Make Directory its own distribution kind (#3519)

## Summary

I think this is overall good change because it explicitly encodes (in
the type system) something that was previously implicit. I'm not a huge
fan of the names here, open to input.

It covers some of https://github.com/astral-sh/uv/issues/3506 but I
don't think it _closes_ it.

crates/distribution-types/src/buildable.rs

@@ -6,7 +6,7 @@ use url::Url;
 
 use uv_normalize::PackageName;
 
-use crate::{GitSourceDist, Name, PathSourceDist, SourceDist};
+use crate::{DirectorySourceDist, GitSourceDist, Name, PathSourceDist, SourceDist};
 
 /// A reference to a source that can be built into a built distribution.
 ///
@@ -62,6 +62,7 @@ pub enum SourceUrl<'a> {
     Direct(DirectSourceUrl<'a>),
     Git(GitSourceUrl<'a>),
     Path(PathSourceUrl<'a>),
+    Directory(DirectorySourceUrl<'a>),
 }
 
 impl<'a> SourceUrl<'a> {
@@ -71,6 +72,7 @@ impl<'a> SourceUrl<'a> {
             Self::Direct(dist) => dist.url,
             Self::Git(dist) => dist.url,
             Self::Path(dist) => dist.url,
+            Self::Directory(dist) => dist.url,
         }
     }
 }
@@ -81,6 +83,7 @@ impl std::fmt::Display for SourceUrl<'_> {
             Self::Direct(url) => write!(f, "{url}"),
             Self::Git(url) => write!(f, "{url}"),
             Self::Path(url) => write!(f, "{url}"),
+            Self::Directory(url) => write!(f, "{url}"),
         }
     }
 }
@@ -133,3 +136,24 @@ impl<'a> From<&'a PathSourceDist> for PathSourceUrl<'a> {
         }
     }
 }
+
+#[derive(Debug, Clone)]
+pub struct DirectorySourceUrl<'a> {
+    pub url: &'a Url,
+    pub path: Cow<'a, Path>,
+}
+
+impl std::fmt::Display for DirectorySourceUrl<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{url}", url = self.url)
+    }
+}
+
+impl<'a> From<&'a DirectorySourceDist> for DirectorySourceUrl<'a> {
+    fn from(dist: &'a DirectorySourceDist) -> Self {
+        Self {
+            url: &dist.url,
+            path: Cow::Borrowed(&dist.path),
+        }
+    }
+}

crates/distribution-types/src/cached.rs

@@ -85,6 +85,13 @@ impl CachedDist {
                 editable: false,
             }),
             Dist::Source(SourceDist::Path(dist)) => Self::Url(CachedDirectUrlDist {
+                filename,
+                url: dist.url,
+                hashes,
+                path,
+                editable: false,
+            }),
+            Dist::Source(SourceDist::Directory(dist)) => Self::Url(CachedDirectUrlDist {
                 filename,
                 url: dist.url,
                 hashes,

crates/distribution-types/src/lib.rs

@@ -152,6 +152,7 @@ pub enum SourceDist {
     DirectUrl(DirectUrlSourceDist),
     Git(GitSourceDist),
     Path(PathSourceDist),
+    Directory(DirectorySourceDist),
 }
 
 /// A built distribution (wheel) that exists in a registry, like `PyPI`.
@@ -203,12 +204,20 @@ pub struct GitSourceDist {
     pub url: VerbatimUrl,
 }
 
-/// A source distribution that exists in a local directory.
+/// A source distribution that exists in a local archive (e.g., a `.tar.gz` file).
 #[derive(Debug, Clone)]
 pub struct PathSourceDist {
     pub name: PackageName,
     pub url: VerbatimUrl,
     pub path: PathBuf,
+}
+
+/// A source distribution that exists in a local directory.
+#[derive(Debug, Clone)]
+pub struct DirectorySourceDist {
+    pub name: PackageName,
+    pub url: VerbatimUrl,
+    pub path: PathBuf,
     pub editable: bool,
 }
 
@@ -281,7 +290,15 @@ impl Dist {
             Err(err) => return Err(err.into()),
         };
 
-        if path
+        // Determine whether the path represents an archive or a directory.
+        if path.is_dir() {
+            Ok(Self::Source(SourceDist::Directory(DirectorySourceDist {
+                name,
+                url,
+                path,
+                editable,
+            })))
+        } else if path
             .extension()
             .is_some_and(|ext| ext.eq_ignore_ascii_case("whl"))
         {
@@ -305,11 +322,14 @@ impl Dist {
                 path,
             })))
         } else {
+            if editable {
+                return Err(Error::EditableFile(url));
+            }
+
             Ok(Self::Source(SourceDist::Path(PathSourceDist {
                 name,
                 url,
                 path,
-                editable,
             })))
         }
     }
@@ -382,7 +402,7 @@ impl Dist {
     /// Create a [`Dist`] for a local editable distribution.
     pub fn from_editable(name: PackageName, editable: LocalEditable) -> Result<Self, Error> {
         let LocalEditable { url, path, .. } = editable;
-        Ok(Self::Source(SourceDist::Path(PathSourceDist {
+        Ok(Self::Source(SourceDist::Directory(DirectorySourceDist {
             name,
             url,
             path,
@@ -454,7 +474,7 @@ impl SourceDist {
     pub fn index(&self) -> Option<&IndexUrl> {
         match self {
             Self::Registry(registry) => Some(&registry.index),
-            Self::DirectUrl(_) | Self::Git(_) | Self::Path(_) => None,
+            Self::DirectUrl(_) | Self::Git(_) | Self::Path(_) | Self::Directory(_) => None,
         }
     }
 
