Respect resolved Git SHAs in uv lock (#3956)

## Summary

This PR ensures that if a lockfile already contains a resolved reference
(e.g., you locked with `main` previously, and it locked to a specific
commit), and you run `uv lock`, we use the same SHA, even if it's not
the latest SHA for that tag. This avoids upgrading Git dependencies
without `--upgrade`.

Closes #3920.

crates/uv-git/src/lib.rs

@@ -2,7 +2,9 @@ use std::str::FromStr;
 use url::Url;
 
 pub use crate::git::GitReference;
-pub use crate::resolver::{GitResolver, GitResolverError, RepositoryReference};
+pub use crate::resolver::{
+    GitResolver, GitResolverError, RepositoryReference, ResolvedRepositoryReference,
+};
 pub use crate::sha::{GitOid, GitSha, OidParseError};
 pub use crate::source::{Fetch, GitSource, Reporter};
 

crates/uv-git/src/resolver.rs

@@ -27,6 +27,15 @@ pub enum GitResolverError {
 pub struct GitResolver(Arc<DashMap<RepositoryReference, GitSha>>);
 
 impl GitResolver {
+    /// Initialize a [`GitResolver`] with a set of resolved references.
+    pub fn from_refs(refs: Vec<ResolvedRepositoryReference>) -> Self {
+        Self(Arc::new(
+            refs.into_iter()
+                .map(|ResolvedRepositoryReference { reference, sha }| (reference, sha))
+                .collect(),
+        ))
+    }
+
     /// Returns the [`GitSha`] for the given [`RepositoryReference`], if it exists.
     pub fn get(&self, reference: &RepositoryReference) -> Option<Ref<RepositoryReference, GitSha>> {
         self.0.get(reference)
@@ -136,11 +145,20 @@ impl GitResolver {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct ResolvedRepositoryReference {
+    /// An abstract reference to a Git repository, including the URL and the commit (e.g., a branch,
+    /// tag, or revision).
+    pub reference: RepositoryReference,
+    /// The precise commit SHA of the reference.
+    pub sha: GitSha,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct RepositoryReference {
     /// The URL of the Git repository, with any query parameters and fragments removed.
     pub url: RepositoryUrl,
-    /// The reference to the commit to use, which could be a branch, tag or revision.
+    /// The reference to the commit to use, which could be a branch, tag, or revision.
     pub reference: GitReference,
 }
 

crates/uv-requirements/src/upgrade.rs

@@ -7,8 +7,17 @@ use requirements_txt::RequirementsTxt;
 use uv_client::{BaseClientBuilder, Connectivity};
 use uv_configuration::Upgrade;
 use uv_distribution::ProjectWorkspace;
+use uv_git::ResolvedRepositoryReference;
 use uv_resolver::{Lock, Preference, PreferenceError};
 
+#[derive(Debug, Default)]
+pub struct LockedRequirements {
+    /// The pinned versions from the lockfile.
+    pub preferences: Vec<Preference>,
+    /// The pinned Git SHAs from the lockfile.
+    pub git: Vec<ResolvedRepositoryReference>,
+}
+
 /// Load the preferred requirements from an existing `requirements.txt`, applying the upgrade strategy.
 pub async fn read_requirements_txt(
     output_file: Option<&Path>,
@@ -58,10 +67,10 @@ pub async fn read_requirements_txt(
 pub async fn read_lockfile(
     project: &ProjectWorkspace,
     upgrade: &Upgrade,
-) -> Result<Vec<Preference>> {
+) -> Result<LockedRequirements> {
     // As an optimization, skip reading the lockfile is we're upgrading all packages anyway.
     if upgrade.is_all() {
-        return Ok(Vec::new());
+        return Ok(LockedRequirements::default());
     }
 
     // If an existing lockfile exists, build up a set of preferences.
@@ -71,32 +80,36 @@ pub async fn read_lockfile(
             Ok(lock) => lock,
             Err(err) => {
                 eprint!("Failed to parse lockfile; ignoring locked requirements: {err}");
-                return Ok(Vec::new());
+                return Ok(LockedRequirements::default());
             }
         },
         Err(err) if err.kind() == std::io::ErrorKind::NotFound => {
-            return Ok(Vec::new());
+            return Ok(LockedRequirements::default());
         }
         Err(err) => return Err(err.into()),
     };
 
-    // Map each entry in the lockfile to a preference.
-    let preferences: Vec<Preference> = lock
-        .distributions()
-        .iter()
-        .map(Preference::from_lock)
-        .collect();
+    let mut preferences = Vec::new();
+    let mut git = Vec::new();
 
