# Sichuan Mahjong — licensing

Two licences apply to this project: **MIT** for the code, and **CC BY-SA 4.0**
for the tile artwork. Section 3 states what that means for the compiled release
binary, which contains both.

---

## 1. Code — MIT

MIT License

Copyright (c) 2026 the Sichuan Mahjong contributors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

---

## 2. Tile artwork — CC BY-SA 4.0

The 27 suit tiles in `packages/client/public/tiles/` — `man-1`…`man-9`,
`pin-1`…`pin-9`, `sou-1`…`sou-9` — come from the Wikimedia Commons category
[SVG Planar illustrations of Mahjong tiles][commons].

- **Author:** Cangjie6 (primary); Jerry Crimson Mann (original);
  User:Dewclouds (vectorisation)
- **Licence:** [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/)
- **Changes:** the files are renamed (`MJw1-.svg` → `man-1.svg`, and so on) and
  are otherwise used as published. Per-file attribution, including each file's
  upstream name and Commons URL, is in
  [`packages/client/public/tiles/credits.json`](packages/client/public/tiles/credits.json).
- **Obtained via:** [*Mahjong: a Visual Guide*](https://themahjong.guide/), which
  is where the files were downloaded from. That is provenance, not licensing —
  the attribution above is owed to the Commons authors, and each file's
  `wikimediaUrl` in `credits.json` is the evidence for it.

`back.svg` is an original work for this project, drawn to match the dimensions
and border of the Cangjie6 set. It is MIT, like the code.

[commons]: https://commons.wikimedia.org/wiki/Category:SVG_Planar_illustrations_of_Mahjong_tiles

---

## 3. The release binary is a combined work, and ships both licences

The standalone binaries built by `scripts/release/compile.ts` base64-embed the
whole built client — the 27 CC BY-SA tiles included — into the executable. That
is deliberate: a single self-contained file is the point of that build, and
splitting the art back out would mean shipping a folder beside every binary.

So a release binary is a combined work. **The MIT terms in section 1 cover its
code; the CC BY-SA 4.0 terms in section 2 cover the tile artwork inside it, and
travel with it.** Anyone redistributing a binary is redistributing the artwork
and takes on the section 2 attribution obligation. The binary carries the
attribution needed to satisfy it in three places, so it is never separated from
the art:

- `sichuan-mahjong --credits` prints it to the terminal,
- the in-app About screen states it in all three UI languages, and
- `/tiles/credits.json` is served with the per-file detail.

Nothing here restricts the code: the engine, server and client sources remain
MIT, and a build that omits `tiles/` carries no CC BY-SA obligation at all. The
npm package and the from-source path serve the tiles from disk as ordinary
files and are unaffected either way.


Tile artwork: https://github.com/zddd312/mahjong-tiles
本素材沿用两个来源共同采用的「M+ 字型授权条款」发布。

這些字型爲自由軟件，您可以自由使用、複製和分發它。不論是否修改過它，不論作爲商業使用還是作爲非商業性使用，都是許可的。我們按照這些字型的「現狀」釋出它們，然而我們並無責任確保這一點。

These fonts are free softwares. Unlimited permission is granted to use, copy, and distribute it, with or without modification, either commercially and noncommercially. THESE FONTS ARE PROVIDED "AS IS" WITHOUT WARRANTY.

これらのフォントはフリー（自由な）ソフトウエアです。あらゆる改変の有無に関わらず、また商業的な利用であっても、自由にご利用、複製、再配布することができますが、全て無保証とさせていただきます。

（条款原文里的「字型」在这里指本仓库中的牌面图片与 SVG 源文件。）

来源 / Sources:
- lietxia/mahjong_graphic — https://github.com/lietxia/mahjong_graphic
- I.Mahjong by 內木一郎, based on GL-MahjongTile (Gutenberg Labo) — https://github.com/SyaoranHinata/I.Mahjong