diff --git a/crates/uv-resolver/src/resolver/mod.rs b/crates/uv-resolver/src/resolver/mod.rs
index 80bd0d4f35ec..1125e8f202a1 100644
--- a/crates/uv-resolver/src/resolver/mod.rs
+++ b/crates/uv-resolver/src/resolver/mod.rs
@@ -26,7 +26,7 @@ use distribution_types::{
 };
 pub(crate) use locals::Locals;
 use pep440_rs::{Version, MIN_VERSION};
-use pep508_rs::MarkerEnvironment;
+use pep508_rs::{MarkerEnvironment, MarkerTree};
 use platform_tags::Tags;
 use pypi_types::{Metadata23, Requirement};
 pub(crate) use urls::Urls;
@@ -476,45 +476,27 @@ impl<InstalledPackages: InstalledPackagesProvider> ResolverState<InstalledPackag
                 {
                     // Retrieve that package dependencies.
                     let package = state.next.clone();
-                    let forks = self.get_dependencies_forking(
+                    let forked_deps = self.get_dependencies_forking(
                         &package,
                         &version,
                         &mut state.priorities,
                         &request_sink,
                     )?;
-                    let forks_len = forks.len();
-                    // This is a somewhat tortured technique to ensure
-                    // that our resolver state is only cloned as much
-                    // as it needs to be. And *especially*, in the case
-                    // when no forks occur, the state should not be
-                    // cloned at all. We basically move the state into
-                    // `forked_states`, and then only clone it if there
-                    // it at least one more fork to visit.
-                    let mut cur_state = Some(state);
-                    for (i, fork) in forks.into_iter().enumerate() {
-                        let is_last = i == forks_len - 1;
-
-                        let dependencies = match fork {
-                            Dependencies::Unavailable(reason) => {
-                                let mut forked_state = cur_state.take().unwrap();
-                                if !is_last {
-                                    cur_state = Some(forked_state.clone());
-                                }
-
-                                forked_state.pubgrub.add_incompatibility(
-                                    Incompatibility::custom_version(
-                                        package.clone(),
-                                        version.clone(),
-                                        UnavailableReason::Version(reason),
-                                    ),
-                                );
-                                forked_states.push(forked_state);
-                                continue;
-                            }
-                            Dependencies::Available(constraints)
-                                if constraints
-                                    .iter()
-                                    .any(|(dependency, _)| dependency == &package) =>
+                    match forked_deps {
+                        ForkedDependencies::Unavailable(reason) => {
+                            state
+                                .pubgrub
+                                .add_incompatibility(Incompatibility::custom_version(
+                                    package.clone(),
+                                    version.clone(),
+                                    UnavailableReason::Version(reason),
+                                ));
+                            forked_states.push(state);
+                        }
+                        ForkedDependencies::Unforked(constraints) => {
+                            if constraints
+                                .iter()
+                                .any(|(dependency, _)| dependency == &package)
                             {
                                 if enabled!(Level::DEBUG) {
                                     prefetcher.log_tried_versions();
@@ -525,28 +507,69 @@ impl<InstalledPackages: InstalledPackagesProvider> ResolverState<InstalledPackag
                                 }
                                 .into());
                             }
-                            Dependencies::Available(constraints) => constraints,
-                        };
-
-                        let mut forked_state = cur_state.take().unwrap();
-                        if !is_last {
-                            cur_state = Some(forked_state.clone());
-                        }
 
-                        // Add that package and version if the dependencies are not problematic.
-                        let dep_incompats =
-                            forked_state.pubgrub.add_incompatibility_from_dependencies(
+                            // Add that package and version if the dependencies are not problematic.
+                            let dep_incompats =
+                                state.pubgrub.add_incompatibility_from_dependencies(
+                                    package.clone(),
+                                    version.clone(),
+                                    constraints,
+                                );
+                            state.pubgrub.partial_solution.add_version(
                                 package.clone(),
                                 version.clone(),
-                                dependencies,
+                                dep_incompats,
+                                &state.pubgrub.incompatibility_store,
                             );
-                        forked_state.pubgrub.partial_solution.add_version(
-                            package.clone(),
-                            version.clone(),
-                            dep_incompats,
-                            &forked_state.pubgrub.incompatibility_store,
-                        );
-                        forked_states.push(forked_state);
+                            forked_states.push(state);
+                        }
+                        ForkedDependencies::Forked(forks) => {
+                            assert!(forks.len() >= 2);
+                            // This is a somewhat tortured technique to ensure
+                            // that our resolver state is only cloned as much
+                            // as it needs to be. We basically move the state
+                            // into `forked_states`, and then only clone it if
+                            // there it at least one more fork to visit.
+                            let mut cur_state = Some(state);
+                            let forks_len = forks.len();
+                            for (i, fork) in forks.into_iter().enumerate() {
+                                if fork
+                                    .dependencies
+                                    .iter()
+                                    .any(|(dependency, _)| dependency == &package)
+                                {
+                                    if enabled!(Level::DEBUG) {
+                                        prefetcher.log_tried_versions();
+                                    }
+                                    return Err(PubGrubError::SelfDependency {
+                                        package: package.clone(),
+                                        version: version.clone(),
+                                    }
+                                    .into());
+                                }
+
+                                let is_last = i == forks_len - 1;
+                                let mut forked_state = cur_state.take().unwrap();
+                                if !is_last {
+                                    cur_state = Some(forked_state.clone());
+                                }
+
+                                // Add that package and version if the dependencies are not problematic.
+                                let dep_incompats =
+                                    forked_state.pubgrub.add_incompatibility_from_dependencies(
+                                        package.clone(),
+                                        version.clone(),
+                                        fork.dependencies,
+                                    );
+                                forked_state.pubgrub.partial_solution.add_version(
+                                    package.clone(),
+                                    version.clone(),
+                                    dep_incompats,
+                                    &forked_state.pubgrub.incompatibility_store,
+                                );
+                                forked_states.push(forked_state);
+                            }
+                        }
                     }
                     continue 'FORK;
                 }
@@ -896,62 +919,15 @@ impl<InstalledPackages: InstalledPackagesProvider> ResolverState<InstalledPackag
         version: &Version,
         priorities: &mut PubGrubPriorities,
         request_sink: &Sender<Request>,
-    ) -> Result<Vec<Dependencies>, ResolveError> {
-        type Dep = (PubGrubPackage, Range<Version>);
-
+    ) -> Result<ForkedDependencies, ResolveError> {
         let result = self.get_dependencies(package, version, priorities, request_sink);
         if self.markers.is_some() {
-            return result.map(|deps| vec![deps]);
+            return result.map(|deps| match deps {
+                Dependencies::Available(deps) => ForkedDependencies::Unforked(deps),
+                Dependencies::Unavailable(err) => ForkedDependencies::Unavailable(err),
+            });
         }
-        let deps: Vec<Dep> = match result? {
-            Dependencies::Available(deps) => deps,
-            Dependencies::Unavailable(err) => return Ok(vec![Dependencies::Unavailable(err)]),
-        };
-
-        let mut by_grouping: FxHashMap<&PackageName, FxHashMap<&Range<Version>, Vec<&Dep>>> =
-            FxHashMap::default();
-        for dep in &deps {
-            let (ref pkg, ref range) = *dep;
-            let name = match &**pkg {
-                // A root can never be a dependency of another package, and a `Python` pubgrub
-                // package is never returned by `get_dependencies`. So these cases never occur.
-                // TODO(charlie): This might be overly conservative for `Extra` and `Group`. If
-                // multiple groups are enabled, we shouldn't need to fork. Similarly, if multiple
-                // extras are enabled, we shouldn't need to fork.
-                PubGrubPackageInner::Root(_) | PubGrubPackageInner::Python(_) => unreachable!(),
-                PubGrubPackageInner::Package { ref name, .. }
-                | PubGrubPackageInner::Marker { ref name, .. }
-                | PubGrubPackageInner::Extra { ref name, .. }
-                | PubGrubPackageInner::Dev { ref name, .. } => name,
-            };
-            by_grouping
-                .entry(name)
-                .or_default()
-                .entry(range)
-                .or_default()
-                .push(dep);
-        }
-        let mut forks: Vec<Vec<Dep>> = vec![vec![]];
-        for (_, groups) in by_grouping {
-            if groups.len() <= 1 {
-                for deps in groups.into_values() {
-                    for fork in &mut forks {
-                        fork.extend(deps.iter().map(|dep| (*dep).clone()));
-                    }
-                }
-            } else {
-                let mut new_forks: Vec<Vec<Dep>> = vec![];
-                for deps in groups.into_values() {
-                    let mut new_forks_for_group = forks.clone();
-                    for fork in &mut new_forks_for_group {
-                        fork.extend(deps.iter().map(|dep| (*dep).clone()));
-                    }
-                    new_forks.extend(new_forks_for_group);
-                }
-                forks = new_forks;
-            }
-        }
-        Ok(forks.into_iter().map(Dependencies::Available).collect())
+        Ok(result?.fork())
     }
 
