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Color Book — Architecture Guide

A toddler-targeted (ages 2–6) coloring book game built on the same Strict Modular Monolith pattern as the Bus Game. Powered by VContainer for DI, UniTask for async, Addressables for shipped content, and a hybrid Sprites + Canvas render strategy.

This document is the canonical reference for the Color Book game's structure. The Bus Game's Darkmatter Architecture Guide is the parent contract; this doc only adds game-specific structure.

1. Game Flow

App launch
  └─ Boot scene (RootLifetimeScope)
      └─ MainMenu scene
          ├─ Press "Play"   → ColorBook scene
          │     ├─ Drawing catalog (grid of templates)
          │     ├─ Select drawing
          │     ├─ Shape Builder panel  (drag pieces → snap to slots)
          │     ├─ ↓ on assembly complete
          │     ├─ Color panel          (tap color → tap region)
          │     ├─ Undo / Redo any time
          │     ├─ "Capture" → save to Gallery with paper background
          │     └─ "Next"   → auto-save + load next drawing
          └─ Press "Art Book" → ArtBook scene (gallery viewer)
                ├─ Grid of saved artworks
                ├─ View / share / delete
                └─ Save to device camera roll

2. Philosophy

Identical to Bus Game:

Vertical slices — code grouped by Feature, not by type.
Strict layering — dependencies flow downward only.
Composition over inheritance — wired by DI.
Code vs Content — Code/ for logic, Contents/ for assets.

Game-specific additions:

Toddler-first UX — large hitboxes, forgiving snap radii, no fail states, no timers.
Stateless replay — every action (paint, snap) is an ICommand so undo/redo and auto-save are trivial.
Capture-as-truth — the gallery is a folder of PNGs on disk, not a serialized scene graph. What the child sees is what gets saved.

3. Dependency Graph

App   ──────────┐
                ▼
Features ──► Core ◄── Services
                ▲
                └── Libs

Forbidden actions

Services cannot reference Features.
Features cannot reference Service implementations — only Core contracts via DI.
Features cannot reference other Features — use IEventBus signals or Core contracts.
Core may not contain logic. Interfaces, enums, DTOs, signal records only.
Core may reference UniTask for async contract signatures. Nothing else.

4. Folder Structure

Assets/Darkmatter/Code/
├── App/
│   ├── Boot/
│   │   └── AppBoot.cs
│   └── LifetimeScopes/
│       ├── RootLifetimeScope.cs
│       ├── MainMenuLifetimeScope.cs
│       ├── ColorBookLifetimeScope.cs
│       └── ArtBookLifetimeScope.cs
│
├── Core/
│   ├── Drawing/
│   │   ├── IDrawingTemplate.cs
│   │   ├── IDrawingTemplateCatalog.cs
│   │   ├── ShapePieceDTO.cs
│   │   └── ColorRegionDTO.cs
│   ├── Coloring/
│   │   ├── IColorPalette.cs
│   │   └── PaintCommandDTO.cs
│   ├── Paper/                          (shared art rig — RT-as-paper)
│   │   ├── IPaperRig.cs
│   │   └── IArtInputBridge.cs
│   ├── History/
│   │   ├── ICommand.cs
│   │   └── IUndoStack.cs
│   ├── Gallery/
│   │   ├── IGalleryService.cs
│   │   └── SavedArtworkDTO.cs
│   ├── Capture/
│   │   └── ICaptureService.cs
│   ├── Progression/
│   │   └── IProgressionService.cs
│   └── Signals/
│       ├── DrawingSelectedSignal.cs
│       ├── ShapeAssembledSignal.cs
│       ├── ColorAppliedSignal.cs
│       ├── ArtworkCapturedSignal.cs
│       └── ArtworkSavedSignal.cs
│
├── Libs/
│   ├── CommandStack/          (generic bounded undo/redo)
│   ├── EventBus/              (shared with bus game if monorepo)
│   └── FSM/                   (optional, for ColorBookFlow)
│
├── Services/
│   ├── Audio/
│   ├── Inputs/
│   ├── Assets/                (Addressables wrapper — IAssetProviderService)
│   ├── Scenes/
│   ├── Persistence/           (JSON / PlayerPrefs for non-image state)
│   ├── Gallery/               (file IO — PNG + sidecar JSON)
│   └── Capture/               (RenderTexture → PNG, paper bg compositing)
│
└── Features/
    ├── MainMenu/
    ├── DrawingCatalog/
    ├── Paper/                (RT paper rig — ArtCamera + RenderTexture + input bridge)
    ├── ShapeBuilder/
    ├── Coloring/
    ├── History/
    ├── Capture/
    ├── Progression/
    ├── ColorBookFlow/         (orchestrates panel swap, next, capture chain)
    └── ArtBook/

Per-feature folder layout

Every feature follows the same internal shape:

Features/[Name]/
├── Installers/        IInstaller — VContainer registrations
├── Systems/           Controllers, services (pure C#)
├── Repository/        In-memory state holders
├── Commands/          ICommand implementations (if feature mutates undoable state)
├── UI/
│   ├── *Presenter.cs  Pure C#, listens to model, drives view
│   └── *View.cs       MonoBehaviour, setters only
├── Views/             World-space MonoBehaviours (sprites, colliders)
└── Docs/              Feature-specific markdown

Asset folder parallel

Assets/Darkmatter/Contents/
├── Drawings/
│   ├── Animals/<id>/
│   │   ├── Template.asset           (DrawingTemplateSO)
│   │   ├── Pieces/*.png
│   │   ├── Regions/*.png
│   │   └── PaperBackground.png
│   └── Vehicles/...
├── Palettes/*.asset                 (ColorPaletteSO)
├── Audio/
│   ├── UI/                          (tap, swipe, button)
│   └── Coloring/                    (fill, complete, sparkle)
└── UI/                              (HUD prefabs, fonts, icons)

5. Namespaces

Darkmatter.[Layer].[Module]

Darkmatter.Features.Coloring
Darkmatter.Features.ShapeBuilder
Darkmatter.Services.Gallery
Darkmatter.Services.Capture
Darkmatter.Core.Drawing
Darkmatter.Lib.CommandStack

Each maps 1:1 to a .asmdef.

6. Scenes & Lifetime Scopes

Scene	Scope	Contents
`Boot.unity`	`RootLifetimeScope`	All Services + `IEventBus`. Persists forever.
`MainMenu.unity`	`MainMenuLifetimeScope`	Menu presenter, art book entry.
`ColorBook.unity`	`ColorBookLifetimeScope`	DrawingCatalog, ShapeBuilder, Coloring, History, Capture, ColorBookFlow.
`ArtBook.unity`	`ArtBookLifetimeScope`	Gallery presenter, viewer, share.

Scopes nest: Root → (MainMenu | ColorBook | ArtBook). Services resolved from the root parent. Scene scopes only register their own features.

Boot chain

AppBoot runs once, in order:

Initialize IAssetProviderService (Addressables init).
Preload essential bundles (palettes, UI sounds).
Load IProgressionService from disk.
Load MainMenu scene.

Failures show a child-friendly retry screen; never crash.

7. Rendering Strategy

RT-as-paper. ArtCamera renders the drawing world to an offscreen RenderTexture. A Canvas RawImage displays that RT. HUD lives on the same Canvas, above the RawImage. The RT is the paper — same fixed coordinate system on every device.

┌──────────────────────────────────────────────────────┐
│ UICanvas (Screen-Space - Camera, UICamera)          │
│                                                      │
│   ┌────────────────────────────────────┐             │
│   │ RawImage (AspectRatioFitter 1:1)   │   [HUD]    │
│   │  └─ texture = PaperRig.Surface     │   palette  │
│   │                                    │   undo etc │
│   │  ArtCamera renders → here          │             │
│   └────────────────────────────────────┘             │
│                                                      │
└──────────────────────────────────────────────────────┘
                       ▲
                       │  rendered offscreen
                       │
   ArtCamera (orthographicSize fixed, aspect = 1f)
       culling mask: Artwork, PaperBackground, Effects
       target texture: PaperRig.Surface (2048×2048 ARGB32)

Cameras

Camera	Type	Culling Mask	Render Target	Purpose
`ArtCamera`	Orthographic, fixed ortho size, aspect = 1	`Artwork`, `PaperBackground`, `Effects`	`PaperRig.Surface` (offscreen RT)	Renders the drawing world. Never sees the screen.
`UICamera`	Camera (Screen-Space – Camera)	`UI`	Screen	Displays the paper RawImage + HUD.

Layers

Layer	Used by
`Artwork`	Drawing region sprites, shape pieces, paper bg, all in ArtCamera world
`Effects`	Particle bursts, sparkles — also in ArtCamera world (so they're captured into the PNG)
`UI`	All Canvas elements (RawImage paper + HUD)

Why RT-as-paper

Need	Choice	Why
Per-region tap-to-fill	Sprites + `PolygonCollider2D` in ArtCamera world; tapped via `IArtInputBridge`	Coordinate system is fixed (RT space). One `Physics2D.OverlapPoint` call after screen→art-world conversion.
Drag/drop shape pieces	Sprites + Physics2D in art world	Same fixed bounds on every device — no per-aspect tray layout.
Capture to PNG	`RT → Texture2D → PNG`	The RT is the saved image. No camera state override, no compositing pass, no determinism worries.
Multi-resolution support	`AspectRatioFitter (1:1, FitInParent)` on the RawImage	The "fit camera" problem reduces to a single Canvas property. Letterbox/pillarbox = whatever the Canvas around the RawImage looks like.
Color palette, buttons	Canvas above the RawImage	Anchors handle aspect ratios. Buttons + ScrollRect free.
Drawing catalog grid	Canvas	`GridLayoutGroup` + ScrollRect, async thumbnail loader.

