# Conversation Summary (Jan 29, 2026)

## Goals and constraints
- User wants design suggestions only (no code changes) for refactoring `SphereLevel` into core architecture.
- Keep gameplay logic in projected 2D for now; 4D is future-facing and should not drive current implementation details.
- Prefer an approach that does not introduce "code smell" for 2D levels.

## Key decisions and conclusions
- **Projected 2D collisions** are acceptable; the game remains 2D at its core with spatial presentation layers.
- **Arrow effects** already spawn **after connection** via `EffectsFactory` and should continue to follow projected line points.
- **Obstacles** should remain 2D overlays under projected-2D rules (same as current Sphere behavior).
- **Clock in 3D** should remain a 2D overlay to match current Sphere behavior and maintain collision semantics.
- Avoid a mandatory "space mode" for 2D. Use an **optional spatializer** only when Dimension > 2.
- Spatializer can act as a **preset** that also owns **core behaviors**, with optional internal modifiers. (optional)

## Architecture options discussed
- **Option A (Optional Spatializer)** is preferred:
  - Keep existing `BaseLevel` rule classes (Standard/Clock/DarkMode/etc).
  - Add an optional spatializer only for Dimension > 2.
  - Spatializer owns projection, visibility/backface logic, overlays (equator), and rotation input.
  - 2D levels remain unchanged and bypass the spatializer entirely.
- **Option B (Level Modifiers)** was discussed as a more composable alternative:
  - Keep rules unchanged.
  - Add a list of `LevelModifier`s in data (e.g., SphereProjection, EquatorOverlay, RotationInput).
  - Only levels that need 3D/4D attach modifiers.
  - Requires ordering/dependency management between modifiers.

## Files referenced
- `Assets/Game/4-scripts/01-core/4-level/SphereLevel.cs`
- `Assets/Game/4-scripts/01-core/4-level/ClockLevel.cs`
- `Assets/Game/4-scripts/04-gameplay/1-mgrs/LevelMgr.cs`
- `Assets/Game/4-scripts/04-gameplay/2-cntrls/DotConnectionController.cs`
- `Assets/Game/4-scripts/07-effects/1-core/EffectsFactory.cs`
- `Assets/Game/4-scripts/07-effects/ArrowEffect.cs`