     /// Given a candidate package and version, return its dependencies.
@@ -1814,6 +1790,246 @@ enum Dependencies {
     Available(Vec<(PubGrubPackage, Range<Version>)>),
 }
 
+impl Dependencies {
+    fn fork(self) -> ForkedDependencies {
+        use std::collections::hash_map::Entry;
+
+        let deps = match self {
+            Dependencies::Available(deps) => deps,
+            Dependencies::Unavailable(err) => return ForkedDependencies::Unavailable(err),
+        };
+
+        let mut by_name: FxHashMap<&PackageName, PossibleForks> = FxHashMap::default();
+        for (index, (ref pkg, _)) in deps.iter().enumerate() {
+            let (name, marker) = match &**pkg {
+                // A root can never be a dependency of another package, and a `Python` pubgrub
+                // package is never returned by `get_dependencies`. So these cases never occur.
+                PubGrubPackageInner::Root(_) | PubGrubPackageInner::Python(_) => unreachable!(),
+                PubGrubPackageInner::Package { name, marker, .. }
+                | PubGrubPackageInner::Extra { name, marker, .. }
+                | PubGrubPackageInner::Dev { name, marker, .. } => (name, marker.as_ref()),
+                PubGrubPackageInner::Marker { name, marker, .. } => (name, Some(marker)),
+            };
+            let Some(marker) = marker else {
+                // When no marker is found, it implies there is a dependency on
+                // this package that is unconditional with respect to marker
+                // expressions. Therefore, it should never be the cause of a
+                // fork since it is necessarily overlapping with every other
+                // possible marker expression that isn't pathological.
+                match by_name.entry(name) {
+                    Entry::Vacant(e) => {
+                        e.insert(PossibleForks::NoForkPossible(vec![index]));
+                    }
+                    Entry::Occupied(mut e) => {
+                        e.get_mut().push_unconditional_package(index);
+                    }
+                }
+                continue;
+            };
+            let possible_forks = match by_name.entry(name) {
+                // If one doesn't exist, then this is the first dependency
+                // with this package name. And since it has a marker, we can
+                // add it as the initial instance of a possibly forking set of
+                // dependencies. (A fork will only actually happen if another
+                // dependency is found with the same package name *and* where
+                // its marker expression is disjoint with this one.)
+                Entry::Vacant(e) => {
+                    let possible_fork = PossibleFork {
+                        packages: vec![(index, marker)],
+                    };
+                    let fork_groups = PossibleForkGroups {
+                        forks: vec![possible_fork],
+                    };
+                    e.insert(PossibleForks::PossiblyForking(fork_groups));
+                    continue;
+                }
+                // Now that we have a marker, look for an existing entry. If
+                // one already exists and is "no fork possible," then we know
+                // we can't fork.
+                Entry::Occupied(e) => match *e.into_mut() {
+                    PossibleForks::NoForkPossible(ref mut indices) => {
+                        indices.push(index);
+                        continue;
+                    }
+                    PossibleForks::PossiblyForking(ref mut possible_forks) => possible_forks,
+                },
+            };
+            // At this point, we know we 1) have a duplicate dependency on
+            // a package and 2) the original and this one both have marker
+            // expressions. This still doesn't guarantee that a fork occurs
+            // though. A fork can only occur when the marker expressions from
+            // (2) are provably disjoint. Otherwise, we could end up with
+            // a resolution that would result in installing two different
+            // versions of the same package. Specifically, this could occur in
+            // precisely the cases where the marker expressions intersect.
+            //
+            // By construction, the marker expressions *in* each fork group
+            // have some non-empty intersection, and the marker expressions
+            // *between* each fork group are completely disjoint. So what we do
+            // is look for a group in which there is some overlap. If so, this
+            // package gets added to that fork group. Otherwise, we create a
+            // new fork group.
+            // possible_forks.push(PossibleFork { packages: vec![] });
+            let Some(possible_fork) = possible_forks.find_overlapping_fork_group(marker) else {
+                // Create a new fork since there was no overlap.
+                possible_forks.forks.push(PossibleFork {
+                    packages: vec![(index, marker)],
+                });
+                continue;
+            };
+            // Add to an existing fork since there was overlap.
+            possible_fork.packages.push((index, marker));
+        }
+        // If all possible forks have exactly 1 group, then there is no forking.
+        if !by_name.values().any(PossibleForks::has_fork) {
+            return ForkedDependencies::Unforked(deps);
+        }
+        let mut forks = vec![Fork {
+            dependencies: vec![],
+        }];
+        for (_, possible_forks) in by_name {
+            let fork_groups = match possible_forks {
+                PossibleForks::PossiblyForking(fork_groups) => fork_groups,
+                PossibleForks::NoForkPossible(indices) => {
+                    // No fork is provoked by this package, so just add
+                    // everything in this group to each of the forks.
+                    for index in indices {
+                        for fork in &mut forks {
+                            fork.dependencies.push(deps[index].clone());
+                        }
+                    }
+                    continue;
+                }
+            };
+            let mut new_forks: Vec<Fork> = vec![];
+            for group in fork_groups.forks {
+                let mut new_forks_for_group = forks.clone();
+                for (index, _) in group.packages {
+                    for fork in &mut new_forks_for_group {
+                        fork.dependencies.push(deps[index].clone());
+                    }
+                }
+                new_forks.extend(new_forks_for_group);
+            }
+            forks = new_forks;
+        }
+        ForkedDependencies::Forked(forks)
+    }
+}
+
+#[derive(Debug)]
+enum ForkedDependencies {
+    /// Package dependencies are not available.
+    Unavailable(UnavailableVersion),
+    /// No forking occurred.
+    Unforked(Vec<(PubGrubPackage, Range<Version>)>),
+    /// Forked containers for all available package versions.
+    ///
+    /// Note that there is always at least two forks. If there would
+    /// be fewer than 2 forks, then there is no fork at all and the
+    /// `Unforked` variant is used instead.
+    Forked(Vec<Fork>),
+}
+
+#[derive(Clone, Debug)]
+struct Fork {
+    dependencies: Vec<(PubGrubPackage, Range<Version>)>,
+}
+
+#[derive(Debug)]
+enum PossibleForks<'a> {
+    NoForkPossible(Vec<usize>),
+    PossiblyForking(PossibleForkGroups<'a>),
+}
+
+impl<'a> PossibleForks<'a> {
+    /// Returns true if and only if this contains a fork assuming there are
+    /// no other dependencies to be considered.
+    fn has_fork(&self) -> bool {
+        let PossibleForks::PossiblyForking(ref fork_groups) = *self else {
+            return false;
+        };
+        fork_groups.forks.len() > 1
+    }
+
+    /// Pushes an unconditional index to a package.
+    ///
+    /// If this previously contained possible forks, those are combined into
+    /// one single set of dependencies that can never be forked.
+    ///
+    /// That is, adding an unconditional package means it is not disjoint with
+    /// all other possible dependencies using the same package name.
+    fn push_unconditional_package(&mut self, index: usize) {
+        self.make_no_forks_possible();
+        let PossibleForks::NoForkPossible(ref mut indices) = *self else {
+            unreachable!("all forks should be eliminated")
+        };
+        indices.push(index);
+    }
+
+    /// Convert this set of possible forks into something that can never fork.
+    ///
+    /// This is useful in cases where a dependency on a package is found
+    /// without any marker expressions at all. In this case, it is never
+    /// possible for this package to provoke a fork. Since it is unconditional,
+    /// it implies it is never disjoint with any other dependency specification
+    /// on the same package. (Except for pathological cases of marker
+    /// expressions that always evaluate to false. But we generally ignore
+    /// those.)
+    fn make_no_forks_possible(&mut self) {
+        let PossibleForks::PossiblyForking(ref fork_groups) = *self else {
+            return;
+        };
+        let mut indices = vec![];
+        for possible_fork in &fork_groups.forks {
+            for &(index, _) in &possible_fork.packages {
+                indices.push(index);
+            }
+        }
+        *self = PossibleForks::NoForkPossible(indices);
+    }
+}
+
+#[derive(Debug)]
+struct PossibleForkGroups<'a> {
+    forks: Vec<PossibleFork<'a>>,
+}
+
+impl<'a> PossibleForkGroups<'a> {
+    /// Given a marker expression, if there is a fork in this set of fork
+    /// groups with non-empty overlap with it, then that fork group is
+    /// returned. Otherwise, `None` is returned.
+    fn find_overlapping_fork_group<'g>(
+        &'g mut self,
+        marker: &MarkerTree,
+    ) -> Option<&'g mut PossibleFork<'a>> {
+        self.forks
+            .iter_mut()
+            .find(|fork| fork.is_overlapping(marker))
+    }
+}
+
+#[derive(Debug)]
+struct PossibleFork<'a> {
+    packages: Vec<(usize, &'a MarkerTree)>,
+}
+
+impl<'a> PossibleFork<'a> {
+    /// Returns true if and only if the given marker expression has a non-empty
+    /// intersection with *any* of the package markers within this possible
+    /// fork.
+    fn is_overlapping(&self, marker: &MarkerTree) -> bool {
+        use crate::marker::is_disjoint;
+
+        for (_, tree) in &self.packages {
+            if !is_disjoint(marker, tree) {
+                return true;
+            }
+        }
+        false
+    }
+}
+
 fn uncapitalize<T: AsRef<str>>(string: T) -> String {
     let mut chars = string.as_ref().chars();
     match chars.next() {
diff --git a/crates/uv/tests/common/mod.rs b/crates/uv/tests/common/mod.rs
index c56676cd503d..5f25ac6a1e18 100644
--- a/crates/uv/tests/common/mod.rs
+++ b/crates/uv/tests/common/mod.rs
@@ -26,7 +26,7 @@ pub static EXCLUDE_NEWER: &str = "2024-03-25T00:00:00Z";
 /// Using a find links url allows using `--index-url` instead of `--extra-index-url` in tests
 /// to prevent dependency confusion attacks against our test suite.
 pub const BUILD_VENDOR_LINKS_URL: &str =
-    "https://raw.githubusercontent.com/astral-sh/packse/0.3.17/vendor/links.html";
+    "https://raw.githubusercontent.com/astral-sh/packse/0.3.18/vendor/links.html";
 
