Merge pull request #13 from m1sk9/feat/add-command-system

feat: Add LunaticChat command system

27 files changed, 789 insertions, 72 deletions

diff --git a/README.md b/README.md
index 8237ac4..e3a306d 100644
--- a/README.md
+++ b/README.md
@@ -23,8 +23,8 @@ _[Supports Minecraft 1.21.X](https://minecraft.wiki/w/Java_Edition_version_histo
 
 ## Todo
 
-- [ ] 1on1 Direct Messaging System
-- [ ] Quick Reply Functionality
+- [x] 1on1 Direct Messaging System
+- [x] Quick Reply Functionality
 - [ ] Romaji to Japanese Conversion
 - [ ] Velocity Support
 - [ ] Channel Chat System
diff --git a/docker/compose.yaml b/docker/compose.yaml
index 536242a..c3814d1 100644
--- a/docker/compose.yaml
+++ b/docker/compose.yaml
@@ -1,13 +1,13 @@
 services:
   minecraft:
     image: itzg/minecraft-server:java21
-    container_name: runecore-debug-server
+    container_name: debug-server
     user: "0:0"
     ports:
       - "25565:25565"
       - "25575:25575"
     volumes:
-      - minecraft-data:/data
+      - lunatic-debug-minecraft-data:/data
       - ../platform-paper/build/libs:/plugins:ro
       - ./plugins:/data/plugins
       - ./bukkit.yml:/data/bukkit.yml
@@ -40,4 +40,4 @@ services:
     stdin_open: true
 
 volumes:
-  minecraft-data:
+  lunatic-debug-minecraft-data:
diff --git a/engine/build.gradle.kts b/engine/build.gradle.kts
index e1b7c51..7afc78f 100644
--- a/engine/build.gradle.kts
+++ b/engine/build.gradle.kts
@@ -4,6 +4,5 @@ plugins {
 }
 
 dependencies {
-    // JSON シリアライゼーション
     implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.9.0")
 }
diff --git a/engine/src/main/kotlin/dev/m1sk9/lunaticChat/engine/exception/RequirePermissionException.kt b/engine/src/main/kotlin/dev/m1sk9/lunaticChat/engine/exception/RequirePermissionException.kt
new file mode 100644
index 0000000..dace909
--- /dev/null
+++ b/engine/src/main/kotlin/dev/m1sk9/lunaticChat/engine/exception/RequirePermissionException.kt
@@ -0,0 +1,12 @@
+package dev.m1sk9.lunaticChat.engine.exception
+
+import dev.m1sk9.lunaticChat.engine.permission.LunaticChatPermissionNode
+
+/**
+ * Exception thrown when required permissions are missing.
+ *
+ * @param permissions The list of missing permissions.
+ */
+class RequirePermissionException(
+    permissions: List<LunaticChatPermissionNode>,
+) : Exception("Missing required permissions: ${permissions.joinToString { it.permissionNode }}")
diff --git a/engine/src/main/kotlin/dev/m1sk9/lunaticChat/engine/permission/LunaticChatPermissionNode.kt b/engine/src/main/kotlin/dev/m1sk9/lunaticChat/engine/permission/LunaticChatPermissionNode.kt
new file mode 100644
index 0000000..304d531
--- /dev/null
+++ b/engine/src/main/kotlin/dev/m1sk9/lunaticChat/engine/permission/LunaticChatPermissionNode.kt
@@ -0,0 +1,11 @@
+package dev.m1sk9.lunaticChat.engine.permission
+
+sealed class LunaticChatPermissionNode(
+    val permissionNode: String,
+) {
+    object Tell : LunaticChatPermissionNode("lunaticchat.command.tell")
+
+    object Reply : LunaticChatPermissionNode("lunaticchat.command.reply")
+
+    object Spy : LunaticChatPermissionNode("lunaticchat.spy")
+}
diff --git a/platform-paper/build.gradle.kts b/platform-paper/build.gradle.kts
index 315061f..4624a4b 100644
--- a/platform-paper/build.gradle.kts
+++ b/platform-paper/build.gradle.kts
@@ -12,19 +12,21 @@ repositories {
 }
 
 dependencies {
-    // engine モジュールを使用
     api(project(":engine"))
-
-    // Paper API
     compileOnly("io.papermc.paper:paper-api:1.21.11-R0.1-SNAPSHOT")
+    implementation("org.jetbrains.kotlin:kotlin-reflect")
 }
 
 tasks {
     shadowJar {
-        archiveClassifier.set("all")
+        archiveClassifier.set("")
         archiveBaseName.set("LunaticChat")
     }
 
+    jar {
+        enabled = false
+    }
+
     runServer {
         minecraftVersion("1.21")
     }
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/LunaticChat.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/LunaticChat.kt
index 360ebb9..00f2eb9 100644
--- a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/LunaticChat.kt
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/LunaticChat.kt
@@ -1,9 +1,22 @@
 package dev.m1sk9.lunaticChat.paper
 