@@ -462,14 +482,14 @@ impl SourceDist {
     pub fn file(&self) -> Option<&File> {
         match self {
             Self::Registry(registry) => Some(&registry.file),
-            Self::DirectUrl(_) | Self::Git(_) | Self::Path(_) => None,
+            Self::DirectUrl(_) | Self::Git(_) | Self::Path(_) | Self::Directory(_) => None,
         }
     }
 
     pub fn version(&self) -> Option<&Version> {
         match self {
             Self::Registry(source_dist) => Some(&source_dist.filename.version),
-            Self::DirectUrl(_) | Self::Git(_) | Self::Path(_) => None,
+            Self::DirectUrl(_) | Self::Git(_) | Self::Path(_) | Self::Directory(_) => None,
         }
     }
 
@@ -487,7 +507,7 @@ impl SourceDist {
     /// Return true if the distribution is editable.
     pub fn is_editable(&self) -> bool {
         match self {
-            Self::Path(PathSourceDist { editable, .. }) => *editable,
+            Self::Directory(DirectorySourceDist { editable, .. }) => *editable,
             _ => false,
         }
     }
@@ -496,6 +516,7 @@ impl SourceDist {
     pub fn as_path(&self) -> Option<&Path> {
         match self {
             Self::Path(dist) => Some(&dist.path),
+            Self::Directory(dist) => Some(&dist.path),
             _ => None,
         }
     }
@@ -543,6 +564,12 @@ impl Name for PathSourceDist {
     }
 }
 
+impl Name for DirectorySourceDist {
+    fn name(&self) -> &PackageName {
+        &self.name
+    }
+}
+
 impl Name for SourceDist {
     fn name(&self) -> &PackageName {
         match self {
@@ -550,6 +577,7 @@ impl Name for SourceDist {
             Self::DirectUrl(dist) => dist.name(),
             Self::Git(dist) => dist.name(),
             Self::Path(dist) => dist.name(),
+            Self::Directory(dist) => dist.name(),
         }
     }
 }
@@ -615,6 +643,12 @@ impl DistributionMetadata for PathSourceDist {
     }
 }
 
+impl DistributionMetadata for DirectorySourceDist {
+    fn version_or_url(&self) -> VersionOrUrlRef {
+        VersionOrUrlRef::Url(&self.url)
+    }
+}
+
 impl DistributionMetadata for SourceDist {
     fn version_or_url(&self) -> VersionOrUrlRef {
         match self {
@@ -622,6 +656,7 @@ impl DistributionMetadata for SourceDist {
             Self::DirectUrl(dist) => dist.version_or_url(),
             Self::Git(dist) => dist.version_or_url(),
             Self::Path(dist) => dist.version_or_url(),
+            Self::Directory(dist) => dist.version_or_url(),
         }
     }
 }
@@ -760,6 +795,16 @@ impl RemoteSource for PathSourceDist {
     }
 }
 
+impl RemoteSource for DirectorySourceDist {
+    fn filename(&self) -> Result<Cow<'_, str>, Error> {
+        self.url.filename()
+    }
+
+    fn size(&self) -> Option<u64> {
+        self.url.size()
+    }
+}
+
 impl RemoteSource for SourceDist {
     fn filename(&self) -> Result<Cow<'_, str>, Error> {
         match self {
@@ -767,6 +812,7 @@ impl RemoteSource for SourceDist {
             Self::DirectUrl(dist) => dist.filename(),
             Self::Git(dist) => dist.filename(),
             Self::Path(dist) => dist.filename(),
+            Self::Directory(dist) => dist.filename(),
         }
     }
 
@@ -776,6 +822,7 @@ impl RemoteSource for SourceDist {
             Self::DirectUrl(dist) => dist.size(),
             Self::Git(dist) => dist.size(),
             Self::Path(dist) => dist.size(),
+            Self::Directory(dist) => dist.size(),
         }
     }
 }
@@ -934,6 +981,16 @@ impl Identifier for PathSourceDist {
     }
 }
 
+impl Identifier for DirectorySourceDist {
+    fn distribution_id(&self) -> DistributionId {
+        self.url.distribution_id()
+    }
+
+    fn resource_id(&self) -> ResourceId {
+        self.url.resource_id()
+    }
+}
+
 impl Identifier for GitSourceDist {
     fn distribution_id(&self) -> DistributionId {
         self.url.distribution_id()
@@ -951,6 +1008,7 @@ impl Identifier for SourceDist {
             Self::DirectUrl(dist) => dist.distribution_id(),
             Self::Git(dist) => dist.distribution_id(),
             Self::Path(dist) => dist.distribution_id(),
+            Self::Directory(dist) => dist.distribution_id(),
         }
     }
 
