diff --git a/crates/uv-pep508/src/marker/tree.rs b/crates/uv-pep508/src/marker/tree.rs
index 450096e50..d493fe4b1 100644
--- a/crates/uv-pep508/src/marker/tree.rs
+++ b/crates/uv-pep508/src/marker/tree.rs
@@ -1158,6 +1158,32 @@ impl MarkerTree {
         }
     }
 
+    /// Returns true if this marker simplifies to true if the given set of extras is activated.
+    pub fn evaluate_only_extras(self, extras: &[ExtraName]) -> bool {
+        match self.kind() {
+            MarkerTreeKind::True => true,
+            MarkerTreeKind::False => false,
+            MarkerTreeKind::Version(marker) => marker
+                .edges()
+                .all(|(_, tree)| tree.evaluate_only_extras(extras)),
+            MarkerTreeKind::String(marker) => marker
+                .children()
+                .all(|(_, tree)| tree.evaluate_only_extras(extras)),
+            MarkerTreeKind::In(marker) => marker
+                .children()
+                .all(|(_, tree)| tree.evaluate_only_extras(extras)),
+            MarkerTreeKind::Contains(marker) => marker
+                .children()
+                .all(|(_, tree)| tree.evaluate_only_extras(extras)),
+            MarkerTreeKind::List(marker) => marker
+                .children()
+                .all(|(_, tree)| tree.evaluate_only_extras(extras)),
+            MarkerTreeKind::Extra(marker) => marker
+                .edge(extras.contains(marker.name().extra()))
+                .evaluate_only_extras(extras),
+        }
+    }
+
     /// Find a top level `extra == "..."` expression.
     ///
     /// ASSUMPTION: There is one `extra = "..."`, and it's either the only marker or part of the
@@ -3660,4 +3686,27 @@ mod test {
         let right = "python_full_version == '3.10.*'";
         assert_eq!(left, right, "{left} != {right}");
     }
+
+    #[test]
+    fn evaluate_only_extras() {
+        let a = ExtraName::from_str("a").unwrap();
+        let b = ExtraName::from_str("b").unwrap();
+
+        let marker = m("extra == 'a' and extra == 'b'");
+        assert!(!marker.evaluate_only_extras(&[a.clone()]));
+        assert!(!marker.evaluate_only_extras(&[b.clone()]));
+        assert!(marker.evaluate_only_extras(&[a.clone(), b.clone()]));
+
+        let marker = m("(platform_machine == 'inapplicable' and extra == 'b') or extra == 'a'");
+        assert!(marker.evaluate_only_extras(&[a.clone()]));
+        assert!(!marker.evaluate_only_extras(&[b.clone()]));
+        assert!(marker.evaluate_only_extras(&[a.clone(), b.clone()]));
+
+        let marker = m(
+            "(platform_machine == 'inapplicable' and extra == 'a') or (platform_machine != 'inapplicable' and extra == 'b')",
+        );
+        assert!(!marker.evaluate_only_extras(&[a.clone()]));
+        assert!(!marker.evaluate_only_extras(&[b.clone()]));
+        assert!(marker.evaluate_only_extras(&[a.clone(), b.clone()]));
+    }
 }
diff --git a/crates/uv-pypi-types/src/conflicts.rs b/crates/uv-pypi-types/src/conflicts.rs
index 5ebeb160a..0dcd1393d 100644
--- a/crates/uv-pypi-types/src/conflicts.rs
+++ b/crates/uv-pypi-types/src/conflicts.rs
@@ -756,3 +756,24 @@ impl From<SchemaConflictItem> for ConflictItemWire {
         }
     }
 }
+
+/// An inference about whether a conflicting item is always included or
+/// excluded.
+///
+/// We collect these for each node in the graph after determining which
+/// extras/groups are activated for each node. Once we know what's
+/// activated, we can infer what must also be *inactivated* based on what's
+/// conflicting with it. So for example, if we have a conflict marker like
+/// `extra == 'foo' and extra != 'bar'`, and `foo` and `bar` have been
+/// declared as conflicting, and we are in a part of the graph where we
+/// know `foo` must be activated, then it follows that `extra != 'bar'`
+/// must always be true. Because if it were false, it would imply both
+/// `foo` and `bar` were activated simultaneously, which uv guarantees
+/// won't happen.
+///
+/// We then use these inferences to simplify the conflict markers.
+#[derive(Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
+pub struct Inference {
+    pub included: bool,
+    pub item: ConflictItem,
+}
diff --git a/crates/uv-resolver/src/graph_ops.rs b/crates/uv-resolver/src/graph_ops.rs
index 878074e77..84143326b 100644
--- a/crates/uv-resolver/src/graph_ops.rs
+++ b/crates/uv-resolver/src/graph_ops.rs
@@ -1,3 +1,4 @@
+use std::collections::BTreeSet;
 use std::collections::hash_map::Entry;
 
 use petgraph::graph::{EdgeIndex, NodeIndex};
@@ -6,7 +7,7 @@ use petgraph::{Direction, Graph};
 use rustc_hash::{FxBuildHasher, FxHashMap, FxHashSet};
 
 use uv_pep508::MarkerTree;
-use uv_pypi_types::{ConflictItem, Conflicts};
+use uv_pypi_types::{ConflictItem, Conflicts, Inference};
 
 use crate::resolution::ResolutionGraphNode;
 use crate::universal_marker::UniversalMarker;
@@ -99,27 +100,6 @@ pub(crate) fn simplify_conflict_markers(
     conflicts: &Conflicts,
     graph: &mut Graph<ResolutionGraphNode, UniversalMarker>,
 ) {
-    /// An inference about whether a conflicting item is always included or
-    /// excluded.
-    ///
-    /// We collect these for each node in the graph after determining which
-    /// extras/groups are activated for each node. Once we know what's
-    /// activated, we can infer what must also be *inactivated* based on what's
-    /// conflicting with it. So for example, if we have a conflict marker like
-    /// `extra == 'foo' and extra != 'bar'`, and `foo` and `bar` have been
-    /// declared as conflicting, and we are in a part of the graph where we
-    /// know `foo` must be activated, then it follows that `extra != 'bar'`
-    /// must always be true. Because if it were false, it would imply both
-    /// `foo` and `bar` were activated simultaneously, which uv guarantees
-    /// won't happen.
-    ///
-    /// We then use these inferences to simplify the conflict markers.
-    #[derive(Clone, Debug, Eq, Hash, PartialEq)]
-    struct Inference {
-        item: ConflictItem,
-        included: bool,
-    }
-
     // Do nothing if there are no declared conflicts. Without any declared
     // conflicts, we know we have no conflict markers and thus nothing to
     // simplify by determining which extras are activated at different points
@@ -198,11 +178,11 @@ pub(crate) fn simplify_conflict_markers(
         }
     }
 
