diff --git a/Cargo.lock b/Cargo.lock
index 3ea7ea3d1..edac5deab 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6235,7 +6235,6 @@ dependencies = [
  "uv-scripts",
  "uv-types",
  "uv-warnings",
- "uv-workspace",
 ]
 
 [[package]]
@@ -6279,6 +6278,7 @@ dependencies = [
  "clap",
  "dashmap",
  "either",
+ "fs-err",
  "futures",
  "hashbrown 0.15.5",
  "indexmap",
diff --git a/crates/uv-distribution/src/distribution_database.rs b/crates/uv-distribution/src/distribution_database.rs
index 7a158db25..ef2227df6 100644
--- a/crates/uv-distribution/src/distribution_database.rs
+++ b/crates/uv-distribution/src/distribution_database.rs
@@ -26,7 +26,7 @@ use uv_distribution_types::{
 use uv_extract::hash::Hasher;
 use uv_fs::write_atomic;
 use uv_platform_tags::Tags;
-use uv_pypi_types::{HashDigest, HashDigests};
+use uv_pypi_types::{HashDigest, HashDigests, PyProjectToml};
 use uv_redacted::DisplaySafeUrl;
 use uv_types::{BuildContext, BuildStack};
 
@@ -550,10 +550,11 @@ impl<'a, Context: BuildContext> DistributionDatabase<'a, Context> {
     /// Return the [`RequiresDist`] from a `pyproject.toml`, if it can be statically extracted.
     pub async fn requires_dist(
         &self,
-        source_tree: impl AsRef<Path>,
+        path: &Path,
+        pyproject_toml: &PyProjectToml,
     ) -> Result<Option<RequiresDist>, Error> {
         self.builder
-            .source_tree_requires_dist(source_tree.as_ref())
+            .source_tree_requires_dist(path, pyproject_toml)
             .await
     }
 
diff --git a/crates/uv-distribution/src/metadata/requires_dist.rs b/crates/uv-distribution/src/metadata/requires_dist.rs
index 7df61bb21..b7da5eef3 100644
--- a/crates/uv-distribution/src/metadata/requires_dist.rs
+++ b/crates/uv-distribution/src/metadata/requires_dist.rs
@@ -459,7 +459,8 @@ mod test {
             &WorkspaceCache::default(),
         )
         .await?;
-        let requires_dist = uv_pypi_types::RequiresDist::parse_pyproject_toml(contents)?;
+        let pyproject_toml = uv_pypi_types::PyProjectToml::from_toml(contents)?;
+        let requires_dist = uv_pypi_types::RequiresDist::from_pyproject_toml(pyproject_toml)?;
         Ok(RequiresDist::from_project_workspace(
             requires_dist,
             &project_workspace,
diff --git a/crates/uv-distribution/src/source/mod.rs b/crates/uv-distribution/src/source/mod.rs
index de4ed960d..1bedb7cba 100644
--- a/crates/uv-distribution/src/source/mod.rs
+++ b/crates/uv-distribution/src/source/mod.rs
@@ -1488,18 +1488,16 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
     /// Return the [`RequiresDist`] from a `pyproject.toml`, if it can be statically extracted.
     pub(crate) async fn source_tree_requires_dist(
         &self,
-        source_tree: &Path,
+        path: &Path,
+        pyproject_toml: &PyProjectToml,
     ) -> Result<Option<RequiresDist>, Error> {
         // Attempt to read static metadata from the `pyproject.toml`.
-        match read_requires_dist(source_tree).await {
+        match uv_pypi_types::RequiresDist::from_pyproject_toml(pyproject_toml.clone()) {
             Ok(requires_dist) => {
-                debug!(
-                    "Found static `requires-dist` for: {}",
-                    source_tree.display()
-                );
+                debug!("Found static `requires-dist` for: {}", path.display());
                 let requires_dist = RequiresDist::from_project_maybe_workspace(
                     requires_dist,
-                    source_tree,
+                    path,
                     None,
                     self.build_context.locations(),
                     self.build_context.sources(),
@@ -1509,21 +1507,18 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
                 Ok(Some(requires_dist))
             }
             Err(
-                err @ (Error::MissingPyprojectToml
-                | Error::PyprojectToml(
-                    uv_pypi_types::MetadataError::Pep508Error(_)
-                    | uv_pypi_types::MetadataError::DynamicField(_)
-                    | uv_pypi_types::MetadataError::FieldNotFound(_)
-                    | uv_pypi_types::MetadataError::PoetrySyntax,
-                )),
+                err @ (uv_pypi_types::MetadataError::Pep508Error(_)
+                | uv_pypi_types::MetadataError::DynamicField(_)
+                | uv_pypi_types::MetadataError::FieldNotFound(_)
+                | uv_pypi_types::MetadataError::PoetrySyntax),
             ) => {
                 debug!(
                     "No static `requires-dist` available for: {} ({err:?})",
-                    source_tree.display()
+                    path.display()
                 );
                 Ok(None)
             }
-            Err(err) => Err(err),
+            Err(err) => Err(Error::PyprojectToml(err)),
         }
     }
 