@@ -960,6 +1018,7 @@ impl Identifier for SourceDist {
             Self::DirectUrl(dist) => dist.resource_id(),
             Self::Git(dist) => dist.resource_id(),
             Self::Path(dist) => dist.resource_id(),
+            Self::Directory(dist) => dist.resource_id(),
         }
     }
 }
@@ -1038,12 +1097,23 @@ impl Identifier for PathSourceUrl<'_> {
     }
 }
 
+impl Identifier for DirectorySourceUrl<'_> {
+    fn distribution_id(&self) -> DistributionId {
+        self.url.distribution_id()
+    }
+
+    fn resource_id(&self) -> ResourceId {
+        self.url.resource_id()
+    }
+}
+
 impl Identifier for SourceUrl<'_> {
     fn distribution_id(&self) -> DistributionId {
         match self {
             Self::Direct(url) => url.distribution_id(),
             Self::Git(url) => url.distribution_id(),
             Self::Path(url) => url.distribution_id(),
+            Self::Directory(url) => url.distribution_id(),
         }
     }
 
@@ -1052,6 +1122,7 @@ impl Identifier for SourceUrl<'_> {
             Self::Direct(url) => url.resource_id(),
             Self::Git(url) => url.resource_id(),
             Self::Path(url) => url.resource_id(),
+            Self::Directory(url) => url.resource_id(),
         }
     }
 }

crates/distribution-types/src/resolution.rs

@@ -126,6 +126,11 @@ impl From<&ResolvedDist> for Requirement {
                     url: sdist.url.clone(),
                     editable: None,
                 },
+                Dist::Source(SourceDist::Directory(sdist)) => RequirementSource::Path {
+                    path: sdist.path.clone(),
+                    url: sdist.url.clone(),
+                    editable: None,
+                },
             },
             ResolvedDist::Installed(dist) => RequirementSource::Registry {
                 specifier: pep440_rs::VersionSpecifiers::from(

crates/uv-cache/src/lib.rs

@@ -770,41 +770,7 @@ impl ArchiveTimestamp {
         if metadata.is_file() {
             Ok(Some(Self::Exact(Timestamp::from_metadata(&metadata))))
         } else {
-            // Compute the modification timestamp for the `pyproject.toml`, `setup.py`, and
-            // `setup.cfg` files, if they exist.
-            let pyproject_toml = path
-                .as_ref()
-                .join("pyproject.toml")
-                .metadata()
-                .ok()
-                .filter(std::fs::Metadata::is_file)
-                .as_ref()
-                .map(Timestamp::from_metadata);
-
-            let setup_py = path
-                .as_ref()
-                .join("setup.py")
-                .metadata()
-                .ok()
-                .filter(std::fs::Metadata::is_file)
-                .as_ref()
-                .map(Timestamp::from_metadata);
-
-            let setup_cfg = path
-                .as_ref()
-                .join("setup.cfg")
-                .metadata()
-                .ok()
-                .filter(std::fs::Metadata::is_file)
-                .as_ref()
-                .map(Timestamp::from_metadata);
-
-            // Take the most recent timestamp of the three files.
-            let Some(timestamp) = max(pyproject_toml, max(setup_py, setup_cfg)) else {
-                return Ok(None);
-            };
-
-            Ok(Some(Self::Approximate(timestamp)))
+            Self::from_source_tree(path)
         }
     }
 
@@ -814,6 +780,48 @@ impl ArchiveTimestamp {
         Ok(Self::Exact(Timestamp::from_metadata(&metadata)))
     }
 
+    /// Return the modification timestamp for a source tree, i.e., a directory.
+    ///
+    /// If the source tree doesn't contain an entrypoint (i.e., no `pyproject.toml`, `setup.py`, or
+    /// `setup.cfg`), returns `None`.
+    pub fn from_source_tree(path: impl AsRef<Path>) -> Result<Option<Self>, io::Error> {
+        // Compute the modification timestamp for the `pyproject.toml`, `setup.py`, and
+        // `setup.cfg` files, if they exist.
+        let pyproject_toml = path
+            .as_ref()
+            .join("pyproject.toml")
+            .metadata()
+            .ok()
+            .filter(std::fs::Metadata::is_file)
+            .as_ref()
+            .map(Timestamp::from_metadata);
+
+        let setup_py = path
+            .as_ref()
+            .join("setup.py")
+            .metadata()
+            .ok()
+            .filter(std::fs::Metadata::is_file)
+            .as_ref()
+            .map(Timestamp::from_metadata);
+
+        let setup_cfg = path
+            .as_ref()
+            .join("setup.cfg")
+            .metadata()
+            .ok()
+            .filter(std::fs::Metadata::is_file)
+            .as_ref()
+            .map(Timestamp::from_metadata);
+
+        // Take the most recent timestamp of the three files.
+        let Some(timestamp) = max(pyproject_toml, max(setup_py, setup_cfg)) else {
+            return Ok(None);
+        };
+
+        Ok(Some(Self::Approximate(timestamp)))
+    }
+
     /// Return the modification timestamp for an archive.
     pub fn timestamp(&self) -> Timestamp {
         match self {

crates/uv-distribution/src/index/built_wheel_index.rs

@@ -1,5 +1,5 @@
 use distribution_types::{
-    git_reference, DirectUrlSourceDist, GitSourceDist, Hashed, PathSourceDist,
+    git_reference, DirectUrlSourceDist, DirectorySourceDist, GitSourceDist, Hashed, PathSourceDist,
 };
 use platform_tags::Tags;
 use uv_cache::{ArchiveTimestamp, Cache, CacheBucket, CacheShard, WheelCache};
@@ -67,9 +67,43 @@ impl<'a> BuiltWheelIndex<'a> {
             return Ok(None);
         };
 