-    let mut inferences: FxHashMap<NodeIndex, Vec<FxHashSet<Inference>>> = FxHashMap::default();
+    let mut inferences: FxHashMap<NodeIndex, Vec<BTreeSet<Inference>>> = FxHashMap::default();
     for (node_id, sets) in activated {
         let mut new_sets = Vec::with_capacity(sets.len());
         for set in sets {
-            let mut new_set = FxHashSet::default();
+            let mut new_set = BTreeSet::default();
             for item in set {
                 for conflict_set in conflicts.iter() {
                     if !conflict_set.contains(item.package(), item.as_ref().conflict()) {
@@ -270,19 +250,27 @@ pub(crate) fn simplify_conflict_markers(
                     Some((inf.item.package(), inf.item.group()?))
                 })
                 .collect::<Vec<_>>();
-            graph[edge_index].conflict().evaluate(&extras, &groups)
+            // Notably, the marker must be possible to satisfy with the extras and groups alone.
+            // For example, when `a` and `b` conflict, this marker does not simplify:
+            // ```
+            // (platform_machine == 'x86_64' and extra == 'extra-5-foo-b') or extra == 'extra-5-foo-a'
+            // ````
+            graph[edge_index].evaluate_only_extras(&extras, &groups)
         });
-        if !all_paths_satisfied {
-            continue;
-        }
-        for set in inference_sets {
-            for inf in set {
-                if inf.included {
-                    graph[edge_index].assume_conflict_item(&inf.item);
-                } else {
-                    graph[edge_index].assume_not_conflict_item(&inf.item);
+        if all_paths_satisfied {
+            for set in inference_sets {
+                for inf in set {
+                    // TODO(konsti): Now that `Inference` is public, move more `included` handling
+                    // to `UniversalMarker`.
+                    if inf.included {
+                        graph[edge_index].assume_conflict_item(&inf.item);
+                    } else {
+                        graph[edge_index].assume_not_conflict_item(&inf.item);
+                    }
                 }
             }
+        } else {
+            graph[edge_index].unify_inference_sets(inference_sets);
         }
     }
 }
diff --git a/crates/uv-resolver/src/resolver/environment.rs b/crates/uv-resolver/src/resolver/environment.rs
index 8faec48c4..cab258aea 100644
--- a/crates/uv-resolver/src/resolver/environment.rs
+++ b/crates/uv-resolver/src/resolver/environment.rs
@@ -1,9 +1,13 @@
+use std::collections::BTreeSet;
 use std::sync::Arc;
+
+use itertools::Itertools;
 use tracing::trace;
+
 use uv_distribution_types::{RequiresPython, RequiresPythonRange};
 use uv_pep440::VersionSpecifiers;
 use uv_pep508::{MarkerEnvironment, MarkerTree};
-use uv_pypi_types::{ConflictItem, ConflictItemRef, ResolverMarkerEnvironment};
+use uv_pypi_types::{ConflictItem, ConflictItemRef, ConflictPackage, ResolverMarkerEnvironment};
 
 use crate::pubgrub::{PubGrubDependency, PubGrubPackage};
 use crate::resolver::ForkState;
@@ -374,15 +378,62 @@ impl ResolverEnvironment {
     /// This is useful in contexts where one wants to display a message
     /// relating to a particular fork, but either no message or an entirely
     /// different message when this isn't a fork.
-    pub(crate) fn end_user_fork_display(&self) -> Option<impl std::fmt::Display + '_> {
-        match self.kind {
+    pub(crate) fn end_user_fork_display(&self) -> Option<String> {
+        match &self.kind {
             Kind::Specific { .. } => None,
-            Kind::Universal { ref markers, .. } => {
-                if markers.is_true() {
-                    None
-                } else {
-                    Some(format!("split ({markers:?})"))
+            Kind::Universal {
+                initial_forks: _,
+                markers,
+                include,
+                exclude,
+            } => {
+                let format_conflict_item = |conflict_item: &ConflictItem| {
+                    format!(
+                        "{}{}",
+                        conflict_item.package(),
+                        match conflict_item.conflict() {
+                            ConflictPackage::Extra(extra) => format!("[{extra}]"),
+                            ConflictPackage::Group(group) => {
+                                format!("[group:{group}]")
+                            }
+                        }
+                    )
+                };
+
+                if markers.is_true() && include.is_empty() && exclude.is_empty() {
+                    return None;
                 }
+
+                let mut descriptors = Vec::new();
+                if !markers.is_true() {
+                    descriptors.push(format!("markers: {markers:?}"));
+                }
+                if !include.is_empty() {
+                    descriptors.push(format!(
+                        "included: {}",
+                        // Sort to ensure stable error messages
+                        include
+                            .iter()
+                            .map(format_conflict_item)
+                            .collect::<BTreeSet<_>>()
+                            .into_iter()
+                            .join(", "),
+                    ));
+                }
+                if !exclude.is_empty() {
+                    descriptors.push(format!(
+                        "excluded: {}",
+                        // Sort to ensure stable error messages
+                        exclude
+                            .iter()
+                            .map(format_conflict_item)
+                            .collect::<BTreeSet<_>>()
+                            .into_iter()
+                            .join(", "),
+                    ));
+                }
+
+                Some(format!("split ({})", descriptors.join("; ")))
             }
         }
     }
diff --git a/crates/uv-resolver/src/resolver/mod.rs b/crates/uv-resolver/src/resolver/mod.rs
index 4d0ecf125..eed7a3955 100644
--- a/crates/uv-resolver/src/resolver/mod.rs
+++ b/crates/uv-resolver/src/resolver/mod.rs
@@ -708,12 +708,19 @@ impl<InstalledPackages: InstalledPackagesProvider> ResolverState<InstalledPackag
                 resolutions.len()
             );
         }
-        for resolution in &resolutions {
-            if let Some(env) = resolution.env.end_user_fork_display() {
-                debug!(
-                    "Distinct solution for {env} with {} packages",
-                    resolution.nodes.len()
-                );
+        if tracing::enabled!(Level::DEBUG) {
+            for resolution in &resolutions {
+                if let Some(env) = resolution.env.end_user_fork_display() {
+                    let packages: FxHashSet<_> = resolution
+                        .nodes
+                        .keys()
+                        .map(|package| &package.name)
+                        .collect();
+                    debug!(
+                        "Distinct solution for {env} with {} package(s)",
+                        packages.len()
+                    );
+                }
             }
         }
         for resolution in &resolutions {
diff --git a/crates/uv-resolver/src/universal_marker.rs b/crates/uv-resolver/src/universal_marker.rs
index e0643520b..c40aaf77a 100644
--- a/crates/uv-resolver/src/universal_marker.rs
+++ b/crates/uv-resolver/src/universal_marker.rs
@@ -1,15 +1,13 @@
 use std::borrow::Borrow;
+use std::collections::BTreeSet;
 use std::str::FromStr;
 
 use itertools::Itertools;
 use rustc_hash::FxHashMap;
 
 use uv_normalize::{ExtraName, GroupName, PackageName};
-use uv_pep508::{
-    ExtraOperator, MarkerEnvironment, MarkerEnvironmentBuilder, MarkerExpression, MarkerOperator,
-    MarkerTree,
-};
-use uv_pypi_types::{ConflictItem, ConflictPackage, Conflicts};
+use uv_pep508::{ExtraOperator, MarkerEnvironment, MarkerExpression, MarkerOperator, MarkerTree};
+use uv_pypi_types::{ConflictItem, ConflictPackage, Conflicts, Inference};
 
 use crate::ResolveError;
 
