i have already turned a few offers of people wanting to trade items [or Chrono for items], mainly sense there is no real direct trading tool in place, meaning someone needs to go first, and i don't feel comfortable to ask the other to go first when i don't want to....
this can be implemented in a few ways, as its a bit tricky, and you need to be careful, sense you don't want it to be exploited, like as endless inventory, or scams, or other things like that.... [and also you want it to work even for 2 people that play in different hours]
so what i suggest is this, in the bank, you can send a direct trade offer to someone, offering them a list of things [like a sword, 50 Chrono, and 10k crowne], when you do, all the items are taken from your inventory into that trade offer, and the space they take is calculated from the bank space.... [so make sure this can only be done from the town so ppl won't use it as massive inventory in the field].
for convenience, each side can update what they offer in that trade as much as they want, and naturally there can be multiple trade offers ongoing w the same 2 people.
however i will warn the devs, as other games experienced, sense you don't want a situation when person 1 offer something, person 2 respond w stuff, then person 2 change the stuff to some junk just a second before person 1 accept the trade, making an exploitable thing for scams [or just weird mistakes]....
so to make sure that doesn't happen, you can do something like, after every trade change, its id or whatever will also change or something like that in the system, and naturally in addition, accepting the trade will take a few confirms, that are auto canceled if the trade is changed, like 3 confirms, one from the first person to confirm, then one from the second person, then a last confirm from the first person, so to make sure it was the right offer and it wasn't changed right before the first person confirmed it at the start, also make sure that each confirm point have a different color to indicate it boldly, or something like that, and make sure that if someone click to confirm first, and it was a second after the second person clicked that, it will NOT count as second stage confirm, or else i think you need to make 2 confirms from the second person as well, making a total of 4 confirms, and considering this may be when each player log in different hours.... but if necessary, so be it.
that said, i guess if you just make sure one action can Never be mistaken as a similar action by the system, like first confirm by one player without reloading the page when the trade was just changed by the other person, will give an error that the trade was changed and this trade is no longer available, ye thats what i meant by having the trade change id or something w every change, also now that i think about it, to decrease the times one player will need to wait for the confirm of the other player, sense they might be in diffrent time zones ect', actually just having each player that confirm, needing to confirm twice w a 10 seconds delay counter and a bold screen of the state of the trade they confirm a second time, without the need of the other player to confirm in the middle, what was i thinking this is the simplest idea so far XD.
so ye this last one ^ is the best solution, anyway i went w this comment too long and going a bit messy so i think ill end it here, i might try to sums it up a bit better later in a comment....