+        // Determine the last-modified time of the source distribution.
+        let modified = ArchiveTimestamp::from_file(&source_dist.path).map_err(Error::CacheRead)?;
+
+        // If the distribution is stale, omit it from the index.
+        if !pointer.is_up_to_date(modified) {
+            return Ok(None);
+        }
+
+        // Enforce hash-checking by omitting any wheels that don't satisfy the required hashes.
+        let revision = pointer.into_revision();
+        if !revision.satisfies(self.hasher.get(source_dist)) {
+            return Ok(None);
+        }
+
+        Ok(self.find(&cache_shard.shard(revision.id())))
+    }
+
+    /// Return the most compatible [`CachedWheel`] for a given source distribution built from a
+    /// local directory (source tree).
+    pub fn directory(
+        &self,
+        source_dist: &DirectorySourceDist,
+    ) -> Result<Option<CachedWheel>, Error> {
+        let cache_shard = self.cache.shard(
+            CacheBucket::BuiltWheels,
+            WheelCache::Path(&source_dist.url).root(),
+        );
+
+        // Read the revision from the cache.
+        let Some(pointer) = LocalRevisionPointer::read_from(cache_shard.entry(LOCAL_REVISION))?
+        else {
+            return Ok(None);
+        };
+
         // Determine the last-modified time of the source distribution.
         let Some(modified) =
-            ArchiveTimestamp::from_path(&source_dist.path).map_err(Error::CacheRead)?
+            ArchiveTimestamp::from_source_tree(&source_dist.path).map_err(Error::CacheRead)?
         else {
             return Err(Error::DirWithoutEntrypoint);
         };

crates/uv-distribution/src/source/mod.rs

@@ -16,8 +16,9 @@ use zip::ZipArchive;
 
 use distribution_filename::WheelFilename;
 use distribution_types::{
-    BuildableSource, Dist, FileLocation, GitSourceUrl, HashPolicy, Hashed, LocalEditable,
-    ParsedArchiveUrl, PathSourceDist, PathSourceUrl, RemoteSource, SourceDist, SourceUrl,
+    BuildableSource, DirectorySourceDist, DirectorySourceUrl, Dist, FileLocation, GitSourceUrl,
+    HashPolicy, Hashed, LocalEditable, ParsedArchiveUrl, PathSourceUrl, RemoteSource, SourceDist,
+    SourceUrl,
 };
 use install_wheel_rs::metadata::read_archive_metadata;
 use platform_tags::Tags;
@@ -163,26 +164,25 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
                     .boxed_local()
                     .await?
             }
-            BuildableSource::Dist(SourceDist::Path(dist)) => {
-                if dist.path.is_dir() {
-                    self.source_tree(source, &PathSourceUrl::from(dist), tags, hashes)
-                        .boxed_local()
-                        .await?
-                } else {
-                    let cache_shard = self
-                        .build_context
-                        .cache()
-                        .shard(CacheBucket::BuiltWheels, WheelCache::Path(&dist.url).root());
-                    self.archive(
-                        source,
-                        &PathSourceUrl::from(dist),
-                        &cache_shard,
-                        tags,
-                        hashes,
-                    )
+            BuildableSource::Dist(SourceDist::Directory(dist)) => {
+                self.source_tree(source, &DirectorySourceUrl::from(dist), tags, hashes)
                     .boxed_local()
                     .await?
-                }
+            }
+            BuildableSource::Dist(SourceDist::Path(dist)) => {
+                let cache_shard = self
+                    .build_context
+                    .cache()
+                    .shard(CacheBucket::BuiltWheels, WheelCache::Path(&dist.url).root());
+                self.archive(
+                    source,
+                    &PathSourceUrl::from(dist),
+                    &cache_shard,
+                    tags,
+                    hashes,
+                )
+                .boxed_local()
+                .await?
             }
             BuildableSource::Url(SourceUrl::Direct(resource)) => {
                 let filename = resource
@@ -216,20 +216,19 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
                     .boxed_local()
                     .await?
             }
+            BuildableSource::Url(SourceUrl::Directory(resource)) => {
+                self.source_tree(source, resource, tags, hashes)
+                    .boxed_local()
+                    .await?
+            }
             BuildableSource::Url(SourceUrl::Path(resource)) => {
-                if resource.path.is_dir() {
-                    self.source_tree(source, resource, tags, hashes)
-                        .boxed_local()
-                        .await?
-                } else {
-                    let cache_shard = self.build_context.cache().shard(
-                        CacheBucket::BuiltWheels,
-                        WheelCache::Path(resource.url).root(),
-                    );
-                    self.archive(source, resource, &cache_shard, tags, hashes)
-                        .boxed_local()
-                        .await?
-                }
+                let cache_shard = self.build_context.cache().shard(
+                    CacheBucket::BuiltWheels,
+                    WheelCache::Path(resource.url).root(),
+                );
+                self.archive(source, resource, &cache_shard, tags, hashes)
+                    .boxed_local()
+                    .await?
             }
         };
 