@@ -140,6 +138,36 @@ impl UniversalMarker {
         self.pep508 = self.marker.without_extras();
     }
 
+    /// If all inference sets reduce to the same marker, simplify the marker using that knowledge.
+    pub(crate) fn unify_inference_sets(&mut self, conflict_sets: &[BTreeSet<Inference>]) {
+        let mut previous_marker = None;
+
+        for conflict_set in conflict_sets {
+            let mut marker = self.marker;
+            for inference in conflict_set {
+                let extra = encode_conflict_item(&inference.item);
+
+                marker = if inference.included {
+                    marker.simplify_extras_with(|candidate| *candidate == extra)
+                } else {
+                    marker.simplify_not_extras_with(|candidate| *candidate == extra)
+                };
+            }
+            if let Some(previous_marker) = &previous_marker {
+                if previous_marker != &marker {
+                    return;
+                }
+            } else {
+                previous_marker = Some(marker);
+            }
+        }
+
+        if let Some(all_branches_marker) = previous_marker {
+            self.marker = all_branches_marker;
+            self.pep508 = self.marker.without_extras();
+        }
+    }
+
     /// Assumes that a given extra/group for the given package is activated.
     ///
     /// This may simplify the conflicting marker component of this universal
@@ -265,6 +293,23 @@ impl UniversalMarker {
             .evaluate(env, &extras.chain(groups).collect::<Vec<ExtraName>>())
     }
 
+    /// Returns true if the marker always evaluates to true if the given set of extras is activated.
+    pub(crate) fn evaluate_only_extras<P, E, G>(self, extras: &[(P, E)], groups: &[(P, G)]) -> bool
+    where
+        P: Borrow<PackageName>,
+        E: Borrow<ExtraName>,
+        G: Borrow<GroupName>,
+    {
+        let extras = extras
+            .iter()
+            .map(|(package, extra)| encode_package_extra(package.borrow(), extra.borrow()));
+        let groups = groups
+            .iter()
+            .map(|(package, group)| encode_package_group(package.borrow(), group.borrow()));
+        self.marker
+            .evaluate_only_extras(&extras.chain(groups).collect::<Vec<ExtraName>>())
+    }
+
     /// Returns the internal marker that combines both the PEP 508
     /// and conflict marker.
     pub fn combined(self) -> MarkerTree {
@@ -421,40 +466,6 @@ impl ConflictMarker {
         self.marker.is_false()
     }
 
-    /// Returns true if this conflict marker is satisfied by the given
-    /// list of activated extras and groups.
-    pub(crate) fn evaluate<P, E, G>(self, extras: &[(P, E)], groups: &[(P, G)]) -> bool
-    where
-        P: Borrow<PackageName>,
-        E: Borrow<ExtraName>,
-        G: Borrow<GroupName>,
-    {
-        static DUMMY: std::sync::LazyLock<MarkerEnvironment> = std::sync::LazyLock::new(|| {
-            MarkerEnvironment::try_from(MarkerEnvironmentBuilder {
-                implementation_name: "",
-                implementation_version: "3.7",
-                os_name: "linux",
-                platform_machine: "",
-                platform_python_implementation: "",
-                platform_release: "",
-                platform_system: "",
-                platform_version: "",
-                python_full_version: "3.7",
-                python_version: "3.7",
-                sys_platform: "linux",
-            })
-            .unwrap()
-        });
-        let extras = extras
-            .iter()
-            .map(|(package, extra)| encode_package_extra(package.borrow(), extra.borrow()));
-        let groups = groups
-            .iter()
-            .map(|(package, group)| encode_package_group(package.borrow(), group.borrow()));
-        self.marker
-            .evaluate(&DUMMY, &extras.chain(groups).collect::<Vec<ExtraName>>())
-    }
-
     /// Returns inclusion and exclusion (respectively) conflict items parsed
     /// from this conflict marker.
     ///
@@ -491,6 +502,14 @@ impl std::fmt::Debug for ConflictMarker {
     }
 }
 
+/// Encodes the given conflict into a valid `extra` value in a PEP 508 marker.
+fn encode_conflict_item(conflict: &ConflictItem) -> ExtraName {
+    match conflict.conflict() {
+        ConflictPackage::Extra(extra) => encode_package_extra(conflict.package(), extra),
+        ConflictPackage::Group(group) => encode_package_group(conflict.package(), group),
+    }
+}
+
 /// Encodes the given package name and its corresponding extra into a valid
 /// `extra` value in a PEP 508 marker.
 fn encode_package_extra(package: &PackageName, extra: &ExtraName) -> ExtraName {
@@ -791,7 +810,7 @@ mod tests {
     /// This is just the underlying marker. And if it's `true`, then a
     /// non-conforming `true` string is returned. (Which is fine since
     /// this is just for tests.)
-    fn tostr(cm: ConflictMarker) -> String {
+    fn to_str(cm: ConflictMarker) -> String {
         cm.marker
             .try_to_string()
             .unwrap_or_else(|| "true".to_string())
@@ -805,14 +824,14 @@ mod tests {
         let conflicts = create_conflicts([create_set(["foo", "bar"])]);
         let cm = ConflictMarker::from_conflicts(&conflicts);
         assert_eq!(
-            tostr(cm),
+            to_str(cm),
             "extra != 'extra-3-pkg-foo' or extra != 'extra-3-pkg-bar'"
         );
 