+import dev.m1sk9.lunaticChat.paper.command.core.CommandRegistry
+import dev.m1sk9.lunaticChat.paper.command.handler.DirectMessageHandler
+import dev.m1sk9.lunaticChat.paper.command.impl.ReplyCommand
+import dev.m1sk9.lunaticChat.paper.command.impl.TellCommand
+import dev.m1sk9.lunaticChat.paper.common.SpyPermissionManager
 import dev.m1sk9.lunaticChat.paper.config.ConfigManager
+import dev.m1sk9.lunaticChat.paper.listener.PlayerPresenceListener
+import org.bukkit.event.Listener
 import org.bukkit.plugin.java.JavaPlugin
 
-class LunaticChat : JavaPlugin() {
+class LunaticChat :
+    JavaPlugin(),
+    Listener {
+    lateinit var directMessageHandler: DirectMessageHandler
+
+    private lateinit var commandRegistry: CommandRegistry
+
     override fun onEnable() {
         saveDefaultConfig()
         val lunaticChatConfiguration = ConfigManager.loadConfiguration(config)
@@ -11,9 +24,21 @@ class LunaticChat : JavaPlugin() {
         if (lunaticChatConfiguration.debug) {
             logger.warning("LunaticChat is running in debug mode.")
             logger.info("Debug: $lunaticChatConfiguration")
-            // TODO: Enable debug features
         }
 
+        directMessageHandler = DirectMessageHandler()
+
+        commandRegistry =
+            CommandRegistry(this)
+                .registerAll(
+                    TellCommand(this, directMessageHandler),
+                    ReplyCommand(this, directMessageHandler),
+                )
+        commandRegistry.initialize()
+
+        server.pluginManager.registerEvents(SpyPermissionManager, this)
+        server.pluginManager.registerEvents(PlayerPresenceListener(), this)
+
         logger.info("LunaticChat enabled.")
     }
 