@@ -319,20 +318,19 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
                     .boxed_local()
                     .await?
             }
+            BuildableSource::Dist(SourceDist::Directory(dist)) => {
+                self.source_tree_metadata(source, &DirectorySourceUrl::from(dist), hashes)
+                    .boxed_local()
+                    .await?
+            }
             BuildableSource::Dist(SourceDist::Path(dist)) => {
-                if dist.path.is_dir() {
-                    self.source_tree_metadata(source, &PathSourceUrl::from(dist), hashes)
-                        .boxed_local()
-                        .await?
-                } else {
-                    let cache_shard = self
-                        .build_context
-                        .cache()
-                        .shard(CacheBucket::BuiltWheels, WheelCache::Path(&dist.url).root());
-                    self.archive_metadata(source, &PathSourceUrl::from(dist), &cache_shard, hashes)
-                        .boxed_local()
-                        .await?
-                }
+                let cache_shard = self
+                    .build_context
+                    .cache()
+                    .shard(CacheBucket::BuiltWheels, WheelCache::Path(&dist.url).root());
+                self.archive_metadata(source, &PathSourceUrl::from(dist), &cache_shard, hashes)
+                    .boxed_local()
+                    .await?
             }
             BuildableSource::Url(SourceUrl::Direct(resource)) => {
                 let filename = resource
@@ -365,20 +363,20 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
                     .boxed_local()
                     .await?
             }
+            BuildableSource::Url(SourceUrl::Directory(resource)) => {
+                self.source_tree_metadata(source, resource, hashes)
+                    .boxed_local()
+                    .await?
+            }
+
             BuildableSource::Url(SourceUrl::Path(resource)) => {
-                if resource.path.is_dir() {
-                    self.source_tree_metadata(source, resource, hashes)
-                        .boxed_local()
-                        .await?
-                } else {
-                    let cache_shard = self.build_context.cache().shard(
-                        CacheBucket::BuiltWheels,
-                        WheelCache::Path(resource.url).root(),
-                    );
-                    self.archive_metadata(source, resource, &cache_shard, hashes)
-                        .boxed_local()
-                        .await?
-                }
+                let cache_shard = self.build_context.cache().shard(
+                    CacheBucket::BuiltWheels,
+                    WheelCache::Path(resource.url).root(),
+                );
+                self.archive_metadata(source, resource, &cache_shard, hashes)
+                    .boxed_local()
+                    .await?
             }
         };
 
@@ -826,7 +824,7 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
     async fn source_tree(
         &self,
         source: &BuildableSource<'_>,
-        resource: &PathSourceUrl<'_>,
+        resource: &DirectorySourceUrl<'_>,
         tags: &Tags,
         hashes: HashPolicy<'_>,
     ) -> Result<BuiltWheelMetadata, Error> {
@@ -891,7 +889,7 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
     async fn source_tree_metadata(
         &self,
         source: &BuildableSource<'_>,
-        resource: &PathSourceUrl<'_>,
+        resource: &DirectorySourceUrl<'_>,
         hashes: HashPolicy<'_>,
     ) -> Result<ArchiveMetadata, Error> {
         // Before running the build, check that the hashes match.
@@ -967,12 +965,12 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
     async fn source_tree_revision(
         &self,
         source: &BuildableSource<'_>,
-        resource: &PathSourceUrl<'_>,
+        resource: &DirectorySourceUrl<'_>,
         cache_shard: &CacheShard,
     ) -> Result<Revision, Error> {
         // Determine the last-modified time of the source distribution.
         let Some(modified) =
-            ArchiveTimestamp::from_path(&resource.path).map_err(Error::CacheRead)?
+            ArchiveTimestamp::from_source_tree(&resource.path).map_err(Error::CacheRead)?
         else {
             return Err(Error::DirWithoutEntrypoint);
         };
@@ -1432,8 +1430,9 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             .await
             .map_err(|err| Error::BuildEditable(editable.to_string(), err))?;
         let filename = WheelFilename::from_str(&disk_filename)?;
+
         // We finally have the name of the package and can construct the dist.
-        let dist = Dist::Source(SourceDist::Path(PathSourceDist {
+        let dist = Dist::Source(SourceDist::Directory(DirectorySourceDist {
             name: filename.name.clone(),
             url: editable.url().clone(),
             path: editable.path.clone(),

crates/uv-installer/src/plan.rs

@@ -9,9 +9,10 @@ use tracing::{debug, warn};
 
