diff --git a/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/Codegen.kt b/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/Codegen.kt
index 152ac798b..8857cb0c1 100644
--- a/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/Codegen.kt
+++ b/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/Codegen.kt
@@ -12,6 +12,25 @@
 package net.mamoe.mirai.console.codegen
 
 import org.intellij.lang.annotations.Language
+import kotlin.reflect.KClass
+import kotlin.reflect.full.functions
+import kotlin.reflect.full.hasAnnotation
+import kotlin.reflect.full.isSubclassOf
+
+inline fun <reified T> runCodegenInObject() = runCodegenInObject(T::class)
+
+fun runCodegenInObject(clazz: KClass<*>) {
+    clazz.nestedClasses
+        .filter { it.isSubclassOf(RegionCodegen::class) }
+        .associateWith { kClass -> kClass.functions.find { it.name == "main" && it.hasAnnotation<JvmStatic>() } }
+        .filter { it.value != null }
+        .forEach { (kClass, entryPoint) ->
+            println("---------------------------------------------")
+            println("Running Codegen: ${kClass.simpleName}")
+            entryPoint!!.call(kClass.objectInstance, arrayOf<String>())
+            println("---------------------------------------------")
+        }
+}
 
 abstract class Replacer(private val name: String) : (String) -> String {
     override fun toString(): String {
diff --git a/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/MessageScopeCodegen.kt b/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/MessageScopeCodegen.kt
new file mode 100644
index 000000000..0f5dd7839
--- /dev/null
+++ b/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/MessageScopeCodegen.kt
@@ -0,0 +1,198 @@
+/*
+ * 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
+ */
+
+package net.mamoe.mirai.console.codegen
+
+internal val TypeCandidatesForMessageScope = arrayOf(
+    KtType("Contact"),
+    KtType("CommandSender"),
+)
+
+internal val KtMessageScope = KtType("MessageScope")
+
+internal fun <A> Array<A>.arrangements(): List<Pair<A, A>> {
+    val result = mutableListOf<Pair<A, A>>()
+    for (a in this) {
+        for (b in this) {
+            result.add(a to b)
+        }
+    }
+    return result
+}
+
+internal fun <A> Array<A>.distinctArrangements(): List<Pair<A, A>> {
+    return this.arrangements().distinctBy { it.first.toString().hashCode() + it.second.toString().hashCode() }
+}
+
+internal object MessageScopeCodegen {
+    object IterableMessageScopeBuildersCodegen : RegionCodegen("MessageScope.kt"), DefaultInvoke {
+        @JvmStatic
+        fun main(args: Array<String>) = super.startIndependently()
+        override val defaultInvokeArgs: List<KtType> = listOf(KtString) // invoke once
+
+        @Suppress(
+            "RedundantVisibilityModifier", "ClassName", "KDocUnresolvedReference", "RedundantSuspendModifier",
+            "SpellCheckingInspection"
+        )
+        override fun StringBuilder.apply(ktType: KtType) {
+            for (collectionName in arrayOf("Iterable", "Sequence", "Array")) {
+                for (candidate in (TypeCandidatesForMessageScope + KtMessageScope)) {
+                    appendKCode(
+                        """
+                                @JvmName("toMessageScope${candidate.standardName.capitalize()}${collectionName.capitalize()}")
+                                public fun $collectionName<$candidate?>.toMessageScope(): MessageScope {
+                                    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope -> CombinedScope(acc, messageScope.asMessageScopeOrNoop()) }
+                                }
+                                """
+                    )
+                    appendLine()
+                }
+            }
+            for (candidate in (TypeCandidatesForMessageScope + KtMessageScope)) {
+                appendKCode(
+                    """
+                    @JvmSynthetic
+                    @JvmName("toMessageScope${candidate.standardName.capitalize()}Flow")
+                    public suspend fun Flow<$candidate>.toMessageScope(): MessageScope { // Flow<Any?>.firstOrNull isn't yet supported
+                        return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope -> CombinedScope(acc, messageScope.asMessageScope()) }
+                    }
+                    """
+                )
+                appendLine()
+            }
+        }
+    }
+
+    object MessageScopeBuildersCodegen : RegionCodegen("MessageScope.kt"), DefaultInvoke {