         let conflicts = create_conflicts([create_set(["foo", "bar", "baz"])]);
         let cm = ConflictMarker::from_conflicts(&conflicts);
         assert_eq!(
-            tostr(cm),
+            to_str(cm),
             "(extra != 'extra-3-pkg-baz' and extra != 'extra-3-pkg-foo') \
              or (extra != 'extra-3-pkg-bar' and extra != 'extra-3-pkg-foo') \
              or (extra != 'extra-3-pkg-bar' and extra != 'extra-3-pkg-baz')",
@@ -821,7 +840,7 @@ mod tests {
         let conflicts = create_conflicts([create_set(["foo", "bar"]), create_set(["fox", "ant"])]);
         let cm = ConflictMarker::from_conflicts(&conflicts);
         assert_eq!(
-            tostr(cm),
+            to_str(cm),
             "(extra != 'extra-3-pkg-bar' and extra != 'extra-3-pkg-fox') or \
              (extra != 'extra-3-pkg-ant' and extra != 'extra-3-pkg-foo') or \
              (extra != 'extra-3-pkg-ant' and extra != 'extra-3-pkg-bar') or \
@@ -856,7 +875,7 @@ mod tests {
                 .collect::<Vec<(PackageName, ExtraName)>>();
             let groups = Vec::<(PackageName, GroupName)>::new();
             assert!(
-                !cm.evaluate(&extras, &groups),
+                !UniversalMarker::new(MarkerTree::TRUE, cm).evaluate_only_extras(&extras, &groups),
                 "expected `{extra_names:?}` to evaluate to `false` in `{cm:?}`"
             );
         }
@@ -879,7 +898,7 @@ mod tests {
                 .collect::<Vec<(PackageName, ExtraName)>>();
             let groups = Vec::<(PackageName, GroupName)>::new();
             assert!(
-                cm.evaluate(&extras, &groups),
+                UniversalMarker::new(MarkerTree::TRUE, cm).evaluate_only_extras(&extras, &groups),
                 "expected `{extra_names:?}` to evaluate to `true` in `{cm:?}`"
             );
         }
diff --git a/crates/uv/tests/it/lock.rs b/crates/uv/tests/it/lock.rs
index ef8075e3d..88322d794 100644
--- a/crates/uv/tests/it/lock.rs
+++ b/crates/uv/tests/it/lock.rs
@@ -3671,7 +3671,7 @@ fn lock_requires_python() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies for split (python_full_version >= '3.7' and python_full_version < '3.7.9'):
+      × No solution found when resolving dependencies for split (markers: python_full_version >= '3.7' and python_full_version < '3.7.9'):
       ╰─▶ Because the requested Python version (>=3.7) does not satisfy Python>=3.7.9 and pygls>=1.1.0,<=1.2.1 depends on Python>=3.7.9,<4, we can conclude that pygls>=1.1.0,<=1.2.1 cannot be used.
           And because only the following versions of pygls are available:
               pygls<=1.1.0
@@ -28520,7 +28520,7 @@ fn lock_conflict_for_disjoint_python_version() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies for split (python_full_version >= '3.11'):
+      × No solution found when resolving dependencies for split (markers: python_full_version >= '3.11'):
       ╰─▶ Because only the following versions of numpy{python_full_version >= '3.10'} are available:
               numpy{python_full_version >= '3.10'}<=1.21.0
               numpy{python_full_version >= '3.10'}==1.21.1
@@ -28774,7 +28774,7 @@ fn lock_conflict_for_disjoint_platform() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies for split (sys_platform == 'exotic'):
+      × No solution found when resolving dependencies for split (markers: sys_platform == 'exotic'):
       ╰─▶ Because only the following versions of numpy{sys_platform == 'exotic'} are available:
               numpy{sys_platform == 'exotic'}<=1.24.0
               numpy{sys_platform == 'exotic'}==1.24.1
diff --git a/crates/uv/tests/it/lock_conflict.rs b/crates/uv/tests/it/lock_conflict.rs
index b809d2199..5305289c4 100644
--- a/crates/uv/tests/it/lock_conflict.rs
+++ b/crates/uv/tests/it/lock_conflict.rs
@@ -546,16 +546,16 @@ fn extra_multiple_not_conflicting2() -> Result<()> {
         project4 = ["sortedcontainers==2.4.0"]
         "#,
     )?;
-    uv_snapshot!(context.filters(), context.lock(), @r###"
+    uv_snapshot!(context.filters(), context.lock(), @r"
     success: false
     exit_code: 1
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies:
+      × No solution found when resolving dependencies for split (included: project[extra2], project[project3]; excluded: project[extra1], project[project4]):
       ╰─▶ Because project[project3] depends on sortedcontainers==2.3.0 and project[extra2] depends on sortedcontainers==2.4.0, we can conclude that project[extra2] and project[project3] are incompatible.
           And because your project requires project[extra2] and project[project3], we can conclude that your project's requirements are unsatisfiable.
-    "###);
+    ");
 
     // One could try to declare all pairs of conflicting extras as
     // conflicting, but this doesn't quite work either. For example,
@@ -703,16 +703,16 @@ fn extra_multiple_independent() -> Result<()> {
         project4 = ["anyio==4.2.0"]
         "#,
     )?;
-    uv_snapshot!(context.filters(), context.lock(), @r###"
+    uv_snapshot!(context.filters(), context.lock(), @r"
     success: false
     exit_code: 1
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies:
+      × No solution found when resolving dependencies for split (included: project[project4]; excluded: project[project3]):
       ╰─▶ Because project[extra2] depends on sortedcontainers==2.4.0 and project[extra1] depends on sortedcontainers==2.3.0, we can conclude that project[extra1] and project[extra2] are incompatible.
           And because your project requires project[extra1] and project[extra2], we can conclude that your project's requirements are unsatisfiable.
-    "###);
+    ");
 
     // Once we declare ALL our conflicting extras, resolution succeeds.
     let pyproject_toml = context.temp_dir.child("pyproject.toml");
@@ -1551,20 +1551,20 @@ fn extra_nested_across_workspace() -> Result<()> {
     // `dummy[extra1]` conflicts with `dummysub[extra2]` and that
     // `dummy[extra2]` conflicts with `dummysub[extra1]`. So we end
     // up with a resolution failure.
-    uv_snapshot!(context.filters(), context.lock(), @r###"
+    uv_snapshot!(context.filters(), context.lock(), @r"
     success: false
     exit_code: 1
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies:
+      × No solution found when resolving dependencies for split (included: dummy[extra2], dummysub[extra1]; excluded: dummy[extra1], dummysub[extra2]):
       ╰─▶ Because dummy[extra2] depends on proxy1[extra2] and only proxy1[extra2]==0.1.0 is available, we can conclude that dummy[extra2] depends on proxy1[extra2]==0.1.0. (1)
 
