Should uv python install 3 install an alpha version?

[bersbersbers]

Summary

Because it does:

'uv' (0.6.6) was installed successfully!

>uv python install 3    
cpython-3.14.0a5-windows-x86_64-none ------------------------------ 2.11 MiB/20.26 MiB                                                            

Platform

Windows 11

Version

0.6.6

Python version

No response

[charliermarsh]

Hmm. Probably not, no.

[zanieb]

Huh, that's surprising.

[zanieb]

I think the logic isn't quite right

uv/crates/uv-python/src/downloads.rs

Lines 172 to 178 in 553bccc

	/// Construct a new [`PythonDownloadRequest`] from a [`PythonRequest`] if possible.
	///
	/// Returns [`None`] if the request kind is not compatible with a download, e.g., it is
	/// a request for a specific directory or executable name.
	pub fn from_request(request: &PythonRequest) -> Option<Self> {
	match request {
	PythonRequest::Version(version) => Some(Self::default().with_version(version.clone())),

uv/crates/uv-python/src/downloads.rs

Lines 277 to 280 in 553bccc

	// If we don't allow pre-releases, don't match a key with a pre-release tag
	if !self.allows_prereleases() && key.prerelease.is_some() {
	return false;
	}

uv/crates/uv-python/src/downloads.rs

Lines 304 to 311 in 553bccc

	/// Whether this download request opts-in to pre-release Python versions.
	pub fn allows_prereleases(&self) -> bool {
	self.prereleases.unwrap_or_else(|| {
	self.version
	.as_ref()
	.is_some_and(VersionRequest::allows_prereleases)
	})
	}

uv/crates/uv-python/src/discovery.rs

Lines 2273 to 2284 in 3a53ec3

	/// Whether this request should allow selection of pre-release versions.
	pub(crate) fn allows_prereleases(&self) -> bool {
	match self {
	Self::Default => false,
	Self::Any => true,
	Self::Major(..) => true,
	Self::MajorMinor(..) => true,
	Self::MajorMinorPatch(..) => true,
	Self::MajorMinorPrerelease(..) => true,
	Self::Range(specifiers, _) => specifiers.iter().any(VersionSpecifier::any_prerelease),
	}
	}

We'll want to try to apply

diff --git a/crates/uv-python/src/discovery.rs b/crates/uv-python/src/discovery.rs
index b5a4972d6..1aa58c20e 100644
--- a/crates/uv-python/src/discovery.rs
+++ b/crates/uv-python/src/discovery.rs
@@ -2275,9 +2275,9 @@ impl VersionRequest {
         match self {
             Self::Default => false,
             Self::Any => true,
-            Self::Major(..) => true,
-            Self::MajorMinor(..) => true,
-            Self::MajorMinorPatch(..) => true,
+            Self::Major(..) => false,
+            Self::MajorMinor(..) => false,
+            Self::MajorMinorPatch(..) => false,
             Self::MajorMinorPrerelease(..) => true,
             Self::Range(specifiers, _) => specifiers.iter().any(VersionSpecifier::any_prerelease),
         }

but we still want uv python install 3.14 to work so we'll need to implement logic for downloads like this existing pattern for discovery

uv/crates/uv-python/src/discovery.rs

Lines 1100 to 1103 in 3a53ec3

	// If we only found pre-releases, they're implicitly allowed and we should return the first one.
	if let Some(installation) = first_prerelease {
	return Ok(Ok(installation));
	}