[rickeylev]

Bzlmod supports pip.parse(uv_lock = ...) to install PyPI dependencies
from a universal uv.lock file, but WORKSPACE setups still required
platform- or version-specific requirements.txt files for pip_parse.
Maintaining separate lockfile formats across MODULE.bazel and
WORKSPACE duplicated lockfile generation targets and complicated
dependency updates.

Add the uv_lock macro to //python:pip.bzl for WORKSPACE builds.
It decodes uv.lock with @toml.bzl, converts it to requirements
format via uv_lock_to_requirements, and renders the PyPI hub (and
multi-version spoke repositories when python_interpreter_target is a
dict) using the shared pip_repository rendering logic.

[rickeylev]

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[rickeylev]

@aignas is core of this implementation for a low-effort workspace macro to handle uv.lock look promising? Just look at the files under python/private/pypi, the uv_lock.bzl and uv_lock_repo.bzl. (everything else is migration noise).

The basic impl is to convert the uv.lock to requirements using the uv_lock_to_requirements helper. It basically just converts uv.lock to requirements, then feeds that into the pip rules and pip hub rules.

With just a year left for workspace, I didn't want to put a ton of effort into e.g. full API compatibility with pip_parse. But enough that we can move our own workspace off it