactOrBot
+
+    /**
+     * 消息发送目标. 可能为 [机器人][Bot] 或 [好友][QQ] 或 [群][Group].
+     * 即类型必定为 [Bot], [QQ] 或 [Group]
+     */
+    abstract val target: ContactOrBot
+
+    /**
+     * 消息主体. 群消息时为 [Group]. 好友消息时为 [QQ], 临时消息为 [Member]
+     * 不论是机器人接收的消息还是发送的消息, 此属性都指向机器人能进行回复的目标.
+     */
+    abstract val subject: Contact
+
+    /**
+     * 由 [机器人主动发送消息][Contact.sendMessage] 产生的 [MessageSource]
+     */
+    sealed class Outgoing : OnlineMessageSource() {
+        companion object Key : Message.Key<Outgoing> {
+            override val typeName: String get() = "OnlineMessageSource.Outgoing"
+        }
+
+        abstract override val sender: Bot
+        abstract override val target: Contact
+
+        final override val fromId: Long get() = sender.id
+        final override val targetId: Long get() = target.id
+
+        abstract class ToFriend : Outgoing() {
+            companion object Key : Message.Key<ToFriend> {
+                override val typeName: String get() = "OnlineMessageSource.Outgoing.ToFriend"
+            }
+
+            abstract override val target: Friend
+            final override val subject: Friend get() = target
+            //  final override fun toString(): String = "OnlineMessageSource.ToFriend(target=${target.id})"
+        }
+
+        abstract class ToTemp : Outgoing() {
+            companion object Key : Message.Key<ToTemp> {
+                override val typeName: String get() = "OnlineMessageSource.Outgoing.ToTemp"
+            }
+
+            abstract override val target: Member
+            val group: Group get() = target.group
+            final override val subject: Member get() = target
+        }
+
+        abstract class ToGroup : Outgoing() {
+            companion object Key : Message.Key<ToGroup> {
+                override val typeName: String get() = "OnlineMessageSource.Outgoing.ToGroup"
+            }
+
+            abstract override val target: Group
+            final override val subject: Group get() = target
+            //  final override fun toString(): String = "OnlineMessageSource.ToGroup(group=${target.id})"
+        }
+    }
+
+    /**
+     * 接收到的一条消息的 [MessageSource]
+     */
+    sealed class Incoming : OnlineMessageSource() {
+        companion object Key : Message.Key<Incoming> {
+            override val typeName: String get() = "OnlineMessageSource.Incoming"
+        }
+
+        abstract override val sender: User
+
+        final override val fromId: Long get() = sender.id
+        final override val targetId: Long get() = target.id
+
+        abstract class FromFriend : Incoming() {
+            companion object Key : Message.Key<FromFriend> {
+                override val typeName: String get() = "OnlineMessageSource.Incoming.FromFriend"
+            }
+
+            abstract override val sender: Friend
+            final override val subject: Friend get() = sender
+            final override val target: Bot get() = sender.bot
+            // final override fun toString(): String = "OnlineMessageSource.FromFriend(from=${sender.id})"
+        }
+
+        abstract class FromTemp : Incoming() {
+            companion object Key : Message.Key<FromTemp> {
+                override val typeName: String get() = "OnlineMessageSource.Incoming.FromTemp"
+            }
+
+            abstract override val sender: Member
+            inline val group: Group get() = sender.group
+            final override val subject: Member get() = sender
+            final override val target: Bot get() = sender.bot
+        }
+
+        abstract class FromGroup : Incoming() {
+            companion object Key : Message.Key<FromGroup> {
+                override val typeName: String get() = "OnlineMessageSource.Incoming.FromGroup"
+            }
+
+            abstract override val sender: Member
+            final override val subject: Group get() = sender.group
+            final override val target: Group get() = group
+            inline val group: Group get() = sender.group
+        }
+
+
+        //////////////////////////////////
+        //// FOR BINARY COMPATIBILITY ////
+        //////////////////////////////////
+
+
+        @PlannedRemoval("1.0.0")
+        @Deprecated("for binary compatibility until 1.0.0", level = DeprecationLevel.HIDDEN)
+        @get:JvmName("target")
+        @get:JvmSynthetic
+        final override val target2: Any
+            get() = target
+    }
+
+    @PlannedRemoval("1.0.0")
+    @Deprecated("for binary compatibility until 1.0.0", level = DeprecationLevel.HIDDEN)
+    @get:JvmName("target")
+    @get:JvmSynthetic
+    open val target2: Any
+        get() = target
+
+    @PlannedRemoval("1.0.0")
+    @Deprecated("for binary compatibility until 1.0.0", level = DeprecationLevel.HIDDEN)
+    @get:JvmName("sender")
+    @get:JvmSynthetic
+    open val sender2: Any
+        get() = sender
+}
+
+/**
+ * 由一条消息中的 [QuoteReply] 得到的 [MessageSource].
