Serialization Review

name: serialization-review description: Review JSON serialization for scenes, prefabs, and components. Use when: (1) implementing serializable components, (2) debugging save/load failures, (3) adding asset types, (4) reviewing serialization code, (5) investigating data corruption, (6) implementing JsonConverters.

Serialization Review

Overview

This skill audits JSON serialization implementation to ensure scenes, prefabs, and components serialize/deserialize correctly, maintain version compatibility, handle resource references properly, and follow established serialization patterns.

Table of Contents

• Overview
• When to Use
• Serialization Architecture
• Serialization Patterns
• Review Checklist
• Review Output Format
• Examples

When to Use

Invoke this skill when:

• Adding new serializable components
• Debugging scene save/load issues
• Implementing new asset types (prefabs, animations, tilemaps)
• Refactoring component data structures
• Versioning serialization format
• Questions about custom JsonConverter implementation
• Investigating data corruption or missing data after load

Serialization Architecture

SceneSerializer

Location: Engine/Scene/Serializer/SceneSerializer.cs

Responsibilities:

• Serialize/deserialize entire scene to/from JSON
• Handle entity hierarchy and component serialization
• Manage custom converters and serialization options

Key Methods: Serialize(Scene, path), Deserialize(path)

Custom Converters

Location: Engine/Scene/Serializer/

Existing Converters:

• Vector2Converter, Vector3Converter, Vector4Converter
• TileMapComponentConverter
• Component-specific converters for complex types

Serialization Patterns

1. JsonIgnore for Runtime Data

Pattern: Use [JsonIgnore] for runtime-only data

public class RigidBody2DComponent
{
    // Serialized properties
    public BodyType Type { get; set; } = BodyType.Dynamic;
    public float Mass { get; set; } = 1.0f;
    public bool FixedRotation { get; set; } = false;

    // Runtime-only (not serialized)
    [JsonIgnore]
    public Body? RuntimeBody { get; set; }

    // Runtime-only (not serialized)
    [JsonIgnore]
    public World? RuntimeWorld { get; set; }
}

Why?: Runtime objects (physics bodies, loaded meshes, textures) should not be serialized - they're recreated at runtime.

2. Resource Path Serialization

Pattern: Store paths, not loaded resources

public class SpriteRendererComponent
{
    // Serialize path, not loaded texture
    public string TexturePath { get; set; } = string.Empty;

    // Color is serialized
    public Vector4 Color { get; set; } = Vector4.One;

    // Runtime-only loaded texture (not serialized)
    [JsonIgnore]
    public Texture? LoadedTexture { get; set; }
}

// At runtime, load texture from path with error handling
if (!string.IsNullOrEmpty(sprite.TexturePath))
{
    try
    {
        sprite.LoadedTexture = textureFactory.LoadTexture(sprite.TexturePath);
    }
    catch (FileNotFoundException)
    {
        logger.Warn($"Missing texture: {sprite.TexturePath}");
        sprite.LoadedTexture = textureFactory.GetDefaultTexture();
    }
}

3. Custom Converter for Complex Types

When Needed:

• Custom serialization format or optimized JSON structure
• Backward compatibility with breaking changes
• Complex type handling (vectors, GUIDs, nested structures)

Review Checklist

When reviewing serialization implementation, verify:

1. Runtime Data Exclusion

• All runtime objects marked with [JsonIgnore]
• Physics bodies, loaded textures/meshes not serialized
• Cached/computed values excluded

2. Resource References

• Paths stored instead of loaded resources
• Valid path format (relative to project root)
• Missing path handling at load time

3. Circular References

• Entity parent/child relationships handled correctly
• Component cross-references resolved properly
• No infinite loops in serialization

4. Version Compatibility

• New fields have default values
• Removed fields handled gracefully
• Custom converters for breaking changes

5. Custom Converters

• Necessary (complex types, optimization, compatibility)
• Read/Write methods symmetric
• Registered in serialization options

Review Output Format

Report findings as:

Issue: [Serialization problem description] Component: [Component class name] Location: [File path and line number] Problem: [What will break or serialize incorrectly] Fix: [Code change with before/after] Priority: [Critical/High/Medium/Low]

Example Report

Issue: Runtime physics body being serialized Component: RigidBody2DComponent Location: Engine/Scene/Components/RigidBody2DComponent.cs:45 Problem: RuntimeBody property will serialize the entire Box2D body object, causing massive JSON files and deserialization failures (Box2D objects aren't JSON-serializable) Fix:

// Before
public Body? RuntimeBody { get; set; }

// After
[JsonIgnore]
public Body? RuntimeBody { get; set; }

Priority: Critical

Examples

For detailed guidance and comprehensive examples:

Custom Converters

Complete JsonConverter implementations with:

• Full AnimationComponent converter with error handling
• Vector3, GUID, and common type converters
• Registration and testing patterns
• Best practices for symmetric Read/Write methods

Common Issues

Anti-pattern catalog with before/after fixes:

• Runtime objects not marked [JsonIgnore]
• Loaded resources instead of paths
• Missing default values for new fields
• Circular references in entity hierarchy
• Platform-specific path separators
• Asymmetric converter implementations