Mephisto 3.x — 2026 site adapters, modern engine lineup, four-player chess

.gitattributes

@@ -1,2 +1,12 @@
 *.dat.gz filter=lfs diff=lfs merge=lfs -text
 *.nnue filter=lfs diff=lfs merge=lfs -text
+
+lib/engine/stockfish-dev/*.nnue -filter -diff -merge -text
+lib/engine/stockfish-18-small/*.nnue -filter -diff -merge -text
+lib/engine/stockfish-18/*.nnue -filter -diff -merge -text
+lib/engine/stockfish-17-79/*.nnue -filter -diff -merge -text
+lib/engine/fairy-stockfish-14/nnue/*.nnue -filter -diff -merge -text
+
+# README screenshots: they belong on GitHub, not inside the installed extension --
+# keep them out of the release zip (git archive honours export-ignore).
+docs/ export-ignore

.github/ISSUE_TEMPLATE/bug.yml

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+name: Something is broken
+description: A bug, a site that stopped working, an engine misbehaving — no diagnosis needed.
+labels: [bug]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        You don't need to know what caused it. Several of the worst bugs here were silent rather
+        than loud — autoplay skipping a move with nothing logged, an engine that never loaded — so
+        "it did nothing" is a real report, not a vague one.
+  - type: textarea
+    id: what
+    attributes:
+      label: What happened?
+      placeholder: It stopped playing moves on lichess this morning. Panel showed a move, nothing clicked.
+    validations:
+      required: true
+  - type: input
+    id: version
+    attributes:
+      label: Version
+      description: Shown at the top of the extension's settings page.
+      placeholder: "3.1.200"
+  - type: input
+    id: where
+    attributes:
+      label: Site and browser
+      placeholder: chess.com, Chrome 141 on Windows 11
+  - type: dropdown
+    id: windows-4pc
+    attributes:
+      label: Is this the Windows four-player setup?
+      description: >
+        If so, which stage failed? Native-messaging failures on Windows are silent — Chrome reports
+        the host as unavailable and says nothing about why — so the stage is most of the diagnosis.
+      options:
+        - "No, not four-player on Windows"
+        - "1. setup.sh does not produce build/tetrarch.dll"
+        - "2. `from tetrarch import core` raises"
+        - "3. `python uci.py` does not answer `go` in a terminal"
+        - "4. Engine works in a terminal, but the panel cannot find it"
+  - type: textarea
+    id: console
+    attributes:
+      label: Anything in the console?
+      description: >
+        Optional. Right-click the page → Inspect → Console, and for the worker, chrome://extensions
+        → Mephisto → "service worker". Paste whatever looks relevant.
+      render: text

.github/ISSUE_TEMPLATE/config.yml

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+# Freeform issues stay enabled on purpose: "it did nothing this morning" is a useful report, and a
+# required-fields form is a good way to lose it.
+blank_issues_enabled: true

.github/ISSUE_TEMPLATE/idea.yml

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+name: Idea or request
+description: A feature, a site to support, an engine to add, or just a thought.
+labels: [idea]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Most of what's in here exists because something was annoying in a real game. Half-formed is fine.
+  - type: textarea
+    id: idea
+    attributes:
+      label: What would you like?
+    validations:
+      required: true

.gitignore

@@ -1,2 +1,5 @@
 .idea
 .DS_Store
+
+__pycache__/
+*.pyc

LICENSING.md

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+# Licensing
+
+This project bundles third-party engines, neural networks, and libraries under several
+licenses. Because some of those components are copyleft, the licensing of the project as a
+**whole distribution** is not simply the MIT license in [`LICENSE`](LICENSE). Please read this
+file before redistributing.
+
+## Short version
+
+- The **original Mephisto source code** (by Alexandru Petrusca) and this fork's own source-code
+  changes are made available under the **MIT License** — see [`LICENSE`](LICENSE).
+- However, the project **bundles and distributes** components licensed under **GPL-3.0**
+  (Stockfish, Fairy-Stockfish, and their NNUE nets; the Maia-1 nets and the Maia 2200 net) and
+  under **AGPL-3.0** (the Maia-3 model, and this project's Maia-3 encoder which is derived from
+  the Maia-3 source).
+- Because AGPL-3.0 is the strongest copyleft here and it is one-way compatible with GPL-3.0, the
+  **combined work as distributed (the released .zip / the installed extension) is governed by the
+  GNU Affero General Public License, version 3** — see [`licenses/AGPL-3.0.txt`](licenses/AGPL-3.0.txt).
+  The GPL-3.0 text is included at [`licenses/GPL-3.0.txt`](licenses/GPL-3.0.txt).
+
+MIT-licensed code stays MIT-licensed (MIT is compatible with, and may be included in, an
+AGPL/GPL work); the copyleft obligations attach to the combined distribution.
+
+## What that means if you redistribute
+
+If you distribute this project (or a modified version), the AGPL-3.0 / GPL-3.0 terms require you to:
+
+1. **Keep the license texts and notices.** Ship `LICENSE`, `LICENSING.md`, `THIRD-PARTY-NOTICES.md`,
+   and `licenses/` intact, and preserve the copyright/permission headers inside the bundled files.
+2. **License your combined work under AGPL-3.0** and make **complete corresponding source** available
+   to the people you distribute to (this repository is that source for the JavaScript; see
+   `THIRD-PARTY-NOTICES.md` for where to obtain the source of the compiled engine binaries and of the
+   neural-network models).
+3. **Do not add further restrictions** beyond those the licenses allow.
+
+## Corresponding source
+
+- This Git repository **is** the corresponding source for all of the project's own JavaScript/HTML/CSS.
+- The **Stockfish** and **Fairy-Stockfish** engines are shipped as pre-compiled WebAssembly. Their
+  corresponding C++ source, and the source used to produce the WebAssembly builds, are available from
+  the upstream projects listed in `THIRD-PARTY-NOTICES.md`.
+- The **Maia** neural networks (Maia-1, Maia 2200, Maia-3) are trained models. Their training code,
+  and where applicable the model weights in their original form, are available from the upstream
+  projects listed in `THIRD-PARTY-NOTICES.md`.
+
+## Note on AGPL-3.0 §13 (network use)
+
+The Maia-3 component is AGPL-3.0, whose §13 requires that users **interacting with a modified version
+over a network** be offered its source. In this project Maia-3 runs **locally in the user's own
+browser** (an offscreen document); it is not offered as a network service. §13 is therefore not
+expected to be triggered by ordinary use of this extension. The ordinary copyleft obligations above
+(source-on-distribution, license text, no added restrictions) still apply because the model and its
+derived code are distributed.
+
+*This file is a good-faith summary, not legal advice. If in doubt, consult a lawyer or the individual
+upstream licenses.*