Multi-resolution rule

The artwork world is screen-size-independent by construction. Author every drawing in a fixed 2048×2048 design rect (or 20×20 world units at PPU=100). Pieces, regions, snap radii, slot positions — all expressed in this space and never scaled at runtime. Different screen sizes only change how the RawImage is laid out on the Canvas; the contents of the RT stay identical.

If you need a backdrop (wood/cloth behind the paper), it's a sibling Canvas Image outside the RawImage, sized to fill the screen. The RT itself has a transparent or paper-colored background.

8. Core Contracts

All Core types are pure data or interfaces.

Drawing

namespace Darkmatter.Core.Drawing;

public interface IDrawingTemplate {
    string Id { get; }
    string DisplayName { get; }
    Sprite Thumbnail { get; }
    Sprite PaperBackground { get; }
    IReadOnlyList<ShapePieceDTO> Pieces { get; }
    IReadOnlyList<ColorRegionDTO> Regions { get; }
}

public readonly struct ShapePieceDTO {
    public string PieceId { get; }
    public Sprite Sprite { get; }
    public Vector2 SlotPosition { get; }
    public float SlotRotation { get; }
    public float SnapRadius { get; }      // generous for toddlers
}

public readonly struct ColorRegionDTO {
    public string RegionId { get; }
    public Sprite Sprite { get; }          // sprite renderer source
    public Vector2[] ColliderPath { get; } // polygon collider points
    public Color InitialColor { get; }     // usually white
}

Coloring

namespace Darkmatter.Core.Coloring;

public interface IColorPalette {
    string Id { get; }
    IReadOnlyList<Color> Colors { get; }
}

public readonly struct PaintCommandDTO {
    public string RegionId { get; }
    public Color FromColor { get; }
    public Color ToColor { get; }
}

Paper (RT rig + input bridge)

namespace Darkmatter.Core.Paper;

public interface IPaperRig {
    Camera ArtCamera { get; }              // offscreen, targetTexture = Surface
    RenderTexture Surface { get; }         // 2048×2048 ARGB32; the paper itself
    Transform PaperRoot { get; }           // parent of regions/pieces/paper bg
    Vector2 DesignSize { get; }            // world units, e.g. (20, 20)
    Rect DesignRect { get; }               // centered on origin, DesignSize wide
}

public interface IArtInputBridge {
    // Converts a screen-space pointer (Input System) to art-world coords
    // inside the RT. Returns false if the pointer is outside the RawImage.
    bool TryScreenToArtWorld(Vector2 screenPos, out Vector2 artWorldPos);
}

IPaperRig is implemented by PaperRig : MonoBehaviour in the ColorBook scene.
IArtInputBridge does the screen → RawImage local → UV → ArtCamera.ViewportToWorldPoint chain.
All consumers (Coloring, ShapeBuilder, Capture, particle effects) read these from DI; they never touch Screen.width/height directly.

History

namespace Darkmatter.Core.History;

public interface ICommand {
    void Execute();
    void Undo();
}

public interface IUndoStack {
    bool CanUndo { get; }
    bool CanRedo { get; }
    void Push(ICommand cmd);   // executes + appends
    void Undo();
    void Redo();
    void Clear();
}

Gallery & Capture

namespace Darkmatter.Core.Gallery;

public readonly struct SavedArtworkDTO {
    public string Id { get; }
    public string TemplateId { get; }
    public DateTime CreatedUtc { get; }
    public string ImagePath { get; }       // persistentDataPath PNG
    public string ThumbnailPath { get; }
}

public interface IGalleryService {
    UniTask<SavedArtworkDTO> SaveAsync(byte[] png, string templateId);
    UniTask<IReadOnlyList<SavedArtworkDTO>> ListAsync();
    UniTask<Texture2D> LoadFullAsync(string artworkId);
    UniTask DeleteAsync(string artworkId);
}

namespace Darkmatter.Core.Capture;

public interface ICaptureService {
    // No camera or paperBg args — capture reads directly from IPaperRig.Surface.
    // Dimensions inherited from the RT; no resize, no compositing.
    UniTask<byte[]> CaptureAsync();
}

ICaptureService resolves IPaperRig via DI and reads Surface directly. The paper background is already baked into the RT because it sits in PaperRoot under the ArtCamera. No special compositing pass is ever needed.

Signals

namespace Darkmatter.Core.Signals;

public readonly struct DrawingSelectedSignal {
    public string TemplateId { get; }
}

public readonly struct ShapeAssembledSignal {
    public string TemplateId { get; }
}

public readonly struct ColorAppliedSignal {
    public string RegionId { get; }
    public Color Color { get; }
}

public readonly struct ArtworkCapturedSignal {
    public string ArtworkId { get; }
}

public readonly struct ArtworkSavedSignal {
    public SavedArtworkDTO Artwork { get; }
}

9. Feature Responsibilities

`DrawingCatalog`

Loads the catalog manifest (list of available template IDs + thumbnail addresses).
Presents a scrollable grid of thumbnails (Canvas).
On select → fires DrawingSelectedSignal(templateId) and unloads the catalog UI.

`Paper`

Scene-scoped infrastructure. Lives in ColorBook.unity only.
Owns PaperRig (MonoBehaviour) — exposes ArtCamera, the RenderTexture Surface, PaperRoot transform, and the design rect.
Owns ArtInputBridge — converts pointer screen positions to art-world coords inside the RT.
Registered in ColorBookLifetimeScope via PaperRigModule. All other features in the scene resolve IPaperRig / IArtInputBridge from DI.
Lifetime is scene-scoped: created on scene load, destroyed on scene unload. RT is allocated in Awake, released in OnDestroy.

`ShapeBuilder`

Listens to DrawingSelectedSignal.
Loads template via IDrawingTemplateLoader, parents shape pieces under IPaperRig.PaperRoot at off-slot positions inside the design rect.
Per piece: drag with ShapePieceView (sprite + collider). Pointer events go through IArtInputBridge.TryScreenToArtWorld. On drop, check distance to SlotPosition against SnapRadius; if within, snap and lock.
Fires ShapeAssembledSignal when all pieces locked.

`Coloring`

Listens to ShapeAssembledSignal.
Spawns one ColorRegionView per ColorRegionDTO under IPaperRig.PaperRoot (sprite + polygon collider on Artwork layer).
Listens to palette selection (current color held in ColoringStateRepository).
On pointer down: IArtInputBridge.TryScreenToArtWorld(screenPos, out var artPos) → Physics2D.OverlapPoint(artPos, artworkMask) → if hit, build PaintRegionCommand(regionId, oldColor, newColor), push to IUndoStack.
Command sets SpriteRenderer.color on undo/redo.
Fires ColorAppliedSignal for SFX / sparkle effects.

`History`

Owns the singleton IUndoStack for the current ColorBook session.
Cleared on DrawingSelectedSignal (new drawing = fresh history).
Capped at ~20 entries (memory + cognitive simplicity).
UI: two big arrow buttons; disabled state when CanUndo / CanRedo is false.

`Capture`

Bound to the "Capture" button.
Calls ICaptureService.CaptureAsync() → PNG bytes. Capture reads IPaperRig.Surface directly; no camera or paper-bg args needed.
Hands bytes to IGalleryService.SaveAsync(...).
Fires ArtworkCapturedSignal then ArtworkSavedSignal.
Shows a quick "saved!" toast with a thumbnail of the new entry.

`Progression`

Tracks completed template IDs and the in-progress draft.
On "Next" button: silently runs Capture pipeline (auto-save), marks current as completed, calls IDrawingTemplateCatalog.NextUnseen().
Persists JSON via IPersistenceService.

`ColorBookFlow`

The only orchestrator inside ColorBook scope.
Subscribes to flow-relevant signals and toggles UI panels (catalog → builder → coloring).
Coordinates "Next" sequence: IProgressionService.MarkCompleted → ICaptureService autosave → IDrawingTemplateLoader.Release(currentId) → load next.
Built as a small FSM (Catalog → Building → Coloring → Done).

`ArtBook`

Separate scene.
GalleryPresenter calls IGalleryService.ListAsync() → grid of thumbnails.
Tap → fullscreen view, share-sheet button, delete.
Saved-to-device-camera-roll uses an optional platform plugin behind IExternalShareService (Core contract).

10. Addressables Strategy

Mirror the Bus Game pattern via IAssetProviderService.