-    // Apply the upgrade strategy to the requirements.
-    Ok(match upgrade {
-        // Respect all pinned versions from the existing lockfile.
-        Upgrade::None => preferences,
-        // Ignore all pinned versions from the existing lockfile.
-        Upgrade::All => vec![],
-        // Ignore pinned versions for the specified packages.
-        Upgrade::Packages(packages) => preferences
-            .into_iter()
-            .filter(|preference| !packages.contains(preference.name()))
-            .collect(),
-    })
+    for dist in lock.distributions() {
+        // Skip the distribution if it's not included in the upgrade strategy.
+        if match upgrade {
+            Upgrade::None => false,
+            Upgrade::All => true,
+            Upgrade::Packages(packages) => packages.contains(dist.name()),
+        } {
+            continue;
+        }
+
+        // Map each entry in the lockfile to a preference.
+        preferences.push(Preference::from_lock(dist));
+
+        // Map each entry in the lockfile to a Git SHA.
+        if let Some(git_ref) = dist.as_git_ref() {
+            git.push(git_ref);
+        }
+    }
+
+    Ok(LockedRequirements { preferences, git })
 }

crates/uv-resolver/src/lock.rs

@@ -7,6 +7,7 @@ use std::path::{Path, PathBuf};
 use std::str::FromStr;
 
 use anyhow::Result;
+use cache_key::RepositoryUrl;
 use rustc_hash::FxHashMap;
 use toml_edit::{value, Array, ArrayOfTables, InlineTable, Item, Table, Value};
 use url::Url;
@@ -21,7 +22,7 @@ use pep440_rs::Version;
 use pep508_rs::{MarkerEnvironment, VerbatimUrl};
 use platform_tags::{TagCompatibility, TagPriority, Tags};
 use pypi_types::{HashDigest, ParsedArchiveUrl, ParsedGitUrl};
-use uv_git::{GitReference, GitSha};
+use uv_git::{GitReference, GitSha, RepositoryReference, ResolvedRepositoryReference};
 use uv_normalize::{ExtraName, PackageName};
 
 use crate::resolution::AnnotatedDist;
@@ -478,6 +479,25 @@ impl Distribution {
         }
         best.map(|(_, i)| i)
     }
+
+    /// Returns the [`PackageName`] of the distribution.
+    pub fn name(&self) -> &PackageName {
+        &self.id.name
+    }
+
+    /// Returns the [`ResolvedRepositoryReference`] for the distribution, if it is a Git source.
+    pub fn as_git_ref(&self) -> Option<ResolvedRepositoryReference> {
+        match &self.id.source.kind {
+            SourceKind::Git(git) => Some(ResolvedRepositoryReference {
+                reference: RepositoryReference {
+                    url: RepositoryUrl::new(&self.id.source.url),
+                    reference: GitReference::from(git.kind.clone()),
+                },
+                sha: git.precise,
+            }),
+            _ => None,
+        }
+    }
 }
 
 #[derive(Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord, serde::Deserialize)]

crates/uv/src/commands/project/lock.rs

@@ -13,7 +13,7 @@ use uv_dispatch::BuildDispatch;
 use uv_distribution::ProjectWorkspace;
 use uv_git::GitResolver;
 use uv_interpreter::PythonEnvironment;
-use uv_requirements::upgrade::read_lockfile;
+use uv_requirements::upgrade::{read_lockfile, LockedRequirements};
 use uv_resolver::{ExcludeNewer, FlatIndex, InMemoryIndex, Lock, OptionsBuilder};
 use uv_types::{BuildIsolation, EmptyInstalledPackages, HashStrategy, InFlight};
 use uv_warnings::warn_user;
@@ -105,7 +105,6 @@ pub(super) async fn do_lock(
     let config_settings = ConfigSettings::default();
     let extras = ExtrasSpecification::default();
     let flat_index = FlatIndex::default();
-    let git = GitResolver::default();
     let in_flight = InFlight::default();
     let index = InMemoryIndex::default();
     let index_locations = IndexLocations::default();
@@ -119,7 +118,10 @@ pub(super) async fn do_lock(
     let options = OptionsBuilder::new().exclude_newer(exclude_newer).build();
 
     // If an existing lockfile exists, build up a set of preferences.
-    let preferences = read_lockfile(project, &upgrade).await?;
+    let LockedRequirements { preferences, git } = read_lockfile(project, &upgrade).await?;
+
+    // Create the Git resolver.
+    let git = GitResolver::from_refs(git);
 
     // Create a build dispatch.
     let build_dispatch = BuildDispatch::new(