@@ -3025,25 +3020,6 @@ async fn read_pyproject_toml(
     Ok(pyproject_toml)
 }
 
-/// Return the [`pypi_types::RequiresDist`] from a `pyproject.toml`, if it can be statically extracted.
-async fn read_requires_dist(project_root: &Path) -> Result<uv_pypi_types::RequiresDist, Error> {
-    // Read the `pyproject.toml` file.
-    let pyproject_toml = project_root.join("pyproject.toml");
-    let content = match fs::read_to_string(pyproject_toml).await {
-        Ok(content) => content,
-        Err(err) if err.kind() == std::io::ErrorKind::NotFound => {
-            return Err(Error::MissingPyprojectToml);
-        }
-        Err(err) => return Err(Error::CacheRead(err)),
-    };
-
-    // Parse the metadata.
-    let requires_dist = uv_pypi_types::RequiresDist::parse_pyproject_toml(&content)
-        .map_err(Error::PyprojectToml)?;
-
-    Ok(requires_dist)
-}
-
 /// Wheel metadata stored in the source distribution cache.
 #[derive(Debug, Clone)]
 struct CachedMetadata(ResolutionMetadata);
diff --git a/crates/uv-pypi-types/src/metadata/pyproject_toml.rs b/crates/uv-pypi-types/src/metadata/pyproject_toml.rs
index 58ef09fc5..d8b877e5f 100644
--- a/crates/uv-pypi-types/src/metadata/pyproject_toml.rs
+++ b/crates/uv-pypi-types/src/metadata/pyproject_toml.rs
@@ -10,7 +10,7 @@ use uv_pep440::Version;
 use crate::MetadataError;
 
 /// A `pyproject.toml` as specified in PEP 517.
-#[derive(Deserialize, Debug)]
+#[derive(Deserialize, Debug, Clone)]
 #[serde(rename_all = "kebab-case")]
 pub struct PyProjectToml {
     pub project: Option<Project>,
@@ -33,7 +33,7 @@ impl PyProjectToml {
 /// relevant for dependency resolution.
 ///
 /// See <https://packaging.python.org/en/latest/specifications/pyproject-toml>.
-#[derive(Deserialize, Debug)]
+#[derive(Deserialize, Debug, Clone)]
 #[serde(try_from = "PyprojectTomlWire")]
 pub struct Project {
     /// The name of the project
@@ -51,7 +51,7 @@ pub struct Project {
     pub dynamic: Option<Vec<String>>,
 }
 
-#[derive(Deserialize, Debug)]
+#[derive(Deserialize, Debug, Clone)]
 #[serde(rename_all = "kebab-case")]
 struct PyprojectTomlWire {
     name: Option<PackageName>,
@@ -78,13 +78,13 @@ impl TryFrom<PyprojectTomlWire> for Project {
     }
 }
 
