game-sprite-pipeline

# Game Sprite Pipeline Local-first AI sprite generation. One skill, four modes behind `--mode`: - `portrait` — single full-body character PNG (road-to-aew wrestlers, card-game characters). - `portrait-loop` — 2×2 = 4-frame subtle idle (breathing + blink) at 200ms/frame in ONE Codex call. Animated portraits without re-prompting new poses. - `spritesheet` — animated multi-frame grid with connected-components detection, ground-line anchor alignment, and Phaser atlas output. - `spritesheet --per-row` — row-strip generation: each animation state generated as a separate strip with layout guide grounding and identity lock, then composited into a final sheet. Eliminates cross-row contamination and reduces retry scope from whole-sheet to single-row. Backend chain (per ADR-198): Codex CLI imagegen is the default when installed and authed. When Codex is unavailable AND `GEMINI_API_KEY` (or `GOOGLE_API_KEY`) is set, the skill falls back to Nano Banana via `nano-banana-builder`'s scripts. When neither is available, the skill fails loud with `BackendUnavailableError` listing both fix paths. Both paths use keys the user already holds — there is no third-party billing the toolkit hides. Reference implementation of the "Local-First, Deterministic Systems Over External APIs" principle in `docs/PHILOSOPHY.md` (user-owned-key clause). ## When to use | User says | Mode | Entry script | |-----------|------|--------------| | "generate a wrestler portrait" | `portrait` | `portrait_pipeline.py` ...