>>512209929
At ratification, one of the most discussed topics was whether the common government could use force against a noncooperating state. This was actually one of the most discussed topics as you will find if you open your copy of Farrand's Minutes. (I doubt yiu have one or have ever even heard of them kek). If the common government cannot use force against the states it is a defacto assent to the concept of leaving the union as a matter of basic logic.

After much discussion, the delegates decided that the common government would have no power to use force against a state or group of state governments- only against individuals defying the government (covering things like Shay's etc). There were even excerpts of written arguments entered into the minutes on this and it was one of the few topics where this was done. At the subsequent state ratification conventions this was again discussed in detail- for example at NY convention, Hamilton described the idea of enforcing the agreement with force as follows
>To coerce the states is one of the maddest projects that was ever devised... Can any reasonable man be well disposed toward a government which makes war and carnage the only means of supporting itself—a government that can exist only by the sword?” (June 24, 1788 NY Ratification Convention).

This is relevant for two reasons 1. Hamilton was a very important delegate at the 1787 convention and he was probabky the biggest central government man in the room 2. The state ratifying conventions are where they states accepted the constitution and representations this unambiguous were needed for them to agree to it in the first place.

So to answer your question. Secession wasnt covered. It would have been seen as unfortunate and they wouldnt have wanted to encourage it- but the southern states were 100% correct in assuming that IF they left, the federal government would not wage war on them.