-#[derive(Deserialize, Debug)]
+#[derive(Deserialize, Debug, Clone)]
 #[serde(rename_all = "kebab-case")]
 pub(super) struct Tool {
     pub(super) poetry: Option<ToolPoetry>,
 }
 
-#[derive(Deserialize, Debug)]
+#[derive(Deserialize, Debug, Clone)]
 #[serde(rename_all = "kebab-case")]
 #[allow(clippy::empty_structs_with_brackets)]
 pub(super) struct ToolPoetry {}
diff --git a/crates/uv-pypi-types/src/metadata/requires_dist.rs b/crates/uv-pypi-types/src/metadata/requires_dist.rs
index 6194a7e56..629f68062 100644
--- a/crates/uv-pypi-types/src/metadata/requires_dist.rs
+++ b/crates/uv-pypi-types/src/metadata/requires_dist.rs
@@ -24,9 +24,7 @@ pub struct RequiresDist {
 
 impl RequiresDist {
     /// Extract the [`RequiresDist`] from a `pyproject.toml` file, as specified in PEP 621.
-    pub fn parse_pyproject_toml(contents: &str) -> Result<Self, MetadataError> {
-        let pyproject_toml = PyProjectToml::from_toml(contents)?;
-
+    pub fn from_pyproject_toml(pyproject_toml: PyProjectToml) -> Result<Self, MetadataError> {
         let project = pyproject_toml
             .project
             .ok_or(MetadataError::FieldNotFound("project"))?;
diff --git a/crates/uv-requirements/Cargo.toml b/crates/uv-requirements/Cargo.toml
index af1092f8b..795ee4dc4 100644
--- a/crates/uv-requirements/Cargo.toml
+++ b/crates/uv-requirements/Cargo.toml
@@ -34,7 +34,6 @@ uv-resolver = { workspace = true, features = ["clap"] }
 uv-scripts = { workspace = true }
 uv-types = { workspace = true }
 uv-warnings = { workspace = true }
-uv-workspace = { workspace = true }
 
 anyhow = { workspace = true }
 configparser = { workspace = true }
diff --git a/crates/uv-requirements/src/source_tree.rs b/crates/uv-requirements/src/source_tree.rs
index 03d146dd7..d7e2dc674 100644
--- a/crates/uv-requirements/src/source_tree.rs
+++ b/crates/uv-requirements/src/source_tree.rs
@@ -1,5 +1,5 @@
 use std::borrow::Cow;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
 use anyhow::{Context, Result};
@@ -16,10 +16,37 @@ use uv_distribution_types::{
 use uv_fs::Simplified;
 use uv_normalize::{ExtraName, PackageName};
 use uv_pep508::RequirementOrigin;
+use uv_pypi_types::PyProjectToml;
 use uv_redacted::DisplaySafeUrl;
 use uv_resolver::{InMemoryIndex, MetadataResponse};
 use uv_types::{BuildContext, HashStrategy};
 
+#[derive(Debug, Clone)]
+pub enum SourceTree {
+    PyProjectToml(PathBuf, PyProjectToml),
+    SetupPy(PathBuf),
+    SetupCfg(PathBuf),
+}
+
+impl SourceTree {
+    /// Return the [`Path`] to the file representing the source tree (e.g., the `pyproject.toml`).
+    pub fn path(&self) -> &Path {
+        match self {
+            Self::PyProjectToml(path, ..) => path,
+            Self::SetupPy(path) => path,
+            Self::SetupCfg(path) => path,
+        }
+    }
+
+    /// Return the [`PyProjectToml`] if this is a `pyproject.toml`-based source tree.
+    pub fn pyproject_toml(&self) -> Option<&PyProjectToml> {
+        match self {
+            Self::PyProjectToml(.., toml) => Some(toml),
+            _ => None,
+        }
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct SourceTreeResolution {
     /// The requirements sourced from the source trees.
@@ -73,7 +100,7 @@ impl<'a, Context: BuildContext> SourceTreeResolver<'a, Context> {
     /// Resolve the requirements from the provided source trees.
     pub async fn resolve(
         self,
-        source_trees: impl Iterator<Item = &Path>,
+        source_trees: impl Iterator<Item = &SourceTree>,
     ) -> Result<Vec<SourceTreeResolution>> {
         let resolutions: Vec<_> = source_trees
             .map(async |source_tree| self.resolve_source_tree(source_tree).await)
@@ -84,9 +111,10 @@ impl<'a, Context: BuildContext> SourceTreeResolver<'a, Context> {
     }
 