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/annotation/Command.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/annotation/Command.kt
new file mode 100644
index 0000000..f16dd20
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/annotation/Command.kt
@@ -0,0 +1,16 @@
+package dev.m1sk9.lunaticChat.paper.command.annotation
+
+/**
+ * Marks a class as a LunaticChat command.
+ *
+ * @param name The primary command name (without leading slash)
+ * @param aliases List of alternative command names
+ * @param description Human-readable description for help text
+ */
+@Target(AnnotationTarget.CLASS)
+@Retention(AnnotationRetention.RUNTIME)
+annotation class Command(
+    val name: String,
+    val aliases: Array<String> = [],
+    val description: String = "",
+)
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/annotation/Permission.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/annotation/Permission.kt
new file mode 100644
index 0000000..d96e1b5
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/annotation/Permission.kt
@@ -0,0 +1,15 @@
+package dev.m1sk9.lunaticChat.paper.command.annotation
+
+import dev.m1sk9.lunaticChat.engine.permission.LunaticChatPermissionNode
+import kotlin.reflect.KClass
+
+/**
+ * Restricts command execution to senders with the specified permission.
+ *
+ * @param value The permission node required to execute this command
+ */
+@Target(AnnotationTarget.CLASS)
+@Retention(AnnotationRetention.RUNTIME)
+annotation class Permission(
+    val value: KClass<out LunaticChatPermissionNode>,
+)
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/annotation/PlayerOnly.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/annotation/PlayerOnly.kt
new file mode 100644
index 0000000..0669e28
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/annotation/PlayerOnly.kt
@@ -0,0 +1,9 @@
+package dev.m1sk9.lunaticChat.paper.command.annotation
+
+/**
+ * Restricts command execution to players only.
+ * Console execution will be rejected with an appropriate message.
+ */
+@Target(AnnotationTarget.CLASS)
+@Retention(AnnotationRetention.RUNTIME)
+annotation class PlayerOnly
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/CommandContext.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/CommandContext.kt
new file mode 100644
index 0000000..7f1bb15
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/CommandContext.kt
@@ -0,0 +1,68 @@
+package dev.m1sk9.lunaticChat.paper.command.core
+
+import io.papermc.paper.command.brigadier.CommandSourceStack
+import net.kyori.adventure.text.Component
+import net.kyori.adventure.text.event.ClickEvent
+import org.bukkit.command.CommandSender
+import org.bukkit.entity.Player
+
+/**
+ * Wrapper for Brigadier command context providing type-safe access
+ * to command sender and arguments.
+ */
+class CommandContext(
+    private val sourceStack: CommandSourceStack,
+) {
+    /** The raw command sender (player, console, or other) */
+    val sender: CommandSender
+        get() = sourceStack.sender
+
+    /** The player if sender is a player, null otherwise */
+    val player: Player?
+        get() = sender as? Player
+
+    /** Whether the sender is a player */
+    val isPlayer: Boolean
+        get() = sender is Player
+
+    /**
+     * Requires the sender to be a player.
+     *
+     * @return The player
+     * @throws IllegalStateException if sender is not a player
+     */
+    fun requirePlayer(): Player = player ?: throw IllegalStateException("This command can only be executed by a player")
+
+    /**
+     * Sends a message to the command sender.
+     *
+     * @param message The message component to send
+     */
+    fun reply(message: Component) {
+        sender.sendMessage(message)
+    }
+
+    /**
+     * Sends a message with a click event to the command sender.
+     *
+     * @param message The message component to send
+     * @param event The click event to attach to the message
+     */
+    fun replyWithEvent(
+        message: Component,
+        event: ClickEvent,
+    ) {
+        message
+            .clickEvent(event)
+            .let { sender.sendMessage(it) }
+    }
+
+    /**
+     * Sends a plain text message to the command sender.
+     *
+     * @param message The plain text message to send
+     */
+    fun replyPlain(message: String) {
+        sender.sendPlainMessage(message)
+    }
+}
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/CommandRegistry.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/CommandRegistry.kt
new file mode 100644
index 0000000..11929cf
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/CommandRegistry.kt
@@ -0,0 +1,65 @@
+package dev.m1sk9.lunaticChat.paper.command.core
+
+import dev.m1sk9.lunaticChat.paper.LunaticChat
+import io.papermc.paper.plugin.lifecycle.event.types.LifecycleEvents
+import java.util.logging.Logger
+
+/**
+ * Central registry for all LunaticChat commands.
+ * Handles registration with Paper's LifecycleEventManager.
+ */
+class CommandRegistry(
+    private val plugin: LunaticChat,
+) {
+    private val logger: Logger = plugin.logger
+    private val commands: MutableList<LunaticCommand> = mutableListOf()
+
+    /**
+     * Registers a command to be registered with the server.
+     * Must be called before initialize().
+     */
+    fun register(command: LunaticCommand): CommandRegistry {
+        commands.add(command)
+        return this
+    }
+
+    /**
+     * Registers multiple commands at once.
+     */
+    fun registerAll(vararg commands: LunaticCommand): CommandRegistry {
+        commands.forEach { register(it) }
+        return this
+    }
+
+    /**
+     * Initializes command registration with Paper's LifecycleEventManager.
+     * This should be called from the plugin's onEnable().
+     */
+    fun initialize() {
+        val lifecycleManager = plugin.lifecycleManager
+
+        lifecycleManager.registerEventHandler(LifecycleEvents.COMMANDS) { event ->
+            val registrar = event.registrar()
+
+            for (command in commands) {
+                try {
+                    val builtCommand = command.buildWithChecks().build()
+
+                    registrar.register(
+                        builtCommand,
+                        command.description,
+                        command.aliases,
+                    )
+
+                    logger.info(
+                        "Registered command: /${command.name} " +
+                            "(aliases: ${command.aliases.joinToString(", ")})",
