Contributing

Language: Rust only. No JavaScript or TypeScript. On the web, wasm-bindgen generates a small loader; never hand-write JS.
Licence: contributions are MIT OR Apache-2.0 (workspace default; see plan/ for the pending licence decision).
Clean-room: do not copy code, shaders, icons or other assets from proprietary software (Photon Studio, Photoshop). Match behaviour and look by observation and public specs. Only use assets with permissive licences, and record them next to the asset (e.g. assets/fonts/OFL-*.txt, assets/icons/LICENSE-lucide.txt).
Commands, not handlers: new features are engine commands with tests, and the UI calls them.
Layering: cargo xtask layers must pass. Register new crates in xtask/src/layers.rs.
Tests: required for every change. Format code needs round-trip and malformed-input tests.
Style: cargo fmt, and cargo clippy -- -D warnings. Match surrounding code. Comments explain why.
UI: use theme::Tokens and widgets::*. Verify visually through the control channel before submitting, and attach before/after screenshots to PRs.
Commits: small, focused, with a clear subject line.