What ships through Addressables

Asset	Why
`DrawingTemplate` ScriptableObject (per drawing)	Many; load on demand.
Shape piece sprites	Only needed when active.
Region sprites + polygon paths	Heavy; loaded per drawing.
Paper backgrounds	Per template, sometimes shared.
Color palette SOs	Swap per theme.
Audio clips (tap, snap, complete, sparkle)	Shared SFX bank.

What does NOT use Addressables

HUD prefabs (palette button, undo icon) — always loaded with scene.
Core UI canvases.
Boot scene assets.
User-saved gallery PNGs — those live in Application.persistentDataPath.

Group layout

Drawings_Animals       (label: drawing, animals)
Drawings_Vehicles      (label: drawing, vehicles)
Drawings_Shapes        (label: drawing, shapes)
Palettes               (label: palette)
Audio_UI               (label: sfx, ui)
Audio_Coloring         (label: sfx, coloring)

Lifecycle

Catalog loads thumbnail handles only (cheap).
On select → full template loads (pieces + regions + paper).
On "Next" or scene exit → previous template Released before next loads.
This bound matters on toddler tablets with limited RAM.

Remote groups (future)

Drawing packs ship as remote bundles. New theme packs (Christmas, Dinosaurs) update without an app store release.

11. Persistence

Two distinct stores, each behind its own Core contract.

`IPersistenceService` (JSON / PlayerPrefs)

Holds:

Completed template IDs.
Last opened drawing.
Audio volume, simple settings.

Path: Application.persistentDataPath/save.json.

`IGalleryService` (file IO)

Holds user artworks:

persistentDataPath/Gallery/
├── {guid}.png            full-res render (~2048×2048)
├── {guid}.thumb.png      256×256 for grid
└── {guid}.json           SavedArtworkDTO sidecar

Writes are atomic (.tmp → rename).
ListAsync enumerates sidecar JSONs sorted by CreatedUtc desc.
Thumbnail generation happens once at save time on a worker thread.

12. Capture Pipeline

With the RT-paper-rig, capture has no setup phase. The RT is already the final image at all times.

[Capture button or Next button]
        │
        ▼
ICaptureService.CaptureAsync()
        │
        ├─ rt = _paperRig.Surface             (already populated each frame)
        ├─ prev = RenderTexture.active
        ├─ RenderTexture.active = rt
        ├─ tex = new Texture2D(rt.width, rt.height, RGBA32, false)
        ├─ tex.ReadPixels(full rect, 0, 0); tex.Apply()
        ├─ RenderTexture.active = prev
        ├─ bytes = tex.EncodeToPNG()          (on worker via UniTask.RunOnThreadPool)
        ├─ Object.Destroy(tex)
        └─ return bytes
        ▼
IGalleryService.SaveAsync(bytes, templateId)
        │
        ├─ Write .png atomically
        ├─ Generate + write thumbnail
        ├─ Write sidecar JSON
        └─ return SavedArtworkDTO
        ▼
EventBus.Publish(new ArtworkSavedSignal(dto))

Notes:

HUD never appears in capture because the HUD is on UICamera / Canvas — it is physically in a different render path. The RT only ever sees ArtCamera's output.
Paper background is a sprite parented under IPaperRig.PaperRoot and is rendered into the RT every frame — already baked in.
Saved PNGs are byte-comparable across devices because the RT dimensions and ArtCamera matrix never depend on screen size.
CaptureAsync is safe to call repeatedly — no camera state is ever mutated.

13. Communication Rules

Use case	Mechanism
Load template, return result	Direct DI call (`IDrawingTemplateLoader.LoadAsync`).
Capture → save chain	Direct DI calls, sequenced.
Notify HUD that a region was painted	`IEventBus` signal.
Notify Progression that a drawing was completed	`IEventBus` signal.
Tell ColorBookFlow that pieces are assembled	`IEventBus` signal.
Tell Coloring which color is currently selected	Direct DI on `ColoringStateRepository`.

Never use signals for request/response. If you need a return value or guaranteed single handler, define a Core interface.

14. UI (MVP — Passive View)

Identical to Bus Game.

Model — controller / repository, fires C# events.
View — MonoBehaviour, only setters (SetColors(IReadOnlyList<Color>)).
Presenter — pure C#, subscribes to model events, calls view setters.

Inspector bridge

For palette icons, undo buttons, region prefabs:

[SerializeField, RequireInterface(typeof(IColorButtonView))]
private MonoBehaviour[] _colorButtons;

15. Toddler UX Constraints

These shape several design decisions and are non-negotiable:

No fail states. Drawings cannot be "wrong".
No timers. Nothing decays or runs out.
No tiny hitboxes. Drag tolerance ≥ 40 px; snap radius ≥ 60 px for shape pieces.
Auto-snap on near-miss. If a piece is dropped within 1.5 × SnapRadius, snap anyway and play a happy sound.
No text-heavy UI. Icons everywhere. Single-word labels max.
Loud, immediate feedback. Every tap plays a sound; every fill bursts a small particle effect.
Undo cap = 20. Toddlers will mash undo. Bound the memory.
Long-press = quick menu off. Avoid surprise modals.

16. Testing

Layer	Test type	Location
`Libs/CommandStack`	EditMode unit tests	`Libs/CommandStack/Tests/`
`Core` DTOs	EditMode	rarely needed, but for `SavedArtworkDTO` serialization, yes.
`Services/Gallery`	EditMode w/ temp directory	mocks `Application.persistentDataPath`.
`Services/Capture`	PlayMode	requires a Camera in the test scene.
`Features/*/Systems`	EditMode w/ DI test container	inject fakes for `IUndoStack`, signals captured by a fake `IEventBus`.
Full flow	PlayMode smoke test	one drawing → assemble → color → capture → assert gallery has 1 file.

17. "Where do I put this?" Checklist

Is it a cross-assembly interface / enum / DTO? → Core/
Is it a generic, sellable utility? → Libs/
Is it infrastructure (input, audio, file IO, addressables, capture)? → Services/
Is it gameplay logic specific to coloring books? → Features/
Is it composition / scene wiring? → App/

When in doubt, ask: would deleting this feature break Core? If yes, the dependency is wrong.

18. Open Questions / Future Work

Pencil/brush mode — currently the design is tap-to-fill regions. A free-draw brush mode would need a BrushStrokeCommand and a dynamic texture per region; out of scope for v1.
Multi-child profiles — single-profile for v1; multi-profile would slot in behind IProgressionService and IGalleryService keyed by profileId.
Cloud sync — gallery sync would happen behind IGalleryService (decorator pattern); local-first stays the source of truth.
Sticker / decoration layer — additive sprite layer above coloring, also ICommand-driven so it integrates with undo/redo cleanly.

19. Quick Reference — Feature ↔ Signal Map

Feature	Subscribes to	Publishes
`DrawingCatalog`	—	`DrawingSelectedSignal`
`ShapeBuilder`	`DrawingSelectedSignal`	`ShapeAssembledSignal`
`Coloring`	`ShapeAssembledSignal`	`ColorAppliedSignal`
`History`	`DrawingSelectedSignal` (to clear)	—
`Capture`	— (button-driven)	`ArtworkCapturedSignal`, `ArtworkSavedSignal`
`Progression`	`ArtworkSavedSignal`	—
`ColorBookFlow`	`ShapeAssembledSignal`, `ArtworkSavedSignal`	—
`ArtBook (Gallery)`	`ArtworkSavedSignal` (if open)	—

Maintained alongside the Darkmatter Architecture Guide. Do not break the dependency arrows.

20. Assembly Definition Map

Every folder under Code/ is its own .asmdef. References follow the layer rules exactly.

Asmdef	Path	References
`Darkmatter.App`	`App/`	All Features, all Services, Core, Libs
`Darkmatter.Core`	`Core/`	(none — `UniTask` allowed in async signatures)
`Darkmatter.Lib.CommandStack`	`Libs/CommandStack/`	`Darkmatter.Core`
`Darkmatter.Lib.EventBus`	`Libs/EventBus/`	`Darkmatter.Core`
`Darkmatter.Lib.FSM`	`Libs/FSM/`	`Darkmatter.Core`
`Darkmatter.Services.Audio`	`Services/Audio/`	`Darkmatter.Core`
`Darkmatter.Services.Inputs`	`Services/Inputs/`	`Darkmatter.Core`
`Darkmatter.Services.Assets`	`Services/Assets/`	`Darkmatter.Core`
`Darkmatter.Services.Scenes`	`Services/Scenes/`	`Darkmatter.Core`
`Darkmatter.Services.Persistence`	`Services/Persistence/`	`Darkmatter.Core`
`Darkmatter.Services.Gallery`	`Services/Gallery/`	`Darkmatter.Core`
`Darkmatter.Services.Capture`	`Services/Capture/`	`Darkmatter.Core`
`Darkmatter.Features.MainMenu`	`Features/MainMenu/`	`Darkmatter.Core`, Libs
`Darkmatter.Features.DrawingCatalog`	`Features/DrawingCatalog/`	`Darkmatter.Core`, Libs
`Darkmatter.Features.Paper`	`Features/Paper/`	`Darkmatter.Core`, `Lib.Installers`
`Darkmatter.Features.ShapeBuilder`	`Features/ShapeBuilder/`	`Darkmatter.Core`, Libs
`Darkmatter.Features.Coloring`	`Features/Coloring/`	`Darkmatter.Core`, `Lib.CommandStack`
`Darkmatter.Features.History`	`Features/History/`	`Darkmatter.Core`, `Lib.CommandStack`
`Darkmatter.Features.Capture`	`Features/Capture/`	`Darkmatter.Core`
`Darkmatter.Features.Progression`	`Features/Progression/`	`Darkmatter.Core`
`Darkmatter.Features.ColorBookFlow`	`Features/ColorBookFlow/`	`Darkmatter.Core`, `Lib.FSM`
`Darkmatter.Features.ArtBook`	`Features/ArtBook/`	`Darkmatter.Core`

Hard rule: No Service asmdef references any Feature asmdef. No Feature asmdef references another Feature asmdef. Compiler enforces the architecture.