+        @JvmStatic
+        fun main(args: Array<String>) = super.startIndependently()
+        override val defaultInvokeArgs: List<KtType> = listOf(KtString) // invoke once
+
+        @Suppress("RedundantVisibilityModifier", "ClassName", "KDocUnresolvedReference")
+        override fun StringBuilder.apply(ktType: KtType) {
+            for (candidate in TypeCandidatesForMessageScope) {
+                appendKCode(
+                    """
+                       public fun ${candidate}.asMessageScope(): MessageScope = createScopeDelegate(this)
+                    """
+                )
+                appendLine()
+            }
+
+            for ((a, b) in (TypeCandidatesForMessageScope + KtMessageScope).arrangements()) {
+                appendKCode(
+                    """
+                    @LowPriorityInOverloadResolution
+                    public fun ${a}.scopeWith(vararg others: ${b}): MessageScope {
+                        return others.fold(this.asMessageScope()) { acc, other -> CombinedScope(acc, other.asMessageScope()) }
+                    }
+                """
+                )
+                appendLine()
+            }
+
+            for ((a, b) in (TypeCandidatesForMessageScope + KtMessageScope).arrangements()) {
+                appendKCode(
+                    """
+                    @LowPriorityInOverloadResolution
+                    public fun ${a}?.scopeWithNotNull(vararg others: ${b}?): MessageScope {
+                        return others.fold(this.asMessageScopeOrNoop()) { acc, other -> acc.scopeWithNotNull(other?.asMessageScope()) }
+                    }
+                """
+                )
+                appendLine()
+            }
+
+            for ((a, b) in (TypeCandidatesForMessageScope + KtMessageScope).distinctArrangements()) {
+                appendKCode(
+                    """
+                    public fun ${a}.scopeWith(other: ${b}): MessageScope {
+                        return CombinedScope(asMessageScope(), other.asMessageScope())
+                    }
+                """
+                )
+                appendLine()
+            }
+
+            for ((a, b) in (TypeCandidatesForMessageScope + KtMessageScope).distinctArrangements()) {
+                appendKCode(
+                    """
+                    public fun ${a}?.scopeWithNotNull(other: ${b}?): MessageScope {
+                        @Suppress("DuplicatedCode")
+                        return when {
+                            this == null && other == null -> NoopMessageScope
+                            this == null && other != null -> other.asMessageScope()
+                            this != null && other == null -> this.asMessageScope()
+                            this != null && other != null -> CombinedScope(asMessageScope(), other.asMessageScope())
+                            else -> null!!
+                        }
+                    }
+                """
+                )
+                appendLine()
+            }
+
+            for ((a, b) in (TypeCandidatesForMessageScope + KtMessageScope).arrangements()) {
+                appendKCode(
+                    """
+                    public inline fun <R> ${a}.scopeWith(vararg others: ${b}, action: MessageScope.() -> R): R {
+                        return scopeWith(*others).invoke(action)
+                    }
+                """
+                )
+                appendLine()
+            }
+
+            for ((a, b) in (TypeCandidatesForMessageScope + KtMessageScope).arrangements()) {
+                appendKCode(
+                    """
+                    public inline fun <R> ${a}?.scopeWithNotNull(vararg others: ${b}?, action: MessageScope.() -> R): R {
+                        return scopeWithNotNull(*others).invoke(action)
+                    }
+                """
+                )
+                appendLine()
+            }
+
+            for (a in (TypeCandidatesForMessageScope + KtMessageScope)) {
+                appendKCode(
+                    """
+                    @Deprecated("Senseless scopeWith. Use asMessageScope.", ReplaceWith("this.asMessageScope()", "net.mamoe.mirai.console.util.asMessageScope"))
+                    public inline fun ${a}.scopeWith(): MessageScope = asMessageScope()
+                """
+                )
+                appendLine()
+            }
+
+            for (a in (TypeCandidatesForMessageScope + KtMessageScope)) {
+                appendKCode(
+                    """
