Offline mode confusion

[minusf]

Here I go again trying to use uv as poor man's devpi offline replacement.

Some confusions about this were cleared up in an issue before (#3468)

Everything is working as explained there, however it doesn't seem to work for private packages (not on pypi).

Consider the following case (first I download our private package, but it could come from extra index url as well):

$ uv pip install /path/to/private_package-0.1.whl  # ends up in uv cache
$ uv pip install all_the_rest_from_pypi

when blowing away this venv and trying to recreate it offline, private_package.whl is not picked up from the cache (~/Library/Caches/uv/wheels-v1/url/...):

$ uv pip install private_package==0.1
  × No solution found when resolving dependencies:
  ╰─▶ Because private_package was not found in the package registry and you require private_package==0.1, we can conclude that the requirements are unsatisfiable.

$ uv --offline pip install private_package==0.1
  × No solution found when resolving dependencies:
  ╰─▶ Because private_package was not found in the cache and you require private_package==0.1, we can conclude that the requirements are unsatisfiable.
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^

      hint: Packages were unavailable because the network was disabled

My happy path expectation was that once I add private_package-0.1.whl to an existing venv, it will be cached forever and I don't need to setup an extra index url and/or keep the private packages offline manually in some folder.