21. LifetimeScope Concrete Sample

`RootLifetimeScope` (Boot scene, persists forever)

namespace Darkmatter.App.LifetimeScopes;

public sealed class RootLifetimeScope : LifetimeScope {
    [SerializeField] private AudioServiceConfig _audioConfig;
    [SerializeField] private InputReaderSO _inputReader;

    protected override void Configure(IContainerBuilder builder) {
        // EventBus
        builder.Register<IEventBus, EventBus>(Lifetime.Singleton);

        // Services
        builder.RegisterInstance(_inputReader).As<IInputReader>();
        builder.Register<IAudioService, AudioService>(Lifetime.Singleton)
               .WithParameter(_audioConfig);
        builder.Register<IAssetProviderService, AddressableAssetProviderService>(Lifetime.Singleton);
        builder.Register<ISceneService, SceneService>(Lifetime.Singleton);
        builder.Register<IPersistenceService, JsonPersistenceService>(Lifetime.Singleton);
        builder.Register<IGalleryService, FileGalleryService>(Lifetime.Singleton);
        builder.Register<ICaptureService, RenderTextureCaptureService>(Lifetime.Singleton);

        // App entry
        builder.RegisterEntryPoint<AppBoot>();
    }
}

`ColorBookLifetimeScope` (per-scene, child of Root)

namespace Darkmatter.App.LifetimeScopes;

public sealed class ColorBookLifetimeScope : LifetimeScope {
    [SerializeField] private ColorBookSceneRefs _sceneRefs;   // ArtCamera, panel roots, prefabs
    [SerializeField] private IInstaller[] _installers;        // assigned in inspector

    protected override void Configure(IContainerBuilder builder) {
        builder.RegisterInstance(_sceneRefs);

        // Each feature ships an IInstaller
        foreach (var installer in _installers) installer.Install(builder);

        // Scene-scoped orchestrator
        builder.RegisterEntryPoint<ColorBookFlowController>();
    }
}

Drag these installers in the inspector:

DrawingCatalogServiceModule
ShapeBuilderServiceModule
ColoringServiceModule
HistoryServiceModule
CaptureFeatureModule
ProgressionServiceModule

22. Installer Pattern — Concrete Coloring Sample

namespace Darkmatter.Features.Coloring.Installers;

[CreateAssetMenu(menuName = "Darkmatter/Installers/Coloring")]
public sealed class ColoringServiceModule : ScriptableObject, IInstaller {
    [SerializeField] private ColoringConfig _config;

    public void Install(IContainerBuilder builder) {
        builder.RegisterInstance(_config);
        builder.Register<ColoringStateRepository>(Lifetime.Scoped).AsSelf();
        builder.Register<ColoringController>(Lifetime.Scoped)
               .As<IColoringController>()
               .AsSelf();
        builder.Register<ColorPalettePresenter>(Lifetime.Scoped).AsSelf();
        builder.RegisterEntryPoint<ColoringInputBinder>();
    }
}

Convention:

One IInstaller per feature.
ScriptableObject so it can be referenced by scene scope inspector.
Registers only its own types. Never touches another feature's types.

23. Command Pattern — `PaintRegionCommand`

namespace Darkmatter.Features.Coloring.Commands;

internal sealed class PaintRegionCommand : ICommand {
    private readonly ColorRegionView _view;
    private readonly Color _fromColor;
    private readonly Color _toColor;
    private readonly IEventBus _bus;

    public PaintRegionCommand(ColorRegionView view, Color from, Color to, IEventBus bus) {
        _view = view;
        _fromColor = from;
        _toColor = to;
        _bus = bus;
    }

    public void Execute() {
        _view.SetColor(_toColor);
        _bus.Publish(new ColorAppliedSignal(_view.RegionId, _toColor));
    }

    public void Undo() {
        _view.SetColor(_fromColor);
        _bus.Publish(new ColorAppliedSignal(_view.RegionId, _fromColor));
    }
}

Usage in controller:

public void PaintRegion(ColorRegionView view) {
    var current = _state.CurrentColor;
    if (view.Color == current) return;            // no-op
    var cmd = new PaintRegionCommand(view, view.Color, current, _bus);
    _undoStack.Push(cmd);                          // Push executes + records
}

Same pattern applies to SnapPieceCommand if shape-builder steps should be undoable (optional for v1).

24. CommandStack — `Libs/CommandStack`

namespace Darkmatter.Lib.CommandStack;

public sealed class BoundedUndoStack : IUndoStack {
    private readonly Deque<ICommand> _undo = new();
    private readonly Stack<ICommand> _redo = new();
    private readonly int _capacity;

    public BoundedUndoStack(int capacity = 20) => _capacity = capacity;

    public bool CanUndo => _undo.Count > 0;
    public bool CanRedo => _redo.Count > 0;

    public void Push(ICommand cmd) {
        cmd.Execute();
        _undo.AddLast(cmd);
        if (_undo.Count > _capacity) _undo.RemoveFirst();
        _redo.Clear();
    }

    public void Undo() {
        if (!CanUndo) return;
        var cmd = _undo.Last;
        _undo.RemoveLast();
        cmd.Undo();
        _redo.Push(cmd);
    }

    public void Redo() {
        if (!CanRedo) return;
        var cmd = _redo.Pop();
        cmd.Execute();
        _undo.AddLast(cmd);
    }

    public void Clear() {
        _undo.Clear();
        _redo.Clear();
    }
}

Deque<T> keeps the oldest entry cheap to evict when the cap fires.

25. View / Presenter Pair — Color Palette

View (MonoBehaviour, setters only)

namespace Darkmatter.Features.Coloring.UI;

public sealed class ColorPaletteView : MonoBehaviour, IColorPaletteView {
    [SerializeField, RequireInterface(typeof(IColorButtonView))]
    private MonoBehaviour[] _buttonsRaw;

    private IColorButtonView[] _buttons;

    public event Action<int> OnColorButtonClicked;

    private void Awake() {
        _buttons = _buttonsRaw.Cast<IColorButtonView>().ToArray();
        for (var i = 0; i < _buttons.Length; i++) {
            var idx = i;
            _buttons[i].OnClicked += () => OnColorButtonClicked?.Invoke(idx);
        }
    }

    public void SetColors(IReadOnlyList<Color> colors) {
        for (var i = 0; i < _buttons.Length; i++)
            _buttons[i].SetVisible(i < colors.Count);
        for (var i = 0; i < colors.Count; i++)
            _buttons[i].SetColor(colors[i]);
    }

    public void SetSelected(int index) {
        for (var i = 0; i < _buttons.Length; i++)
            _buttons[i].SetSelected(i == index);
    }
}

Presenter (pure C#)

namespace Darkmatter.Features.Coloring.UI;

public sealed class ColorPalettePresenter : IStartable, IDisposable {
    private readonly IColorPaletteView _view;
    private readonly ColoringStateRepository _state;

    public ColorPalettePresenter(IColorPaletteView view, ColoringStateRepository state) {
        _view = view;
        _state = state;
    }

    public void Start() {
        _view.SetColors(_state.Palette.Colors);
        _view.SetSelected(_state.SelectedIndex);
        _view.OnColorButtonClicked += OnClicked;
        _state.SelectedIndexChanged += OnIndexChanged;
    }

    private void OnClicked(int index) => _state.SelectColor(index);
    private void OnIndexChanged(int index) => _view.SetSelected(index);

    public void Dispose() {
        _view.OnColorButtonClicked -= OnClicked;
        _state.SelectedIndexChanged -= OnIndexChanged;
    }
}

Same shape repeats for every feature's UI.

26. ShapeBuilder — Snap Algorithm

// In ShapePieceView.OnPointerUp:
public void OnDragEnd(Vector2 worldPos) {
    var slot = transform.position;            // assigned target slot
    var d = Vector2.Distance(worldPos, slot);

    if (d <= _piece.SnapRadius) {
        SnapToSlot();
    } else if (d <= _piece.SnapRadius * 1.5f) {
        // Toddler grace zone — snap anyway, play happy sound
        SnapToSlot();
        _audio.PlayOneShot(_clips.NiceTry);
    } else {
        ReturnToTrayAnimated();
    }
}

private void SnapToSlot() {
    _locked = true;
    transform.DOMove(_piece.SlotPosition, 0.25f).SetEase(Ease.OutBack);
    _audio.PlayOneShot(_clips.Snap);
    _bus.Publish(new PieceSnappedSignal(_piece.PieceId));
}

Controller listens for PieceSnappedSignal, counts against expected piece count, fires ShapeAssembledSignal when complete.