+                    )
+                } catch (e: Exception) {
+                    logger.severe("Failed to register command /${command.name}: ${e.message}")
+                    e.printStackTrace()
+                }
+            }
+        }
+    }
+}
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/CommandResult.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/CommandResult.kt
new file mode 100644
index 0000000..0a2de3d
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/CommandResult.kt
@@ -0,0 +1,37 @@
+package dev.m1sk9.lunaticChat.paper.command.core
+
+import net.kyori.adventure.text.Component
+
+/**
+ * Represents the result of a command execution.
+ * Uses Kotlin sealed classes for type-safe result handling.
+ */
+sealed class CommandResult {
+    /** Command executed successfully */
+    data object Success : CommandResult()
+
+    /** Command executed successfully with a message to display */
+    data class SuccessWithMessage(
+        val message: Component,
+    ) : CommandResult()
+
+    /** Command failed with an error message */
+    data class Failure(
+        val message: Component,
+    ) : CommandResult()
+
+    /** Command failed due to invalid usage */
+    data class InvalidUsage(
+        val usageHint: String,
+    ) : CommandResult()
+
+    /**
+     * Converts result to Brigadier return value.
+     * @return 1 for success, 0 for failure (Brigadier convention)
+     */
+    fun toBrigadierResult(): Int =
+        when (this) {
+            is Success, is SuccessWithMessage -> 1
+            is Failure, is InvalidUsage -> 0
+        }
+}
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/LunaticCommand.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/LunaticCommand.kt
new file mode 100644
index 0000000..07a7823
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/core/LunaticCommand.kt
@@ -0,0 +1,110 @@
+package dev.m1sk9.lunaticChat.paper.command.core
+
+import com.mojang.brigadier.builder.LiteralArgumentBuilder
+import dev.m1sk9.lunaticChat.paper.LunaticChat
+import dev.m1sk9.lunaticChat.paper.command.annotation.Command
+import dev.m1sk9.lunaticChat.paper.command.annotation.Permission
+import dev.m1sk9.lunaticChat.paper.command.annotation.PlayerOnly
+import io.papermc.paper.command.brigadier.CommandSourceStack
+import net.kyori.adventure.text.Component
+import net.kyori.adventure.text.format.NamedTextColor
+
+/**
+ * Abstract base class for all LunaticChat commands.
+ * Provides common functionality and enforces consistent command structure.
+ */
+abstract class LunaticCommand(
+    protected val plugin: LunaticChat,
+) {
+    private val commandAnnotation: Command by lazy {
+        this::class.annotations.filterIsInstance<Command>().firstOrNull()
+            ?: throw IllegalStateException("Command class must be annotated with @Command")
+    }
+
+    private val permissionAnnotation: Permission? by lazy {
+        this::class.annotations.filterIsInstance<Permission>().firstOrNull()
+    }
+
+    private val isPlayerOnly: Boolean by lazy {
+        this::class.annotations.any { it is PlayerOnly }
+    }
+
+    /** The primary command name */
+    val name: String get() = commandAnnotation.name
+
+    /** Command aliases */
+    val aliases: List<String> get() = commandAnnotation.aliases.toList()
+
+    /** Command description for help text */
+    val description: String get() = commandAnnotation.description
+
+    /** Required permission node, if any */
+    val permission: String? get() = permissionAnnotation?.value?.objectInstance?.permissionNode
+
+    /**
+     * Build the Brigadier command tree.
+     * Subclasses implement this to define arguments and execution logic.
+     *
+     * @return The command builder with all arguments and executors attached
+     */
+    abstract fun buildCommand(): LiteralArgumentBuilder<CommandSourceStack>
+
+    /**
+     * Wraps the command builder with permission checks.
+     * Called by CommandRegistry during registration.
+     */
+    fun buildWithChecks(): LiteralArgumentBuilder<CommandSourceStack> {
+        var builder = buildCommand()
+        permission?.let { perm ->
+            builder =
+                builder.requires { source ->
+                    source.sender.hasPermission(perm)
+                }
+        }
+
+        return builder
+    }
+
+    /**
+     * Helper method for checking player-only restriction.
+     * Called at the beginning of execute methods.
+     */
+    protected fun checkPlayerOnly(ctx: CommandContext): CommandResult? {
+        if (isPlayerOnly && !ctx.isPlayer) {
+            return CommandResult.Failure(
+                Component
+                    .text("This command can only be executed by a player.")
+                    .color(NamedTextColor.RED),
+            )
+        }
+
+        return null
+    }
+
+    /**
+     * Utility to wrap Brigadier context into LunaticChat CommandContext.
+     */
+    protected fun wrapContext(ctx: com.mojang.brigadier.context.CommandContext<CommandSourceStack>): CommandContext =
+        CommandContext(ctx.source)
+
+    /**
+     * Helper for handling command results and sending appropriate messages.
+     */
+    protected fun handleResult(
+        ctx: CommandContext,
+        result: CommandResult,
+    ): Int {
+        when (result) {
+            is CommandResult.Success -> {}
+            is CommandResult.SuccessWithMessage -> ctx.reply(result.message)
+            is CommandResult.Failure -> ctx.reply(result.message)
+            is CommandResult.InvalidUsage ->
+                ctx.reply(
+                    Component
+                        .text("Usage: ${result.usageHint}")
+                        .color(NamedTextColor.RED),
+                )
+        }
+        return result.toBrigadierResult()
+    }
+}
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/handler/DirectMessageHandler.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/handler/DirectMessageHandler.kt
new file mode 100644
index 0000000..0a28a2d
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/handler/DirectMessageHandler.kt
@@ -0,0 +1,103 @@
+package dev.m1sk9.lunaticChat.paper.command.handler
+
+import dev.m1sk9.lunaticChat.paper.common.SpyPermissionManager
+import dev.m1sk9.lunaticChat.paper.config.ConfigManager
+import net.kyori.adventure.text.Component
+import net.kyori.adventure.text.event.ClickEvent
+import org.bukkit.Bukkit