 use distribution_filename::WheelFilename;
 use distribution_types::{
-    CachedDirectUrlDist, CachedDist, DirectUrlBuiltDist, DirectUrlSourceDist, Error, GitSourceDist,
-    Hashed, IndexLocations, InstalledDist, InstalledMetadata, InstalledVersion, Name,
-    PathBuiltDist, PathSourceDist, RemoteSource, Requirement, RequirementSource, Verbatim,
+    CachedDirectUrlDist, CachedDist, DirectUrlBuiltDist, DirectUrlSourceDist, DirectorySourceDist,
+    Error, GitSourceDist, Hashed, IndexLocations, InstalledDist, InstalledMetadata,
+    InstalledVersion, Name, PathBuiltDist, PathSourceDist, RemoteSource, Requirement,
+    RequirementSource, Verbatim,
 };
 use platform_tags::Tags;
 use uv_cache::{ArchiveTimestamp, Cache, CacheBucket, WheelCache};
@@ -328,7 +329,23 @@ impl<'a> Planner<'a> {
                     };
 
                     // Check if we have a wheel or a source distribution.
-                    if path
+                    if path.is_dir() {
+                        let sdist = DirectorySourceDist {
+                            name: requirement.name.clone(),
+                            url: url.clone(),
+                            path,
+                            editable: false,
+                        };
+
+                        // Find the most-compatible wheel from the cache, since we don't know
+                        // the filename in advance.
+                        if let Some(wheel) = built_index.directory(&sdist)? {
+                            let cached_dist = wheel.into_url_dist(url.clone());
+                            debug!("Path source requirement already cached: {cached_dist}");
+                            cached.push(CachedDist::Url(cached_dist));
+                            continue;
+                        }
+                    } else if path
                         .extension()
                         .is_some_and(|ext| ext.eq_ignore_ascii_case("whl"))
                     {
@@ -395,8 +412,8 @@ impl<'a> Planner<'a> {
                             name: requirement.name.clone(),
                             url: url.clone(),
                             path,
-                            editable: false,
                         };
+
                         // Find the most-compatible wheel from the cache, since we don't know
                         // the filename in advance.
                         if let Some(wheel) = built_index.path(&sdist)? {

crates/uv-requirements/src/source_tree.rs

@@ -7,10 +7,9 @@ use futures::TryStreamExt;
 use url::Url;
 
 use distribution_types::{
-    BuildableSource, HashPolicy, PathSourceUrl, Requirement, SourceUrl, VersionId,
+    BuildableSource, DirectorySourceUrl, HashPolicy, Requirement, SourceUrl, VersionId,
 };
 use pep508_rs::RequirementOrigin;
-
 use uv_distribution::{DistributionDatabase, Reporter};
 use uv_fs::Simplified;
 use uv_resolver::{InMemoryIndex, MetadataResponse};
@@ -97,7 +96,7 @@ impl<'a, Context: BuildContext> SourceTreeResolver<'a, Context> {
         let Ok(url) = Url::from_directory_path(source_tree) else {
             return Err(anyhow::anyhow!("Failed to convert path to URL"));
         };
-        let source = SourceUrl::Path(PathSourceUrl {
+        let source = SourceUrl::Directory(DirectorySourceUrl {
             url: &url,
             path: Cow::Borrowed(source_tree),
         });

crates/uv-requirements/src/unnamed.rs

@@ -10,8 +10,9 @@ use tracing::debug;
 
 use distribution_filename::{SourceDistFilename, WheelFilename};
 use distribution_types::{
-    BuildableSource, DirectSourceUrl, GitSourceUrl, PathSourceUrl, RemoteSource, Requirement,
-    SourceUrl, UnresolvedRequirement, UnresolvedRequirementSpecification, VersionId,
+    BuildableSource, DirectSourceUrl, DirectorySourceUrl, GitSourceUrl, PathSourceUrl,
+    RemoteSource, Requirement, SourceUrl, UnresolvedRequirement,
+    UnresolvedRequirementSpecification, VersionId,
 };
 use pep508_rs::{Scheme, UnnamedRequirement, VersionOrUrl};
 use pypi_types::Metadata10;
@@ -222,12 +223,17 @@ impl<'a, Context: BuildContext> NamedRequirementsResolver<'a, Context> {
                             }
                         }
                     }
-                }
 
-                SourceUrl::Path(PathSourceUrl {
-                    url: &requirement.url,
-                    path: Cow::Owned(path),
-                })
+                    SourceUrl::Directory(DirectorySourceUrl {
+                        url: &requirement.url,
+                        path: Cow::Owned(path),
+                    })
+                } else {
+                    SourceUrl::Path(PathSourceUrl {
+                        url: &requirement.url,
+                        path: Cow::Owned(path),
+                    })
+                }
             }
             Some(Scheme::Http | Scheme::Https) => SourceUrl::Direct(DirectSourceUrl {
                 url: &requirement.url,

crates/uv-resolver/src/error.rs

@@ -9,10 +9,7 @@ use pubgrub::range::Range;
 use pubgrub::report::{DefaultStringReporter, DerivationTree, External, Reporter};
 use rustc_hash::FxHashMap;
 