27. Rendering Order & Sorting

URP 2D with a single ArtCamera ortho cam.

Sorting Layer	Order	Contents
`PaperBackground`	0	Paper bg sprite (under everything)
`ArtworkRegions`	100	`ColorRegionView` sprites (the colorable shapes)
`ArtworkPieces`	200	`ShapePieceView` sprites (during build)
`Effects`	300	Particle bursts, sparkles
`UIWorld`	400	World-space prompts (rare; mostly Canvas)

Canvas HUD lives on UICamera (Overlay), never sorts against ArtCamera. Capture renders only ArtCamera's layers → HUD physically cannot leak into saved PNG.

28. SavedArtwork JSON Schema

{
  "id": "f3a8e2d4-...",
  "templateId": "animals/elephant",
  "createdUtc": "2026-05-26T16:42:11Z",
  "imagePath": "Gallery/f3a8e2d4-....png",
  "thumbnailPath": "Gallery/f3a8e2d4-....thumb.png",
  "regions": [
    { "regionId": "body", "color": "#FFB347" },
    { "regionId": "ears", "color": "#FF6961" }
  ]
}

regions[] lets the gallery reopen an artwork for further edits in a future version (out of scope v1, but the schema reserves the field now to avoid migration later).

Paths are relative to persistentDataPath. Never store absolute paths — they change between OS updates on some platforms.

29. Boot & Error Handling

AppBoot.StartAsync()
  ├─ try Addressables.InitializeAsync()
  │     fail → show "Tap to retry" splash
  ├─ try preload palette + UI sounds (Addressables labels)
  │     fail → log + continue (non-fatal)
  ├─ try _persistence.LoadAsync()
  │     fail → start with empty progression (don't crash)
  ├─ _scenes.LoadAsync("MainMenu")
  └─ done

Toddler-mode error UI:

One large smiling icon.
One big "tap" button.
No text, no error codes.
A small upper-right gear opens a parent-only diagnostic screen (long-press 3 s to unlock).

30. Setup Checklist (new dev, day one)

Open Bus Game.sln (color book lives in same repo / Unity project per plan).
Verify Addressables groups exist: Drawings_*, Palettes, Audio_*.
Open Boot.unity → confirm RootLifetimeScope references the right configs.
Open ColorBook.unity → confirm ColorBookLifetimeScope._installers[] is fully populated.
Hit Play from Boot.unity (entry scene). Never start mid-flow — DI parent scope must exist.
To author a new drawing: duplicate Animals/elephant/, edit Template.asset (pieces + regions), add to the appropriate Addressables group.
Run Tests > EditMode and Tests > PlayMode before pushing.

31. Quick Reference — Class ↔ Layer ↔ Asmdef

Class	Layer	Asmdef
`IDrawingTemplate`, `ShapePieceDTO`, `ColorRegionDTO`	Core	`Darkmatter.Core`
`IPaperRig`, `IArtInputBridge`	Core	`Darkmatter.Core`
`ICommand`, `IUndoStack`	Core	`Darkmatter.Core`
`BoundedUndoStack`	Libs	`Darkmatter.Lib.CommandStack`
`AddressableAssetProviderService`	Services	`Darkmatter.Services.Assets`
`FileGalleryService`	Services	`Darkmatter.Services.Gallery`
`RenderTextureCaptureService`	Services	`Darkmatter.Services.Capture`
`PaperRig`, `ArtInputBridge`, `PaperRigModule`	Features	`Darkmatter.Features.Paper`
`ColoringController`, `PaintRegionCommand`	Features	`Darkmatter.Features.Coloring`
`ShapeBuilderController`, `ShapePieceView`	Features	`Darkmatter.Features.ShapeBuilder`
`HistoryController`	Features	`Darkmatter.Features.History`
`ColorBookFlowController`	Features	`Darkmatter.Features.ColorBookFlow`
`GalleryPresenter`, `GalleryGridView`	Features	`Darkmatter.Features.ArtBook`
`ColorBookLifetimeScope`, `AppBoot`	App	`Darkmatter.App`

If a class's natural home doesn't match its asmdef, the architecture is bent — fix the placement, don't add a reference.

32. Class Reference (Detailed)

Canonical breakdown of every concrete class and interface. For each: purpose, public surface (signatures), injected dependencies, and collaborators (signals or interfaces it talks to).

Convention used below

// fields: = constructor-injected dependencies

// pub: = events / signals fired

// sub: = events / signals consumed

All async returns are UniTask unless noted.

32.1 Core Contracts

Pure interfaces and DTOs. Zero logic.

`IDrawingTemplate` (Core/Drawing)

Immutable view of a single drawing's authored data.

public interface IDrawingTemplate {
    string Id { get; }                              // e.g. "animals/elephant"
    string DisplayName { get; }                     // user-facing
    Sprite Thumbnail { get; }                       // 256×256 for catalog grid
    Sprite PaperBackground { get; }                 // composited under artwork
    IReadOnlyList<ShapePieceDTO> Pieces { get; }    // for ShapeBuilder
    IReadOnlyList<ColorRegionDTO> Regions { get; }  // for Coloring
}

Implemented by DrawingTemplateSO (ScriptableObject) loaded via Addressables.

`IDrawingTemplateCatalog` (Core/Drawing)

Authority on which drawings exist, completion state, and "next" selection.

public interface IDrawingTemplateCatalog {
    UniTask InitializeAsync();                       // pulls manifest from Addressables
    IReadOnlyList<string> AllTemplateIds { get; }
    UniTask<Sprite> GetThumbnailAsync(string id);    // cheap; for grid
    UniTask<IDrawingTemplate> LoadAsync(string id);  // expensive; full template
    void Release(string id);                         // Addressables ref count down
    string NextUnseen(string currentId);             // progression hint
}

`IColorPalette` (Core/Coloring)

Set of colors offered to the child. Authored as ColorPaletteSO.

public interface IColorPalette {
    string Id { get; }
    IReadOnlyList<Color> Colors { get; }             // 6–10 entries typical
}

`ICommand` & `IUndoStack` (Core/History)

Already shown in section 8. Each undoable user action is one ICommand; the stack is bounded.

`IGalleryService` (Core/Gallery)

Persistent store of saved artwork PNGs.

public interface IGalleryService {
    UniTask<SavedArtworkDTO> SaveAsync(byte[] png, string templateId);
    UniTask<IReadOnlyList<SavedArtworkDTO>> ListAsync();   // sorted newest first
    UniTask<Texture2D> LoadFullAsync(string artworkId);    // for fullscreen view
    UniTask<Texture2D> LoadThumbnailAsync(string artworkId);
    UniTask DeleteAsync(string artworkId);
}

`ICaptureService` (Core/Capture)

Snapshots the paper RT to a PNG blob. No arguments — dimensions and content come from IPaperRig.Surface.

public interface ICaptureService {
    UniTask<byte[]> CaptureAsync();
}

`IPaperRig` (Core/Paper)

Shared art rig. The single source of truth for everything that lives in the drawing world.

public interface IPaperRig {
    Camera ArtCamera { get; }              // offscreen, targetTexture = Surface
    RenderTexture Surface { get; }         // 2048×2048 ARGB32 — the paper itself
    Transform PaperRoot { get; }           // parent of regions/pieces/paper bg
    Vector2 DesignSize { get; }            // world units, e.g. (20, 20)
    Rect DesignRect { get; }               // centered on origin
}

`IArtInputBridge` (Core/Paper)

Converts screen-space pointer coords to art-world coords inside the RT.

public interface IArtInputBridge {
    bool TryScreenToArtWorld(Vector2 screenPos, out Vector2 artWorldPos);
}

Returns false when the pointer is outside the displayed RawImage rect (toddler tapped the HUD or backdrop). Every art-world raycast goes through this.

`IProgressionService` (Core/Progression)

Tracks which templates the child has completed and what they last opened.

public interface IProgressionService {
    UniTask LoadAsync();
    UniTask SaveAsync();
    IReadOnlyCollection<string> CompletedTemplateIds { get; }
    string LastOpenedTemplateId { get; }
    void MarkCompleted(string templateId);
    void SetLastOpened(string templateId);
}

`IAssetProviderService` (Core/Assets)

Addressables wrapper. Hides handle bookkeeping from features.

public interface IAssetProviderService {
    UniTask InitializeAsync();
    UniTask<T> LoadAsync<T>(string address) where T : UnityEngine.Object;
    UniTask<IReadOnlyList<T>> LoadByLabelAsync<T>(string label) where T : UnityEngine.Object;
    void Release(string address);
    void ReleaseAll();
}

`IEventBus` (Libs/EventBus, also referenced from Core)

public interface IEventBus {
    void Publish<T>(T signal) where T : struct;
    IDisposable Subscribe<T>(Action<T> handler) where T : struct;
}

Signals are structs to avoid GC. Disposable subscription so presenters can unsubscribe in Dispose().

32.2 Services Layer

Concrete infrastructure. One implementation each. All singletons in RootLifetimeScope.

