UV settings not respected in pyproject.toml

[Tayum]

Problem: Some uv settings, set in pyproject.toml, aren't respected, whereas some are.

Steps to reproduce:

# pyproject.toml
[tool.uv.sources]
pytest = { index = "pypi" }

[[tool.uv.index]]
name = "pypi"
url = "https://pypi.org/simple/"
explicit = true

[[tool.uv.index]]
name = "another"
url = "https://something.wrong"
default = true

[tool.hatch.envs.example]
installer = "uv"
dependencies = [
    "pytest",
]

Run command:

% hatch run example:true

Expected output: The command finishes successfully, as a package is found in https://pypi.org/simple/.

Actual output:

error: Failed to fetch: `https://something.wrong/pytest/`
  Caused by: Could not connect, are you offline?
  Caused by: Request failed after 3 retries
  Caused by: error sending request for url (https://something.wrong/pytest/)
  Caused by: client error (Connect)
  Caused by: dns error: failed to lookup address information: nodename nor servname provided, or not known
  Caused by: failed to lookup address information: nodename nor servname provided, or not known

---

In case default and explicit are swapped:

# pyproject.toml
[tool.uv.sources]
pytest = { index = "another" }

[[tool.uv.index]]
name = "pypi"
url = "https://pypi.org/simple/"
default = true

[[tool.uv.index]]
name = "another"
url = "https://something.wrong"
explicit = true

[tool.hatch.envs.example]
installer = "uv"
dependencies = [
    "pytest",
]

Then the command finishes successfully. It means that [[tool.uv.index]] seems to be respected, whereas [tool.uv.sources] is not.

[djcopley]

UV sources are only used with the UV sync/lock/run commands. The uv pip interface does not look at uv sources.

The uv indices are not considered project specific config, so the pip indices are considered.

I made a uv environment plugin for hatch that uses the locked UV sync interface (instead of uv pip) here: https://github.com/djcopley/hatch-uvenv

Since it uses the uv sync interface, it will respect UV sources.

[flying-sheep]

cc @ded8393