Clean-room policy

mocanvas is an original work. It is shaped like tldraw so that projects can migrate, but it is not derived from it.

Rules for contributors (human or agent)

1. Never open tldraw source. Not the GitHub repository, not a copy in some node_modules, not a fork, not a gist of it. This includes reading it "just to check how they did X".
2. Allowed inputs: the public API reference and guides on tldraw.dev, blog posts, conference talks, sample .tldr files produced by the app, and your own knowledge of computational geometry, rendering, and reactive systems.
3. What compatibility means here: the same names for public types, methods, record fields, style values and file-envelope fields where that makes migration mechanical. Names are not copyrightable expression (Google v. Oracle, 2021). Implementation is written from first principles.
4. No branding. No tldraw logos, watermarks, product names, company names, links to their services, or their asset URLs anywhere in the codebase. The only permitted literal is the .tldr envelope field tldrawFileFormatVersion, which is part of the file format we read and write.
5. Dependencies must be MIT, Apache-2.0, BSD, ISC, CC0 or 0BSD. Check the license before adding a crate or npm package. cargo deny and license-checker run in CI.
6. Vendored third-party assets follow rule 5 and must be listed in NOTICE. Artwork, fonts and data copied into this repository rather than installed count here even though no package manager sees them. Record where the material came from, at which version, and by which script — and never vendor material whose licence rule 5 would not have allowed as a dependency. The icon set's Phosphor artwork is the worked example.
7. If in doubt, name it differently and add an alias in the compat package.

The one exception: apps/bench

apps/bench is a private, never-published benchmark harness. It is the only place in this repository that may depend on tldraw, name it, or read its .d.ts declaration files, and it does so purely to drive the other library through its public API so the two can be measured and their rendering compared.

The exception is bounded:

• apps/bench is "private": true and is never published.
• Nothing under packages/** or apps/playground may import it, import tldraw, or mention it.
• Reading tldraw's implementation (bundled .js/.mjs, or its source) is still forbidden there. Declaration files and public documentation only.
• No code is copied in either direction. The fixture in apps/bench/public/compare.tldr is data produced by running the other library, which is exactly the kind of sample document rule 2 permits.
• License tooling (license-checker, cargo deny) must therefore exclude apps/bench rather than have rule 5's allowlist relaxed for everyone.

Where the compat surface is documented

docs/COMPAT.md lists every public symbol that intentionally matches, and every one that intentionally differs, with the migration note.