It works like this: beside your normal communication, you can sign a "treaty", that is recorded and revealed at the end of the game beside the moves: it changes nothing about the game mechanics. After a game, when you click "maps", all maps appear with all moves and all alliances made and broken during every turn.

The treaty can be
A) Non-Agression Pact (with / without bounce(s))
B) Alliance (with / without bounce(s))
C) Alliance (Against: E/F/I/G/A/T/R / Including: E/F/I/G/A/T/R)
D) All agreements unilaterally dissolved
E) All agreements bilaterally dissolved
F) Included moves pact
G) Excluded moves pact

Two players can simply click the options, followed by a set of suboptions. In case of A and B you're recording the existence of an alliance or NAP into the game history. In case of C two players agree to attack X and it is recorded (X cannot know directly, to him this agreement is only revealed at the end), or to add X to the agreement. D means you unilaterally dissolve an alliance and send a standard message about it to your former ally, E proposes the dissolution with a standard message, which is subsequently confirmed by the ally if he agrees.

If you click F or G, a menu appears that has all possible moves by all players in it. You click the moves you agree on and send it to the other player. He/She confirms. In case of F the moves you won't move are denoted, in case of G the moves you will move are denoted. Obviously the agreements are not binding, you still make your own moves and you're perfectly free to submit an entirely different set of moves and your allies and opponents won't know until the end of the game who stabbed whom.

At the end of the game, the "Alliance History" is revealed and depicted next to every map. So now, instead of just looking at moves, you can see in big strokes which agreements were signed and broken. It will make a lot of things easier: people who like to play on their phones can very easily send and confirm deals. Sitters can take a look at the last map, their personal alliance history, and see how best to continue the previous player's plan. Same when the game is taken back by the person who left, he can immediately tend to the most dramatic changes. New players can use it as study material.