 #[doc(hidden)] // Macro and test context only, don't use directly.
 pub const INSTA_FILTERS: &[(&str, &str)] = &[
diff --git a/crates/uv/tests/lock_scenarios.rs b/crates/uv/tests/lock_scenarios.rs
index 3edc2a060c2e..d5701b3c0daa 100644
--- a/crates/uv/tests/lock_scenarios.rs
+++ b/crates/uv/tests/lock_scenarios.rs
@@ -1,7 +1,7 @@
 //! DO NOT EDIT
 //!
 //! Generated with `./scripts/sync_scenarios.sh`
-//! Scenarios from <https://github.com/astral-sh/packse/tree/0.3.17/scenarios>
+//! Scenarios from <https://github.com/astral-sh/packse/tree/0.3.18/scenarios>
 //!
 #![cfg(all(feature = "python", feature = "pypi"))]
 #![allow(clippy::needless_raw_string_hashes)]
@@ -44,7 +44,6 @@ fn fork_basic() -> Result<()> {
         [project]
         name = "project"
         version = "0.1.0"
-        requires-python = ">=3.8"
         dependencies = [
           '''fork-basic-a>=2; sys_platform == "linux"''',
           '''fork-basic-a<2; sys_platform == "darwin"''',
@@ -54,7 +53,7 @@ fn fork_basic() -> Result<()> {
 
     let mut cmd = context.lock_without_exclude_newer();
     cmd.arg("--index-url")
-        .arg("https://astral-sh.github.io/packse/0.3.17/simple-html/");
+        .arg("https://astral-sh.github.io/packse/0.3.18/simple-html/");
     uv_snapshot!(filters, cmd, @r###"
     success: true
     exit_code: 0
@@ -62,6 +61,7 @@ fn fork_basic() -> Result<()> {
 
     ----- stderr -----
     warning: `uv lock` is experimental and may change without warning.
+    warning: No `requires-python` field found in `project`. Defaulting to `>=3.8`.
     Resolved 3 packages in [TIME]
     "###
     );
@@ -78,18 +78,18 @@ fn fork_basic() -> Result<()> {
         [[distribution]]
         name = "package-a"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "sys_platform == 'darwin'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_basic_a-1.0.0.tar.gz#sha256=3e45d6136e4a52416f85b7f53f405493db8f9fea33210299e6a68895bf0acf2a", hash = "sha256:3e45d6136e4a52416f85b7f53f405493db8f9fea33210299e6a68895bf0acf2a" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_basic_a-1.0.0-py3-none-any.whl#sha256=b81a7553af25f15c9d49ed26af9c5b86eb2be107f3dd1bd97d7a4b0e8ca0329e", hash = "sha256:b81a7553af25f15c9d49ed26af9c5b86eb2be107f3dd1bd97d7a4b0e8ca0329e" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_basic_a-1.0.0.tar.gz#sha256=3e45d6136e4a52416f85b7f53f405493db8f9fea33210299e6a68895bf0acf2a", hash = "sha256:3e45d6136e4a52416f85b7f53f405493db8f9fea33210299e6a68895bf0acf2a" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_basic_a-1.0.0-py3-none-any.whl#sha256=b81a7553af25f15c9d49ed26af9c5b86eb2be107f3dd1bd97d7a4b0e8ca0329e", hash = "sha256:b81a7553af25f15c9d49ed26af9c5b86eb2be107f3dd1bd97d7a4b0e8ca0329e" }]
 
