The first Taís hears of the Constitutional Convention is when the messenger comes to tell them they need to vote for a representative to attend.
Taís writes down Matties's name, because he used to let his goats eat her crops and because she's pretty sure he's too old to hurt her when he finds out. He doesn't find out, or at least doesn't bother to pick a fight about it. The messenger tells them there'll also be delegates chosen from the clergy and the nobility, as well as a group chosen by lot. Taís isn't nobility and isn't clergy, so that only leaves the lots. But they never bring around lots for her to draw from, and when it's been a month since the messenger's arrival she figures she's safe.