`AddressableAssetProviderService` (Services/Assets)

Implements IAssetProviderService.

Responsibility: Wrap Addressables.LoadAssetAsync<T> and ref-count handles by address.
State: Dictionary<string, AsyncOperationHandle> keyed by address.
Notes: Release(address) decrements; ReleaseAll() for scene teardown. Initialization must complete before any other service may load.

`FileGalleryService` (Services/Gallery)

Implements IGalleryService.

// fields:
//   IPathProvider _paths           (wraps Application.persistentDataPath for tests)
//   IThumbnailGenerator _thumb     (downscale + encode)
//   IEventBus _bus
// pub: ArtworkSavedSignal, ArtworkDeletedSignal

Save flow: write {guid}.png.tmp → fsync → rename; generate thumbnail on a worker; write sidecar JSON last (so partial saves are detectable by absence of JSON).
List flow: enumerate *.json in Gallery/, deserialize, sort by CreatedUtc desc.
Delete flow: delete png + thumb + json; missing files ignored (idempotent).

`RenderTextureCaptureService` (Services/Capture)

Implements ICaptureService.

Steps: allocate RenderTexture(width, height, 0, ARGB32) → bind to artCamera.targetTexture → artCamera.Render() → ReadPixels into Texture2D → composite paperBackground underneath (single shader blit) → EncodeToPNG → release RT + textures.
Threading: PNG encode happens on a UniTask.RunOnThreadPool to avoid hitching the main thread on tablets.
Sizing: default 2048², overridable. Capped at device max texture size.

`JsonPersistenceService` (Services/Persistence)

Implements IPersistenceService (small JSON blob; not the gallery).

public interface IPersistenceService {
    UniTask<T> LoadAsync<T>(string key) where T : class, new();
    UniTask SaveAsync<T>(string key, T value);
}

Path: Application.persistentDataPath/save.json.
Format: single JSON object keyed by key so multiple services can share one file.
Atomicity: write to save.json.tmp → rename.

`SceneService` (Services/Scenes)

Implements ISceneService. Wraps SceneManager.LoadSceneAsync with UniTask plus a fade-curtain.

public interface ISceneService {
    UniTask LoadAsync(string sceneName, LoadSceneMode mode = LoadSceneMode.Single);
    UniTask UnloadAsync(string sceneName);
}

`AudioService` (Services/Audio)

Implements IAudioService. Plays SFX clips loaded by address, mixes via Unity AudioMixer groups.

public interface IAudioService {
    UniTask PreloadAsync(string label);              // e.g. "sfx,ui"
    void PlayOneShot(string clipId, float volume = 1f);
    void SetCategoryVolume(AudioCategory cat, float v01);
}

Holds an internal Dictionary<string, AudioClip> populated at preload.

`InputReaderSO` (Services/Inputs)

ScriptableObject wrapping the new Input System; exposes events.

public interface IInputReader {
    event Action<Vector2> PointerDown;     // world pos
    event Action<Vector2> PointerDrag;
    event Action<Vector2> PointerUp;
}

Why an SO: assignable in inspector and survives scene loads, but still resolvable via DI (builder.RegisterInstance(_inputReader).As<IInputReader>()).

32.3 Libs

Generic, project-agnostic utilities.

`BoundedUndoStack` (Libs/CommandStack)

Implements IUndoStack. Source already in section 24.

Capacity: default 20.
Invariant: _redo cleared on any new Push.
Edge cases: Undo/Redo on empty stack is a no-op (never throws).

`EventBus` (Libs/EventBus)

Implements IEventBus with a Dictionary<Type, Delegate> of Action<T> per signal type.

Subscribe returns an IDisposable that removes the handler on Dispose.
Publish snapshots the invocation list before iterating (so handlers may safely unsubscribe during dispatch).

`Fsm<TState>` (Libs/FSM)

Generic state machine used by ColorBookFlowController.

public sealed class Fsm<TState> where TState : struct, Enum {
    public TState Current { get; }
    public event Action<TState, TState> Transitioned;
    public void Bind(TState state, IFsmState handler);
    public void Go(TState next);                     // calls Exit on old, Enter on new
}

public interface IFsmState { void Enter(); void Exit(); }

32.4 Feature — `DrawingCatalog`

`DrawingCatalogController` (Systems)

Headless logic. Owns the list of template IDs visible in the grid.

// fields: IDrawingTemplateCatalog _catalog, IEventBus _bus
public sealed class DrawingCatalogController : IAsyncStartable {
    public IReadOnlyList<string> VisibleIds { get; }
    public event Action ListChanged;
    public UniTask StartAsync(CancellationToken ct);     // pulls catalog, refreshes list
    public void OnTemplateSelected(string id);           // bus.Publish(new DrawingSelectedSignal(id))
}
// pub: DrawingSelectedSignal

`DrawingCatalogPresenter` (UI)

Bridges controller ↔ view.

// fields: IDrawingCatalogView _view, DrawingCatalogController _ctrl, IDrawingTemplateCatalog _catalog
public sealed class DrawingCatalogPresenter : IStartable, IDisposable {
    public void Start();         // wires view.OnItemClicked → _ctrl.OnTemplateSelected
    public void Dispose();
}

Thumbnail load: _catalog.GetThumbnailAsync(id) per visible cell, with placeholder while loading.

`DrawingCatalogView : MonoBehaviour` (UI)

Implements IDrawingCatalogView. Pure setters + click event.

public interface IDrawingCatalogView {
    event Action<string> OnItemClicked;
    void SetItems(IReadOnlyList<CatalogItemVM> items);   // vm = id + Sprite thumbnail
}

32.5 Feature — `ShapeBuilder`

`ShapeBuilderController` (Systems)

Spawns shape pieces for the selected template, tracks snap progress, fires ShapeAssembledSignal when complete.

// fields: IDrawingTemplateCatalog _catalog, ShapePieceFactory _factory, IEventBus _bus, ShapeBuilderConfig _cfg
public sealed class ShapeBuilderController : IDisposable {
    public IReadOnlyList<ShapePieceView> Active { get; }
    public UniTask BuildAsync(string templateId);    // load template, spawn pieces in tray
    public void Reset();                             // clear, unsubscribe
}
// sub: DrawingSelectedSignal
// pub: ShapeAssembledSignal

Internal: counts PieceSnappedSignal against expected piece count.

`ShapePieceView : MonoBehaviour` (Views)

World-space draggable sprite with collider. Source for snap-or-return logic shown in section 26.

public sealed class ShapePieceView : MonoBehaviour {
    public string PieceId { get; }
    public bool IsLocked { get; }
    public event Action<string> Snapped;             // raised when piece locks into slot
    public void Initialize(ShapePieceDTO dto, IInputReader input, IAudioService audio);
}

No public mutators for position once locked — controller treats IsLocked as the source of truth.

`ShapePieceFactory` (Systems)

Instantiates ShapePieceView prefabs from a pool. Avoids re-instantiating across "Next" cycles on the same template family.

public sealed class ShapePieceFactory {
    public ShapePieceView Spawn(ShapePieceDTO dto, Transform parent);
    public void Despawn(ShapePieceView view);
}

32.5b Feature — `Paper`

The shared art rig — RT, offscreen camera, screen↔world bridge. Every other feature in the ColorBook scene resolves IPaperRig and IArtInputBridge from DI and never touches Screen.* or Camera.* directly.

`PaperRig : MonoBehaviour, IPaperRig` (Rig)

Scene-bound component placed on a GameObject in ColorBook.unity. Owns the RT lifecycle.

// inspector fields:
//   Camera _artCamera                  (Orthographic, aspect=1, fixed ortho size)
//   Transform _paperRoot               (parent of regions/pieces)
//   Vector2  _designSize = (20, 20)    (world units; matches 2048×2048 at PPU=100)
//   int      _surfaceSize = 2048       (RT side length, square)

public sealed class PaperRig : MonoBehaviour, IPaperRig {
    public Camera ArtCamera => _artCamera;
    public RenderTexture Surface => _surface;
    public Transform PaperRoot => _paperRoot;
    public Vector2 DesignSize => _designSize;
    public Rect DesignRect => new(-_designSize / 2f, _designSize);
}

Awake: allocate _surface = new RenderTexture(_surfaceSize, _surfaceSize, 0, ARGB32) { name = "PaperSurface" }; then _surface.Create() and _artCamera.targetTexture = _surface; _artCamera.aspect = 1f; _artCamera.orthographicSize = _designSize.y / 2f;.
OnDestroy: _surface.Release(); Object.Destroy(_surface);.
No update logic — the camera renders every frame automatically because targetTexture is set.
Important: _artCamera's orthographicSize and aspect are set once and never touched again. The RT contents are deterministic.

`ArtInputBridge : MonoBehaviour, IArtInputBridge` (Input)

Lives on the same UI Canvas as the paper RawImage.

