# Pocketjs Gba Imagegen

> Generate original GBA-friendly pixel-art asset source sheets through Codex app-server and ImageGen, then save PNGs for PocketJS AOT asset baking. Use when a local coding agent needs reusable tiles, 16x16 character sprites, RPG item icons, or generic Game Boy Advance-style pixel art through the shared Codex image generation path.

- Skill: `pocket-stack/pocketjs-gba-imagegen` (Agent Skill)
- Install (CLI): `npx skillmds@latest add pocket-stack/pocketjs-gba-imagegen`
- Raw SKILL.md: https://api.skillmd.com/api/skills/pocket-stack/pocketjs-gba-imagegen/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: pocket-stack (https://skillmd.com/u/pocket-stack)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/pocket-stack/pocketjs-gba-imagegen

---


# PocketJS GBA ImageGen

## Overview

Use this skill when a PocketJS or local Codex agent needs GBA-class pixel-art source images without hand-driving the built-in ImageGen tool. The standard entrypoint is `bun imagegen`; it starts a temporary Codex app-server on localhost, sends a single ImageGen turn, captures the `image_generation` result from the app-server event stream, and writes the PNG requested by `--out`.

The prompt is intentionally generic to the platform category. It must not ask for a specific existing game, franchise, creature, character, logo, or visual style clone.

## Standard Workflow

1. Confirm the target branch and local changes:

```text
git status --short --branch
```

2. Generate a source sheet with the Bun TypeScript CLI:

```text
bun imagegen --out aot/demo/imagegen/gba-source.png
```

3. Add an art-direction seed only when the user asks for one:

```text
bun imagegen --out aot/demo/imagegen/rainy-port-source.png --theme "rainy port town with stone quays and lanterns"
```

4. Use `--json` when another coding agent needs machine-readable output:

```text
bun imagegen --out /tmp/gba-sheet.png --json
```

5. If replacing the AOT demo source sheet, rerun the deterministic extractor:

```text
bun aot/demo/imagegen/build-assets.ts
```

## Prompt Profiles

Use `--kind sprite-sheet` for the default mixed source sheet: terrain cells plus one generic four-direction walking character.

Use `--kind tileset` for top-down background terrain and props.

Use `--kind character` for one 16x16-style walking sprite with down/up/left/right facings and two walk frames per facing.

Use `--kind items` for small RPG item icons that remain readable as 16x16 sprites.

## Constraints

- Keep all command wrappers in Bun TypeScript. Do not add native shell scripts for this workflow.
- Generate original assets only; avoid franchise terms and existing character references.
- Keep the output as a source sheet on a neutral background with gutters so later scripts can crop or quantize it.
- Treat the generated PNG as source art. The AOT runtime still requires deterministic 4bpp extraction before the image can ship as cartridge data.