+ * 此消息源可能来自一条与机器人无关的消息. 因此无法提供对象化的 `sender` 或 `target` 获取.
+ */
+@SinceMirai("0.33.0")
+abstract class OfflineMessageSource : MessageSource() {
+    companion object Key : Message.Key<OfflineMessageSource> {
+        override val typeName: String
+            get() = "OfflineMessageSource"
+    }
+
+    enum class Kind {
+        GROUP,
+        FRIEND,
+
+        @SinceMirai("0.36.0")
+        TEMP
+    }
+
+    /**
+     * 消息种类
+     */
+    abstract val kind: Kind
+
+    // final override fun toString(): String = "OfflineMessageSource(sender=$senderId, target=$targetId)"
+}
+
 // inline for future removal
 inline fun MessageSource.isAboutGroup(): Boolean {
     return when (this) {
diff --git a/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/OfflineMessageSource.kt b/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/OfflineMessageSource.kt
index f363f192f..6980d6c70 100644
--- a/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/OfflineMessageSource.kt
+++ b/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/OfflineMessageSource.kt
@@ -25,34 +25,10 @@ import kotlin.jvm.JvmMultifileClass
 import kotlin.jvm.JvmName
 import kotlin.jvm.JvmSynthetic
 
-
-/**
- * 由一条消息中的 [QuoteReply] 得到的 [MessageSource].
- * 此消息源可能来自一条与机器人无关的消息. 因此无法提供对象化的 `sender` 或 `target` 获取.
- */
-@SinceMirai("0.33.0")
-abstract class OfflineMessageSource : MessageSource() {
-    companion object Key : Message.Key<OfflineMessageSource> {
-        override val typeName: String
-            get() = "OfflineMessageSource"
-    }
-
-    enum class Kind {
-        GROUP,
-        FRIEND,
-
-        @SinceMirai("0.36.0")
-        TEMP
-    }
-
-    /**
-     * 消息种类
-     */
-    abstract val kind: Kind
-
-    // final override fun toString(): String = "OfflineMessageSource(sender=$senderId, target=$targetId)"
-}
-
+@SinceMirai("0.39.0")
+@JvmName("toOfflineMessageSource")
+fun OnlineMessageSource.toOffline(): OfflineMessageSource =
+    OfflineMessageSourceByOnline(this)
 
 ///////////////
 //// AMEND ////
@@ -281,4 +257,23 @@ private fun determineKind(source: MessageSource): OfflineMessageSource.Kind {
         source.isAboutTemp() -> OfflineMessageSource.Kind.TEMP
         else -> error("stub")
     }
-}
\ No newline at end of file
+}
+
+internal class OfflineMessageSourceByOnline(
+    private val onlineMessageSource: OnlineMessageSource
+) : OfflineMessageSource() {
+    override val kind: Kind
+        get() = when {
+            onlineMessageSource.isAboutGroup() -> Kind.GROUP
+            onlineMessageSource.isAboutFriend() -> Kind.FRIEND
+            onlineMessageSource.isAboutTemp() -> Kind.TEMP
+            else -> error("stub")
+        }
+    override val bot: Bot get() = onlineMessageSource.bot
+    override val id: Int get() = onlineMessageSource.id
+    override val internalId: Int get() = onlineMessageSource.internalId
+    override val time: Int get() = onlineMessageSource.time
+    override val fromId: Long get() = onlineMessageSource.fromId
+    override val targetId: Long get() = onlineMessageSource.targetId
+    override val originalMessage: MessageChain get() = onlineMessageSource.originalMessage
+}
diff --git a/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/OnlineMessageSource.kt b/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/OnlineMessageSource.kt
deleted file mode 100644
index 74909187f..000000000
--- a/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/data/OnlineMessageSource.kt
+++ /dev/null
@@ -1,209 +0,0 @@
-/*
- * Copyright 2020 Mamoe Technologies and contributors.