+import org.bukkit.entity.Player
+import java.util.UUID
+import java.util.concurrent.ConcurrentHashMap
+
+/**
+ * Manages direct message state including reply targets.
+ * Tracks the last player who messaged each player for /reply functionality.
+ */
+class DirectMessageHandler {
+    private var lunaticChatConfiguration = ConfigManager.getConfiguration()
+
+    private val lastMessager: ConcurrentHashMap<UUID, UUID> = ConcurrentHashMap()
+    private val lastRecipient: ConcurrentHashMap<UUID, UUID> = ConcurrentHashMap()
+
+    /**
+     * Records a direct message between two players.
+     * Updates both the sender's last recipient and the receiver's last messager.
+     */
+    fun recordMessage(
+        sender: Player,
+        recipient: Player,
+    ) {
+        lastRecipient[sender.uniqueId] = recipient.uniqueId
+        lastMessager[recipient.uniqueId] = sender.uniqueId
+    }
+
+    /**
+     * Gets the player to reply to.
+     * First checks if someone has messaged this player, otherwise falls back
+     * to the last person they messaged.
+     */
+    fun getReplyTarget(player: Player): Player? {
+        val messager = lastMessager[player.uniqueId]?.let { Bukkit.getPlayer(it) }
+        if (messager != null && messager.isOnline) {
+            return messager
+        }
+
+        val recipient = lastRecipient[player.uniqueId]?.let { Bukkit.getPlayer(it) }
+        if (recipient != null && recipient.isOnline) {
+            return recipient
+        }
+
+        return null
+    }
+
+    /**
+     * Clears message history for a player (called on disconnect).
+     */
+    fun clearPlayer(player: Player) {
+        lastMessager.remove(player.uniqueId)
+        lastRecipient.remove(player.uniqueId)
+    }
+
+    /**
+     * Sends a direct message from one player to another.
+     * Handles formatting and recording the conversation.
+     *
+     * @return true if message was sent successfully
+     */
+    fun sendDirectMessage(
+        sender: Player,
+        recipient: Player,
+        message: String,
+    ): Boolean {
+        recordMessage(sender, recipient)
+        val format = lunaticChatConfiguration.messageFormat.directMessageFormat
+        val formattedMessage = formatMessage(format, sender.name, recipient.name, message)
+
+        SpyPermissionManager.getDirectMessageSpyPlayers().values.forEach {
+            if (it.isOnline && it.uniqueId != sender.uniqueId && it.uniqueId != recipient.uniqueId) {
+                it.sendMessage(formattedMessage)
+            }
+        }
+
+        sender.sendMessage(formattedMessage)
+        recipient.sendMessage(formattedMessage)
+        return true
+    }
+
+    private fun formatMessage(
+        format: String,
+        senderName: String,
+        recipientName: String,
+        message: String,
+    ): Component {
+        val text =
+            format
+                .replace("{sender}", senderName)
+                .replace("{recipient}", recipientName)
+                .replace("{message}", message)
+
+        return Component
+            .text(text)
+            .clickEvent(ClickEvent.suggestCommand("/tell $senderName "))
+    }
+}
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/impl/ReplyCommand.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/impl/ReplyCommand.kt
new file mode 100644
index 0000000..37e0a82
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/impl/ReplyCommand.kt
@@ -0,0 +1,68 @@
+package dev.m1sk9.lunaticChat.paper.command.impl
+
+import com.mojang.brigadier.arguments.StringArgumentType
+import com.mojang.brigadier.builder.LiteralArgumentBuilder
+import dev.m1sk9.lunaticChat.engine.permission.LunaticChatPermissionNode
+import dev.m1sk9.lunaticChat.paper.LunaticChat
+import dev.m1sk9.lunaticChat.paper.command.annotation.Command
+import dev.m1sk9.lunaticChat.paper.command.annotation.Permission
+import dev.m1sk9.lunaticChat.paper.command.annotation.PlayerOnly
+import dev.m1sk9.lunaticChat.paper.command.core.CommandContext
+import dev.m1sk9.lunaticChat.paper.command.core.CommandResult
+import dev.m1sk9.lunaticChat.paper.command.core.LunaticCommand
+import dev.m1sk9.lunaticChat.paper.command.handler.DirectMessageHandler
+import io.papermc.paper.command.brigadier.CommandSourceStack
+import io.papermc.paper.command.brigadier.Commands
+import net.kyori.adventure.text.Component
+import net.kyori.adventure.text.format.NamedTextColor
+
+/**
+ * Quick reply command for responding to the last person who messaged you.
+ * Usage: /reply <message>
+ */
+@Command(
+    name = "reply",
+    aliases = ["r"],
+    description = "Reply to the last person who messaged you",
+)
+@Permission(LunaticChatPermissionNode.Reply::class)
+@PlayerOnly
+class ReplyCommand(
+    plugin: LunaticChat,
+    private val dmHandler: DirectMessageHandler,
+) : LunaticCommand(plugin) {
+    override fun buildCommand(): LiteralArgumentBuilder<CommandSourceStack> =
+        Commands
+            .literal(name)
+            .then(
+                Commands
+                    .argument("message", StringArgumentType.greedyString())
+                    .executes { ctx ->
+                        val context = wrapContext(ctx)
+
+                        checkPlayerOnly(context)?.let { return@executes handleResult(context, it) }
+                        val message = StringArgumentType.getString(ctx, "message")
+                        val result = execute(context, message)
+
+                        handleResult(context, result)
+                    },
+            )
+
+    private fun execute(
+        ctx: CommandContext,
+        message: String,
+    ): CommandResult {
+        val sender = ctx.requirePlayer()
+        val target =
+            dmHandler.getReplyTarget(sender)
+                ?: return CommandResult.Failure(
+                    Component
+                        .text("You have no one to reply to.")
+                        .color(NamedTextColor.RED),
+                )
+
+        dmHandler.sendDirectMessage(sender, target, message)
+
+        return CommandResult.Success
+    }
+}
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/impl/TellCommand.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/impl/TellCommand.kt
new file mode 100644
index 0000000..54ab036
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/command/impl/TellCommand.kt
@@ -0,0 +1,95 @@
+package dev.m1sk9.lunaticChat.paper.command.impl
+
+import com.mojang.brigadier.arguments.StringArgumentType
