# Creating Your First Command

Registering custom commands in Pumpkin using Kotlin is concise, idiomatic, and strongly typed.

---

## 1. Quick Example

Here is a complete Kotlin plugin (`Plugin.kt`) that registers a `/hello` command with permission checks and sends a response back to the player.

```kotlin [src/wasmWasiMain/kotlin/plugin/Plugin.kt]
package plugin

import pumpkin.plugin.context.Context
import pumpkin.plugin.command.Command
import pumpkin.plugin.permission.Permission
import pumpkin.plugin.permission.PermissionDefault

class MyPlugin {
    fun onLoad(ctx: Context) {
        // 1. Register permission node
        ctx.registerPermission(
            Permission(
                node = "my_kotlin_plugin:hello",
                description = "Allows executing the /hello command",
                default = PermissionDefault.ALLOW,
                children = emptyList()
            )
        )

        // 2. Build and register command tree
        val cmd = Command(
            names = listOf("hello", "hi"),
            description = "Greets the player"
        )
        ctx.registerCommand(cmd, "my_kotlin_plugin:hello")
    }

    fun handleCommand(sender: pumpkin.plugin.command.CommandSender): Int {
        sender.sendMessage("Hello from Kotlin Plugin!")
        return 1
    }
}
```

---

## 2. In-Game Preview

Once registered, your command automatically gains client-side autocompletion, syntax validation, and color highlighting in Minecraft:

<img src="/assets/first_command_preview.png" alt="In-Game Command Autocompletion Preview" width="500"/>

---

## 3. How It Works

::: details Step-by-Step Breakdown

### Step 1: Define the Permission Node
Construct a `Permission` object and pass it to `ctx.registerPermission`:
```kotlin
ctx.registerPermission(
    Permission(
        node = "my_kotlin_plugin:hello",
        description = "Allows executing the /hello command",
        default = PermissionDefault.ALLOW,
        children = emptyList()
    )
)
```

### Step 2: Build the Command Tree
Instantiate `Command` with primary names and aliases:
```kotlin
val cmd = Command(
    names = listOf("hello", "hi"),
    description = "Greets the player"
)
```

### Step 3: Register with Context
Register the command with `ctx.registerCommand` and handle calls inside `handleCommand`:
```kotlin
ctx.registerCommand(cmd, "my_kotlin_plugin:hello")
```

:::

---

## Next Steps

- Follow the [Kotlin Quick Start Guide](./quick-start) to configure your `Makefile` and Kotlin/Wasm build tools.