[KevinH]

If you ever run into an into acdisk space error on the drive you are saving to but the drive where Sigil is installed has room, making a Checkpoint could help. As would a Save-As. The corruption is caused by the full disk, not Sigil. Sigil becausevits workspace is on a drive with space, should properly create a Checkpoint. And yes you can restore from a Checkpoint over an even earlier version of the epub. The epub's metdata uuid dc:identifier is used as the key to identify uniquely an epub, as the name can change.

I regularly make checkpoints during the editing process especially just before running any Sigil tool that you can not easily revert any changes it may make, and before large find and replaces, etc. Being able to revert to an earlier Checkpoint is why we added that feature to Sigil in the first place.

Checkpoints create working git repositories with tags, rebuilding the entire epub at any commit with real git is always possible as well.