         [[distribution]]
         name = "package-a"
         version = "2.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "sys_platform == 'linux'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_basic_a-2.0.0.tar.gz#sha256=ceb7349a6dd7640be952c70dce8ee6a44e3442dfd9b248b96242e37623e1028e", hash = "sha256:ceb7349a6dd7640be952c70dce8ee6a44e3442dfd9b248b96242e37623e1028e" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_basic_a-2.0.0-py3-none-any.whl#sha256=9cab1de38d28e75ac5fe5c4dda9157555c60dd03ee26e6ad51b01ca18d8a0f01", hash = "sha256:9cab1de38d28e75ac5fe5c4dda9157555c60dd03ee26e6ad51b01ca18d8a0f01" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_basic_a-2.0.0.tar.gz#sha256=ceb7349a6dd7640be952c70dce8ee6a44e3442dfd9b248b96242e37623e1028e", hash = "sha256:ceb7349a6dd7640be952c70dce8ee6a44e3442dfd9b248b96242e37623e1028e" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_basic_a-2.0.0-py3-none-any.whl#sha256=9cab1de38d28e75ac5fe5c4dda9157555c60dd03ee26e6ad51b01ca18d8a0f01", hash = "sha256:9cab1de38d28e75ac5fe5c4dda9157555c60dd03ee26e6ad51b01ca18d8a0f01" }]
 
         [[distribution]]
         name = "project"
@@ -100,12 +100,12 @@ fn fork_basic() -> Result<()> {
         [[distribution.dependencies]]
         name = "package-a"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution.dependencies]]
         name = "package-a"
         version = "2.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         "###
         );
     });
@@ -153,7 +153,6 @@ fn fork_marker_accrue() -> Result<()> {
         [project]
         name = "project"
         version = "0.1.0"
-        requires-python = ">=3.8"
         dependencies = [
           '''fork-marker-accrue-a==1.0.0; implementation_name == "cpython"''',
           '''fork-marker-accrue-b==1.0.0; implementation_name == "pypy"''',
@@ -163,7 +162,7 @@ fn fork_marker_accrue() -> Result<()> {
 
     let mut cmd = context.lock_without_exclude_newer();
     cmd.arg("--index-url")
-        .arg("https://astral-sh.github.io/packse/0.3.17/simple-html/");
+        .arg("https://astral-sh.github.io/packse/0.3.18/simple-html/");
     uv_snapshot!(filters, cmd, @r###"
     success: true
     exit_code: 0
@@ -171,6 +170,7 @@ fn fork_marker_accrue() -> Result<()> {
 
     ----- stderr -----
     warning: `uv lock` is experimental and may change without warning.
+    warning: No `requires-python` field found in `project`. Defaulting to `>=3.8`.
     Resolved 4 packages in [TIME]
     "###
     );
@@ -187,36 +187,36 @@ fn fork_marker_accrue() -> Result<()> {
         [[distribution]]
         name = "package-a"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "implementation_name == 'cpython'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_accrue_a-1.0.0.tar.gz#sha256=9096dbf9c8e8c2da4a1527be515f740f697ee833ec1492953883f36c8931bc37", hash = "sha256:9096dbf9c8e8c2da4a1527be515f740f697ee833ec1492953883f36c8931bc37" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_accrue_a-1.0.0-py3-none-any.whl#sha256=5fed1607b73cc7a5e9703206c24cc3fa730600a776bf40ae264ad364ad610e0a", hash = "sha256:5fed1607b73cc7a5e9703206c24cc3fa730600a776bf40ae264ad364ad610e0a" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_accrue_a-1.0.0.tar.gz#sha256=9096dbf9c8e8c2da4a1527be515f740f697ee833ec1492953883f36c8931bc37", hash = "sha256:9096dbf9c8e8c2da4a1527be515f740f697ee833ec1492953883f36c8931bc37" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_accrue_a-1.0.0-py3-none-any.whl#sha256=5fed1607b73cc7a5e9703206c24cc3fa730600a776bf40ae264ad364ad610e0a", hash = "sha256:5fed1607b73cc7a5e9703206c24cc3fa730600a776bf40ae264ad364ad610e0a" }]
 
         [[distribution.dependencies]]
         name = "package-c"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution]]
         name = "package-b"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "implementation_name == 'pypy'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_accrue_b-1.0.0.tar.gz#sha256=d92d0083d2d5da2f83180c08dfc79a03ec9606c00bc3153566f7b577c0e6b859", hash = "sha256:d92d0083d2d5da2f83180c08dfc79a03ec9606c00bc3153566f7b577c0e6b859" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_accrue_b-1.0.0-py3-none-any.whl#sha256=e5382e438f417f2de9427296a5960f9f9631ff1fa11c93d6b0b3b9d7fb60760f", hash = "sha256:e5382e438f417f2de9427296a5960f9f9631ff1fa11c93d6b0b3b9d7fb60760f" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_accrue_b-1.0.0.tar.gz#sha256=d92d0083d2d5da2f83180c08dfc79a03ec9606c00bc3153566f7b577c0e6b859", hash = "sha256:d92d0083d2d5da2f83180c08dfc79a03ec9606c00bc3153566f7b577c0e6b859" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_accrue_b-1.0.0-py3-none-any.whl#sha256=e5382e438f417f2de9427296a5960f9f9631ff1fa11c93d6b0b3b9d7fb60760f", hash = "sha256:e5382e438f417f2de9427296a5960f9f9631ff1fa11c93d6b0b3b9d7fb60760f" }]
 
         [[distribution.dependencies]]
         name = "package-c"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution]]
         name = "package-c"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "sys_platform == 'darwin' or sys_platform == 'linux'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_accrue_c-1.0.0.tar.gz#sha256=81068ae8b43deb3165cab17eb52aa5f99cda64f51c359b4659918d86995b9cad", hash = "sha256:81068ae8b43deb3165cab17eb52aa5f99cda64f51c359b4659918d86995b9cad" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_accrue_c-1.0.0-py3-none-any.whl#sha256=f5fe6d35f360ea802b3a7da030e9ed1dce776c30ed028ea7be04fafcb7ac55b6", hash = "sha256:f5fe6d35f360ea802b3a7da030e9ed1dce776c30ed028ea7be04fafcb7ac55b6" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_accrue_c-1.0.0.tar.gz#sha256=81068ae8b43deb3165cab17eb52aa5f99cda64f51c359b4659918d86995b9cad", hash = "sha256:81068ae8b43deb3165cab17eb52aa5f99cda64f51c359b4659918d86995b9cad" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_accrue_c-1.0.0-py3-none-any.whl#sha256=f5fe6d35f360ea802b3a7da030e9ed1dce776c30ed028ea7be04fafcb7ac55b6", hash = "sha256:f5fe6d35f360ea802b3a7da030e9ed1dce776c30ed028ea7be04fafcb7ac55b6" }]
 
         [[distribution]]
         name = "project"
@@ -227,12 +227,12 @@ fn fork_marker_accrue() -> Result<()> {
         [[distribution.dependencies]]
         name = "package-a"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution.dependencies]]
         name = "package-b"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         "###
         );
     });
@@ -240,6 +240,70 @@ fn fork_marker_accrue() -> Result<()> {
     Ok(())
 }
 
