The assistant never runs out of checkpoints before a risky change

A cloud computer keeps up to 20 checkpoints you own. When the assistant reached that number it used to refuse to take a new one, and a schema migration could go in without a rollback point. Now, at the cap, the assistant replaces its own oldest checkpoint and tells you which one it replaced. The checkpoints you saved yourself are never the ones replaced.

If the Checkpoint history dialog cannot open, it now says why instead of staying blank.