-use distribution_types::{
-    BuiltDist, IndexLocations, InstalledDist, ParsedUrlError, PathBuiltDist, PathSourceDist,
-    SourceDist,
-};
+use distribution_types::{BuiltDist, IndexLocations, InstalledDist, ParsedUrlError, SourceDist};
 use once_map::OnceMap;
 use pep440_rs::Version;
 use pep508_rs::Requirement;
@@ -75,14 +72,14 @@ pub enum ResolveError {
     FetchAndBuild(Box<SourceDist>, #[source] uv_distribution::Error),
 
     #[error("Failed to read `{0}`")]
-    Read(Box<PathBuiltDist>, #[source] uv_distribution::Error),
+    Read(Box<BuiltDist>, #[source] uv_distribution::Error),
 
     // TODO(zanieb): Use `thiserror` in `InstalledDist` so we can avoid chaining `anyhow`
     #[error("Failed to read metadata from installed package `{0}`")]
     ReadInstalled(Box<InstalledDist>, #[source] anyhow::Error),
 
     #[error("Failed to build `{0}`")]
-    Build(Box<PathSourceDist>, #[source] uv_distribution::Error),
+    Build(Box<SourceDist>, #[source] uv_distribution::Error),
 
     #[error(transparent)]
     NoSolution(#[from] NoSolutionError),

crates/uv-resolver/src/lock.rs

@@ -6,9 +6,10 @@ use std::collections::VecDeque;
 
 use distribution_filename::WheelFilename;
 use distribution_types::{
-    BuiltDist, DirectUrlBuiltDist, DirectUrlSourceDist, Dist, DistributionMetadata, FileLocation,
-    GitSourceDist, IndexUrl, Name, PathBuiltDist, PathSourceDist, RegistryBuiltDist,
-    RegistrySourceDist, Resolution, ResolvedDist, ToUrlError, VersionOrUrlRef,
+    BuiltDist, DirectUrlBuiltDist, DirectUrlSourceDist, DirectorySourceDist, Dist,
+    DistributionMetadata, FileLocation, GitSourceDist, IndexUrl, Name, PathBuiltDist,
+    PathSourceDist, RegistryBuiltDist, RegistrySourceDist, Resolution, ResolvedDist, ToUrlError,
+    VersionOrUrlRef,
 };
 use pep440_rs::Version;
 use pep508_rs::{MarkerEnvironment, VerbatimUrl};
@@ -360,6 +361,9 @@ impl Source {
             distribution_types::SourceDist::Path(ref path_dist) => {
                 Source::from_path_source_dist(path_dist)
             }
+            distribution_types::SourceDist::Directory(ref directory) => {
+                Source::from_directory_source_dist(directory)
+            }
         }
     }
 
@@ -399,6 +403,13 @@ impl Source {
         }
     }
 
+    fn from_directory_source_dist(directory_dist: &DirectorySourceDist) -> Source {
+        Source {
+            kind: SourceKind::Directory,
+            url: directory_dist.url.to_url(),
+        }
+    }
+
     fn from_index_url(index_url: &IndexUrl) -> Source {
         match *index_url {
             IndexUrl::Pypi(ref verbatim_url) => Source {
@@ -497,6 +508,7 @@ pub(crate) enum SourceKind {
     Git(GitSource),
     Direct,
     Path,
+    Directory,
 }
 
 impl SourceKind {
@@ -506,6 +518,7 @@ impl SourceKind {
             SourceKind::Git(_) => "git",
             SourceKind::Direct => "direct",
             SourceKind::Path => "path",
+            SourceKind::Directory => "directory",
         }
     }
 
@@ -515,13 +528,8 @@ impl SourceKind {
     /// _not_ be present.
     fn requires_hash(&self) -> bool {
         match *self {
-            SourceKind::Registry | SourceKind::Direct => true,
-            // TODO: A `Path` dependency, if it points to a specific source
-            // distribution or wheel, should have a hash. But if it points to a
-            // directory, then it should not have a hash.
-            //
-            // See: https://github.com/astral-sh/uv/issues/3506
-            SourceKind::Git(_) | SourceKind::Path => false,
+            SourceKind::Registry | SourceKind::Direct | SourceKind::Path => true,
+            SourceKind::Git(_) | SourceKind::Directory => false,
         }
     }
 }
@@ -620,6 +628,9 @@ impl SourceDist {
             distribution_types::SourceDist::Path(ref path_dist) => {
                 Ok(SourceDist::from_path_dist(path_dist))
             }
+            distribution_types::SourceDist::Directory(ref directory_dist) => {
+                Ok(SourceDist::from_directory_dist(directory_dist))
+            }
         }
     }
 
@@ -659,6 +670,13 @@ impl SourceDist {
             hash: None,
         }
     }
+
+    fn from_directory_dist(directory_dist: &DirectorySourceDist) -> SourceDist {
+        SourceDist {
+            url: directory_dist.url.to_url(),
+            hash: None,
+        }
+    }
 }
 
 /// Inspired by: <https://discuss.python.org/t/lock-files-again-but-this-time-w-sdists/46593>
@@ -1148,7 +1166,7 @@ url = "https://files.pythonhosted.org/packages/14/fd/2f20c40b45e4fb4324834aea24b
     }
 
