Hey, thanks for the detailed report. This is a known issue with the code action menu opened from the keyboard using Cmd+Enter or Alt+Enter. When you pick an item, the extension command doesn’t resolve and you get an error like Actual command not found. It’s not just cSpell. We’re seeing the same thing with TS, C#, Dart, and other extensions.
Good news, the fix is already done and will be included in an upcoming release. It’s not in 3.15.6 yet. I can’t share an exact date, but I’ll reply here once the update is out.
For now, the workaround is to use the right click context menu like you noticed. It goes through a different path and isn’t affected by this issue.
Related thread with the same behavior if you’re curious: Cursor IDE coding error, the options that appear when pressing Alt Enter don't work