Nlelouche Unity3d Antigravityskills AI Behavior Trees

name: ai-behavior-trees description: "Implements modular Behavior Trees for AI decision making with composite, decorator, and action nodes." version: 2.0.0 tags: ["gameplay", "AI", "behavior-tree", "NPCs", "enemies"] argument-hint: "root='Selector' children='PatrolSequence,ChaseSequence'" disable-model-invocation: false user-invocable: true allowed-tools: - run_command - list_dir - write_to_file requirements: unity_version: ">=6.0" render_pipeline: "Any" dependencies: [] context_discovery: check_unity_version: true check_render_pipeline: false scan_manifest_for: [] performance_budget: gc_alloc_per_frame: "0 bytes target in hot paths" max_update_cost: "O(n) - profiler-guided" tdd_first: true # ⚠️ Updated by audit v2.0.1 - needs manual test implementation

AI Behavior Trees

Overview

Modular Behavior Tree system for AI decision making. Supports composite nodes (Selector, Sequence), decorators (Inverter, Repeater), and custom action/condition nodes.

When to Use

• Use when implementing complex enemy AI
• Use when NPCs need decision-making logic
• Use when AI needs to prioritize tasks
• Use when state machines become too complex
• Use when AI behavior needs to be modular/reusable

Architecture

                    ┌─────────────────┐
                    │   Root Selector │
                    └────────┬────────┘
            ┌────────────────┼────────────────┐
            ↓                                 ↓
    ┌───────────────┐               ┌───────────────┐
    │ Chase Sequence│               │ Patrol Sequence│
    └───────┬───────┘               └───────┬───────┘
        ┌───┴───┐                       ┌───┴───┐
        ↓       ↓                       ↓       ↓
    ┌──────┐ ┌──────┐              ┌──────┐ ┌──────┐
    │CanSee│ │MoveTo│              │HasPath│ │Follow │
    │Player│ │Player│              │      │ │Path   │
    └──────┘ └──────┘              └──────┘ └──────┘

Node Types

Node Return Values

• Success: Node completed successfully
• Failure: Node failed
• Running: Node still processing

Best Practices

• ✅ Keep nodes small and focused
• ✅ Use Blackboard for shared data
• ✅ Cache frequently used references
• ✅ Use decorators for flow control
• ❌ NEVER put heavy calculations in Tick
• ❌ NEVER use deep nested trees (max 5-6 levels)

Few-Shot Examples

Example 1: Enemy AI

User: "Enemy patrols, chases player when seen."

Agent:

Root Selector
├── Chase Sequence
│   ├── Condition: CanSeePlayer
│   └── Action: MoveToPlayer
└── Patrol Sequence
    ├── Condition: HasPatrolPath
    └── Action: FollowPatrolPath

Example 2: Attack Priority

User: "Attack melee if close, else ranged."

Agent:

Root Selector
├── Melee Sequence
│   ├── Condition: InMeleeRange
│   └── Action: MeleeAttack
└── Ranged Sequence
    ├── Condition: HasAmmo
    └── Action: RangedAttack

TDD Contract

⚠️ Legacy Skill — Refactor Pending Este skill NO tiene tests automatizados aún. El siguiente boilerplate es un punto de partida.

// Escribe estos tests ANTES de implementar:

// Test 1: should [expected behavior] when [condition]
[Test]
public void AiBehaviorTrees_Should{ExpectedBehavior}_When{Condition}()
{{
    // Arrange
    // TODO: Setup test fixtures
    
    // Act
    // TODO: Execute system under test
    
    // Assert
    Assert.Fail("Not implemented — write test first");
}}

// Test 2: should handle [edge case]
[Test]
public void AiBehaviorTrees_ShouldHandle{EdgeCase}()
{{
    // Arrange
    // TODO: Setup edge case scenario
    
    // Act
    // TODO: Execute
    
    // Assert
    Assert.Fail("Not implemented");
}}

// Test 3: should throw when [invalid input]
[Test]
public void AiBehaviorTrees_ShouldThrow_When{InvalidInput}()
{{
    // Arrange
    var invalidInput = default;
    
    // Act & Assert
    Assert.Throws<Exception>(() => {{ /* execute */ }});
}}

Pasos para completar el TDD:

1. Descomenta los tests above
2. Implementa la funcionalidad mínima para que compile
3. Ejecuta los tests — deben fallar (RED)
4. Implementa la funcionalidad real
5. Verifica que los tests pasen (GREEN)
6. Refactorea manteniendo los tests verdes

Nota: Este skill fue marcado como tdd_first: false durante la auditoría v2.0.1. La sección TDD fue agregada automáticamente pero requiere customización manual para reflejar el comportamiento real del skill.

Related Skills

• @state-machine-architect - Simpler state-based AI
• @navmesh-pathfinding - Movement for AI
• @damage-health-framework - Combat integration

Template Files

Available in templates/ folder.

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