/trade

• /trade <player>

  Sends a trade request to that player. Also available as /mxt trade <player>.

Once the other player accepts, both sides get a trade window: each puts items into their own offer and presses Accept to agree to that offer.

An acceptance is bound to the offer as it stood. If either side changes their offer after confirming (taking an item out, putting one in, shift-clicking, changing a count), both acceptances are cleared and have to be given again; the trade settles only when both sides have accepted the same offer — so nobody can swap items in after the other side has agreed.

Closing the window ends the trade: pressing Esc, having another screen replace it, or the server closing it all return the items in both offers to their owners, and neither side stays stuck "in a trade".