// inspector fields:
//   RawImage _paperImage              (the on-screen paper)
//   RectTransform _paperRect          (== _paperImage.rectTransform)
//   Camera _uiCamera                  (Canvas event camera)
//   IPaperRig _rig                    (injected via VContainer + IInjectable, or resolved in Start)

public bool TryScreenToArtWorld(Vector2 screenPos, out Vector2 artWorldPos) {
    if (!RectTransformUtility.ScreenPointToLocalPointInRectangle(
            _paperRect, screenPos, _uiCamera, out var local)) {
        artWorldPos = default; return false;
    }
    var rect = _paperRect.rect;
    var uv = new Vector2(
        (local.x - rect.xMin) / rect.width,
        (local.y - rect.yMin) / rect.height);
    if (uv.x < 0 || uv.x > 1 || uv.y < 0 || uv.y > 1) {
        artWorldPos = default; return false;
    }
    artWorldPos = _rig.ArtCamera.ViewportToWorldPoint(uv);
    return true;
}

Returns false when the toddler tapped outside the RawImage (HUD button area, backdrop, off-screen).
Used by every feature that does world-space picking — Coloring, ShapeBuilder, and any future feature like stickers.

`PaperRigModule : MonoBehaviour, IServiceModule` (Installers)

Scene-scoped installer. Dragged onto ColorBookLifetimeScope._installers[].

// inspector fields:
//   PaperRig _rig
//   ArtInputBridge _bridge

public void Register(IContainerBuilder builder) {
    builder.RegisterInstance<IPaperRig>(_rig);
    builder.RegisterInstance<IArtInputBridge>(_bridge);
}

Registers as Instance because both are MonoBehaviours already in the scene.
Lifetime is implicitly tied to the scene (Unity destroys them on unload).

32.6 Feature — `Coloring`

`ColoringStateRepository` (Repository)

In-memory model. Owns "currently selected color" and the palette in use.

public sealed class ColoringStateRepository {
    public IColorPalette Palette { get; private set; }
    public int SelectedIndex { get; private set; }
    public Color CurrentColor => Palette.Colors[SelectedIndex];
    public event Action<int> SelectedIndexChanged;
    public void SetPalette(IColorPalette palette);   // resets SelectedIndex to 0
    public void SelectColor(int index);
}

Why a repository: presenter and controller both need to read/write current color; an event-emitting POCO is simpler than wiring two signals.

`ColoringController` (Systems) — implements `IColoringController`

Builds and pushes PaintRegionCommand instances; spawns ColorRegionView per region.

// fields: IUndoStack _undo, ColoringStateRepository _state, ColorRegionFactory _factory, IEventBus _bus
public interface IColoringController {
    UniTask SpawnRegionsAsync(IDrawingTemplate template);
    void PaintRegion(ColorRegionView view);          // builds command, pushes to undo stack
    void Clear();
}
// sub: ShapeAssembledSignal (via flow controller, not direct)
// pub: ColorAppliedSignal (via PaintRegionCommand)

`ColorRegionView : MonoBehaviour` (Views)

Sprite + PolygonCollider2D, on Artwork layer. Tapped via Physics2D.OverlapPoint from ColoringInputBinder.

public sealed class ColorRegionView : MonoBehaviour {
    public string RegionId { get; }
    public Color Color { get; }                      // current paint
    public void Initialize(ColorRegionDTO dto);
    public void SetColor(Color c);                   // setter only; no logic
}

`ColoringInputBinder` (Systems) — `IStartable, IDisposable`

Subscribes to IInputReader.PointerDown. On each tap:

_bridge.TryScreenToArtWorld(screenPos, out var artPos) — bail if outside the paper.
Physics2D.OverlapPoint(artPos, _artworkMask) against the Artwork layer.
If hit, ColoringController.PaintRegion(hit.GetComponent<ColorRegionView>()).

// fields: IInputReader _input, IArtInputBridge _bridge, IColoringController _coloring, LayerMask _artworkMask

Note: _bridge is the same instance the entire scene uses — no per-feature coordinate math.

`PaintRegionCommand` (Commands)

Source in section 23. Holds view, fromColor, toColor, bus. Symmetrical execute/undo.

`ColorPaletteView`, `ColorPalettePresenter` (UI)

Sources in section 25. Presenter binds ColoringStateRepository.SelectedIndexChanged ↔ IColorPaletteView.

`ColorRegionFactory` (Systems)

Mirror of ShapePieceFactory for regions. Pool-friendly.

32.7 Feature — `History`

`HistoryController` (Systems) — `IStartable, IDisposable`

Owns the per-session IUndoStack (registered scoped, so a new ColorBook scene = new stack).

// fields: IUndoStack _stack, IEventBus _bus
public sealed class HistoryController : IStartable, IDisposable {
    public bool CanUndo => _stack.CanUndo;
    public bool CanRedo => _stack.CanRedo;
    public event Action StateChanged;
    public void Undo();                              // _stack.Undo() + StateChanged
    public void Redo();
    // sub: DrawingSelectedSignal → _stack.Clear()
}

`HistoryButtonsView : MonoBehaviour` (UI)

Two big arrow buttons. Setters only.

public interface IHistoryButtonsView {
    event Action UndoClicked;
    event Action RedoClicked;
    void SetUndoEnabled(bool enabled);
    void SetRedoEnabled(bool enabled);
}

`HistoryPresenter` (UI)

Wires controller StateChanged ↔ view enable/disable; view click events → controller.

32.8 Feature — `Capture`

`CaptureController` (Systems)

The orchestrator behind the "Capture" button. Stateless other than guarding against concurrent captures.

// fields: ICaptureService _capture, IGalleryService _gallery, IEventBus _bus
public sealed class CaptureController {
    public bool IsCapturing { get; }
    public UniTask<SavedArtworkDTO> CaptureCurrentAsync(string templateId);
}
// pub: ArtworkCapturedSignal (mid-flow), ArtworkSavedSignal (post-save)

Flow: _capture.CaptureAsync() → _gallery.SaveAsync(bytes, templateId) → publish signals.
Concurrency: sets IsCapturing = true on entry; UI binds button enabled to !IsCapturing to prevent double-tap.
No camera or sprite args — capture reads IPaperRig.Surface directly inside the service.

`CaptureButtonPresenter` (UI)

Wires button click → CaptureController.CaptureCurrentAsync. Disables button while in progress. Shows toast on ArtworkSavedSignal.

32.9 Feature — `Progression`

`ProgressionService` (Systems) — implements `IProgressionService`

The only place that knows what "completed" means.

Persistence: delegates to IPersistenceService under key "progression".
Load order: AppBoot calls LoadAsync() early.
Save trigger: after MarkCompleted, debounced 500 ms to coalesce a burst of "Next" presses.

`ProgressionRepository` (Repository)

Pure in-memory holder used by the service. Separated so tests can inspect state without going through file IO.

32.10 Feature — `ColorBookFlow`

`ColorBookFlowController` (Systems) — `IStartable, IDisposable`

The only orchestrator inside the ColorBook scene. Drives the panel FSM: Catalog → Building → Coloring → Done.

// fields:
//   IEventBus _bus
//   IDrawingTemplateCatalog _catalog
//   ShapeBuilderController _builder
//   IColoringController _coloring
//   CaptureController _capture
//   IProgressionService _progression
//   ColorBookSceneRefs _refs        (panel roots to enable/disable)
//   Fsm<ColorBookState> _fsm

State table:

State	On enter	Triggers exit
`Catalog`	Show catalog panel	`DrawingSelectedSignal`
`Building`	`_builder.BuildAsync(id)`	`ShapeAssembledSignal`
`Coloring`	`_coloring.SpawnRegionsAsync(template)`	"Next" or "Capture" pressed
`Done`	Run autosave capture, mark completed, `Go(Catalog)` for next	always advances

"Next" sequence: _capture.CaptureCurrentAsync → _progression.MarkCompleted → _catalog.Release(current) → _catalog.LoadAsync(_catalog.NextUnseen(current)) → re-enter Building.

32.11 Feature — `ArtBook`

`GalleryPresenter` (UI) — `IAsyncStartable, IDisposable`

Lists artworks, opens fullscreen view, deletes, shares.

// fields: IGalleryService _gallery, IGalleryView _view, IExternalShareService _share, IEventBus _bus

Start: _gallery.ListAsync() → _view.SetItems(...).
Subscribes to ArtworkSavedSignal to live-refresh if the user pops back in.

`IGalleryView` (UI)

public interface IGalleryView {
    event Action<string> OnArtworkTapped;
    event Action<string> OnDeleteRequested;
    event Action<string> OnShareRequested;
    void SetItems(IReadOnlyList<GalleryItemVM> items);
    void ShowFullscreen(Texture2D full);
    void HideFullscreen();
}

`IExternalShareService` (Core)

Platform plugin shim (iOS Photos / Android MediaStore).

public interface IExternalShareService {
    UniTask SaveToCameraRollAsync(byte[] png);
    UniTask ShareAsync(byte[] png, string subject);
}

32.12 App Layer

`AppBoot` (App/Boot) — `IAsyncStartable`

Single entry point. Steps in section 29.