+                    @Deprecated(
+                        "Senseless scopeWith. Use .asMessageScope().invoke.",
+                        ReplaceWith("this.asMessageScope()(action)", "net.mamoe.mirai.console.util.asMessageScope", "net.mamoe.mirai.console.util.invoke")
+                    )
+                    public inline fun <R> ${a}.scopeWith(action: MessageScope.() -> R): R = asMessageScope()(action)
+"""
+                )
+                appendLine()
+            }
+
+        }
+    }
+
+
+    /**
+     * 运行本 object 中所有嵌套 object Codegen
+     */
+    @OptIn(ExperimentalStdlibApi::class)
+    @JvmStatic
+    fun main(args: Array<String>) {
+        runCodegenInObject(this::class)
+    }
+}
\ No newline at end of file
diff --git a/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/util.kt b/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/util.kt
index 57852db47..0066d071b 100644
--- a/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/util.kt
+++ b/backend/codegen/src/main/kotlin/net/mamoe/mirai/console/codegen/util.kt
@@ -7,7 +7,7 @@
  * https://github.com/mamoe/mirai/blob/master/LICENSE
  */
 
-@file:Suppress("NOTHING_TO_INLINE", "MemberVisibilityCanBePrivate", "unused","PRE_RELEASE_CLASS")
+@file:Suppress("NOTHING_TO_INLINE", "MemberVisibilityCanBePrivate", "unused", "PRE_RELEASE_CLASS")
 
 package net.mamoe.mirai.console.codegen
 
@@ -71,6 +71,16 @@ sealed class KtType {
     object KtMap : KtType() {
         override val standardName: String get() = "Map"
     }
+
+    data class Custom(override val standardName: String) : KtType() {
+        override fun toString(): String {
+            return standardName
+        }
+    }
+
+    companion object {
+        operator fun invoke(standardName: String): KtType = Custom(standardName)
+    }
 }
 
 val KtPrimitiveIntegers = listOf(KtByte, KtShort, KtInt, KtLong)
diff --git a/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/command/CommandSender.kt b/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/command/CommandSender.kt
index 1521889da..aa734e47f 100644
--- a/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/command/CommandSender.kt
+++ b/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/command/CommandSender.kt
@@ -165,6 +165,7 @@ public interface CommandSender : CoroutineScope {
      *
      * 对于 [MemberCommandSender], 这个函数总是发送给所在群
      */
+    @JvmDefault
     @JvmBlockingBridge
     public suspend fun sendMessage(message: String): MessageReceipt<User>?
 
@@ -259,9 +260,7 @@ public sealed class AbstractCommandSender : CommandSender, CoroutineScope {
     public abstract override val bot: Bot?
     public abstract override val subject: Contact?
     public abstract override val user: User?
-    public abstract override suspend fun sendMessage(message: Message): MessageReceipt<User>?
     public abstract override fun toString(): String
-    public override suspend fun sendMessage(message: String): MessageReceipt<User>? = sendMessage(PlainText(message))
 
     @ConsoleExperimentalAPI("This is unstable and might get changed")
     override suspend fun catchExecutionException(e: Throwable) {
@@ -502,6 +501,11 @@ public abstract class ConsoleCommandSender @ConsoleFrontEndImplementation constr
             MiraiConsoleImplementationBridge.consoleCommandSender.sendMessage(message)
             return null
         }
+
+        override suspend fun sendMessage(message: String): MessageReceipt<User>? {
+            MiraiConsoleImplementationBridge.consoleCommandSender.sendMessage(message)
+            return null
+        }
     }
 }
 
@@ -567,7 +571,11 @@ public interface UserCommandSender : CommandSender {
 public sealed class AbstractUserCommandSender : UserCommandSender, AbstractCommandSender() {
     public override val bot: Bot get() = user.bot // don't final
     public final override val name: String get() = user.nameCardOrNick
+
+    @JvmBlockingBridge
     public override suspend fun sendMessage(message: String): MessageReceipt<User> = sendMessage(PlainText(message))
+
+    @JvmBlockingBridge
     public override suspend fun sendMessage(message: Message): MessageReceipt<User> = user.sendMessage(message)
 }
 
@@ -580,7 +588,11 @@ public open class FriendCommandSender internal constructor(
 ) : AbstractUserCommandSender(), CoroutineScope by user.childScope("FriendCommandSender") {
     public override val subject: Contact get() = user
     public override fun toString(): String = "FriendCommandSender($user)"
+
+    @JvmBlockingBridge
