We need automatic offers, on the old system of "if stockpile > x then put y bushels on the market for z gold" resp. "if stockpile < x then post an offer for y bushels for z gold". It needs a bit of work to integrate it with the new tax system and all, but it can work (bonds required could be taken from the tax collection, bonds gained would be added to the tax income).
i don't know... if you are going to tie it back into the tax system again, maybe it'll make more sense for the whole thing (manual offers for lords/stewards) to be tied into the tax system.