     /// Infer the dependencies for a directory dependency.
-    async fn resolve_source_tree(&self, path: &Path) -> Result<SourceTreeResolution> {
-        let metadata = self.resolve_requires_dist(path).await?;
-        let origin = RequirementOrigin::Project(path.to_path_buf(), metadata.name.clone());
+    async fn resolve_source_tree(&self, source_tree: &SourceTree) -> Result<SourceTreeResolution> {
+        let metadata = self.resolve_requires_dist(source_tree).await?;
+        let origin =
+            RequirementOrigin::Project(source_tree.path().to_path_buf(), metadata.name.clone());
 
         // Determine the extras to include when resolving the requirements.
         let extras = self
@@ -124,15 +152,15 @@ impl<'a, Context: BuildContext> SourceTreeResolver<'a, Context> {
     /// requirements without building the distribution, even if the project contains (e.g.) a
     /// dynamic version since, critically, we don't need to install the package itself; only its
     /// dependencies.
-    async fn resolve_requires_dist(&self, path: &Path) -> Result<RequiresDist> {
+    async fn resolve_requires_dist(&self, source_tree: &SourceTree) -> Result<RequiresDist> {
         // Convert to a buildable source.
-        let source_tree = fs_err::canonicalize(path).with_context(|| {
+        let path = fs_err::canonicalize(source_tree.path()).with_context(|| {
             format!(
                 "Failed to canonicalize path to source tree: {}",
-                path.user_display()
+                source_tree.path().user_display()
             )
         })?;
-        let source_tree = source_tree.parent().ok_or_else(|| {
+        let path = path.parent().ok_or_else(|| {
             anyhow::anyhow!(
                 "The file `{}` appears to be a `pyproject.toml`, `setup.py`, or `setup.cfg` file, which must be in a directory",
                 path.user_display()
@@ -144,16 +172,18 @@ impl<'a, Context: BuildContext> SourceTreeResolver<'a, Context> {
         // _only_ need the requirements. So, for example, even if the version is dynamic, we can
         // still extract the requirements without performing a build, unlike in the database where
         // we typically construct a "complete" metadata object.
-        if let Some(metadata) = self.database.requires_dist(source_tree).await? {
-            return Ok(metadata);
+        if let Some(pyproject_toml) = source_tree.pyproject_toml() {
+            if let Some(metadata) = self.database.requires_dist(path, pyproject_toml).await? {
+                return Ok(metadata);
+            }
         }
 
-        let Ok(url) = Url::from_directory_path(source_tree).map(DisplaySafeUrl::from) else {
+        let Ok(url) = Url::from_directory_path(path).map(DisplaySafeUrl::from) else {
             return Err(anyhow::anyhow!("Failed to convert path to URL"));
         };
         let source = SourceUrl::Directory(DirectorySourceUrl {
             url: &url,
-            install_path: Cow::Borrowed(source_tree),
+            install_path: Cow::Borrowed(path),
             editable: None,
         });
 
diff --git a/crates/uv-requirements/src/specification.rs b/crates/uv-requirements/src/specification.rs
index bc21b3bf0..67984a11b 100644
--- a/crates/uv-requirements/src/specification.rs
+++ b/crates/uv-requirements/src/specification.rs
@@ -44,12 +44,12 @@ use uv_distribution_types::{
 };
 use uv_fs::{CWD, Simplified};
 use uv_normalize::{ExtraName, PackageName, PipGroupName};
+use uv_pypi_types::PyProjectToml;
 use uv_requirements_txt::{RequirementsTxt, RequirementsTxtRequirement};
 use uv_scripts::{Pep723Error, Pep723Item, Pep723Script};
 use uv_warnings::warn_user;
-use uv_workspace::pyproject::PyProjectToml;
 