- *
- * 此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
- * Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
- *
- * https://github.com/mamoe/mirai/blob/master/LICENSE
- */
-
-@file:JvmMultifileClass
-@file:JvmName("MessageUtils")
-@file:Suppress("NOTHING_TO_INLINE", "unused", "INAPPLICABLE_JVM_NAME", "INVISIBLE_MEMBER")
-
-package net.mamoe.mirai.message.data
-
-import net.mamoe.mirai.Bot
-import net.mamoe.mirai.contact.*
-import net.mamoe.mirai.message.ContactMessage
-import net.mamoe.mirai.message.MessageReceipt
-import net.mamoe.mirai.utils.MiraiExperimentalAPI
-import net.mamoe.mirai.utils.PlannedRemoval
-import net.mamoe.mirai.utils.SinceMirai
-import kotlin.jvm.JvmMultifileClass
-import kotlin.jvm.JvmName
-import kotlin.jvm.JvmSynthetic
-
-
-/**
- * 在线消息的 [MessageSource].
- * 拥有对象化的 [sender], [target], 也可以直接 [recall] 和 [quote]
- *
- * ### 来源
- * **必定是一个发出去的消息或接收到的消息的 [MessageChain] 中的一个元数据 [MessageMetadata].**
- *
- * #### 机器人主动发送消息
- * 当机器人 [主动发出消息][Member.sendMessage], 将会得到一个 [消息回执][MessageReceipt].
- * 此回执的 [消息源][MessageReceipt.source] 即为一个 [外向消息源][OnlineMessageSource.Outgoing], 代表着刚刚发出的那条消息的来源.
- *
- * #### 机器人接受消息
- * 当机器人接收一条消息 [ContactMessage], 这条消息包含一个 [内向消息源][OnlineMessageSource.Incoming], 代表着接收到的这条消息的来源.
- */
-@SinceMirai("0.33.0")
-@OptIn(MiraiExperimentalAPI::class)
-sealed class OnlineMessageSource : MessageSource() {
-    companion object Key : Message.Key<OnlineMessageSource> {
-        override val typeName: String get() = "OnlineMessageSource"
-    }
-
-    /**
-     * 消息发送人. 可能为 [机器人][Bot] 或 [好友][QQ] 或 [群员][Member].
-     * 即类型必定为 [Bot], [QQ] 或 [Member]
-     */
-    abstract val sender: ContactOrBot
-
-    /**
-     * 消息发送目标. 可能为 [机器人][Bot] 或 [好友][QQ] 或 [群][Group].
-     * 即类型必定为 [Bot], [QQ] 或 [Group]
-     */
-    abstract val target: ContactOrBot
-
-    /**
-     * 消息主体. 群消息时为 [Group]. 好友消息时为 [QQ], 临时消息为 [Member]
-     * 不论是机器人接收的消息还是发送的消息, 此属性都指向机器人能进行回复的目标.
