uv selects the project Python from requires-python and from the UV_PYTHON
env var, both of which override an already-created venv on the next
'uv sync'. With no upper bound on requires-python, an inherited
UV_PYTHON=3.14 (or a fresh distro whose newest interpreter uv auto-picks)
silently recreated the installer's 3.11 venv at 3.14, where Rust-backed
transitives (pydantic-core) have no cp314 wheel and fall back to a maturin
source build that fails. This bit a Windows/WSL user with UV_PYTHON set in
their shell and a fresh WSL-arch box where uv auto-picked 3.14.
Two layers:
- pyproject: requires-python '>=3.11' -> '>=3.11,<3.14' (+ uv lock regen).
uv now refuses a 3.14 interpreter with a clear error instead of attempting
the maturin build. Backstop independent of the installer.
- install.sh / install.ps1: pin UV_PYTHON to the venv interpreter after
creating it (in both the venv step and the deps step, since bootstrap runs
those stages as separate processes). An inherited UV_PYTHON can no longer
hijack the sync/pip tiers, so the install just works regardless of shell env.
Verified E2E: hostile UV_PYTHON=3.14 + uv venv --python 3.11 + uv sync now
installs into 3.11 with pydantic-core's 3.11 wheel; without the re-pin the
capped requires-python produces a legible incompatibility error rather than a
cryptic build failure.