           Because proxy1[extra1]==0.1.0 depends on anyio==4.1.0 and proxy1[extra2]==0.1.0 depends on anyio==4.2.0, we can conclude that proxy1[extra1]==0.1.0 and proxy1[extra2]==0.1.0 are incompatible.
           And because we know from (1) that dummy[extra2] depends on proxy1[extra2]==0.1.0, we can conclude that dummy[extra2] and proxy1[extra1]==0.1.0 are incompatible.
           And because only proxy1[extra1]==0.1.0 is available and dummysub[extra1] depends on proxy1[extra1], we can conclude that dummysub[extra1] and dummy[extra2] are incompatible.
           And because your workspace requires dummy[extra2] and dummysub[extra1], we can conclude that your workspace's requirements are unsatisfiable.
-    "###);
+    ");
 
     // Now let's write out the full set of conflicts, taking
     // advantage of the optional `package` key.
@@ -1696,7 +1696,7 @@ fn extra_depends_on_conflicting_extra() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies:
+      × No solution found when resolving dependencies for split (included: example[foo]; excluded: example[bar]):
       ╰─▶ Because example[foo] depends on sortedcontainers==2.3.0 and sortedcontainers==2.4.0, we can conclude that example[foo]'s requirements are unsatisfiable.
           And because your project requires example[foo], we can conclude that your project's requirements are unsatisfiable.
     ");
@@ -6005,7 +6005,7 @@ fn extra_inferences() -> Result<()> {
         version = "8.1.7"
         source = { registry = "https://pypi.org/simple" }
         dependencies = [
-            { name = "colorama", marker = "sys_platform == 'win32'" },
+            { name = "colorama", marker = "sys_platform == 'win32' or (extra == 'extra-3-pkg-x1' and extra == 'extra-3-pkg-x2')" },
         ]
         sdist = { url = "https://files.pythonhosted.org/packages/96/d3/f04c7bfcf5c1862a2a5b845c6b2b360488cf47af55dfa79c98f6a6bf98b5/click-8.1.7.tar.gz", hash = "sha256:ca9853ad459e787e2192211578cc907e7594e294c7ccc834310722b41b9ca6de", size = 336121, upload-time = "2023-08-17T17:29:11.868Z" }
         wheels = [
@@ -6026,7 +6026,7 @@ fn extra_inferences() -> Result<()> {
         version = "4.8.0"
         source = { registry = "https://pypi.org/simple" }
         dependencies = [
-            { name = "colorama", marker = "sys_platform == 'win32'" },
+            { name = "colorama", marker = "sys_platform == 'win32' or (extra == 'extra-3-pkg-x1' and extra == 'extra-3-pkg-x2')" },
         ]
         sdist = { url = "https://files.pythonhosted.org/packages/75/32/cdfba08674d72fe7895a8ec7be8f171e8502274999cae9497e4545404873/colorlog-4.8.0.tar.gz", hash = "sha256:59b53160c60902c405cdec28d38356e09d40686659048893e026ecbd589516b1", size = 28770, upload-time = "2021-03-22T11:26:32.319Z" }
         wheels = [
@@ -6100,7 +6100,7 @@ fn extra_inferences() -> Result<()> {
         version = "42.0.5"
         source = { registry = "https://pypi.org/simple" }
         dependencies = [
-            { name = "cffi", marker = "platform_python_implementation != 'PyPy'" },
+            { name = "cffi", marker = "platform_python_implementation != 'PyPy' or (extra == 'extra-3-pkg-x1' and extra == 'extra-3-pkg-x2')" },
         ]
         sdist = { url = "https://files.pythonhosted.org/packages/13/9e/a55763a32d340d7b06d045753c186b690e7d88780cafce5f88cb931536be/cryptography-42.0.5.tar.gz", hash = "sha256:6fe07eec95dfd477eb9530aef5bead34fec819b3aaf6c5bd6d20565da607bfe1", size = 671025, upload-time = "2024-02-24T01:17:48.141Z" }
         wheels = [
@@ -6804,7 +6804,7 @@ fn extra_inferences() -> Result<()> {
         source = { registry = "https://pypi.org/simple" }
         dependencies = [
             { name = "python-dateutil" },
-            { name = "time-machine", marker = "implementation_name != 'pypy'" },
+            { name = "time-machine", marker = "implementation_name != 'pypy' or (extra == 'extra-3-pkg-x1' and extra == 'extra-3-pkg-x2')" },
             { name = "tzdata" },
         ]
         sdist = { url = "https://files.pythonhosted.org/packages/b8/fe/27c7438c6ac8b8f8bef3c6e571855602ee784b85d072efddfff0ceb1cd77/pendulum-3.0.0.tar.gz", hash = "sha256:5d034998dea404ec31fae27af6b22cff1708f830a1ed7353be4d1019bb9f584e", size = 84524, upload-time = "2023-12-16T21:27:19.742Z" }
@@ -7189,7 +7189,7 @@ fn extra_inferences() -> Result<()> {
         version = "1.4.52"
         source = { registry = "https://pypi.org/simple" }
         dependencies = [
-            { name = "greenlet", marker = "platform_machine == 'AMD64' or platform_machine == 'WIN32' or platform_machine == 'aarch64' or platform_machine == 'amd64' or platform_machine == 'ppc64le' or platform_machine == 'win32' or platform_machine == 'x86_64'" },
+            { name = "greenlet", marker = "platform_machine == 'AMD64' or platform_machine == 'WIN32' or platform_machine == 'aarch64' or platform_machine == 'amd64' or platform_machine == 'ppc64le' or platform_machine == 'win32' or platform_machine == 'x86_64' or (extra == 'extra-3-pkg-x1' and extra == 'extra-3-pkg-x2')" },
         ]
         sdist = { url = "https://files.pythonhosted.org/packages/8a/a4/b5991829c34af0505e0f2b1ccf9588d1ba90f2d984ee208c90c985f1265a/SQLAlchemy-1.4.52.tar.gz", hash = "sha256:80e63bbdc5217dad3485059bdf6f65a7d43f33c8bde619df5c220edf03d87296", size = 8514200, upload-time = "2024-03-04T13:29:44.258Z" }
         wheels = [
@@ -10165,7 +10165,7 @@ fn incorrect_extra_simplification_leads_to_multiple_torch_packages() -> Result<(
         version = "4.67.1"
         source = { registry = "https://pypi.org/simple" }
         dependencies = [
-            { name = "colorama", marker = "sys_platform == 'win32'" },
+            { name = "colorama", marker = "sys_platform == 'win32' or (extra == 'extra-4-test-chgnet' and extra == 'extra-4-test-m3gnet')" },
         ]
         sdist = { url = "https://files.pythonhosted.org/packages/a8/4b/29b4ef32e036bb34e4ab51796dd745cdba7ed47ad142a9f4a1eb8e0c744d/tqdm-4.67.1.tar.gz", hash = "sha256:f8aef9c52c08c13a65f30ea34f4e5aac3fd1a34959879d7e59e63027286627f2", size = 169737, upload-time = "2024-11-24T20:12:22.481Z" }
         wheels = [
@@ -10511,7 +10511,7 @@ fn duplicate_torch_and_sympy_because_of_wrong_inferences() -> Result<()> {
         dependencies = [
             { name = "aiohappyeyeballs" },
             { name = "aiosignal" },
-            { name = "async-timeout", marker = "python_full_version < '3.11'" },
+            { name = "async-timeout", marker = "python_full_version < '3.11' or (extra == 'extra-4-test-alignn' and extra == 'extra-4-test-all') or (extra == 'extra-4-test-alignn' and extra == 'extra-4-test-chgnet') or (extra == 'extra-4-test-all' and extra == 'extra-4-test-m3gnet') or (extra == 'extra-4-test-chgnet' and extra == 'extra-4-test-m3gnet')" },