+import com.mojang.brigadier.builder.LiteralArgumentBuilder
+import com.mojang.brigadier.suggestion.Suggestions
+import com.mojang.brigadier.suggestion.SuggestionsBuilder
+import dev.m1sk9.lunaticChat.engine.permission.LunaticChatPermissionNode
+import dev.m1sk9.lunaticChat.paper.LunaticChat
+import dev.m1sk9.lunaticChat.paper.command.annotation.Command
+import dev.m1sk9.lunaticChat.paper.command.annotation.Permission
+import dev.m1sk9.lunaticChat.paper.command.annotation.PlayerOnly
+import dev.m1sk9.lunaticChat.paper.command.core.CommandContext
+import dev.m1sk9.lunaticChat.paper.command.core.CommandResult
+import dev.m1sk9.lunaticChat.paper.command.core.LunaticCommand
+import dev.m1sk9.lunaticChat.paper.command.handler.DirectMessageHandler
+import io.papermc.paper.command.brigadier.CommandSourceStack
+import io.papermc.paper.command.brigadier.Commands
+import net.kyori.adventure.text.Component
+import net.kyori.adventure.text.format.NamedTextColor
+import org.bukkit.Bukkit
+import java.util.concurrent.CompletableFuture
+
+/**
+ * Direct messaging command.
+ * Usage: /tell <player> <message>
+ */
+@Command(
+    name = "tell",
+    aliases = ["t", "msg", "m", "w", "whisper"],
+    description = "Send a private message to another player",
+)
+@Permission(LunaticChatPermissionNode.Tell::class)
+@PlayerOnly
+class TellCommand(
+    plugin: LunaticChat,
+    private val directMessageHandler: DirectMessageHandler,
+) : LunaticCommand(plugin) {
+    override fun buildCommand(): LiteralArgumentBuilder<CommandSourceStack> =
+        Commands
+            .literal(name)
+            .then(
+                Commands
+                    .argument("player", StringArgumentType.word())
+                    .suggests { _, builder -> suggestOnlinePlayers(builder) }
+                    .then(
+                        Commands
+                            .argument("message", StringArgumentType.greedyString())
+                            .executes { ctx ->
+                                val context = wrapContext(ctx)
+                                checkPlayerOnly(context)?.let { return@executes handleResult(context, it) }
+
+                                val targetName = StringArgumentType.getString(ctx, "player")
+                                val message = StringArgumentType.getString(ctx, "message")
+
+                                val result = execute(context, targetName, message)
+                                handleResult(context, result)
+                            },
+                    ),
+            )
+
+    private fun execute(
+        ctx: CommandContext,
+        targetName: String,
+        message: String,
+    ): CommandResult {
+        val sender = ctx.requirePlayer()
+        val recipient =
+            Bukkit.getPlayer(targetName)
+                ?: return CommandResult.Failure(
+                    Component
+                        .text("Player '$targetName' is not online.")
+                        .color(NamedTextColor.RED),
+                )
+
+        if (recipient.uniqueId == sender.uniqueId) {
+            return CommandResult.Failure(
+                Component
+                    .text("You cannot send a message to yourself.")
+                    .color(NamedTextColor.RED),
+            )
+        }
+        directMessageHandler.sendDirectMessage(sender, recipient, message)
+
+        return CommandResult.Success
+    }
+
+    private fun suggestOnlinePlayers(builder: SuggestionsBuilder): CompletableFuture<Suggestions> {
+        val input = builder.remaining.lowercase()
+        Bukkit
+            .getOnlinePlayers()
+            .filter { it.name.lowercase().startsWith(input) }
+            .forEach { builder.suggest(it.name) }
+        return builder.buildFuture()
+    }
+}
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/common/PermissionCollector.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/common/PermissionCollector.kt
new file mode 100644
index 0000000..4edfe34
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/common/PermissionCollector.kt
@@ -0,0 +1,60 @@
+package dev.m1sk9.lunaticChat.paper.common
+
+import dev.m1sk9.lunaticChat.engine.exception.RequirePermissionException
+import dev.m1sk9.lunaticChat.engine.permission.LunaticChatPermissionNode
+import org.bukkit.entity.Player
+
+@DslMarker
+annotation class PermissionDsl
+
+@PermissionDsl
+class PermissionCollector {
+    internal val permissions = mutableListOf<LunaticChatPermissionNode>()
+
+    operator fun LunaticChatPermissionNode.unaryPlus() {
+        permissions.add(this)
+    }
+}
+
+fun LunaticChatPermissionNode.has(player: Player): Boolean = player.hasPermission(this.permissionNode)
+
+/**
+ * Checks if the player has at least one of the specified permissions.
+ *
+ * @param block A lambda with receiver to collect permissions.
+ * @return `true` if the player has at least one of the specified permissions.
+ */
+fun Player.hasAnyPermission(block: PermissionCollector.() -> Unit): Boolean =
+    PermissionCollector()
+        .apply(block)
+        .permissions
+        .any { it.has(this) }
+
+/**
+ * Checks if the player has all the specified permissions.
+ *
+ * @param block A lambda with receiver to collect permissions.
+ * @return `true` if the player has all the specified permissions.
+ */
+fun Player.hasAllPermission(block: PermissionCollector.() -> Unit): Boolean =
+    PermissionCollector()
+        .apply(block)
+        .permissions
+        .all { it.has(this) }
+
+/**
+ * Requires the player to have at least one of the specified permissions.
+ *
+ * @param block A lambda with receiver to collect permissions.
+ * @return Throws [RequirePermissionException] if the player lacks all specified permissions.
+ * @throws RequirePermissionException if the player lacks all specified permissions.
+ */
+fun Player.requirePermission(block: PermissionCollector.() -> Unit) {
+    val result =
+        PermissionCollector()
+            .apply(block)
+            .permissions
+    if (!result.any { it.has(this) }) {
+        throw RequirePermissionException(result)
+    }
+}
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/ConfigManager.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/ConfigManager.kt
index b12e935..d10a4e6 100644
--- a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/ConfigManager.kt
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/ConfigManager.kt
@@ -2,7 +2,6 @@ package dev.m1sk9.lunaticChat.paper.config
 