     public override suspend fun sendMessage(message: String): MessageReceipt<Friend> = sendMessage(PlainText(message))
+
+    @JvmBlockingBridge
     public override suspend fun sendMessage(message: Message): MessageReceipt<Friend> = user.sendMessage(message)
 }
 
@@ -596,7 +608,11 @@ public open class MemberCommandSender internal constructor(
     public override val group: Group get() = user.group
     public override val subject: Contact get() = group
     public override fun toString(): String = "MemberCommandSender($user)"
+
+    @JvmBlockingBridge
     public override suspend fun sendMessage(message: String): MessageReceipt<Member> = sendMessage(PlainText(message))
+
+    @JvmBlockingBridge
     public override suspend fun sendMessage(message: Message): MessageReceipt<Member> = user.sendMessage(message)
 }
 
@@ -612,7 +628,11 @@ public open class TempCommandSender internal constructor(
     public override val group: Group get() = user.group
     public override val subject: Contact get() = group
     public override fun toString(): String = "TempCommandSender($user)"
+
+    @JvmBlockingBridge
     public override suspend fun sendMessage(message: String): MessageReceipt<Member> = sendMessage(PlainText(message))
+
+    @JvmBlockingBridge
     public override suspend fun sendMessage(message: Message): MessageReceipt<Member> = user.sendMessage(message)
 }
 
diff --git a/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/util/MessageScope.kt b/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/util/MessageScope.kt
new file mode 100644
index 000000000..57d2fab0c
--- /dev/null
+++ b/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/util/MessageScope.kt
@@ -0,0 +1,555 @@
+/*
+ * Copyright 2019-2020 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 AFFERO GENERAL PUBLIC LICENSE version 3 license that can be found via the following link.
+ *
+ * https://github.com/mamoe/mirai/blob/master/LICENSE
+ */
+
+@file:Suppress(
+    "NOTHING_TO_INLINE", "INAPPLICABLE_JVM_NAME", "FunctionName", "SuspendFunctionOnCoroutineScope",
+    "unused", "INVISIBLE_REFERENCE", "INVISIBLE_MEMBER"
+)
+
+package net.mamoe.mirai.console.util
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.firstOrNull
+import kotlinx.coroutines.flow.fold
+import net.mamoe.kjbb.JvmBlockingBridge
+import net.mamoe.mirai.console.command.CommandSender
+import net.mamoe.mirai.contact.Contact
+import net.mamoe.mirai.message.data.Message
+import kotlin.internal.InlineOnly
+import kotlin.internal.LowPriorityInOverloadResolution
+
+@ConsoleExperimentalAPI
+public interface MessageScope {
+    /**
+     * 立刻发送一条消息.
+     */
+    @JvmBlockingBridge
+    public suspend fun sendMessage(message: Message)
+
+    /**
+     * 立刻发送一条消息.
+     */
+    @JvmDefault
+    @JvmBlockingBridge
+    public suspend fun sendMessage(message: String)
+}
+
+@JvmSynthetic
+public inline operator fun <R, MS : MessageScope> MS.invoke(action: MS.() -> R): R = this.action()
+
+///////////////////////////////////////////////////////////////////////////
+// Builders
+///////////////////////////////////////////////////////////////////////////
+
+//// region MessageScopeBuilders CODEGEN ////
+
+public fun Contact.asMessageScope(): MessageScope = createScopeDelegate(this)
+
+public fun CommandSender.asMessageScope(): MessageScope = createScopeDelegate(this)
+
+@LowPriorityInOverloadResolution
+public fun Contact.scopeWith(vararg others: Contact): MessageScope {
+    return others.fold(this.asMessageScope()) { acc, other -> CombinedScope(acc, other.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun Contact.scopeWith(vararg others: CommandSender): MessageScope {
+    return others.fold(this.asMessageScope()) { acc, other -> CombinedScope(acc, other.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun Contact.scopeWith(vararg others: MessageScope): MessageScope {
+    return others.fold(this.asMessageScope()) { acc, other -> CombinedScope(acc, other.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun CommandSender.scopeWith(vararg others: Contact): MessageScope {
+    return others.fold(this.asMessageScope()) { acc, other -> CombinedScope(acc, other.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun CommandSender.scopeWith(vararg others: CommandSender): MessageScope {
+    return others.fold(this.asMessageScope()) { acc, other -> CombinedScope(acc, other.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun CommandSender.scopeWith(vararg others: MessageScope): MessageScope {
