Yes, very different from Sigil other than targeting coding agents. Mog seems to enhance coding agents by offering a (very fast) way for them to write quick scripts or apply hooks. Also, the security features are great, explicit capabilities.

Sigil is a general purpose programming language, with tooling to help the AI agents write and fix programs.

In theory it seems both of them could be used together, suppose you're writing a new big app using Sigil, you could then plug in Mog to speed up that even more.