+/// A basic test that ensures, at least in this one basic case, that forking in
+/// universal resolution happens only when the corresponding marker expressions are
+/// completely disjoint. Here, we provide two completely incompatible dependency
+/// specifications with equivalent markers. Thus, they are trivially not disjoint,
+/// and resolution should fail.  NOTE: This acts a regression test for the initial
+/// version of universal resolution that would fork whenever a package was repeated
+/// in the list of dependency specifications. So previously, this would produce a
+/// resolution with both `1.0.0` and `2.0.0` of `a`. But of course, the correct
+/// behavior is to fail resolving.
+///
+/// ```text
+/// fork-marker-disjoint
+/// ├── environment
+/// │   └── python3.8
+/// ├── root
+/// │   ├── requires a>=2; sys_platform == "linux"
+/// │   │   └── satisfied by a-2.0.0
+/// │   └── requires a<2; sys_platform == "linux"
+/// │       └── satisfied by a-1.0.0
+/// └── a
+///     ├── a-1.0.0
+///     └── a-2.0.0
+/// ```
+#[test]
+fn fork_marker_disjoint() -> Result<()> {
+    let context = TestContext::new("3.8");
+
+    // In addition to the standard filters, swap out package names for shorter messages
+    let mut filters = context.filters();
+    filters.push((r"fork-marker-disjoint-", "package-"));
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r###"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        dependencies = [
+          '''fork-marker-disjoint-a>=2; sys_platform == "linux"''',
+          '''fork-marker-disjoint-a<2; sys_platform == "linux"''',
+        ]
+        "###,
+    )?;
+
+    let mut cmd = context.lock_without_exclude_newer();
+    cmd.arg("--index-url")
+        .arg("https://astral-sh.github.io/packse/0.3.18/simple-html/");
+    uv_snapshot!(filters, cmd, @r###"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: `uv lock` is experimental and may change without warning.
+    warning: No `requires-python` field found in `project`. Defaulting to `>=3.8`.
+      × No solution found when resolving dependencies:
+      ╰─▶ Because project==0.1.0 depends on package-a{sys_platform == 'linux'}>=2 and package-a{sys_platform == 'linux'}<2, we can conclude that project==0.1.0 cannot be used.
+          And because only project==0.1.0 is available and project depends on project, we can conclude that the requirements are unsatisfiable.
+    "###
+    );
+
+    Ok(())
+}
+
 /// This tests a case where the resolver forks because of non-overlapping marker
 /// expressions on `b`. In the original universal resolver implementation, this
 /// resulted in multiple versions of `a` being unconditionally included in the lock
@@ -281,7 +345,6 @@ fn fork_marker_selection() -> Result<()> {
         [project]
         name = "project"
         version = "0.1.0"
-        requires-python = ">=3.8"
         dependencies = [
           '''fork-marker-selection-a''',
           '''fork-marker-selection-b>=2; sys_platform == "linux"''',
@@ -292,7 +355,7 @@ fn fork_marker_selection() -> Result<()> {
 
     let mut cmd = context.lock_without_exclude_newer();
     cmd.arg("--index-url")
-        .arg("https://astral-sh.github.io/packse/0.3.17/simple-html/");
+        .arg("https://astral-sh.github.io/packse/0.3.18/simple-html/");
     uv_snapshot!(filters, cmd, @r###"
     success: true
     exit_code: 0
@@ -300,6 +363,7 @@ fn fork_marker_selection() -> Result<()> {
 
     ----- stderr -----
     warning: `uv lock` is experimental and may change without warning.
+    warning: No `requires-python` field found in `project`. Defaulting to `>=3.8`.
     Resolved 5 packages in [TIME]
     "###
     );
@@ -316,37 +380,37 @@ fn fork_marker_selection() -> Result<()> {
         [[distribution]]
         name = "package-a"
         version = "0.1.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_selection_a-0.1.0.tar.gz#sha256=03c464276ee75f5a1468da2a4090ee6b5fda0f26f548707c9ffcf06d3cf69282", hash = "sha256:03c464276ee75f5a1468da2a4090ee6b5fda0f26f548707c9ffcf06d3cf69282" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_selection_a-0.1.0-py3-none-any.whl#sha256=0e45ca7b3616810a583dc9754b52b91c69aeea4070d6fe0806c67081d0e95473", hash = "sha256:0e45ca7b3616810a583dc9754b52b91c69aeea4070d6fe0806c67081d0e95473" }]
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_selection_a-0.1.0.tar.gz#sha256=03c464276ee75f5a1468da2a4090ee6b5fda0f26f548707c9ffcf06d3cf69282", hash = "sha256:03c464276ee75f5a1468da2a4090ee6b5fda0f26f548707c9ffcf06d3cf69282" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_selection_a-0.1.0-py3-none-any.whl#sha256=0e45ca7b3616810a583dc9754b52b91c69aeea4070d6fe0806c67081d0e95473", hash = "sha256:0e45ca7b3616810a583dc9754b52b91c69aeea4070d6fe0806c67081d0e95473" }]
 
         [[distribution]]
         name = "package-a"
         version = "0.2.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_selection_a-0.2.0.tar.gz#sha256=ef1d840fe2e86c6eecd4673606076d858b51a3712c1de097b7503fee0c96b97f", hash = "sha256:ef1d840fe2e86c6eecd4673606076d858b51a3712c1de097b7503fee0c96b97f" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_selection_a-0.2.0-py3-none-any.whl#sha256=78797f388900cece9866aa20917c6a40040dd65f906f8ef034a8cedb4dd75e6c", hash = "sha256:78797f388900cece9866aa20917c6a40040dd65f906f8ef034a8cedb4dd75e6c" }]
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_selection_a-0.2.0.tar.gz#sha256=ef1d840fe2e86c6eecd4673606076d858b51a3712c1de097b7503fee0c96b97f", hash = "sha256:ef1d840fe2e86c6eecd4673606076d858b51a3712c1de097b7503fee0c96b97f" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_selection_a-0.2.0-py3-none-any.whl#sha256=78797f388900cece9866aa20917c6a40040dd65f906f8ef034a8cedb4dd75e6c", hash = "sha256:78797f388900cece9866aa20917c6a40040dd65f906f8ef034a8cedb4dd75e6c" }]
 
         [[distribution.dependencies]]
         name = "package-b"
         version = "2.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution]]
         name = "package-b"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "sys_platform == 'darwin'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_selection_b-1.0.0.tar.gz#sha256=97f1098f4c89457ab2b16982990d487ac6ae2c664f8e22e822a086df71999dc1", hash = "sha256:97f1098f4c89457ab2b16982990d487ac6ae2c664f8e22e822a086df71999dc1" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_selection_b-1.0.0-py3-none-any.whl#sha256=aba998c3dfa70f4118a4587f636c96f5a2785081b733120cf81b6d762f67b1ca", hash = "sha256:aba998c3dfa70f4118a4587f636c96f5a2785081b733120cf81b6d762f67b1ca" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_selection_b-1.0.0.tar.gz#sha256=97f1098f4c89457ab2b16982990d487ac6ae2c664f8e22e822a086df71999dc1", hash = "sha256:97f1098f4c89457ab2b16982990d487ac6ae2c664f8e22e822a086df71999dc1" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_selection_b-1.0.0-py3-none-any.whl#sha256=aba998c3dfa70f4118a4587f636c96f5a2785081b733120cf81b6d762f67b1ca", hash = "sha256:aba998c3dfa70f4118a4587f636c96f5a2785081b733120cf81b6d762f67b1ca" }]
 
         [[distribution]]
         name = "package-b"
         version = "2.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "sys_platform == 'linux'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_selection_b-2.0.0.tar.gz#sha256=1f66e4ba827d2913827fa52cc9fd08491b16ab409fa31c40a2fe4e3cde91cb4a", hash = "sha256:1f66e4ba827d2913827fa52cc9fd08491b16ab409fa31c40a2fe4e3cde91cb4a" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_selection_b-2.0.0-py3-none-any.whl#sha256=ad1b23547813b9ac69b33d3fcf1896cd49a90cd8f957e954dbdd77b628d631cf", hash = "sha256:ad1b23547813b9ac69b33d3fcf1896cd49a90cd8f957e954dbdd77b628d631cf" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_selection_b-2.0.0.tar.gz#sha256=1f66e4ba827d2913827fa52cc9fd08491b16ab409fa31c40a2fe4e3cde91cb4a", hash = "sha256:1f66e4ba827d2913827fa52cc9fd08491b16ab409fa31c40a2fe4e3cde91cb4a" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_selection_b-2.0.0-py3-none-any.whl#sha256=ad1b23547813b9ac69b33d3fcf1896cd49a90cd8f957e954dbdd77b628d631cf", hash = "sha256:ad1b23547813b9ac69b33d3fcf1896cd49a90cd8f957e954dbdd77b628d631cf" }]
 