+    return others.fold(this.asMessageScope()) { acc, other -> CombinedScope(acc, other.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun MessageScope.scopeWith(vararg others: Contact): MessageScope {
+    return others.fold(this.asMessageScope()) { acc, other -> CombinedScope(acc, other.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun MessageScope.scopeWith(vararg others: CommandSender): MessageScope {
+    return others.fold(this.asMessageScope()) { acc, other -> CombinedScope(acc, other.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun MessageScope.scopeWith(vararg others: MessageScope): MessageScope {
+    return others.fold(this.asMessageScope()) { acc, other -> CombinedScope(acc, other.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun Contact?.scopeWithNotNull(vararg others: Contact?): MessageScope {
+    return others.fold(this.asMessageScopeOrNoop()) { acc, other -> acc.scopeWithNotNull(other?.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun Contact?.scopeWithNotNull(vararg others: CommandSender?): MessageScope {
+    return others.fold(this.asMessageScopeOrNoop()) { acc, other -> acc.scopeWithNotNull(other?.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun Contact?.scopeWithNotNull(vararg others: MessageScope?): MessageScope {
+    return others.fold(this.asMessageScopeOrNoop()) { acc, other -> acc.scopeWithNotNull(other?.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun CommandSender?.scopeWithNotNull(vararg others: Contact?): MessageScope {
+    return others.fold(this.asMessageScopeOrNoop()) { acc, other -> acc.scopeWithNotNull(other?.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun CommandSender?.scopeWithNotNull(vararg others: CommandSender?): MessageScope {
+    return others.fold(this.asMessageScopeOrNoop()) { acc, other -> acc.scopeWithNotNull(other?.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun CommandSender?.scopeWithNotNull(vararg others: MessageScope?): MessageScope {
+    return others.fold(this.asMessageScopeOrNoop()) { acc, other -> acc.scopeWithNotNull(other?.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun MessageScope?.scopeWithNotNull(vararg others: Contact?): MessageScope {
+    return others.fold(this.asMessageScopeOrNoop()) { acc, other -> acc.scopeWithNotNull(other?.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun MessageScope?.scopeWithNotNull(vararg others: CommandSender?): MessageScope {
+    return others.fold(this.asMessageScopeOrNoop()) { acc, other -> acc.scopeWithNotNull(other?.asMessageScope()) }
+}
+
+@LowPriorityInOverloadResolution
+public fun MessageScope?.scopeWithNotNull(vararg others: MessageScope?): MessageScope {
+    return others.fold(this.asMessageScopeOrNoop()) { acc, other -> acc.scopeWithNotNull(other?.asMessageScope()) }
+}
+
+public fun Contact.scopeWith(other: Contact): MessageScope {
+    return CombinedScope(asMessageScope(), other.asMessageScope())
+}
+
+public fun Contact.scopeWith(other: CommandSender): MessageScope {
+    return CombinedScope(asMessageScope(), other.asMessageScope())
+}
+
+public fun Contact.scopeWith(other: MessageScope): MessageScope {
+    return CombinedScope(asMessageScope(), other.asMessageScope())
+}
+
+public fun CommandSender.scopeWith(other: CommandSender): MessageScope {
+    return CombinedScope(asMessageScope(), other.asMessageScope())
+}
+
+public fun CommandSender.scopeWith(other: MessageScope): MessageScope {
+    return CombinedScope(asMessageScope(), other.asMessageScope())
+}
+
+public fun MessageScope.scopeWith(other: MessageScope): MessageScope {
+    return CombinedScope(asMessageScope(), other.asMessageScope())
+}
+
+public fun Contact?.scopeWithNotNull(other: Contact?): MessageScope {
+    @Suppress("DuplicatedCode")
+    return when {
+        this == null && other == null -> NoopMessageScope
+        this == null && other != null -> other.asMessageScope()
+        this != null && other == null -> this.asMessageScope()
+        this != null && other != null -> CombinedScope(asMessageScope(), other.asMessageScope())
+        else -> null!!
+    }
+}
+
+public fun Contact?.scopeWithNotNull(other: CommandSender?): MessageScope {
+    @Suppress("DuplicatedCode")
+    return when {
+        this == null && other == null -> NoopMessageScope
+        this == null && other != null -> other.asMessageScope()
+        this != null && other == null -> this.asMessageScope()
+        this != null && other != null -> CombinedScope(asMessageScope(), other.asMessageScope())
+        else -> null!!