             { name = "attrs" },
             { name = "frozenlist" },
             { name = "multidict" },
@@ -11621,7 +11621,7 @@ fn duplicate_torch_and_sympy_because_of_wrong_inferences() -> Result<()> {
         version = "6.1.0"
         source = { registry = "https://pypi.org/simple" }
         dependencies = [
-            { name = "typing-extensions", marker = "python_full_version < '3.11'" },
+            { name = "typing-extensions", marker = "python_full_version < '3.11' or (extra == 'extra-4-test-alignn' and extra == 'extra-4-test-all') or (extra == 'extra-4-test-alignn' and extra == 'extra-4-test-chgnet') or (extra == 'extra-4-test-all' and extra == 'extra-4-test-m3gnet') or (extra == 'extra-4-test-chgnet' and extra == 'extra-4-test-m3gnet')" },
         ]
         sdist = { url = "https://files.pythonhosted.org/packages/d6/be/504b89a5e9ca731cd47487e91c469064f8ae5af93b7259758dcfc2b9c848/multidict-6.1.0.tar.gz", hash = "sha256:22ae2ebf9b0c69d206c003e2f6a914ea33f0a932d4aa16f236afc049d9958f4a", size = 64002, upload-time = "2024-09-09T23:49:38.163Z" }
         wheels = [
@@ -13398,7 +13398,7 @@ fn duplicate_torch_and_sympy_because_of_wrong_inferences() -> Result<()> {
         version = "4.67.1"
         source = { registry = "https://pypi.org/simple" }
         dependencies = [
-            { name = "colorama", marker = "sys_platform == 'win32'" },
+            { name = "colorama", marker = "sys_platform == 'win32' or (extra == 'extra-4-test-alignn' and extra == 'extra-4-test-all') or (extra == 'extra-4-test-alignn' and extra == 'extra-4-test-chgnet') or (extra == 'extra-4-test-all' and extra == 'extra-4-test-m3gnet') or (extra == 'extra-4-test-chgnet' and extra == 'extra-4-test-m3gnet')" },
         ]
         sdist = { url = "https://files.pythonhosted.org/packages/a8/4b/29b4ef32e036bb34e4ab51796dd745cdba7ed47ad142a9f4a1eb8e0c744d/tqdm-4.67.1.tar.gz", hash = "sha256:f8aef9c52c08c13a65f30ea34f4e5aac3fd1a34959879d7e59e63027286627f2", size = 169737, upload-time = "2024-11-24T20:12:22.481Z" }
         wheels = [
@@ -14159,10 +14159,10 @@ fn overlapping_resolution_markers() -> Result<()> {
             "sys_platform == 'darwin' and extra == 'extra-14-ads-mega-model-cpu' and extra != 'extra-14-ads-mega-model-cu118'",
         ]
         dependencies = [
-            { name = "filelock" },
-            { name = "fsspec" },
-            { name = "jinja2" },
-            { name = "networkx" },
+            { name = "filelock", marker = "(sys_platform != 'darwin' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform == 'darwin' and extra == 'extra-14-ads-mega-model-cpu') or (extra != 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
+            { name = "fsspec", marker = "(sys_platform != 'darwin' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform == 'darwin' and extra == 'extra-14-ads-mega-model-cpu') or (extra != 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
+            { name = "jinja2", marker = "(sys_platform != 'darwin' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform == 'darwin' and extra == 'extra-14-ads-mega-model-cpu') or (extra != 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
+            { name = "networkx", marker = "(sys_platform != 'darwin' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform == 'darwin' and extra == 'extra-14-ads-mega-model-cpu') or (extra != 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
             { name = "nvidia-cublas-cu12", marker = "(platform_machine == 'x86_64' and sys_platform == 'linux' and extra == 'extra-14-ads-mega-model-cu118') or (platform_machine != 'x86_64' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform != 'linux' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
             { name = "nvidia-cuda-cupti-cu12", marker = "(platform_machine == 'x86_64' and sys_platform == 'linux' and extra == 'extra-14-ads-mega-model-cu118') or (platform_machine != 'x86_64' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform != 'linux' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
             { name = "nvidia-cuda-nvrtc-cu12", marker = "(platform_machine == 'x86_64' and sys_platform == 'linux' and extra == 'extra-14-ads-mega-model-cu118') or (platform_machine != 'x86_64' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform != 'linux' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
@@ -14174,9 +14174,9 @@ fn overlapping_resolution_markers() -> Result<()> {
             { name = "nvidia-cusparse-cu12", marker = "(platform_machine == 'x86_64' and sys_platform == 'linux' and extra == 'extra-14-ads-mega-model-cu118') or (platform_machine != 'x86_64' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform != 'linux' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
             { name = "nvidia-nccl-cu12", marker = "(platform_machine == 'x86_64' and sys_platform == 'linux' and extra == 'extra-14-ads-mega-model-cu118') or (platform_machine != 'x86_64' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform != 'linux' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
             { name = "nvidia-nvtx-cu12", marker = "(platform_machine == 'x86_64' and sys_platform == 'linux' and extra == 'extra-14-ads-mega-model-cu118') or (platform_machine != 'x86_64' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform != 'linux' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
-            { name = "sympy" },
+            { name = "sympy", marker = "(sys_platform != 'darwin' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform == 'darwin' and extra == 'extra-14-ads-mega-model-cpu') or (extra != 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
             { name = "triton", marker = "(platform_machine == 'x86_64' and sys_platform == 'linux' and extra == 'extra-14-ads-mega-model-cu118') or (platform_machine != 'x86_64' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform != 'linux' and extra == 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
-            { name = "typing-extensions" },
+            { name = "typing-extensions", marker = "(sys_platform != 'darwin' and extra == 'extra-14-ads-mega-model-cu118') or (sys_platform == 'darwin' and extra == 'extra-14-ads-mega-model-cpu') or (extra != 'extra-14-ads-mega-model-cpu' and extra == 'extra-14-ads-mega-model-cu118')" },
         ]
         wheels = [
             { url = "https://files.pythonhosted.org/packages/33/b3/1fcc3bccfddadfd6845dcbfe26eb4b099f1dfea5aa0e5cfb92b3c98dba5b/torch-2.2.2-cp310-cp310-manylinux1_x86_64.whl", hash = "sha256:bc889d311a855dd2dfd164daf8cc903a6b7273a747189cebafdd89106e4ad585", size = 755526581, upload-time = "2024-03-27T21:06:46.5Z" },
@@ -15143,3 +15143,160 @@ fn avoids_exponential_lock_file_growth() -> Result<()> {
 
