$ cue help mod fix
Fix provides a way to migrate from a legacy module.cue file
to the new standard syntax. It

- adds a language.version field
- moves unrecognized fields into the custom.legacy field
- adds a major version to the module path

If there is no module path, it chooses an arbitrary path (test.example@v0).

If the module.cue file is already compatible with the new syntax,
it is just formatted without making any other changes.

Usage:
  cue mod fix [flags]

Global Flags:
  -E, --all-errors   print all available errors
  -i, --ignore       proceed in the presence of errors
  -s, --simplify     simplify output
      --trace        trace computation
  -v, --verbose      print information about progress