+    }
+}
+
+public fun Contact?.scopeWithNotNull(other: MessageScope?): MessageScope {
+    @Suppress("DuplicatedCode")
+    return when {
+        this == null && other == null -> NoopMessageScope
+        this == null && other != null -> other.asMessageScope()
+        this != null && other == null -> this.asMessageScope()
+        this != null && other != null -> CombinedScope(asMessageScope(), other.asMessageScope())
+        else -> null!!
+    }
+}
+
+public fun CommandSender?.scopeWithNotNull(other: CommandSender?): MessageScope {
+    @Suppress("DuplicatedCode")
+    return when {
+        this == null && other == null -> NoopMessageScope
+        this == null && other != null -> other.asMessageScope()
+        this != null && other == null -> this.asMessageScope()
+        this != null && other != null -> CombinedScope(asMessageScope(), other.asMessageScope())
+        else -> null!!
+    }
+}
+
+public fun CommandSender?.scopeWithNotNull(other: MessageScope?): MessageScope {
+    @Suppress("DuplicatedCode")
+    return when {
+        this == null && other == null -> NoopMessageScope
+        this == null && other != null -> other.asMessageScope()
+        this != null && other == null -> this.asMessageScope()
+        this != null && other != null -> CombinedScope(asMessageScope(), other.asMessageScope())
+        else -> null!!
+    }
+}
+
+public fun MessageScope?.scopeWithNotNull(other: MessageScope?): MessageScope {
+    @Suppress("DuplicatedCode")
+    return when {
+        this == null && other == null -> NoopMessageScope
+        this == null && other != null -> other.asMessageScope()
+        this != null && other == null -> this.asMessageScope()
+        this != null && other != null -> CombinedScope(asMessageScope(), other.asMessageScope())
+        else -> null!!
+    }
+}
+
+public inline fun <R> Contact.scopeWith(vararg others: Contact, action: MessageScope.() -> R): R {
+    return scopeWith(*others).invoke(action)
+}
+
+public inline fun <R> Contact.scopeWith(vararg others: CommandSender, action: MessageScope.() -> R): R {
+    return scopeWith(*others).invoke(action)
+}
+
+public inline fun <R> Contact.scopeWith(vararg others: MessageScope, action: MessageScope.() -> R): R {
+    return scopeWith(*others).invoke(action)
+}
+
+public inline fun <R> CommandSender.scopeWith(vararg others: Contact, action: MessageScope.() -> R): R {
+    return scopeWith(*others).invoke(action)
+}
+
+public inline fun <R> CommandSender.scopeWith(vararg others: CommandSender, action: MessageScope.() -> R): R {
+    return scopeWith(*others).invoke(action)
+}
+
+public inline fun <R> CommandSender.scopeWith(vararg others: MessageScope, action: MessageScope.() -> R): R {
+    return scopeWith(*others).invoke(action)
+}
+
+public inline fun <R> MessageScope.scopeWith(vararg others: Contact, action: MessageScope.() -> R): R {
+    return scopeWith(*others).invoke(action)
+}
+
+public inline fun <R> MessageScope.scopeWith(vararg others: CommandSender, action: MessageScope.() -> R): R {
+    return scopeWith(*others).invoke(action)
+}
+
+public inline fun <R> MessageScope.scopeWith(vararg others: MessageScope, action: MessageScope.() -> R): R {
+    return scopeWith(*others).invoke(action)
+}
+
+public inline fun <R> Contact?.scopeWithNotNull(vararg others: Contact?, action: MessageScope.() -> R): R {
+    return scopeWithNotNull(*others).invoke(action)
+}
+
+public inline fun <R> Contact?.scopeWithNotNull(vararg others: CommandSender?, action: MessageScope.() -> R): R {
+    return scopeWithNotNull(*others).invoke(action)
+}
+
+public inline fun <R> Contact?.scopeWithNotNull(vararg others: MessageScope?, action: MessageScope.() -> R): R {
+    return scopeWithNotNull(*others).invoke(action)
+}
+
+public inline fun <R> CommandSender?.scopeWithNotNull(vararg others: Contact?, action: MessageScope.() -> R): R {