-use crate::RequirementsSource;
+use crate::{RequirementsSource, SourceTree};
 
 #[derive(Debug, Default, Clone)]
 pub struct RequirementsSpecification {
@@ -64,7 +64,7 @@ pub struct RequirementsSpecification {
     /// The `pylock.toml` file from which to extract the resolution.
     pub pylock: Option<PathBuf>,
     /// The source trees from which to extract requirements.
-    pub source_trees: Vec<PathBuf>,
+    pub source_trees: Vec<SourceTree>,
     /// The groups to use for `source_trees`
     pub groups: BTreeMap<PathBuf, DependencyGroups>,
     /// The extras used to collect requirements.
@@ -174,11 +174,11 @@ impl RequirementsSpecification {
                         ));
                     }
                 };
-                let _ = toml::from_str::<PyProjectToml>(&contents)
+                let pyproject_toml = toml::from_str::<PyProjectToml>(&contents)
                     .with_context(|| format!("Failed to parse: `{}`", path.user_display()))?;
 
                 Self {
-                    source_trees: vec![path.clone()],
+                    source_trees: vec![SourceTree::PyProjectToml(path.clone(), pyproject_toml)],
                     ..Self::default()
                 }
             }
@@ -301,13 +301,23 @@ impl RequirementsSpecification {
                     }
                 }
             }
-            RequirementsSource::SetupPy(path) | RequirementsSource::SetupCfg(path) => {
+            RequirementsSource::SetupPy(path) => {
                 if !path.is_file() {
                     return Err(anyhow::anyhow!("File not found: `{}`", path.user_display()));
                 }
 
                 Self {
-                    source_trees: vec![path.clone()],
+                    source_trees: vec![SourceTree::SetupPy(path.clone())],
+                    ..Self::default()
+                }
+            }
+            RequirementsSource::SetupCfg(path) => {
+                if !path.is_file() {
+                    return Err(anyhow::anyhow!("File not found: `{}`", path.user_display()));
+                }
+
+                Self {
+                    source_trees: vec![SourceTree::SetupCfg(path.clone())],
                     ..Self::default()
                 }
             }
diff --git a/crates/uv-resolver/Cargo.toml b/crates/uv-resolver/Cargo.toml
index 81ce654d8..77965eaa9 100644
--- a/crates/uv-resolver/Cargo.toml
+++ b/crates/uv-resolver/Cargo.toml
@@ -47,6 +47,7 @@ arcstr = { workspace = true }
 clap = { workspace = true, features = ["derive"], optional = true }
 dashmap = { workspace = true }
 either = { workspace = true }
+fs-err = { workspace = true, features = ["tokio"] }
 futures = { workspace = true }
 hashbrown = { workspace = true }
 indexmap = { workspace = true }
diff --git a/crates/uv-resolver/src/lock/mod.rs b/crates/uv-resolver/src/lock/mod.rs
index fed3a623a..803b53560 100644
--- a/crates/uv-resolver/src/lock/mod.rs
+++ b/crates/uv-resolver/src/lock/mod.rs
@@ -42,7 +42,7 @@ use uv_platform_tags::{
 };
 use uv_pypi_types::{
     ConflictKind, Conflicts, HashAlgorithm, HashDigest, HashDigests, Hashes, ParsedArchiveUrl,
-    ParsedGitUrl,
+    ParsedGitUrl, PyProjectToml,
 };
 use uv_redacted::DisplaySafeUrl;
 use uv_small_str::SmallString;
@@ -1808,13 +1808,29 @@ impl Lock {
                 // even if the version is dynamic, we can still extract the requirements without
                 // performing a build, unlike in the database where we typically construct a "complete"
                 // metadata object.
-                let metadata = database
-                    .requires_dist(root.join(source_tree))
-                    .await
-                    .map_err(|err| LockErrorKind::Resolution {
-                        id: package.id.clone(),
-                        err,
-                    })?;
+                let parent = root.join(source_tree);
+                let path = parent.join("pyproject.toml");
+                let metadata =
+                    match fs_err::tokio::read_to_string(&path).await {
+                        Ok(contents) => {
+                            let pyproject_toml = toml::from_str::<PyProjectToml>(&contents)
+                                .map_err(|err| LockErrorKind::InvalidPyprojectToml {
+                                    path: path.clone(),
+                                    err,
+                                })?;
+                            database
+                                .requires_dist(&parent, &pyproject_toml)
+                                .await
+                                .map_err(|err| LockErrorKind::Resolution {
+                                    id: package.id.clone(),
+                                    err,
+                                })?
+                        }
+                        Err(err) if err.kind() == io::ErrorKind::NotFound => None,
+                        Err(err) => {
+                            return Err(LockErrorKind::UnreadablePyprojectToml { path, err }.into());
+                        }
+                    };
 