// fields: IAssetProviderService _assets, IPersistenceService _persist, IProgressionService _progress,
//         IAudioService _audio, ISceneService _scenes, BootConfig _cfg
public sealed class AppBoot : IAsyncStartable {
    public UniTask StartAsync(CancellationToken ct);
}

LifetimeScopes

RootLifetimeScope — section 21. Registers all services + IEventBus. Persists for app lifetime.
MainMenuLifetimeScope — registers MainMenuPresenter and view.
ColorBookLifetimeScope — section 21. Registers feature installers + ColorBookFlowController as entry point.
ArtBookLifetimeScope — registers GalleryPresenter + view + IExternalShareService.

All scope classes are thin: serialized fields for scene refs, Configure(IContainerBuilder) only.

32.13 Cross-cutting types

`ColorBookSceneRefs : MonoBehaviour` (App)

Aggregates all scene-bound Unity references that features need: Camera artCamera, Transform catalogRoot, Transform builderRoot, Transform coloringRoot, RectTransform hudRoot, ColorPaletteView paletteView, HistoryButtonsView historyView. Registered as a singleton in ColorBookLifetimeScope so features don't Find things.

`IInstaller` (App)

public interface IInstaller { void Install(IContainerBuilder builder); }

Implemented as ScriptableObject per feature so scopes can drag them in the inspector (section 22).

32.14 Class summary table

Class	Layer	Role	Key dependencies
`AppBoot`	App	Startup sequencer	assets, persist, progression, scenes
`RootLifetimeScope`	App	Root DI	configs
`ColorBookLifetimeScope`	App	Scene DI	scene refs, installers
`DrawingCatalogController`	Feature	Grid logic	catalog, bus
`DrawingCatalogPresenter`	Feature	UI bridge	view, controller, catalog
`ShapeBuilderController`	Feature	Piece spawn + snap tracking	catalog, factory, bus, cfg
`ShapePieceView`	Feature	Draggable piece MB	input, audio
`ColoringStateRepository`	Feature	Current color model	—
`ColoringController`	Feature	Region spawn + paint cmd	undo, state, factory, bus
`ColorRegionView`	Feature	Region sprite MB	—
`PaintRegionCommand`	Feature	Undoable paint	view, bus
`PaperRig`	Feature	RT + ArtCamera owner	—
`ArtInputBridge`	Feature	Screen→art-world picking	rig, raw image, ui cam
`PaperRigModule`	Feature	DI registration	rig, bridge
`HistoryController`	Feature	Undo/redo facade	undo stack, bus
`CaptureController`	Feature	Capture+save orchestration	capture svc, gallery, bus
`ColorBookFlowController`	Feature	Scene FSM	bus, catalog, builder, coloring, capture, progression
`GalleryPresenter`	Feature	Art book listing	gallery, share, view, bus
`BoundedUndoStack`	Lib	Capped undo store	—
`EventBus`	Lib	Pub/sub	—
`Fsm<TState>`	Lib	Generic FSM	—
`AddressableAssetProviderService`	Service	Addressables wrapper	—
`FileGalleryService`	Service	Gallery file IO	paths, thumb gen, bus
`RenderTextureCaptureService`	Service	PNG render from rig.Surface	paper rig
`JsonPersistenceService`	Service	Settings/progression IO	—
`SceneService`	Service	Async scene loads	—
`AudioService`	Service	SFX playback	assets
`ProgressionService`	Service	Completion tracking	persistence

If you add a class not in this table, add it here in the same PR. This table is the cheap mental-model index — keep it honest.

68 KiB Raw Blame History Unescape Escape

Color Book — Architecture Guide

1. Game Flow

2. Philosophy

3. Dependency Graph

Forbidden actions

4. Folder Structure

Per-feature folder layout

Asset folder parallel

5. Namespaces

6. Scenes & Lifetime Scopes

Boot chain

7. Rendering Strategy

Cameras

Layers

Why RT-as-paper

Multi-resolution rule

8. Core Contracts

Drawing

Coloring

Paper (RT rig + input bridge)

History

Gallery & Capture

Signals

9. Feature Responsibilities

DrawingCatalog

Paper

ShapeBuilder

Coloring

History

Capture

Progression

ColorBookFlow

ArtBook

10. Addressables Strategy

What ships through Addressables

What does NOT use Addressables

Group layout

Lifecycle

Remote groups (future)

11. Persistence

IPersistenceService (JSON / PlayerPrefs)

IGalleryService (file IO)

12. Capture Pipeline

13. Communication Rules

14. UI (MVP — Passive View)

Inspector bridge

15. Toddler UX Constraints

16. Testing

17. "Where do I put this?" Checklist

18. Open Questions / Future Work

19. Quick Reference — Feature ↔ Signal Map

20. Assembly Definition Map

21. LifetimeScope Concrete Sample

RootLifetimeScope (Boot scene, persists forever)

ColorBookLifetimeScope (per-scene, child of Root)

22. Installer Pattern — Concrete Coloring Sample

23. Command Pattern — PaintRegionCommand

24. CommandStack — Libs/CommandStack

25. View / Presenter Pair — Color Palette

View (MonoBehaviour, setters only)

Presenter (pure C#)

26. ShapeBuilder — Snap Algorithm

27. Rendering Order & Sorting

28. SavedArtwork JSON Schema

29. Boot & Error Handling

30. Setup Checklist (new dev, day one)

31. Quick Reference — Class ↔ Layer ↔ Asmdef

32. Class Reference (Detailed)

32.1 Core Contracts

IDrawingTemplate (Core/Drawing)

IDrawingTemplateCatalog (Core/Drawing)

IColorPalette (Core/Coloring)

ICommand & IUndoStack (Core/History)

IGalleryService (Core/Gallery)

ICaptureService (Core/Capture)

IPaperRig (Core/Paper)

IArtInputBridge (Core/Paper)

IProgressionService (Core/Progression)

IAssetProviderService (Core/Assets)

68 KiB

Raw Blame History

`DrawingCatalog`

`Paper`

`ShapeBuilder`

`Coloring`

`History`

`Capture`

`Progression`

`ColorBookFlow`

`ArtBook`

`IPersistenceService` (JSON / PlayerPrefs)

`IGalleryService` (file IO)

`RootLifetimeScope` (Boot scene, persists forever)

`ColorBookLifetimeScope` (per-scene, child of Root)

23. Command Pattern — `PaintRegionCommand`

24. CommandStack — `Libs/CommandStack`

`IDrawingTemplate` (Core/Drawing)

`IDrawingTemplateCatalog` (Core/Drawing)

`IColorPalette` (Core/Coloring)

`ICommand` & `IUndoStack` (Core/History)

`IGalleryService` (Core/Gallery)

`ICaptureService` (Core/Capture)

`IPaperRig` (Core/Paper)

`IArtInputBridge` (Core/Paper)

`IProgressionService` (Core/Progression)

`IAssetProviderService` (Core/Assets)

`IEventBus` (Libs/EventBus, also referenced from Core)

`AddressableAssetProviderService` (Services/Assets)

`FileGalleryService` (Services/Gallery)

`RenderTextureCaptureService` (Services/Capture)

`JsonPersistenceService` (Services/Persistence)

`SceneService` (Services/Scenes)

`AudioService` (Services/Audio)

`InputReaderSO` (Services/Inputs)

`BoundedUndoStack` (Libs/CommandStack)

`EventBus` (Libs/EventBus)

`Fsm<TState>` (Libs/FSM)

32.4 Feature — `DrawingCatalog`

`DrawingCatalogController` (Systems)

`DrawingCatalogPresenter` (UI)

`DrawingCatalogView : MonoBehaviour` (UI)

32.5 Feature — `ShapeBuilder`

`ShapeBuilderController` (Systems)

`ShapePieceView : MonoBehaviour` (Views)

`ShapePieceFactory` (Systems)

32.5b Feature — `Paper`

`PaperRig : MonoBehaviour, IPaperRig` (Rig)

`ArtInputBridge : MonoBehaviour, IArtInputBridge` (Input)

`PaperRigModule : MonoBehaviour, IServiceModule` (Installers)

32.6 Feature — `Coloring`

`ColoringStateRepository` (Repository)

`ColoringController` (Systems) — implements `IColoringController`

`ColorRegionView : MonoBehaviour` (Views)

`ColoringInputBinder` (Systems) — `IStartable, IDisposable`

`PaintRegionCommand` (Commands)

`ColorPaletteView`, `ColorPalettePresenter` (UI)

`ColorRegionFactory` (Systems)

32.7 Feature — `History`

`HistoryController` (Systems) — `IStartable, IDisposable`

`HistoryButtonsView : MonoBehaviour` (UI)

`HistoryPresenter` (UI)

32.8 Feature — `Capture`

`CaptureController` (Systems)

`CaptureButtonPresenter` (UI)

32.9 Feature — `Progression`

`ProgressionService` (Systems) — implements `IProgressionService`

`ProgressionRepository` (Repository)

32.10 Feature — `ColorBookFlow`

`ColorBookFlowController` (Systems) — `IStartable, IDisposable`

32.11 Feature — `ArtBook`

`GalleryPresenter` (UI) — `IAsyncStartable, IDisposable`

`IGalleryView` (UI)

`IExternalShareService` (Core)

`AppBoot` (App/Boot) — `IAsyncStartable`

`ColorBookSceneRefs : MonoBehaviour` (App)

`IInstaller` (App)