     Ok(())
 }
+
+/// Check that simplification of conflict markers does not apply with not all paths activate the
+/// marker unconditionally.
+///
+/// For example, when `a` and `b` conflict, this marker does not simplify:
+/// ```text
+/// (platform_machine == 'x86_64' and extra == 'extra-5-foo-b') or extra == 'extra-5-foo-a'
+/// ````
+///
+/// Ref: <https://github.com/astral-sh/uv/issues/14805>
+#[test]
+fn do_not_simplify_if_not_all_conflict_extras_satisfy_the_marker_by_themselves() -> Result<()> {
+    let context = TestContext::new("3.12").with_exclude_newer("2025-02-06T00:00Z");
+
+    let pyproject = r#"
+        [project]
+        name = "debug"
+        version = "0.0.1"
+        requires-python = "==3.12.*"
+
+        [project.optional-dependencies]
+        a = [
+          "python-dateutil==2.8.0",
+        ]
+        b = [
+          "python-dateutil==2.8.1; platform_machine != 'inapplicable'",
+          "python-dateutil==2.8.0; platform_machine == 'inapplicable'",
+        ]
+
+        [tool.uv]
+        conflicts = [
+          [
+            { extra = "a" },
+            { extra = "b" },
+          ],
+        ]
+    "#;
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(pyproject)?;
+
+    uv_snapshot!(context.filters(), context.lock(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 4 packages in [TIME]
+    ");
+
+    let lock = context.read("uv.lock");
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            lock,
+            @r#"
+        version = 1
+        revision = 3
+        requires-python = "==3.12.*"
+        resolution-markers = [
+            "platform_machine != 'inapplicable' and extra != 'extra-5-debug-a' and extra == 'extra-5-debug-b'",
+            "platform_machine == 'inapplicable' and extra != 'extra-5-debug-a' and extra == 'extra-5-debug-b'",
+            "extra == 'extra-5-debug-a' and extra != 'extra-5-debug-b'",
+            "extra != 'extra-5-debug-a' and extra != 'extra-5-debug-b'",
+        ]
+        conflicts = [[
+            { package = "debug", extra = "a" },
+            { package = "debug", extra = "b" },
+        ]]
+
+        [options]
+        exclude-newer = "2025-02-06T00:00:00Z"
+
+        [[package]]
+        name = "debug"
+        version = "0.0.1"
+        source = { virtual = "." }
+
+        [package.optional-dependencies]
+        a = [
+            { name = "python-dateutil", version = "2.8.0", source = { registry = "https://pypi.org/simple" } },
+        ]
+        b = [
+            { name = "python-dateutil", version = "2.8.0", source = { registry = "https://pypi.org/simple" }, marker = "(platform_machine == 'inapplicable' and extra == 'extra-5-debug-b') or (extra == 'extra-5-debug-a' and extra == 'extra-5-debug-b')" },
+            { name = "python-dateutil", version = "2.8.1", source = { registry = "https://pypi.org/simple" }, marker = "(platform_machine != 'inapplicable' and extra == 'extra-5-debug-b') or (extra == 'extra-5-debug-a' and extra == 'extra-5-debug-b')" },
+        ]
+
+        [package.metadata]
+        requires-dist = [
+            { name = "python-dateutil", marker = "platform_machine == 'inapplicable' and extra == 'b'", specifier = "==2.8.0" },
+            { name = "python-dateutil", marker = "platform_machine != 'inapplicable' and extra == 'b'", specifier = "==2.8.1" },
+            { name = "python-dateutil", marker = "extra == 'a'", specifier = "==2.8.0" },
+        ]
+        provides-extras = ["a", "b"]
+
+        [[package]]
+        name = "python-dateutil"
+        version = "2.8.0"
+        source = { registry = "https://pypi.org/simple" }
+        resolution-markers = [
+            "platform_machine == 'inapplicable' and extra != 'extra-5-debug-a' and extra == 'extra-5-debug-b'",
+            "extra == 'extra-5-debug-a' and extra != 'extra-5-debug-b'",
+        ]
+        dependencies = [
+            { name = "six", marker = "(platform_machine == 'inapplicable' and extra == 'extra-5-debug-b') or extra == 'extra-5-debug-a'" },
+        ]
+        sdist = { url = "https://files.pythonhosted.org/packages/ad/99/5b2e99737edeb28c71bcbec5b5dda19d0d9ef3ca3e92e3e925e7c0bb364c/python-dateutil-2.8.0.tar.gz", hash = "sha256:c89805f6f4d64db21ed966fda138f8a5ed7a4fdbc1a8ee329ce1b74e3c74da9e", size = 327134, upload-time = "2019-02-05T14:12:37.493Z" }
+        wheels = [
+            { url = "https://files.pythonhosted.org/packages/41/17/c62faccbfbd163c7f57f3844689e3a78bae1f403648a6afb1d0866d87fbb/python_dateutil-2.8.0-py2.py3-none-any.whl", hash = "sha256:7e6584c74aeed623791615e26efd690f29817a27c73085b78e4bad02493df2fb", size = 226803, upload-time = "2019-02-05T14:12:35.322Z" },
+        ]
+
+        [[package]]
+        name = "python-dateutil"
+        version = "2.8.1"
+        source = { registry = "https://pypi.org/simple" }
+        resolution-markers = [
+            "platform_machine != 'inapplicable'",
+        ]
+        dependencies = [
+            { name = "six", marker = "platform_machine != 'inapplicable'" },
+        ]
+        sdist = { url = "https://files.pythonhosted.org/packages/be/ed/5bbc91f03fa4c839c4c7360375da77f9659af5f7086b7a7bdda65771c8e0/python-dateutil-2.8.1.tar.gz", hash = "sha256:73ebfe9dbf22e832286dafa60473e4cd239f8592f699aa5adaf10050e6e1823c", size = 331745, upload-time = "2019-11-03T05:42:03.923Z" }
+        wheels = [
+            { url = "https://files.pythonhosted.org/packages/d4/70/d60450c3dd48ef87586924207ae8907090de0b306af2bce5d134d78615cb/python_dateutil-2.8.1-py2.py3-none-any.whl", hash = "sha256:75bb3f31ea686f1197762692a9ee6a7550b59fc6ca3a1f4b5d7e32fb98e2da2a", size = 227183, upload-time = "2019-11-03T05:42:01.643Z" },
+        ]
+
+        [[package]]
+        name = "six"
+        version = "1.17.0"
+        source = { registry = "https://pypi.org/simple" }
+        sdist = { url = "https://files.pythonhosted.org/packages/94/e7/b2c673351809dca68a0e064b6af791aa332cf192da575fd474ed7d6f16a2/six-1.17.0.tar.gz", hash = "sha256:ff70335d468e7eb6ec65b95b99d3a2836546063f63acc5171de367e834932a81", size = 34031, upload-time = "2024-12-04T17:35:28.174Z" }
+        wheels = [
+            { url = "https://files.pythonhosted.org/packages/b7/ce/149a00dd41f10bc29e5921b496af8b574d8413afcd5e30dfa0ed46c2cc5e/six-1.17.0-py2.py3-none-any.whl", hash = "sha256:4721f391ed90541fddacab5acf947aa0d3dc7d27b2e1e8eda2be8970586c3274", size = 11050, upload-time = "2024-12-04T17:35:26.475Z" },
+        ]
+        "#
+        );
+    });
+
+    // The incorrect behavior was that only python-dateutil was installed and six was missing.
+    uv_snapshot!(context.filters(), context.sync().arg("--extra").arg("a").arg("--dry-run"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Would use project environment at: .venv
+    Resolved 4 packages in [TIME]
+    Found up-to-date lockfile at: uv.lock
+    Would download 2 packages
+    Would install 2 packages
+     + python-dateutil==2.8.0
+     + six==1.17.0
+    ");
+
+    Ok(())
+}
diff --git a/crates/uv/tests/it/lock_scenarios.rs b/crates/uv/tests/it/lock_scenarios.rs
index f1a72361f..ac1771b63 100644
--- a/crates/uv/tests/it/lock_scenarios.rs
+++ b/crates/uv/tests/it/lock_scenarios.rs
@@ -818,7 +818,7 @@ fn conflict_in_fork() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies for split (sys_platform == 'os2'):
+      × No solution found when resolving dependencies for split (markers: sys_platform == 'os2'):
       ╰─▶ Because only package-b==1.0.0 is available and package-b==1.0.0 depends on package-d==1, we can conclude that all versions of package-b depend on package-d==1.
           And because package-c==1.0.0 depends on package-d==2 and only package-c==1.0.0 is available, we can conclude that all versions of package-b and all versions of package-c are incompatible.
           And because package-a==1.0.0 depends on package-b and package-c, we can conclude that package-a==1.0.0 cannot be used.
diff --git a/crates/uv/tests/it/pip_compile.rs b/crates/uv/tests/it/pip_compile.rs
index 5bba08873..2971930ca 100644
--- a/crates/uv/tests/it/pip_compile.rs
+++ b/crates/uv/tests/it/pip_compile.rs
@@ -14569,7 +14569,7 @@ fn unsupported_requires_python_dynamic_metadata() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies for split (python_full_version >= '3.10'):
+      × No solution found when resolving dependencies for split (markers: python_full_version >= '3.10'):
       ╰─▶ Because source-distribution==0.0.3 requires Python >=3.10 and you require source-distribution{python_full_version >= '3.10'}==0.0.3, we can conclude that your requirements are unsatisfiable.
 
