/limboai

name: limboai
description: Use when using the LimboAI addon — behavior trees and hierarchical state machines (C++ GDExtension) with a visual editor, BTTask subclassing, and a blackboard

LimboAI

> **Related skills:** **ai-navigation** for movement the tasks drive, **state-machine** for core-engine FSM (when you don't need an addon), **godot-brainstorming** for choosing an AI approach.

> **Addon:** LimboAI · version `v1.8.0` · Godot 4.6+ (GDExtension) · MIT · source: https://github.com/limbonaut/limboai · written in C++ (GDExtension; engine-module build also available). GDExtension exposes GDScript; **C# requires the module build** (not GDExtension in v1.8.0), and the v1.8.0 module build targets **Godot 4.7**.

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1. When to use LimboAI

| Approach | Best for | |---|---| | Core-engine FSM (`state-machine` skill) | Simple agents, < 5 states, no addon | | **Beehave** (GDScript addon) | Lightweight BT, GDScript-only projects | | **LimboAI** | BT **and** HSM together, visual editor, C++ performance, C# support (module build) |

Choose LimboAI when you need a behavior tree with a polished visual debugger, want to combine it with a hierarchical state machine (`BTState` bridges them), or need C++ task execution speed. Note: LimboAI requires **Godot 4.6+** and is not usable on 4.3–4.5. For a simpler GDScript-only behavior tree, Beehave is a lighter alternative. For plain state machines without a BT, use the built-in `state-machine` skill instead.

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2. Install & setup

GDExtension (recommended — no custom engine)

1. **Godot AssetLib** → search "LimboAI" → Download → Reload project. Or download from GitHub Releases and place `addons/limboai/` in `res://addons/limboai/`. 2. Enable the plugin: **Project → Project Settings → Plugins** → tick LimboAI. 3. The `.gdextension` manifest ships at `res://addons/limboai/bin/`:

[configuration]
entry_symbol = "limboai_init"
compatibility_minimum = "4.2"

[libraries]
windows.debug.x86_64   = "res://addons/limboai/bin/liblimboai.windows.editor.x86_64.dll"
windows.release.x86_64 = "res://addons/limboai/bin/liblimboai.windows.template_release.x86_64.dll"
linux.debug.x86_64     = "res://addons/limboai/bin/liblimboai.linux.editor.x86_64.so"
linux.release.x86_64   = "res://addons/limboai/bin/liblimboai.linux.template_release.x86_64.so"
macos.debug            = "res://addons/limboai/bin/liblimboai.macos.editor.framework"
macos.release          = "res://addons/limboai/bin/liblimboai.macos.template_release.framework"
# ... (additional platform entries for linux arm64/rv64, android, iOS, web)

**GDExtension limitations:** no in-editor documentation tooltips; `BBParam` property editor not available in the inspector.

Module version (C# or full editor integration)

Download pre-compiled editor + export templates from [GitHub Releases](https://github.com/limbonaut/limboai/releases). Requires the custom engine for export. v1.8.0 module builds are based on **Godot 4.7** (GDExtension supports 4.6+). The module build ships a NuGet package for C#:

# Add local NuGet source to your project:
# dotnet nuget add source path/to/nupkgs --name LimboNugetSource

---

3. Behavior trees

A `BehaviorTree` resource holds the task tree. `BTPlayer` runs it each physics frame (or idle/manual). Add `BTPlayer` as a child of the agent node and assign a `BehaviorTree` resource.

GDScript

# EnemyAI.gd — assign behavior_tree in the Inspector or here
extends CharacterBody2D

@onready var bt_player: BTPlayer = $BTPlayer

func _ready() -> void:
    # BTPlayer starts executing automatically (active = true by default).
    # Connect to updated(status) to react when the tree finishes.
    bt_player.updated.connect(_on_bt_updated)

func _on_bt_updated(status: int) -> void:
    if status == BT.SUCCESS:
        bt_player.restart()  # loop the tree

C#

// EnemyAI.cs
using Godot;

public partial class EnemyAI : CharacterBody2D
{
    [Export] private BTPlayer _btPlayer;

    public override void _Ready()
    {
        _btPlayer.Updated += OnBtUpdated;
    }

    private void OnBtUpdated(int status)
    {
        if (status == (int)BT.Status.Success)
            _btPlayer.Restart();
    }
}

`BTPlayer.UpdateMode` controls when the tree ticks: `IDLE` (every `_process`), `PHYSICS` (every `_physics_process`, default), or `MANUAL` (call `bt_player.update(delta)` yourself).

---

4. Custom tasks

Subclass `BTAction` (multi-tick work) or `BTCondition` (immediate check). Annotate with `@tool` so `_generate_name()` and `_get_configuration_warnings()` work in the editor. Place scripts under `res://ai/tasks/`; subfolders become task categories.

GDScript

@tool
extends BTAction
## Moves the agent toward a blackboard position each tick.

@export var target_pos_var: StringName = &"target_pos"
@export var speed: float = 200.0

func _generate_name() -> String:
    return "MoveToward %s" % LimboUtility.decorate_var(target_pos_var)

func _setup() -> void:
    pass  # one-time init; agent and blackboard are available here

func _enter() -> void:
    pass  # called when task transitions from non-RUNNING → RUNNING

func _tick(delta: float) -> Status:
    var target: Vector2 = blackboard.get_var(target_pos_var, Vector2.ZERO)
    if agent.global_position.distance_to(target) < 5.0:
        return SUCCESS
    agent.velocity = agent.global_position.direction_to(target) * speed
    agent.move_and_slide()
    return RUNNING

func _exit() -> void:
    pass  # cleanup after SUCCESS or FAILURE

@tool
extends BTCondition
## Returns SUCCESS if the agent is within range of a target node.

@export var target_var: StringName = &"target"
@export var distance_max: float = 150.0

var _max_sq: float

func _setup() -> void:
    _max_sq = distance_max * distance_max

func _tick(_delta: float) -> Status:
    var target: Node2D = blackboard.get_var(target_var, null)
    if not is_instance_valid(target):
        return