 import dev.m1sk9.lunaticChat.paper.config.key.FeaturesConfig
 import dev.m1sk9.lunaticChat.paper.config.key.MessageFormatConfig
-import dev.m1sk9.lunaticChat.paper.config.key.VelocityConfig
 import org.bukkit.configuration.file.FileConfiguration
 
 object ConfigManager {
@@ -24,29 +23,8 @@ object ConfigManager {
                         directMessageFormat =
                             configFile.getString(
                                 "messageFormat.directMessageFormat",
-                                "&7[&e{sender} &7>>] &f{message}",
+                                "§7[§e{sender} §7>> §e{recipient}§7] §f{message}",
                             )!!,
-                        crossServerMessageFormat =
-                            configFile.getString(
-                                "messageFormat.crossServerMessageFormat",
-                                "&7[&e{sender} &7(&b{server}&7)] &f{message}",
-                            )!!,
-                        crossServerDirectMessageFormat =
-                            configFile.getString(
-                                "messageFormat.crossServerDirectMessageFormat",
-                                "&7[&e{sender}@&7(&b{server}&7) >>] &f{message}",
-                            )!!,
-                    ),
-                velocity =
-                    VelocityConfig(
-                        enabled = configFile.getBoolean("velocity.enabled", false),
-                        serverName = configFile.getString("velocity.serverName", "s1")!!,
-                        crossServerChatEnabled = configFile.getBoolean("velocity.crossServerChatEnabled", false),
-                        crossServerDirectMessagesEnabled =
-                            configFile.getBoolean(
-                                "velocity.crossServerDirectMessagesEnabled",
-                                false,
-                            ),
                     ),
                 debug = configFile.getBoolean("debug", false),
             )
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/LunaticChatConfiguration.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/LunaticChatConfiguration.kt
index d474de7..2475086 100644
--- a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/LunaticChatConfiguration.kt
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/LunaticChatConfiguration.kt
@@ -2,11 +2,9 @@ package dev.m1sk9.lunaticChat.paper.config
 
