---
id: PLN-0102
ticket: real-render-worker-establishment
title: Introduce Game2DFrameComposer Logical Service
status: done
created: 2026-06-06
completed:
ref_decisions: [DEC-0032]
tags: [runtime, composer, game2d, platform]
---

## Objective

Introduce `Game2DFrameComposer` as the logical-side service/facade for Game2D frame preparation.

## Background

`DEC-0032` states that `bind_scene`, `set_camera`, `emit_sprite`, and `close_game2d_packet` are logical frame preparation, not physical backend behavior.

## Scope

### Included

- Define a `Game2DFrameComposer` facade.
- Move or wrap existing `FrameComposer` behavior under logical-side naming.
- Migrate composer syscalls to use the facade rather than generic hardware.

### Excluded

- Do not rewrite scene cache internals.
- Do not move viewport cache across threads.
- Do not implement worker.

## Execution Steps

### Step 1 - Define composer facade

**What:** Add `Game2DFrameComposer` trait or service contract.
**How:** Include `begin_frame`, `bind_scene`, `unbind_scene`, `set_camera`, `emit_sprite`, `close_game2d_packet`, and required read checks.
**File(s):** `crates/console/prometeu-hal/src/platform.rs` or composer-specific HAL module.

### Step 2 - Implement using current composer

**What:** Make current local driver composer satisfy the new logical service.
**How:** Reuse `FrameComposer` implementation under adapter/implementation.
**File(s):** `crates/console/prometeu-drivers/src/frame_composer.rs`, `crates/console/prometeu-drivers/src/hardware.rs`.

### Step 3 - Migrate composer syscalls

**What:** Dispatch composer syscalls through `Game2DFrameComposer`.
**How:** Remove dependency on `HardwareBridge` methods for composer.
**File(s):** `crates/console/prometeu-system/src/services/vm_runtime/dispatch.rs`.

## Test Requirements

### Unit Tests

- Composer facade closes packets equivalent to previous `FrameComposer`.
- Invalid scene/bank behavior remains unchanged.

### Integration Tests

- Existing scene/composer runtime tests pass.

### Manual Verification

- Composer syscalls no longer require `&mut dyn HardwareBridge`.

## Acceptance Criteria

- [ ] `Game2DFrameComposer` exists as logical service/facade.
- [ ] Composer syscalls route through it.
- [ ] Existing Game2D scene rendering remains correct.

## Dependencies

- `PLN-0098`.
- `PLN-0101`.

## Risks

- Scene cache ownership can be accidentally moved too early. Keep cache behavior local while changing the boundary.