         [[distribution]]
         name = "project"
@@ -357,22 +421,22 @@ fn fork_marker_selection() -> Result<()> {
         [[distribution.dependencies]]
         name = "package-a"
         version = "0.1.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution.dependencies]]
         name = "package-a"
         version = "0.2.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution.dependencies]]
         name = "package-b"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution.dependencies]]
         name = "package-b"
         version = "2.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         "###
         );
     });
@@ -432,7 +496,6 @@ fn fork_marker_track() -> Result<()> {
         [project]
         name = "project"
         version = "0.1.0"
-        requires-python = ">=3.8"
         dependencies = [
           '''fork-marker-track-a''',
           '''fork-marker-track-b>=2.8; sys_platform == "linux"''',
@@ -443,7 +506,7 @@ fn fork_marker_track() -> Result<()> {
 
     let mut cmd = context.lock_without_exclude_newer();
     cmd.arg("--index-url")
-        .arg("https://astral-sh.github.io/packse/0.3.17/simple-html/");
+        .arg("https://astral-sh.github.io/packse/0.3.18/simple-html/");
     uv_snapshot!(filters, cmd, @r###"
     success: true
     exit_code: 0
@@ -451,6 +514,7 @@ fn fork_marker_track() -> Result<()> {
 
     ----- stderr -----
     warning: `uv lock` is experimental and may change without warning.
+    warning: No `requires-python` field found in `project`. Defaulting to `>=3.8`.
     Resolved 6 packages in [TIME]
     "###
     );
@@ -467,50 +531,50 @@ fn fork_marker_track() -> Result<()> {
         [[distribution]]
         name = "package-a"
         version = "1.3.1"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_track_a-1.3.1.tar.gz#sha256=b88e1c256f2f3b2f3d0cff5398fd6a1a17682f3b5fd736e08d44c313ed48ef37", hash = "sha256:b88e1c256f2f3b2f3d0cff5398fd6a1a17682f3b5fd736e08d44c313ed48ef37" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_track_a-1.3.1-py3-none-any.whl#sha256=8f2bd8bcd8f3fc2cfe64621d62a3a9404db665830f7a76db60307a80cf8e632f", hash = "sha256:8f2bd8bcd8f3fc2cfe64621d62a3a9404db665830f7a76db60307a80cf8e632f" }]
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_track_a-1.3.1.tar.gz#sha256=b88e1c256f2f3b2f3d0cff5398fd6a1a17682f3b5fd736e08d44c313ed48ef37", hash = "sha256:b88e1c256f2f3b2f3d0cff5398fd6a1a17682f3b5fd736e08d44c313ed48ef37" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_track_a-1.3.1-py3-none-any.whl#sha256=8f2bd8bcd8f3fc2cfe64621d62a3a9404db665830f7a76db60307a80cf8e632f", hash = "sha256:8f2bd8bcd8f3fc2cfe64621d62a3a9404db665830f7a76db60307a80cf8e632f" }]
 
         [[distribution.dependencies]]
         name = "package-c"
         version = "1.10"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution]]
         name = "package-a"
         version = "4.3.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_track_a-4.3.0.tar.gz#sha256=46a0ab5d6b934f2b8c762893660483036a81ac1f8df9a6555e72a3b4859e1a75", hash = "sha256:46a0ab5d6b934f2b8c762893660483036a81ac1f8df9a6555e72a3b4859e1a75" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_track_a-4.3.0-py3-none-any.whl#sha256=73ad4b017bae8cb4743be03bc406f65594c92ec5038b0f56a4acb07873bfcaa5", hash = "sha256:73ad4b017bae8cb4743be03bc406f65594c92ec5038b0f56a4acb07873bfcaa5" }]
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_track_a-4.3.0.tar.gz#sha256=46a0ab5d6b934f2b8c762893660483036a81ac1f8df9a6555e72a3b4859e1a75", hash = "sha256:46a0ab5d6b934f2b8c762893660483036a81ac1f8df9a6555e72a3b4859e1a75" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_track_a-4.3.0-py3-none-any.whl#sha256=73ad4b017bae8cb4743be03bc406f65594c92ec5038b0f56a4acb07873bfcaa5", hash = "sha256:73ad4b017bae8cb4743be03bc406f65594c92ec5038b0f56a4acb07873bfcaa5" }]
 
         [[distribution.dependencies]]
         name = "package-b"
         version = "2.8"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution]]
         name = "package-b"
         version = "2.7"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "sys_platform == 'darwin'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_track_b-2.7.tar.gz#sha256=25258fd52c9611c9e101138f9986ada5930f5bea08988d0356645c772a8162dd", hash = "sha256:25258fd52c9611c9e101138f9986ada5930f5bea08988d0356645c772a8162dd" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_track_b-2.7-py3-none-any.whl#sha256=be56f5850a343cb02dfc22e75eaa1009db675ac2f1275b78ba4089c6ea2f2808", hash = "sha256:be56f5850a343cb02dfc22e75eaa1009db675ac2f1275b78ba4089c6ea2f2808" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_track_b-2.7.tar.gz#sha256=25258fd52c9611c9e101138f9986ada5930f5bea08988d0356645c772a8162dd", hash = "sha256:25258fd52c9611c9e101138f9986ada5930f5bea08988d0356645c772a8162dd" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_track_b-2.7-py3-none-any.whl#sha256=be56f5850a343cb02dfc22e75eaa1009db675ac2f1275b78ba4089c6ea2f2808", hash = "sha256:be56f5850a343cb02dfc22e75eaa1009db675ac2f1275b78ba4089c6ea2f2808" }]
 
         [[distribution]]
         name = "package-b"
         version = "2.8"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "sys_platform == 'linux'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_track_b-2.8.tar.gz#sha256=7ec0f88f013fa0b75a4c88097799866617de4cae558b18ad0677f7cc65ad6628", hash = "sha256:7ec0f88f013fa0b75a4c88097799866617de4cae558b18ad0677f7cc65ad6628" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_track_b-2.8-py3-none-any.whl#sha256=d9969066117d846fe3a200df5bafc3b3279cc419f36f7275e6e55b2dbde2d5d1", hash = "sha256:d9969066117d846fe3a200df5bafc3b3279cc419f36f7275e6e55b2dbde2d5d1" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_track_b-2.8.tar.gz#sha256=7ec0f88f013fa0b75a4c88097799866617de4cae558b18ad0677f7cc65ad6628", hash = "sha256:7ec0f88f013fa0b75a4c88097799866617de4cae558b18ad0677f7cc65ad6628" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_track_b-2.8-py3-none-any.whl#sha256=d9969066117d846fe3a200df5bafc3b3279cc419f36f7275e6e55b2dbde2d5d1", hash = "sha256:d9969066117d846fe3a200df5bafc3b3279cc419f36f7275e6e55b2dbde2d5d1" }]
 
         [[distribution]]
         name = "package-c"
         version = "1.10"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "implementation_name == 'iron'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_track_c-1.10.tar.gz#sha256=6f4a62bec34fbda0e605dc9acb40af318b1d789816d81cbd0bc7c60595de5930", hash = "sha256:6f4a62bec34fbda0e605dc9acb40af318b1d789816d81cbd0bc7c60595de5930" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_marker_track_c-1.10-py3-none-any.whl#sha256=19791f8bd3bad9a76be5477e1753dc2a4e797d163bef90fdfd99462c271ed6ff", hash = "sha256:19791f8bd3bad9a76be5477e1753dc2a4e797d163bef90fdfd99462c271ed6ff" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_track_c-1.10.tar.gz#sha256=6f4a62bec34fbda0e605dc9acb40af318b1d789816d81cbd0bc7c60595de5930", hash = "sha256:6f4a62bec34fbda0e605dc9acb40af318b1d789816d81cbd0bc7c60595de5930" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_marker_track_c-1.10-py3-none-any.whl#sha256=19791f8bd3bad9a76be5477e1753dc2a4e797d163bef90fdfd99462c271ed6ff", hash = "sha256:19791f8bd3bad9a76be5477e1753dc2a4e797d163bef90fdfd99462c271ed6ff" }]
 
