Build Game Backgrounds

Portable layered-background pack: sources, camera contract, hashes, composite, and scrolling proof agree.

Workflow

1. Define the scene contract before generating art.

   • Canvas size, aspect ratio, horizon, focal safe zone, layer order, depth, parallax factors, repeat behavior, style fingerprint.
   • This skill: background planes. Animated sprites/atlases → $spritesheet-expert; isolated props → $build-static-game-assets.

2. Generate or import the layers.

   • $imagegen default for new user-facing bitmap art. Load $grok-imagine only when Grok stills are selected explicitly. Provider creates semantic pixels; deterministic code may assemble, scroll, measure seams, and render proof — not paint replacement production scenery.
   • Full-bleed scene layers keep authored scene pixels; no forced neutral matte. Isolated transparent overlay: generate on flat gray, black, or white; model-backed removal when connected-matte removal threatens subject colors. Never request new green, blue, cyan, or magenta chroma.
   • Grok: review --dry-run first; --ack-run only with explicit current-task consent. Video animation → $spritesheet-expert; this skill accepts still layers.
   • Every source below one pack root. Portable relative paths; SHA-256 per layer.
   • Provenance per layer: Imagegen, Grok still, imported, or fixture. Fixtures may exercise composition and seam gates but are not representative art.
   • Keep sky, far, mid, near, foreground, overlay, and effects roles explicit. Do not bake gameplay-critical objects into a background without naming the tradeoff.
   • Composition, continuity, depth, or requested semantics fail: regenerate the affected provider layer. Edge harmonization may touch only a narrow provider-derived repeat band and must retain the original hash — not become procedural replacement art.

3. Write background-pack.json against references/schemas/background-pack-v1.schema.json.

   • Require schema_version, kind, pack_id, style_fingerprint, canvas, camera, and layers.
   • Reject duplicate order/depth ambiguity, hash drift, missing sources, unsafe paths, invalid safe zones, or incompatible dimensions.

4. Validate and generate deterministic proof.

python scripts/validate_background_pack.py --pack <pack-root>/background-pack.json --root <pack-root>

Writes qa/background-pack-report.json, qa/background-composite.png, and qa/background-scroll.gif atomically. Installed skill directory: python -m pip install -r requirements-runtime.txt when preflight reports a missing module.

5. Inspect the actual composite and scrolling preview.
   • Seams, focal readability, horizon stability, parallax order, crop behavior, contrast behind gameplay, repeated-edge continuity.
   • Composite proves layer order and framing. Scrolling GIF proves declared offset/repeat behavior. Inspect both; one cannot substitute for the other.
   • Fix source or contract; rerun. Do not approve from JSON alone.

Completion Contract

Done: validator exit 0; current input/provenance hashes; representative true; portable paths; report cites current proof hashes; both proof images inspected. Fixture reports may pass technical checks, not production completion. Keep prior proof if contract validation fails.

Resources

• scripts/validate_background_pack.py: validation and proof CLI.
• scripts/background_pack/: schema and semantic validation.
• references/schemas/background-pack-v1.schema.json: pack contract.