Yes, they did. And no they didn't include them in the final document. None of them accepted the notion of unilateral secession or dissolution “at pleasure”.
We do know that 74 years later, that the United States Congress judged secession to be legal....unilateral or not.
In other words, they recognized that secession was not currently legal and proposed an amendment to the Constitution to make it so. The proposal did not survive the constitutional amendment process and thus is not law.
Read this AGAIN.....If you go back to the 1787-88 debates in the New York, Rhode Island, Virginia, and North Carolina legislatures, you will see many examples of secession discussions. There were several efforts to codify, modify, and place limits on states involved in seceding. State legislatures would not make secession illegal, and thus neither did the Constitution.
So that this is perfectly clear, ratifying state legislatures would not in any way limit secession.
And as I said also, given the opportunity to pass legislation limiting secession, neither would the US Congress.