     #[test]
-    fn hash_required_missing() {
+    fn hash_optional_missing() {
         let data = r#"
 version = 1
 

crates/uv-resolver/src/resolver/mod.rs

@@ -1224,10 +1224,13 @@ impl<'a, Provider: ResolverProvider, InstalledPackages: InstalledPackagesProvide
                     .boxed_local()
                     .await
                     .map_err(|err| match dist.clone() {
-                        Dist::Built(BuiltDist::Path(built_dist)) => {
+                        Dist::Built(built_dist @ BuiltDist::Path(_)) => {
                             ResolveError::Read(Box::new(built_dist), err)
                         }
-                        Dist::Source(SourceDist::Path(source_dist)) => {
+                        Dist::Source(source_dist @ SourceDist::Path(_)) => {
+                            ResolveError::Build(Box::new(source_dist), err)
+                        }
+                        Dist::Source(source_dist @ SourceDist::Directory(_)) => {
                             ResolveError::Build(Box::new(source_dist), err)
                         }
                         Dist::Built(built_dist) => ResolveError::Fetch(Box::new(built_dist), err),
@@ -1311,10 +1314,13 @@ impl<'a, Provider: ResolverProvider, InstalledPackages: InstalledPackagesProvide
                                 .boxed_local()
                                 .await
                                 .map_err(|err| match dist.clone() {
-                                    Dist::Built(BuiltDist::Path(built_dist)) => {
+                                    Dist::Built(built_dist @ BuiltDist::Path(_)) => {
                                         ResolveError::Read(Box::new(built_dist), err)
                                     }
-                                    Dist::Source(SourceDist::Path(source_dist)) => {
+                                    Dist::Source(source_dist @ SourceDist::Path(_)) => {
+                                        ResolveError::Build(Box::new(source_dist), err)
+                                    }
+                                    Dist::Source(source_dist @ SourceDist::Directory(_)) => {
                                         ResolveError::Build(Box::new(source_dist), err)
                                     }
                                     Dist::Built(built_dist) => {

crates/uv-resolver/src/snapshots/uv_resolver__lock__tests__hash_optional_missing.snap

@@ -0,0 +1,96 @@
+---
+source: crates/uv-resolver/src/lock.rs
+expression: result
+---
+Ok(
+    Lock {
+        version: 1,
+        distributions: [
+            Distribution {
+                id: DistributionId {
+                    name: PackageName(
+                        "anyio",
+                    ),
+                    version: "4.3.0",
+                    source: Source {
+                        kind: Path,
+                        url: Url {
+                            scheme: "file",
+                            cannot_be_a_base: false,
+                            username: "",
+                            password: None,
+                            host: None,
+                            port: None,
+                            path: "/foo/bar",
+                            query: None,
+                            fragment: None,
+                        },
+                    },
+                },
+                marker: None,
+                sourcedist: None,
+                wheels: [
+                    Wheel {
+                        url: Url {
+                            scheme: "file",
+                            cannot_be_a_base: false,
+                            username: "",
+                            password: None,
+                            host: None,
+                            port: None,
+                            path: "/foo/bar/anyio-4.3.0-py3-none-any.whl",
+                            query: None,
+                            fragment: None,
+                        },
+                        hash: Some(
+                            Hash(
+                                HashDigest {
+                                    algorithm: Sha256,
+                                    digest: "048e05d0f6caeed70d731f3db756d35dcc1f35747c8c403364a8332c630441b8",
+                                },
+                            ),
+                        ),
+                        filename: WheelFilename {
+                            name: PackageName(
+                                "anyio",
+                            ),
+                            version: "4.3.0",
+                            python_tag: [
+                                "py3",
+                            ],
+                            abi_tag: [
+                                "none",
+                            ],
+                            platform_tag: [
+                                "any",
+                            ],
+                        },
+                    },
+                ],
+                dependencies: [],
+            },
+        ],
+        by_id: {
+            DistributionId {
+                name: PackageName(
+                    "anyio",
+                ),
+                version: "4.3.0",
+                source: Source {
+                    kind: Path,
+                    url: Url {
+                        scheme: "file",
+                        cannot_be_a_base: false,
+                        username: "",
+                        password: None,
+                        host: None,
+                        port: None,
+                        path: "/foo/bar",
+                        query: None,
+                        fragment: None,
+                    },
+                },
+            }: 0,
+        },
+    },
+)

crates/uv-resolver/src/snapshots/uv_resolver__lock__tests__hash_required_missing.snap

@@ -1,16 +0,0 @@
----
-source: crates/uv-resolver/src/lock.rs
-expression: result
----
-Err(
-    Error {
-        inner: Error {
-            inner: TomlError {
-                message: "since the distribution `anyio 4.3.0 path+file:///foo/bar` comes from a path dependency, a hash was not expected but one was found for wheel",
-                raw: None,
-                keys: [],
-                span: None,
-            },
-        },
-    },
-)

crates/uv/tests/pip_install.rs

@@ -2609,7 +2609,7 @@ requires-python = ">=3.8"
     "###
     );
 
-    // Modify the editable package.
+    // Modify the package.
     pyproject_toml.write_str(
         r#"[project]
 name = "example"