One drawing in. A game-ready sprite atlas out.

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Ask an image model for a "sprite sheet" and you know what you get: a character whose face changes every frame, a background that won't key out, poses that overlap and drift off-grid, and a PNG your game engine can't actually consume. Cute demo, useless asset.

sprite-gen is a Codex/Claude skill that closes that gap. Give it one base image and a list of actions — it drives the generation row by row, locks the character's identity, strips the chroma background to real alpha, extracts each pose as a clean transparent frame, and bakes a runtime atlas with a machine-readable manifest.json.frame_layout. Every sprite above was made this way.

And for the last 10% that generation never gets right, there's a curation webview: compare frames side by side, reject the broken ones, nudge rotation/scale/position non-destructively, watch the loop live — then bake. The pipeline does the labor; you keep the taste.

sprite-request.json → layout guides + prompts → image-gen state rows
→ chroma alpha → connected components → transparent frames
→ sprite-sheet-alpha.png + manifest.json.frame_layout

• A transparent sprite atlas (sprite-sheet-alpha.png) — real alpha, no leftover chroma fringe, verified against white backgrounds.
• A runtime manifest (manifest.json.frame_layout) — absolute frame rectangles, per-state fps and loop flags. Your engine samples rectangles; it never guesses a grid.
• QA you can watch — per-state GIFs and contact sheets, so motion is judged as motion before anything ships.
• Honest labels — short readable actions (idle, jump, attack, wave) are the stable path; cyclic locomotion (walk/run) is marked experimental unless motion QA actually passes. No silent overpromising.

Generation gets you 90%. The webview is where a human takes it to shipped — standalone, no Studio or framework dependency, runs anywhere the skill is installed (Claude Code Desktop, the Codex app, a plain terminal).

• Compare frames side by side per state, and select / reject individual frames.
• Non-destructive transform per frame: drag = move, wheel = scale, top handle = rotate, bottom-left handle = shear. Edits live in a curation.json sidecar — source PNGs are never rewritten, and the compose step bakes the result deterministically. Preview and bake share one affine matrix, so what you align is what you get.
• Live preview animates the selected frames at the state's fps.
• Not just for sprites: point it at any folder of image candidates (icons, logos, generated drafts) with unpack_atlas_run.py --pngs-dir and use it as a general pick-the-winner view.

For isometric sets, the webview overlays the floor grid (from meta.json tile/anchor) so you can snap furniture to the diamond axes with the shear handle.

The webview ships with English and Korean. Pass --lang en|ko when launching, or use the in-app toggle:

python3 scripts/serve_curation.py --run-dir <run-dir> --lang en   # or ko

# 0. install dependencies (Pillow) into a fresh virtualenv
python3 -m venv .venv && source .venv/bin/activate
pip install -e .

# 1. prepare a run from a base image
python3 scripts/prepare_sprite_run.py --out-dir <run-dir> --character-id <id> --base-image base.png

# 2. generate one row image per state with image-gen, save as raw/<state>.png
# 3. extract frames
python3 scripts/extract_sprite_row_frames.py --run-dir <run-dir>

# 4. (optional) curate frames in the webview
python3 scripts/serve_curation.py --run-dir <run-dir>

# 5. bake the runtime atlas
python3 scripts/compose_sprite_atlas.py --run-dir <run-dir>

When only the combined sheet survives, rebuild a curator-ready run dir, then curate and export:

# rebuild frames: explicit --grid, --manifest rectangles, or alpha auto-detect (default)
python3 scripts/unpack_atlas_run.py --atlas sheet.png            # auto-detect
python3 scripts/unpack_atlas_run.py --manifest manifest.json     # exact rectangles
python3 scripts/unpack_atlas_run.py --pngs-dir furniture/        # import a loose PNG set

# after curating, bake corrections back to named PNGs
python3 scripts/export_curated_pngs.py --run-dir <run-dir>

Output defaults to a findable <source>-curator folder next to the input.

The full agent-facing workflow and contracts live in SKILL.md.

From Codex skill installer workflows, install this repository as a root skill:

python3 ~/.codex/skills/.system/skill-installer/scripts/install-skill-from-github.py \
  --repo aldegad/sprite-gen --path .

The component-row workflow is inspired by the Apache-2.0 licensed hatch-pet skill, but targets generic game sprite atlases and includes no pet packages or pet visual assets.

Apache-2.0