I'm not convinced that we shouldn't perform an exact sync by default, and while I like the --exact / --no-exact names — I don't feel that we should adjust the default behavior because it's easier to write the names of the flag.

I worry --no-exact is not obvious enough on its own.

(I don't love this name either, but it cannot remain --no-clean due to the conflict with cache clean semantics)

• --no-prune
• --retain
• --preserve-extras (conflicts with the optional deps concept)
• --preserve
• --keep-unused
• --skip-prune

--no-remove
--no-delete (taken from rsync "delete" terminology)

But we will remove packages if they conflict with the requirements of the project.

--ignore-unused? --skip-unused?

I worry a little about "unused" since they could be used just not declared.

Opting for --inexact with a --no-exact alias.