         [[distribution]]
         name = "project"
@@ -521,22 +585,22 @@ fn fork_marker_track() -> Result<()> {
         [[distribution.dependencies]]
         name = "package-a"
         version = "1.3.1"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution.dependencies]]
         name = "package-a"
         version = "4.3.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution.dependencies]]
         name = "package-b"
         version = "2.7"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution.dependencies]]
         name = "package-b"
         version = "2.8"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         "###
         );
     });
@@ -583,7 +647,6 @@ fn fork_non_fork_marker_transitive() -> Result<()> {
         [project]
         name = "project"
         version = "0.1.0"
-        requires-python = ">=3.8"
         dependencies = [
           '''fork-non-fork-marker-transitive-a==1.0.0''',
           '''fork-non-fork-marker-transitive-b==1.0.0''',
@@ -593,7 +656,7 @@ fn fork_non_fork_marker_transitive() -> Result<()> {
 
     let mut cmd = context.lock_without_exclude_newer();
     cmd.arg("--index-url")
-        .arg("https://astral-sh.github.io/packse/0.3.17/simple-html/");
+        .arg("https://astral-sh.github.io/packse/0.3.18/simple-html/");
     uv_snapshot!(filters, cmd, @r###"
     success: true
     exit_code: 0
@@ -601,6 +664,7 @@ fn fork_non_fork_marker_transitive() -> Result<()> {
 
     ----- stderr -----
     warning: `uv lock` is experimental and may change without warning.
+    warning: No `requires-python` field found in `project`. Defaulting to `>=3.8`.
     Resolved 4 packages in [TIME]
     "###
     );
@@ -617,34 +681,34 @@ fn fork_non_fork_marker_transitive() -> Result<()> {
         [[distribution]]
         name = "package-a"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_non_fork_marker_transitive_a-1.0.0.tar.gz#sha256=017f775164ac5e33682262bbd44922938737bb8d7258161abb65d8d22f7f0749", hash = "sha256:017f775164ac5e33682262bbd44922938737bb8d7258161abb65d8d22f7f0749" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_non_fork_marker_transitive_a-1.0.0-py3-none-any.whl#sha256=d0ffdf00cba31099cc02d1419f1d2a0c8add5efe7c916b5e12bc23c8f7fdfb4c", hash = "sha256:d0ffdf00cba31099cc02d1419f1d2a0c8add5efe7c916b5e12bc23c8f7fdfb4c" }]
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_non_fork_marker_transitive_a-1.0.0.tar.gz#sha256=017f775164ac5e33682262bbd44922938737bb8d7258161abb65d8d22f7f0749", hash = "sha256:017f775164ac5e33682262bbd44922938737bb8d7258161abb65d8d22f7f0749" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_non_fork_marker_transitive_a-1.0.0-py3-none-any.whl#sha256=d0ffdf00cba31099cc02d1419f1d2a0c8add5efe7c916b5e12bc23c8f7fdfb4c", hash = "sha256:d0ffdf00cba31099cc02d1419f1d2a0c8add5efe7c916b5e12bc23c8f7fdfb4c" }]
 
         [[distribution.dependencies]]
         name = "package-c"
         version = "2.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution]]
         name = "package-b"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_non_fork_marker_transitive_b-1.0.0.tar.gz#sha256=f930b038c81f712230deda8d3b7d2a9a9758b71e86313722747e0ecd44d86e4a", hash = "sha256:f930b038c81f712230deda8d3b7d2a9a9758b71e86313722747e0ecd44d86e4a" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_non_fork_marker_transitive_b-1.0.0-py3-none-any.whl#sha256=d50cf9f9bcff0c90e969d6eba899bbbcb3c09666217c2c9a8011cdef089070a4", hash = "sha256:d50cf9f9bcff0c90e969d6eba899bbbcb3c09666217c2c9a8011cdef089070a4" }]
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_non_fork_marker_transitive_b-1.0.0.tar.gz#sha256=f930b038c81f712230deda8d3b7d2a9a9758b71e86313722747e0ecd44d86e4a", hash = "sha256:f930b038c81f712230deda8d3b7d2a9a9758b71e86313722747e0ecd44d86e4a" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_non_fork_marker_transitive_b-1.0.0-py3-none-any.whl#sha256=d50cf9f9bcff0c90e969d6eba899bbbcb3c09666217c2c9a8011cdef089070a4", hash = "sha256:d50cf9f9bcff0c90e969d6eba899bbbcb3c09666217c2c9a8011cdef089070a4" }]
 
         [[distribution.dependencies]]
         name = "package-c"
         version = "2.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution]]
         name = "package-c"
         version = "2.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         marker = "sys_platform == 'darwin' or sys_platform == 'linux'"
-        sdist = { url = "https://astral-sh.github.io/packse/0.3.17/files/fork_non_fork_marker_transitive_c-2.0.0.tar.gz#sha256=c989314fe5534401e9b2374e9b0461c9d44c237853d9122bc7d9aee006ee0c34", hash = "sha256:c989314fe5534401e9b2374e9b0461c9d44c237853d9122bc7d9aee006ee0c34" }
-        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.17/files/fork_non_fork_marker_transitive_c-2.0.0-py3-none-any.whl#sha256=661def8c77b372df8146049485a75678ecee810518fb7cba024b609920bdef74", hash = "sha256:661def8c77b372df8146049485a75678ecee810518fb7cba024b609920bdef74" }]
+        sdist = { url = "https://astral-sh.github.io/packse/0.3.18/files/fork_non_fork_marker_transitive_c-2.0.0.tar.gz#sha256=c989314fe5534401e9b2374e9b0461c9d44c237853d9122bc7d9aee006ee0c34", hash = "sha256:c989314fe5534401e9b2374e9b0461c9d44c237853d9122bc7d9aee006ee0c34" }
+        wheels = [{ url = "https://astral-sh.github.io/packse/0.3.18/files/fork_non_fork_marker_transitive_c-2.0.0-py3-none-any.whl#sha256=661def8c77b372df8146049485a75678ecee810518fb7cba024b609920bdef74", hash = "sha256:661def8c77b372df8146049485a75678ecee810518fb7cba024b609920bdef74" }]
 
         [[distribution]]
         name = "project"
@@ -655,12 +719,12 @@ fn fork_non_fork_marker_transitive() -> Result<()> {
         [[distribution.dependencies]]
         name = "package-a"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
 
         [[distribution.dependencies]]
         name = "package-b"
         version = "1.0.0"
-        source = "registry+https://astral-sh.github.io/packse/0.3.17/simple-html/"
+        source = "registry+https://astral-sh.github.io/packse/0.3.18/simple-html/"
         "###
         );
     });
@@ -708,7 +772,6 @@ fn fork_non_local_fork_marker_direct() -> Result<()> {
         [project]
         name = "project"
         version = "0.1.0"
-        requires-python = ">=3.8"
         dependencies = [
           '''fork-non-local-fork-marker-direct-a==1.0.0; sys_platform == "linux"''',
           '''fork-non-local-fork-marker-direct-b==1.0.0; sys_platform == "darwin"''',
@@ -718,7 +781,7 @@ fn fork_non_local_fork_marker_direct() -> Result<()> {
 
     let mut cmd = context.lock_without_exclude_newer();
     cmd.arg("--index-url")
-        .arg("https://astral-sh.github.io/packse/0.3.17/simple-html/");
+        .arg("https://astral-sh.github.io/packse/0.3.18/simple-html/");
     uv_snapshot!(filters, cmd, @r###"
     success: false
     exit_code: 1
@@ -726,9 +789,10 @@ fn fork_non_local_fork_marker_direct() -> Result<()> {
 
