Mephisto 3.1.216 — four-player chess, under your control

Four-player chess gets its mode back under your control, and three things that quietly did nothing now work. If you're on 3.1.215 with automatic updates set up, the panel's update notice will install this one for you — that's the first time that path can be taken end to end.

Which download?

Archive	Size	Use it when
mephisto-3.1.216.zip	585 MB	First install — everything, engines included
mephisto-3.1.216-update.zip	5.9 MB	You already have Mephisto — extract over your existing folder

⚠️ Extract the update over your existing install, never into an empty folder — without the engines it cannot run. Extract in place: Chrome derives an unpacked extension's id from its folder path, so a new folder means a new id and re-running the native-host installer.

On 3.1.215 already? Neither archive. Click the panel's "Update available — click to install", or Settings → Updates → Install Update.

Four-player mode, set by hand

The mode was read from Chess.com's own mode label — a guess about someone else's markup — and it decides the rules the search runs under: promotion is the 8th rank in free-for-all and the 11th in Teams. When that guess was wrong the search was wrong, and there was no way to say so.

Mode now sits in the panel where Variant would be (hidden for Tetrarch anyway, so nothing grew a line): Auto-detect, Teams, Free-for-all. It's on the settings page too. Changing it re-analyses the position already on screen rather than waiting for the next move — the rules just changed, so waiting would keep searching under the ones you said were wrong. Switching back to Auto-detect re-detects rather than serving what was cached while it was forced.

Autoplay works on the analysis board

It was refusing every move there, silently. The guard only accepted /variants/…/game/<id>, and it exists to stop the extension clicking pieces around the lobby and the setup pages, where a board is drawn but there's nothing to play. The analysis board is neither of those — it's your own private board, so playing a line out on it affects nobody. It's allowed now; the lobby and setup pages stay excluded.

Found from a trace, not from reading: automove received {autoplay: true, moving: false} immediately followed by DROPPED: 4PC move outside a game url {path: '/variants/4-player-chess/analysis'}.

Help Mode drew nothing until somebody moved

The four-player lane skips the search entirely when the position hasn't changed, and only the Autoplay toggle cleared that — and only when it was being ticked. So turning Help Mode on asked for an arrow on the position already in front of you, which the dedupe had already decided not to redo. Both toggles clear it now, in both directions.

Four-player traces were hidden from the only person who could report them

bgLog goes quiet when the tab is focused and Premove is off, deliberately, so ordinary play doesn't fill the worker console. The effect on four-player chess was that every line naming why a move never reached the board was suppressed in exactly the situation being investigated: someone sitting in front of the board watching autoplay do nothing. Three sessions of that with nothing to go on.

4PC is one search per move, so there was never any volume to suppress. Its traces bypass the gate now, as do the automove guards for four-player moves — automove received prints autoplay, background_play, moving, visible and focused, which between them name every way a move can be dropped. Ordinary play is unchanged.

Noted while in there: tabActive() is visibility and document.hasFocus(), so opening DevTools on the game tab defers autoplay. Reading the console about autoplay not working stops autoplay. Turn on Background Play while debugging.

Smaller

• Tetrarch no longer offers an Elo slider. It speaks its own four-player protocol and has no UCI_Elo at all, so the control read "3190+ / Full Strength" and did nothing whatever you set it to. It was missing from both no-Elo lists, and the settings page had no such list at all — so it showed the field for every engine, including the Maia nets, whose strength is the net you pick rather than a cap.

Known limits

Free-for-all still isn't searched — Tetrarch implements Teams only, so forcing FFA tells you so rather than handing back a move scored under the wrong rules. The override exists for the case where detection says FFA and the board is actually Teams. The promotion picker is still yours to click, and elimination has still never been seen in a real game.