                 let satisfied = metadata.is_some_and(|metadata| {
                     // Validate that the package is still dynamic.
@@ -5898,6 +5914,18 @@ enum LockErrorKind {
     },
     #[error(transparent)]
     GitUrlParse(#[from] GitUrlParseError),
+    #[error("Failed to read `{path}`")]
+    UnreadablePyprojectToml {
+        path: PathBuf,
+        #[source]
+        err: std::io::Error,
+    },
+    #[error("Failed to parse `{path}`")]
+    InvalidPyprojectToml {
+        path: PathBuf,
+        #[source]
+        err: toml::de::Error,
+    },
 }
 
 /// An error that occurs when a source string could not be parsed.
diff --git a/crates/uv/src/commands/pip/operations.rs b/crates/uv/src/commands/pip/operations.rs
index de079d1ae..c5cbe730a 100644
--- a/crates/uv/src/commands/pip/operations.rs
+++ b/crates/uv/src/commands/pip/operations.rs
@@ -34,7 +34,7 @@ use uv_pypi_types::{Conflicts, ResolverMarkerEnvironment};
 use uv_python::{PythonEnvironment, PythonInstallation};
 use uv_requirements::{
     GroupsSpecification, LookaheadResolver, NamedRequirementsResolver, RequirementsSource,
-    RequirementsSpecification, SourceTreeResolver,
+    RequirementsSpecification, SourceTree, SourceTreeResolver,
 };
 use uv_resolver::{
     DependencyMode, Exclusions, FlatIndex, InMemoryIndex, Manifest, Options, Preference,
@@ -103,7 +103,7 @@ pub(crate) async fn resolve<InstalledPackages: InstalledPackagesProvider>(
     requirements: Vec<UnresolvedRequirementSpecification>,
     constraints: Vec<NameRequirementSpecification>,
     overrides: Vec<UnresolvedRequirementSpecification>,
-    source_trees: Vec<PathBuf>,
+    source_trees: Vec<SourceTree>,
     mut project: Option<PackageName>,
     workspace_members: BTreeSet<PackageName>,
     extras: &ExtrasSpecification,
@@ -167,7 +167,7 @@ pub(crate) async fn resolve<InstalledPackages: InstalledPackagesProvider>(
                 DistributionDatabase::new(client, build_dispatch, concurrency.downloads),
             )
             .with_reporter(Arc::new(ResolverReporter::from(printer)))
-            .resolve(source_trees.iter().map(PathBuf::as_path))
+            .resolve(source_trees.iter())
             .await?;
 
             // If we resolved a single project, use it for the project name.