Sprite Sheet Pipeline Skill

Use this skill as a routing guide for the repo. Keep detailed rules in the project docs; read only the document needed for the current task.

Start Here

• Repo overview and folder map: README.md
• Copy-paste processing commands: docs/QUICKSTART.md
• Folder roles and cleanup rules: docs/WORKSPACE_CONVENTIONS.md
• Active pipeline contract and validation rules: docs/ANIMATION_PIPELINE_NOTES.md
• Frame extraction details: docs/FRAME_EXTRACTION.md
• Game-side usage assumptions: docs/INTEGRATION_GUIDE.md

Prompting Tasks

If the user asks to create an animation and provides only a still image, do not try to process the image directly through the cleanup pipeline. Reply in substance:

This pipeline is designed to process videos into sprite sheets. Would you like me to write a prompt for a video model based on the provided image and animation description?

Tailor the response to the user input. If they provided no animation description, ask what motion they want. If they provided no asset at all, check Videos/To Be Processed/ for queued videos before asking for a new source.

For a new character image, first pose, character reference, or transition frame, read docs/reference/PROMPTING_IMAGE_MODELS.md.

Default image-prompt goal:

• one full-body 2D game character
• animation-safe margins
• full weapon, hair, cape, cloth, and effects visible
• centered character
• flat exact #00FF00 background
• no shadow, floor, text, watermark, border, props, or background objects

For image-to-video, Kling, or source-footage animation prompts, read docs/reference/PROMPTING_VIDEO_MODELS.md.

Default video-prompt goal:

• uploaded image is the exact first frame
• footage is for 2D game animation, not cinematic video
• define an invisible core registration anchor, usually belt/pelvis/torso core
• keep that body anchor locked to the same screen-space point
• do not let the model center on weapon, cloth, hair, effects, or bounding-box extremes
• locked camera with no zoom, pan, rotation, cuts, or shake
• character remains registered/centered with all motion inside frame
• no horizontal screen travel
• flat exact #00FF00 background with no variation
• timestamped step-by-step visible motion
• preserve character design, anatomy, proportions, weapon, and 2D style

For image-to-video jobs, use the context-engineered prompt pattern in docs/reference/PROMPTING_VIDEO_MODELS.md: task, production context, subject scope, fixed registration rule, chroma matte rule, locked camera rule, character preservation, facing/framing rules, timestamped timeline, and failure conditions. Keep the reusable non-motion control block at 2500 characters or less and the motion description at 500 characters or less, including labels.

Return one copy-paste prompt by default. Include avoid/negative constraints inside that prompt unless the target tool explicitly has a separate negative prompt field.

Processing Tasks

Use the current frame-directory workflow. The source of truth is an animation video or ordered frame folder, not a generated grid sheet.

Normal processing order:

1. Put one source animation video in Videos/ or Videos/To Be Processed/.
2. Extract ordered PNG frames into work/extracted/<character>/<action>/.
3. Matte light/off-white backgrounds into work/matted/<character>/<action>/ when needed.
4. Build a horizontal 256 x 256 sprite strip with tools/animation_pipeline.py.
5. Review the preview PNG, individual cleaned frames, and JSON report.
6. Run node tools/serve_sprite_viewer.mjs and open the generated sheet with the Codex integrated Browser tool first. Use a regular desktop browser only after the integrated Browser tool is unavailable or fails. Do not use Playwright CLI as the default human review handoff path. After the server is running, include a Markdown link to the exact review URL in your response so Codex shows a Web preview card with an Open button. Use the link label open sprite viewer for normal review pages.
7. If vertical or horizontal alignment ran, open the server-hosted alignment review page instead of the plain sheet viewer, and include a Markdown link labeled open alignment review.
8. Promote only approved sheets and matching cell frames into Final Sprite Sheets/<GameName>/<CharacterName>/<animation>/.

Use --layout-mode preserve-canvas for normal video-derived animations. Use --layout-mode fit-foreground only for legacy recovery or an explicitly foreground-normalized export.

If the user does not specify a frame count, default to 24 frames. Pass --frames 24 to tools/animation_pipeline.py and use 24f_256 in output paths.

Validation And Promotion

Do not promote raw extracted frames. Promote only cleaned pipeline outputs.

Before promotion, verify:

• output sheet is exactly frames * 256 by 256
• report status is pass
• warnings have been visually reviewed
• no important source or final pixels are clipped
• preview order and timing feel correct
• apparent character scale stays consistent across animations
• final sheet and individual cell frames match exactly

When the hosted alignment review is used, Finalize saves the current working copy, promotes it into Final Sprite Sheets/<GameName>/<CharacterName>/<animation>/, writes exact matching individual frame cells, and opens the promoted sheet in the viewer.

After approval, move the source video to Videos/Processed/ and move non-promoted generated artifacts for that pass into Cleanup/.