 import dev.m1sk9.lunaticChat.paper.config.key.FeaturesConfig
 import dev.m1sk9.lunaticChat.paper.config.key.MessageFormatConfig
-import dev.m1sk9.lunaticChat.paper.config.key.VelocityConfig
 
 data class LunaticChatConfiguration(
     val features: FeaturesConfig,
     val messageFormat: MessageFormatConfig,
-    val velocity: VelocityConfig,
     val debug: Boolean = false,
 )
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/key/MessageFormatConfig.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/key/MessageFormatConfig.kt
index 52eddae..53d4399 100644
--- a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/key/MessageFormatConfig.kt
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/key/MessageFormatConfig.kt
@@ -1,7 +1,5 @@
 package dev.m1sk9.lunaticChat.paper.config.key
 
 data class MessageFormatConfig(
-    val directMessageFormat: String = "&7[&e{sender} &7>>] &f{message}",
-    val crossServerMessageFormat: String = "&7[&e{sender} &7(&b{server}&7)] &f{message}",
-    val crossServerDirectMessageFormat: String = "&7[&e{sender}@&7(&b{server}&7) >>] &f{message}",
+    val directMessageFormat: String = "§7[§e{sender} §7>> §e{recipient}§7] §f{message}",
 )
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/key/VelocityConfig.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/key/VelocityConfig.kt
deleted file mode 100644
index 3932b41..0000000
--- a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/config/key/VelocityConfig.kt
+++ /dev/null
@@ -1,8 +0,0 @@
-package dev.m1sk9.lunaticChat.paper.config.key
-
-data class VelocityConfig(
-    val enabled: Boolean,
-    val serverName: String,
-    val crossServerChatEnabled: Boolean,
-    val crossServerDirectMessagesEnabled: Boolean,
-)
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/listener/PlayerPresenceListener.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/listener/PlayerPresenceListener.kt
new file mode 100644
index 0000000..ad53929
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/listener/PlayerPresenceListener.kt
@@ -0,0 +1,16 @@
+package dev.m1sk9.lunaticChat.paper.listener
+
+import dev.m1sk9.lunaticChat.paper.LunaticChat
+import org.bukkit.event.EventHandler
+import org.bukkit.event.Listener
+import org.bukkit.event.player.PlayerQuitEvent
+
+class PlayerPresenceListener : Listener {
+    @EventHandler(ignoreCancelled = true)
+    fun onQuit(
+        lunaticChat: LunaticChat,
+        event: PlayerQuitEvent,
+    ) {
+        lunaticChat.directMessageHandler.clearPlayer(event.player)
+    }
+}
diff --git a/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/listener/SpyPermissionManager.kt b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/listener/SpyPermissionManager.kt
new file mode 100644
index 0000000..26de098
--- /dev/null
+++ b/platform-paper/src/main/kotlin/dev/m1sk9/lunaticChat/paper/listener/SpyPermissionManager.kt
@@ -0,0 +1,54 @@
+package dev.m1sk9.lunaticChat.paper.common
+
+import dev.m1sk9.lunaticChat.engine.permission.LunaticChatPermissionNode
+import org.bukkit.Bukkit
+import org.bukkit.entity.Player
+import org.bukkit.event.EventHandler
+import org.bukkit.event.Listener
+import org.bukkit.event.player.PlayerJoinEvent
+import org.bukkit.event.player.PlayerQuitEvent
+import java.util.UUID
+import java.util.concurrent.ConcurrentHashMap
+
+/**
+ * Manages spy permission cache for direct messages.
+ * Caches player references to avoid repeated lookups.
+ */
+object SpyPermissionManager : Listener {
+    private val directMessageSpyPlayers: ConcurrentHashMap<UUID, Player> = ConcurrentHashMap()
+
+    /**
+     * Gets all players with spy permission as a map of UUID to Player.
+     */
+    fun getDirectMessageSpyPlayers(): Map<UUID, Player> = directMessageSpyPlayers.toMap()
+
+    /**
+     * Gets all player UUIDs with spy permission.
+     */
+    fun getDirectMessageSpyPlayerIds(): Set<UUID> = directMessageSpyPlayers.keys
+
+    /**
+     * Updates the cache of players with direct message spy permission.
+     * Call this on player join/quit/permission change events.
+     */
+    fun updateSpyCache() {
+        directMessageSpyPlayers.clear()
+        Bukkit
+            .getOnlinePlayers()
+            .filter {
+                it.hasAllPermission {
+                    +LunaticChatPermissionNode.Spy
+                }
+            }.associateByTo(directMessageSpyPlayers) { it.uniqueId }
+    }
+
+    @EventHandler(ignoreCancelled = true)
+    fun onPlayerJoin(e: PlayerJoinEvent) {
+        updateSpyCache()
+    }
+
+    @EventHandler(ignoreCancelled = true)
+    fun onPlayerQuit(event: PlayerQuitEvent) {
+        directMessageSpyPlayers.remove(event.player.uniqueId)
+    }
+}
diff --git a/platform-paper/src/main/resources/config.yml b/platform-paper/src/main/resources/config.yml
index e091954..dd5db15 100644
--- a/platform-paper/src/main/resources/config.yml
+++ b/platform-paper/src/main/resources/config.yml
@@ -38,23 +38,5 @@ features:
 
 messageFormat:
   # Configure the format for direct messages sent via /tell or /msg
-  directMessageFormat: "&7[&e{sender} &7>>] &f{message}"
-  # Configure the format for cross-server messages
-  crossServerMessageFormat: "&7[&e{sender} &7(&b{server}&7)] &f{message}"
-  # Configure the format for cross-server direct messages
-  crossServerDirectMessageFormat: "&7[&e{sender}@&7(&b{server}&7) >>] &f{message}"
+  directMessageFormat: "§7[§e{sender} §7>> §e{recipient}§7] §f{message}"
 
-# ----------------------------------------------
-# -----------   Velocity Settings   ------------
-# ----------------------------------------------
-
-velocity:
-  # If enabled, Activate LunaticChat's Velocity integration features.
-  # This setting overrides all other features; if set to `false`, features such as cross-server chat will become unavailable.
-  enabled: false
-  # The name of the server as recognized by the Velocity proxy.
-  serverName: "s1"
-  # If enabled, allows cross-server chat functionality.
-  crossServerChatEnabled: false
-  # If enabled, allows cross-server direct messaging functionality.
-  crossServerDirectMessagesEnabled: false
diff --git a/platform-paper/src/main/resources/paper-plugin.yml b/platform-paper/src/main/resources/paper-plugin.yml
index b3aeacc..7ad79d6 100644
--- a/platform-paper/src/main/resources/paper-plugin.yml
+++ b/platform-paper/src/main/resources/paper-plugin.yml
@@ -7,3 +7,12 @@ load: STARTUP
 authors: [ m1sk9 ]
 description: Next-generation channel chat plugin for Paper/Velocity
 website: lc.m1sk9.dev
+
+permissions:
+  lunaticchat.command.tell:
+    default: true
+  lunaticchat.command.reply:
+    default: true
+
+  lunaticchat.spy:
+    default: op
diff --git a/platform-velocity/build.gradle.kts b/platform-velocity/build.gradle.kts
index e259a94..6fa7401 100644
--- a/platform-velocity/build.gradle.kts
+++ b/platform-velocity/build.gradle.kts
@@ -11,12 +11,7 @@ repositories {
 }
 
 dependencies {
-    // engine モジュールを使用
     api(project(":engine"))
-
-    // Velocity API (将来追加予定)
-    // compileOnly("com.velocitypowered:velocity-api:3.4.0")
-    // kapt("com.velocitypowered:velocity-api:3.4.0")
 }
 
 tasks {