"Minimal scene: Sun, Skybox, Camera, Bootstrap"

• Giant hand-authored / generated .scene files drift from C# and fight hotload.
• Play starts with no light, no camera, or a Bootstrap that never runs.
• Scene JSON __type can't find your bootstrap class.

The proven pattern: the scene holds only what the editor needs to open a view; C# builds the rest in Bootstrap OnStart. Prefer runtime world-building over giant generated scene files for anything code must know about — hotloads better, no scene/code drift.

Custom components in scene JSON: __type is the plain class name when the class has no namespace. Keep bootstrap-referenced classes namespace-free.

Four GameObjects

Scene JSON details that matter: positions/rotations as strings ("x,y,z", quat "x,y,z,w"), every GO/component needs a unique __guid, Tags comma-separated.

Bootstrap order

protected override void OnStart()
{
    if (Scene.IsEditor) return;

    // 1. manager singletons (OnAwake publishes .Instance on Create)
    // 2. static world
    // 3. player
    // 4. camera / sun attachments
    // 5. UI — one GO: ScreenPanel + every PanelComponent
    // 6. game-state last — its OnStart runs after the world exists
}

Point .sbproj StartupScene at this scene (sbproj-title-ident-startup). Lifecycle details: component-lifecycle-onawake-onstart.

Editor Play only needs a camera and lights to present a frame; everything gameplay-owned stays in code where hotload replaces assemblies without rewriting megabytes of scene JSON. Namespace-free bootstrap types match how scene __type strings resolve.