ScriptableObject Architecture

Generate SO patterns for data, events, and runtime collections.

Before You Start

1. Read docs/ProjectConfig.yaml for:

• architecture_pattern — "so-first" (default, this skill is primary) or "di-first" (SOs still hold data, but events become Commands — see uw-dependency-injection).
• mcp.unity_mcp — if true, call refresh_unity after creating files.

1. Read docs/TDD_Template.md for data architecture decisions.
2. Read docs/NAMING_CONVENTIONS.md for SO file naming (PascalCase: SwordData.asset).
3. Ensure the feature has an .asmdef — create with uw-unity-feature-scaffold if needed.

Three Patterns

1. Data Container

Store game-tunable values in a ScriptableObject. Designers edit them in the Inspector without touching code.

using UnityEngine;

[CreateAssetMenu(fileName = "New WeaponData", menuName = "Game/Data/Weapon Data")]
public class WeaponData : ScriptableObject
{
    [Header("Combat")]
    [SerializeField] private float _damage = 10f;
    [SerializeField] private float _fireRate = 0.5f;
    [SerializeField] private float _range = 15f;

    [Header("Ammo")]
    [SerializeField] private int _maxAmmo = 30;
    [SerializeField] private float _reloadTime = 1.5f;

    [Header("Feel")]
    [SerializeField] private ShakeProfile _hitShakeProfile;
    [SerializeField] private AudioClip _fireSound;
    [SerializeField] private GameObject _muzzleFlashPrefab;

    // Read-only properties — game code reads, designers tune in Inspector
    public float Damage => _damage;
    public float FireRate => _fireRate;
    public float Range => _range;
    public int MaxAmmo => _maxAmmo;
    public float ReloadTime => _reloadTime;
    public ShakeProfile HitShakeProfile => _hitShakeProfile;
    public AudioClip FireSound => _fireSound;
    public GameObject MuzzleFlashPrefab => _muzzleFlashPrefab;
}

2. Event Channel

Decouple systems by broadcasting events through a ScriptableObject asset. Any system can subscribe without knowing who raises the event.

Parameterless event:

using System;
using UnityEngine;

[CreateAssetMenu(fileName = "New GameEvent", menuName = "Game/Events/Game Event")]
public class GameEvent : ScriptableObject
{
    private event Action _onRaise;

    public void Raise() => _onRaise?.Invoke();
    public void Subscribe(Action listener) => _onRaise += listener;
    public void Unsubscribe(Action listener) => _onRaise -= listener;
}

Typed event channels for events that carry data:

using System;
using UnityEngine;

[CreateAssetMenu(fileName = "New IntEvent", menuName = "Game/Events/Int Event")]
public class IntEvent : ScriptableObject
{
    private event Action<int> _onRaise;

    public void Raise(int value) => _onRaise?.Invoke(value);
    public void Subscribe(Action<int> listener) => _onRaise += listener;
    public void Unsubscribe(Action<int> listener) => _onRaise -= listener;
}

[CreateAssetMenu(fileName = "New FloatEvent", menuName = "Game/Events/Float Event")]
public class FloatEvent : ScriptableObject
{
    private event Action<float> _onRaise;

    public void Raise(float value) => _onRaise?.Invoke(value);
    public void Subscribe(Action<float> listener) => _onRaise += listener;
    public void Unsubscribe(Action<float> listener) => _onRaise -= listener;
}

Usage:

// Publisher (doesn't know who listens)
[SerializeField] private IntEvent _onScoreChanged;
_onScoreChanged.Raise(newScore);

// Subscriber (doesn't know who publishes)
[SerializeField] private IntEvent _onScoreChanged;
private void OnEnable() => _onScoreChanged.Subscribe(UpdateScoreUI);
private void OnDisable() => _onScoreChanged.Unsubscribe(UpdateScoreUI);

3. Runtime Set

Track live objects (active enemies, collectibles, spawned projectiles) without FindObjectsOfType. Objects register themselves on spawn and unregister on destroy.

using System.Collections.Generic;
using UnityEngine;

[CreateAssetMenu(fileName = "New RuntimeSet", menuName = "Game/Sets/Runtime Set")]
public class RuntimeSet<T> : ScriptableObject
{
    private readonly List<T> _items = new();
    public IReadOnlyList<T> Items => _items;
    public int Count => _items.Count;

    public void Add(T item)
    {
        if (!_items.Contains(item))
            _items.Add(item);
    }

    public void Remove(T item) => _items.Remove(item);

    private void OnDisable() => _items.Clear(); // Prevent stale refs across play sessions
}

Concrete sets (needed because Unity can't serialize open generics):

[CreateAssetMenu(fileName = "New EnemySet", menuName = "Game/Sets/Enemy Set")]
public class EnemyRuntimeSet : RuntimeSet<EnemyController> { }

Self-registering pattern:

public class EnemyController : MonoBehaviour
{
    [SerializeField] private EnemyRuntimeSet _activeEnemies;

    private void OnEnable() => _activeEnemies.Add(this);
    private void OnDisable() => _activeEnemies.Remove(this);
}

Naming Convention

After Setup

• Add game feel: Use uw-game-feel-integrator — SO data containers pair well with feel parameters (ShakeProfile, tween durations stored in the SO).
• Write tests: Use uw-unity-test-runner — test event channels (subscribe, raise, verify callback) and runtime sets (add, remove, clear) in EditMode tests.
• Custom inspectors: Use uw-unity-editor-tools for designer-friendly SO inspectors (preview panels, validation).
• Graduate to DI: If the project outgrows SO events, use uw-dependency-injection — SO data stays, events become Commands.

When to Consider DI Instead

If your project needs any of these, check ProjectConfig.yaml -> architecture_pattern and consider switching to di-first with the uw-dependency-injection skill:

• Cross-feature orchestration beyond simple events (Command pattern)
• Constructor injection for testability with mock services
• Scoped lifetimes (per-scene, per-level services)
• Factory patterns with automatic dependency resolution

DI + SO coexist: In DI-first projects, ScriptableObjects still hold data — they're injected into the container as instances. Events are replaced by Commands.

Rules

• Always use [CreateAssetMenu] on every ScriptableObject.
• Always use [SerializeField] private + public read-only properties for data fields.
• Use Action/Action<T> delegates for events, not UnityEvents (better performance, no boxing).
• Runtime sets must clear on OnDisable() to prevent stale references across play sessions.
• Always unsubscribe from events in OnDisable — matching every Subscribe with an Unsubscribe.
• All SO code must live inside an .asmdef.
• SO file names use PascalCase (per NAMING_CONVENTIONS.md): SwordData.asset.
• If ProjectConfig.yaml -> mcp.unity_mcp is true, call refresh_unity after creating files.