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

[IchNukeDichWeg]

Mephisto 3.x — a full revival of the 2.x base. Every site adapter was re-anchored against 2026 DOMs, the engine lineup was replaced, and detection moved from polling to events. Released builds: https://github.com/IchNukeDichWeg/Mephisto/releases

• Engines
  • Stockfish dev NNUE, Stockfish 18 / 18 Small NNUE, Stockfish 11 HCE
  • Fairy-Stockfish 14 NNUE — a bundled net per variant
  • Maia — the original human-like nets, 1100–1900 plus a community 2200
  • Maia-3 — one transformer conditioned on a rating you set live, 600–2600
  • Tetrarch — four-player chess, over native messaging
  • Remote / native engines — a real binary outside the browser, auto-launched by Chrome
  • Strength cap per engine, following that engine's real UCI_Elo range
• Four-player chess
  • Chess.com's 4-player variant, read straight to canonical FEN4
  • 14×14 panel board, corners cut, rotated so you are always at the bottom
  • Evaluation normalised to your team rather than flipping sign every seat
  • Teams mode only — the engine does not search free-for-all; the mode is read from the page and
    can be set by hand when that read is wrong
  • Autoplay on the analysis board as well as in a game
  • macOS, Linux and Windows setup (registry + DLL on Windows)
• Analysis
  • Continuous evaluation with multiple lines, each drawn as its own arrow
  • Opening explorer (lichess) with book moves on the board, and weighted book play. Lichess put
    that endpoint behind OAuth, so there is a field for a personal API token: their own site
    passes on a session cookie, but the explorer answers access-control-allow-origin: * to
    every origin except lichess.org's, and a wildcard forbids credentials, so no extension can
    use that route. The token is a password field, is dropped from an exported settings file,
    and appears in the diagnostics report only as set/not-set
  • Endgame tablebase, move confidence, eval history graph
  • Read a position off the screen — video, diagram, image — and follow it live
  • Playable panel board: click or drag to walk a line, with underpromotion
  • Game review — a finished game analysed on the extension's own page, from a PGN, a file, or a
    player's public Chess.com archive. Every position searched once, so before and after come from
    the same search; Lichess accuracy and the panel's own move-quality bands; alternate lines; an
    eval graph with the opening/middlegame/endgame boundaries; think time from the clock comments;
    openings named offline from a bundled CC0 table keyed by position, so transpositions name
    correctly; an optional Maia pass reporting where a move sat in the human model's own ranking,
    and a human-likeness report built on it; batch review pooling a player across every game in the
    file against one engine load; fair-play indicators with an overall estimate that says what it is
    worth, presented as measurements and never a verdict; and an export that clones the page with
    its styles inlined into one self-contained file
• Automated play
  • Autoplay with trusted clicks, human cursor travel and per-move timing
  • Premove, including double premove on forced lines
  • Humanize — move mix and quality thresholds tuned to a target rating, with the mix's own
    accuracy and average win-drop shown as you tune it
  • Clock mode and mirror time
  • Pace to clock — shrinks the simulated think pause and cursor travel when the clock is short,
    separately from clock mode, which paces the search
  • Manual mode, help mode, opponent mistake alerts
• Puzzles
  • Lichess puzzle database in IndexedDB: known solutions play with no search
  • Chess.com puzzle database as well — TCN and daily-archive rows — in a separate store, so a
    position is never answered from the other site's records
  • Rush, Storm, Racer, Training, BlitzTactics, ChessBase Tactics
  • A tunable pause before a database move's first click. It is the one move with no search in
    front of it, so nothing else lets the board finish animating before it is clicked
• Sites
  • Chess.com — including Play Bots, variants, and 4-player
  • Lichess — all variants, live and correspondence
  • TakeTakeTake — WebGPU canvas board, read through a MAIN-world probe
  • BlitzTactics, ChessBase Tactics
• Interface
  • Floating in-page panel that stays open while you play, in a closed shadow root
  • Two-tab layout, configurable hotkeys, compact mode
  • Fourteen languages, switchable live
• Page footprint
  • No web_accessible_resources; panel assets are streamed from the worker
  • Explorer and tablebase lookups issued from the service worker, not the page
  • De-branded MAIN-world probes
• Updating
  • Opt-in self-update from the releases page: the ~6 MB update archive is written into the
    extension's own folder in place, so the extension id — and every native-messaging
    registration made against it — survives
  • Once set up, the panel's own update notice becomes the install button
  • Off by default. The archive is unpacked and checked in memory first: an unexpected path, a
    version that disagrees with the release or a missing file means nothing is written at all
  • Two archives per release: the full one for a first install, the small one for an update
  • Every install is staged, backed up and undoable: Roll Back and Finish Interrupted Update, and
    the panel says once what changed
• Diagnostics
  • Copy Diagnostics puts the version, the bundled assets, the connected hosts, what was detected,
    why the last move was or was not played and the recent trace on the clipboard, with nothing
    identifying in it
  • The reason a move did not happen is shown in the panel rather than left silent
  • Worker cold starts are timed and persisted, so a slow start can be explained by the report even
    though the worker that was slow is long gone
• Various bug fixes, including two worth naming
  • The +/- buttons on the settings page dispatched only change, while the form layer
    persists a number field on input — so every stepper moved the value on screen and stored
    nothing, and typing into the same field always worked, which is what hid it
  • The build marker was a hand-maintained constant and had been wrong for four releases, so
    every bug report named a build that was not running; it reads the manifest now

Supersedes #33, which carries the earlier discussion (including @IazLur's anti-cheat notes and #34).