-     */
-    abstract val subject: Contact
-
-    /**
-     * 由 [机器人主动发送消息][Contact.sendMessage] 产生的 [MessageSource]
-     */
-    sealed class Outgoing : OnlineMessageSource() {
-        companion object Key : Message.Key<Outgoing> {
-            override val typeName: String get() = "OnlineMessageSource.Outgoing"
-        }
-
-        abstract override val sender: Bot
-        abstract override val target: Contact
-
-        final override val fromId: Long get() = sender.id
-        final override val targetId: Long get() = target.id
-
-        abstract class ToFriend : Outgoing() {
-            companion object Key : Message.Key<ToFriend> {
-                override val typeName: String get() = "OnlineMessageSource.Outgoing.ToFriend"
-            }
-
-            abstract override val target: Friend
-            final override val subject: Friend get() = target
-            //  final override fun toString(): String = "OnlineMessageSource.ToFriend(target=${target.id})"
-        }
-
-        abstract class ToTemp : Outgoing() {
-            companion object Key : Message.Key<ToTemp> {
-                override val typeName: String get() = "OnlineMessageSource.Outgoing.ToTemp"
-            }
-
-            abstract override val target: Member
-            val group: Group get() = target.group
-            final override val subject: Member get() = target
-        }
-
-        abstract class ToGroup : Outgoing() {
-            companion object Key : Message.Key<ToGroup> {
-                override val typeName: String get() = "OnlineMessageSource.Outgoing.ToGroup"
-            }
-
-            abstract override val target: Group
-            final override val subject: Group get() = target
-            //  final override fun toString(): String = "OnlineMessageSource.ToGroup(group=${target.id})"
-        }
-    }
-
-    /**
-     * 接收到的一条消息的 [MessageSource]
-     */
-    sealed class Incoming : OnlineMessageSource() {
-        companion object Key : Message.Key<Incoming> {
-            override val typeName: String get() = "OnlineMessageSource.Incoming"
-        }
-
-        abstract override val sender: User
-
-        final override val fromId: Long get() = sender.id
-        final override val targetId: Long get() = target.id
-
-        abstract class FromFriend : Incoming() {
-            companion object Key : Message.Key<FromFriend> {
-                override val typeName: String get() = "OnlineMessageSource.Incoming.FromFriend"
-            }
-
-            abstract override val sender: Friend
-            final override val subject: Friend get() = sender
-            final override val target: Bot get() = sender.bot
-            // final override fun toString(): String = "OnlineMessageSource.FromFriend(from=${sender.id})"
-        }
-
-        abstract class FromTemp : Incoming() {
-            companion object Key : Message.Key<FromTemp> {
-                override val typeName: String get() = "OnlineMessageSource.Incoming.FromTemp"
-            }
-
-            abstract override val sender: Member
-            inline val group: Group get() = sender.group
-            final override val subject: Member get() = sender
-            final override val target: Bot get() = sender.bot
-        }
-
-        abstract class FromGroup : Incoming() {
-            companion object Key : Message.Key<FromGroup> {
-                override val typeName: String get() = "OnlineMessageSource.Incoming.FromGroup"
-            }
-
-            abstract override val sender: Member
-            final override val subject: Group get() = sender.group
-            final override val target: Group get() = group
-            inline val group: Group get() = sender.group
-        }
-
-
-        //////////////////////////////////
-        //// FOR BINARY COMPATIBILITY ////
-        //////////////////////////////////
-
-
-        @PlannedRemoval("1.0.0")
-        @Deprecated("for binary compatibility until 1.0.0", level = DeprecationLevel.HIDDEN)
-        @get:JvmName("target")
-        @get:JvmSynthetic
-        final override val target2: Any
-            get() = target
-    }
-
-    @PlannedRemoval("1.0.0")
-    @Deprecated("for binary compatibility until 1.0.0", level = DeprecationLevel.HIDDEN)
-    @get:JvmName("target")
-    @get:JvmSynthetic
-    open val target2: Any
-        get() = target
-
-    @PlannedRemoval("1.0.0")
-    @Deprecated("for binary compatibility until 1.0.0", level = DeprecationLevel.HIDDEN)
-    @get:JvmName("sender")
-    @get:JvmSynthetic
-    open val sender2: Any
-        get() = sender
-}
-
-@SinceMirai("0.39.0")
-@JvmName("toOfflineMessageSource")
-fun OnlineMessageSource.toOffline(): OfflineMessageSource =
-    OfflineMessageSourceByOnline(this)
-
-internal class OfflineMessageSourceByOnline(
-    private val onlineMessageSource: OnlineMessageSource
-) : OfflineMessageSource() {
-    override val kind: Kind
-        get() = when {
-            onlineMessageSource.isAboutGroup() -> Kind.GROUP
-            onlineMessageSource.isAboutFriend() -> Kind.FRIEND
-            onlineMessageSource.isAboutTemp() -> Kind.TEMP
-            else -> error("stub")
-        }
-    override val bot: Bot get() = onlineMessageSource.bot
-    override val id: Int get() = onlineMessageSource.id
-    override val internalId: Int get() = onlineMessageSource.internalId
-    override val time: Int get() = onlineMessageSource.time
-    override val fromId: Long get() = onlineMessageSource.fromId
-    override val targetId: Long get() = onlineMessageSource.targetId
-    override val originalMessage: MessageChain get() = onlineMessageSource.originalMessage
-}
\ No newline at end of file