+    return scopeWithNotNull(*others).invoke(action)
+}
+
+public inline fun <R> CommandSender?.scopeWithNotNull(vararg others: CommandSender?, action: MessageScope.() -> R): R {
+    return scopeWithNotNull(*others).invoke(action)
+}
+
+public inline fun <R> CommandSender?.scopeWithNotNull(vararg others: MessageScope?, action: MessageScope.() -> R): R {
+    return scopeWithNotNull(*others).invoke(action)
+}
+
+public inline fun <R> MessageScope?.scopeWithNotNull(vararg others: Contact?, action: MessageScope.() -> R): R {
+    return scopeWithNotNull(*others).invoke(action)
+}
+
+public inline fun <R> MessageScope?.scopeWithNotNull(vararg others: CommandSender?, action: MessageScope.() -> R): R {
+    return scopeWithNotNull(*others).invoke(action)
+}
+
+public inline fun <R> MessageScope?.scopeWithNotNull(vararg others: MessageScope?, action: MessageScope.() -> R): R {
+    return scopeWithNotNull(*others).invoke(action)
+}
+
+@Deprecated(
+    "Senseless scopeWith. Use asMessageScope.",
+    ReplaceWith("this.asMessageScope()", "net.mamoe.mirai.console.util.asMessageScope")
+)
+public inline fun Contact.scopeWith(): MessageScope = asMessageScope()
+
+@Deprecated(
+    "Senseless scopeWith. Use asMessageScope.",
+    ReplaceWith("this.asMessageScope()", "net.mamoe.mirai.console.util.asMessageScope")
+)
+public inline fun CommandSender.scopeWith(): MessageScope = asMessageScope()
+
+@Deprecated(
+    "Senseless scopeWith. Use asMessageScope.",
+    ReplaceWith("this.asMessageScope()", "net.mamoe.mirai.console.util.asMessageScope")
+)
+public inline fun MessageScope.scopeWith(): MessageScope = asMessageScope()
+
+@Deprecated(
+    "Senseless scopeWith. Use .asMessageScope().invoke.",
+    ReplaceWith(
+        "this.asMessageScope()(action)",
+        "net.mamoe.mirai.console.util.asMessageScope",
+        "net.mamoe.mirai.console.util.invoke"
+    )
+)
+public inline fun <R> Contact.scopeWith(action: MessageScope.() -> R): R = asMessageScope()(action)
+
+@Deprecated(
+    "Senseless scopeWith. Use .asMessageScope().invoke.",
+    ReplaceWith(
+        "this.asMessageScope()(action)",
+        "net.mamoe.mirai.console.util.asMessageScope",
+        "net.mamoe.mirai.console.util.invoke"
+    )
+)
+public inline fun <R> CommandSender.scopeWith(action: MessageScope.() -> R): R = asMessageScope()(action)
+
+@Deprecated(
+    "Senseless scopeWith. Use .asMessageScope().invoke.",
+    ReplaceWith(
+        "this.asMessageScope()(action)",
+        "net.mamoe.mirai.console.util.asMessageScope",
+        "net.mamoe.mirai.console.util.invoke"
+    )
+)
+public inline fun <R> MessageScope.scopeWith(action: MessageScope.() -> R): R = asMessageScope()(action)
+
+//// endregion MessageScopeBuilders CODEGEN ////
+
+//// region IterableMessageScopeBuilders CODEGEN ////
+
+@JvmName("toMessageScopeContactIterable")
+public fun Iterable<Contact?>.toMessageScope(): MessageScope {
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScopeOrNoop()
+        )
+    }
+}
+
+@JvmName("toMessageScopeCommandSenderIterable")
+public fun Iterable<CommandSender?>.toMessageScope(): MessageScope {
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScopeOrNoop()
+        )
+    }
+}
+
+@JvmName("toMessageScopeMessageScopeIterable")
+public fun Iterable<MessageScope?>.toMessageScope(): MessageScope {
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScopeOrNoop()
+        )
+    }
+}
+
+@JvmName("toMessageScopeContactSequence")
+public fun Sequence<Contact?>.toMessageScope(): MessageScope {
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScopeOrNoop()
+        )
+    }
+}
+
+@JvmName("toMessageScopeCommandSenderSequence")
+public fun Sequence<CommandSender?>.toMessageScope(): MessageScope {
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScopeOrNoop()
+        )
+    }
+}
+