     ----- stderr -----
     warning: `uv lock` is experimental and may change without warning.
+    warning: No `requires-python` field found in `project`. Defaulting to `>=3.8`.
       × No solution found when resolving dependencies:
       ╰─▶ Because package-b{sys_platform == 'darwin'}==1.0.0 depends on package-c>=2.0.0 and package-a{sys_platform == 'linux'}==1.0.0 depends on package-c<2.0.0, we can conclude that package-a{sys_platform == 'linux'}==1.0.0 and package-b{sys_platform == 'darwin'}==1.0.0 are incompatible.
-          And because project==0.1.0 depends on package-b{sys_platform == 'darwin'}==1.0.0 and package-a{sys_platform == 'linux'}==1.0.0, we can conclude that project==0.1.0 cannot be used.
+          And because project==0.1.0 depends on package-a{sys_platform == 'linux'}==1.0.0 and package-b{sys_platform == 'darwin'}==1.0.0, we can conclude that project==0.1.0 cannot be used.
           And because only project==0.1.0 is available and project depends on project, we can conclude that the requirements are unsatisfiable.
     "###
     );
@@ -782,7 +846,6 @@ fn fork_non_local_fork_marker_transitive() -> Result<()> {
         [project]
         name = "project"
         version = "0.1.0"
-        requires-python = ">=3.8"
         dependencies = [
           '''fork-non-local-fork-marker-transitive-a==1.0.0''',
           '''fork-non-local-fork-marker-transitive-b==1.0.0''',
@@ -792,7 +855,7 @@ fn fork_non_local_fork_marker_transitive() -> Result<()> {
 
     let mut cmd = context.lock_without_exclude_newer();
     cmd.arg("--index-url")
-        .arg("https://astral-sh.github.io/packse/0.3.17/simple-html/");
+        .arg("https://astral-sh.github.io/packse/0.3.18/simple-html/");
     uv_snapshot!(filters, cmd, @r###"
     success: false
     exit_code: 1
@@ -800,13 +863,14 @@ fn fork_non_local_fork_marker_transitive() -> Result<()> {
 
     ----- stderr -----
     warning: `uv lock` is experimental and may change without warning.
+    warning: No `requires-python` field found in `project`. Defaulting to `>=3.8`.
       × No solution found when resolving dependencies:
       ╰─▶ Because package-b==1.0.0 depends on package-c{sys_platform == 'darwin'}>=2.0.0 and only package-c{sys_platform == 'darwin'}<=2.0.0 is available, we can conclude that package-b==1.0.0 depends on package-c{sys_platform == 'darwin'}==2.0.0.
           And because only the following versions of package-c{sys_platform == 'linux'} are available:
               package-c{sys_platform == 'linux'}==1.0.0
               package-c{sys_platform == 'linux'}>=2.0.0
           and package-a==1.0.0 depends on package-c{sys_platform == 'linux'}<2.0.0, we can conclude that package-a==1.0.0 and package-b==1.0.0 are incompatible.
-          And because project==0.1.0 depends on package-b==1.0.0 and package-a==1.0.0, we can conclude that project==0.1.0 cannot be used.
+          And because project==0.1.0 depends on package-a==1.0.0 and package-b==1.0.0, we can conclude that project==0.1.0 cannot be used.
           And because only project==0.1.0 is available and project depends on project, we can conclude that the requirements are unsatisfiable.
     "###
     );
diff --git a/crates/uv/tests/pip_compile_scenarios.rs b/crates/uv/tests/pip_compile_scenarios.rs
index 298ba4b80f29..bf282d24c793 100644
--- a/crates/uv/tests/pip_compile_scenarios.rs
+++ b/crates/uv/tests/pip_compile_scenarios.rs
@@ -1,7 +1,7 @@
 //! DO NOT EDIT
 //!
 //! Generated with `./scripts/sync_scenarios.sh`
-//! Scenarios from <https://github.com/astral-sh/packse/tree/0.3.17/scenarios>
+//! Scenarios from <https://github.com/astral-sh/packse/tree/0.3.18/scenarios>
 //!
 #![cfg(all(feature = "python", feature = "pypi", unix))]
 
@@ -27,9 +27,9 @@ fn command(context: &TestContext, python_versions: &[&str]) -> Command {
         .arg("compile")
         .arg("requirements.in")
         .arg("--index-url")
-        .arg("https://astral-sh.github.io/packse/0.3.17/simple-html/")
+        .arg("https://astral-sh.github.io/packse/0.3.18/simple-html/")
         .arg("--find-links")
-        .arg("https://raw.githubusercontent.com/astral-sh/packse/0.3.17/vendor/links.html")
+        .arg("https://raw.githubusercontent.com/astral-sh/packse/0.3.18/vendor/links.html")
         .arg("--cache-dir")
         .arg(context.cache_dir.path())
         .env("VIRTUAL_ENV", context.venv.as_os_str())
diff --git a/crates/uv/tests/pip_install_scenarios.rs b/crates/uv/tests/pip_install_scenarios.rs
index 26410373c948..5785581a833b 100644
--- a/crates/uv/tests/pip_install_scenarios.rs
+++ b/crates/uv/tests/pip_install_scenarios.rs
@@ -1,7 +1,7 @@
 //! DO NOT EDIT
 //!
 //! Generated with `./scripts/sync_scenarios.sh`
-//! Scenarios from <https://github.com/astral-sh/packse/tree/0.3.17/scenarios>
+//! Scenarios from <https://github.com/astral-sh/packse/tree/0.3.18/scenarios>
 //!
 #![cfg(all(feature = "python", feature = "pypi", unix))]
 
@@ -46,9 +46,9 @@ fn command(context: &TestContext) -> Command {
         .arg("pip")
         .arg("install")
         .arg("--index-url")
-        .arg("https://astral-sh.github.io/packse/0.3.17/simple-html/")
+        .arg("https://astral-sh.github.io/packse/0.3.18/simple-html/")
         .arg("--find-links")
-        .arg("https://raw.githubusercontent.com/astral-sh/packse/0.3.17/vendor/links.html")
+        .arg("https://raw.githubusercontent.com/astral-sh/packse/0.3.18/vendor/links.html")
         .arg("--cache-dir")
         .arg(context.cache_dir.path())
         .env("VIRTUAL_ENV", context.venv.as_os_str())
diff --git a/scripts/scenarios/requirements.in b/scripts/scenarios/requirements.in
index 61579afc420f..b01be6d44300 100644
--- a/scripts/scenarios/requirements.in
+++ b/scripts/scenarios/requirements.in
@@ -1,2 +1,2 @@
 chevron-blue
-packse>=0.3.17
+packse>=0.3.18
diff --git a/scripts/scenarios/requirements.txt b/scripts/scenarios/requirements.txt
index b8d11a776487..55551e176095 100644
--- a/scripts/scenarios/requirements.txt
+++ b/scripts/scenarios/requirements.txt
@@ -46,7 +46,7 @@ nh3==0.2.17
     # via readme-renderer
 packaging==24.0
     # via hatchling
-packse==0.3.17
+packse==0.3.18
     # via -r scripts/scenarios/requirements.in
 pathspec==0.12.1
     # via hatchling