[Vatsal2005]

What and why

Convert a finite orthogonal Tiled JSON map into the docs/13 collision schema so Lex can draw collision over the stage instead of editing coordinate arrays. All eleven object layers map to the existing contract. Reference image layers are ignored; no art files were generated or changed in this PR.

Issue

Closes #92

Acceptance criteria

• python scripts/collision_from_tiled.py <export.tmj> writes art/stages/<region>/<chunk>.<state>.collision.json
• Supports walk, slide, one-way, ledge, climb, solid, no-go, hazard, interact, spawn, glide-lift
• Rejects unknown collision layers, open/degenerate boxes, out-of-bounds points; also rejects rotated shapes, fractional/non-finite pixels, duplicate IDs and invalid metadata
• Hand-authored Tiled fixture and CLI tests

Verification

• py -3.13 -m unittest discover -s scripts -p "test_*.py" — 30 tests pass, including 14 converter tests
• py -3.13 scripts/check_docs.py — 382 files pass
• git diff --cached --check
• CLI test copies the script into a temporary repository root, writes the expected path, and verifies a malformed layer exits 1 with a useful error
• Invalid input leaves existing output intact
• Compatibility against all six collision files from PR feat: add Rusty Creek collision with a reach checker #97 at d02f76800704cf88945e4c78b8c260e804e4d214: authored JSON → synthesized Tiled 1.12 JSON → this converter reproduces every field and value exactly. Custom pickup item, spawn patrol, and trigger note metadata are retained. Typed list entries are decoded to plain arrays; custom properties cannot override geometry.
• Real Tiled UI export and runtime debug-overlay comparison — feat: add Rusty Creek collision with a reach checker #97 currently provides hand-authored collision JSON, no .tmj; runtime overlay belongs to [M1-S6] Load collision annotation per chunk, with a debug overlay #34

Game files are unchanged and the scaffold is still pending in #94, so there is no game build on this independent branch.

Authoring setup / question

The existing collision schema stays unchanged. Destination metadata was unspecified: this implementation reads string map properties region, chunk, state. Example: rusty-creek, rc-0-0, anomaly. Is that acceptable for Lex's Tiled files? The CLI help documents this setup. kind, id, and hazard damage are object properties; an object's name can supply its ID. Box layers use Tiled rectangles, not polygons or polylines. Image layers can show the composed stage as a backdrop. Other object custom properties are preserved. Lists use Tiled 1.12 typed list properties, e.g. a patrol list containing two integer items. No implicit JSON-string parsing is performed.

Screenshots

No visible game change. Real overlay evidence remains pending the annotation and #34.

[arudaev]

Lane A answers (Alexander + Claude).

1. Map properties region, chunk, state: accepted. Lex has left the team, so collision is now authored in lane A, and this setup works for us. Chunk ids are grid positions (rc-0-0, hg-0-0). Each region's chunks.json (feat: add Rusty Creek collision with a reach checker #97) maps them to the art, so region is the folder name under art/stages/.
2. Round-trip check against feat: add Rusty Creek collision with a reach checker #97: thank you. That's exactly the compatibility we need. item, patrol and note are deliberate additive fields, as the docs/13 contract allows.
3. The unchecked "real Tiled export" box is fine. feat: add Rusty Creek collision with a reach checker #97 and [3/4] feat: add the Hidden Garden collision and Dexter's waypoints #106 were written directly as JSON, and the next region's collision will go through Tiled and this converter.

No changes needed here. It's ready for Alexander to merge.