+@JvmName("toMessageScopeMessageScopeSequence")
+public fun Sequence<MessageScope?>.toMessageScope(): MessageScope {
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScopeOrNoop()
+        )
+    }
+}
+
+@JvmName("toMessageScopeContactArray")
+public fun Array<Contact?>.toMessageScope(): MessageScope {
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScopeOrNoop()
+        )
+    }
+}
+
+@JvmName("toMessageScopeCommandSenderArray")
+public fun Array<CommandSender?>.toMessageScope(): MessageScope {
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScopeOrNoop()
+        )
+    }
+}
+
+@JvmName("toMessageScopeMessageScopeArray")
+public fun Array<MessageScope?>.toMessageScope(): MessageScope {
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScopeOrNoop()
+        )
+    }
+}
+
+@JvmSynthetic
+@JvmName("toMessageScopeContactFlow")
+public suspend fun Flow<Contact>.toMessageScope(): MessageScope { // Flow<Any?>.firstOrNull isn't yet supported
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScope()
+        )
+    }
+}
+
+@JvmSynthetic
+@JvmName("toMessageScopeCommandSenderFlow")
+public suspend fun Flow<CommandSender>.toMessageScope(): MessageScope { // Flow<Any?>.firstOrNull isn't yet supported
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScope()
+        )
+    }
+}
+
+@JvmSynthetic
+@JvmName("toMessageScopeMessageScopeFlow")
+public suspend fun Flow<MessageScope>.toMessageScope(): MessageScope { // Flow<Any?>.firstOrNull isn't yet supported
+    return this.fold(this.firstOrNull().asMessageScopeOrNoop()) { acc, messageScope ->
+        CombinedScope(
+            acc,
+            messageScope.asMessageScope()
+        )
+    }
+}
+
+//// endregion IterableMessageScopeBuilders CODEGEN ////
+
+///////////////////////////////////////////////////////////////////////////
+// Internals
+///////////////////////////////////////////////////////////////////////////
+
+// these three are for codegen
+
+@PublishedApi
+@InlineOnly
+internal inline fun MessageScope.asMessageScope(): MessageScope = this
+
+@InlineOnly
+private inline fun MessageScope?.asMessageScopeOrNoop(): MessageScope = this?.asMessageScope() ?: NoopMessageScope
+
+@InlineOnly
+private inline fun Contact?.asMessageScopeOrNoop(): MessageScope = this?.asMessageScope() ?: NoopMessageScope
+
+@InlineOnly
+private inline fun CommandSender?.asMessageScopeOrNoop(): MessageScope = this?.asMessageScope() ?: NoopMessageScope
+
+@InlineOnly
+private inline fun createScopeDelegate(o: CommandSender) = CommandSenderAsMessageScope(o)
+
+@InlineOnly
+private inline fun createScopeDelegate(o: Contact) = ContactAsMessageScope(o)
+
+private class CombinedScope(
+    private val first: MessageScope,
+    private val second: MessageScope
+) : MessageScope {
+    override suspend fun sendMessage(message: Message) {
+        first.sendMessage(message)
+        second.sendMessage(message)
+    }
+
+    override suspend fun sendMessage(message: String) {
+        first.sendMessage(message)
+        second.sendMessage(message)
+    }
+}
+
+private class CommandSenderAsMessageScope(
+    private val sender: CommandSender
+) : MessageScope {
+    override suspend fun sendMessage(message: Message) {
+        sender.sendMessage(message)
+    }
+
+    override suspend fun sendMessage(message: String) {
+        sender.sendMessage(message)
+    }
+}
+
+private class ContactAsMessageScope(
+    private val sender: Contact
+) : MessageScope {
+    override suspend fun sendMessage(message: Message) {
+        sender.sendMessage(message)
+    }
+
+    override suspend fun sendMessage(message: String) {
+        sender.sendMessage(message)
+    }
+}
+
+private object NoopMessageScope : MessageScope {
+    override suspend fun sendMessage(message: Message) {
+    }
+
+    override suspend fun sendMessage(message: String) {
+    }
+}
\ No newline at end of file