           hint: The source distribution for `source-distribution` (v0.0.3) does not include static metadata. Generating metadata for this package requires Python >=3.10, but Python 3.8.[X] is installed.
diff --git a/crates/uv/tests/it/sync.rs b/crates/uv/tests/it/sync.rs
index edda357d8..277704197 100644
--- a/crates/uv/tests/it/sync.rs
+++ b/crates/uv/tests/it/sync.rs
@@ -666,7 +666,7 @@ fn group_requires_python_useful_defaults() -> Result<()> {
     ----- stderr -----
     Using CPython 3.8.[X] interpreter at: [PYTHON-3.8]
     Creating virtual environment at: .venv
-      × No solution found when resolving dependencies for split (python_full_version == '3.8.*'):
+      × No solution found when resolving dependencies for split (markers: python_full_version == '3.8.*'):
       ╰─▶ Because the requested Python version (>=3.8) does not satisfy Python>=3.9 and sphinx==7.2.6 depends on Python>=3.9, we can conclude that sphinx==7.2.6 cannot be used.
           And because only sphinx<=7.2.6 is available, we can conclude that sphinx>=7.2.6 cannot be used.
           And because pharaohs-tomp:dev depends on sphinx>=7.2.6 and your project requires pharaohs-tomp:dev, we can conclude that your project's requirements are unsatisfiable.
@@ -681,7 +681,7 @@ fn group_requires_python_useful_defaults() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies for split (python_full_version == '3.8.*'):
+      × No solution found when resolving dependencies for split (markers: python_full_version == '3.8.*'):
       ╰─▶ Because the requested Python version (>=3.8) does not satisfy Python>=3.9 and sphinx==7.2.6 depends on Python>=3.9, we can conclude that sphinx==7.2.6 cannot be used.
           And because only sphinx<=7.2.6 is available, we can conclude that sphinx>=7.2.6 cannot be used.
           And because pharaohs-tomp:dev depends on sphinx>=7.2.6 and your project requires pharaohs-tomp:dev, we can conclude that your project's requirements are unsatisfiable.
@@ -810,7 +810,7 @@ fn group_requires_python_useful_non_defaults() -> Result<()> {
     ----- stderr -----
     Using CPython 3.8.[X] interpreter at: [PYTHON-3.8]
     Creating virtual environment at: .venv
-      × No solution found when resolving dependencies for split (python_full_version == '3.8.*'):
+      × No solution found when resolving dependencies for split (markers: python_full_version == '3.8.*'):
       ╰─▶ Because the requested Python version (>=3.8) does not satisfy Python>=3.9 and sphinx==7.2.6 depends on Python>=3.9, we can conclude that sphinx==7.2.6 cannot be used.
           And because only sphinx<=7.2.6 is available, we can conclude that sphinx>=7.2.6 cannot be used.
           And because pharaohs-tomp:mygroup depends on sphinx>=7.2.6 and your project requires pharaohs-tomp:mygroup, we can conclude that your project's requirements are unsatisfiable.
@@ -826,7 +826,7 @@ fn group_requires_python_useful_non_defaults() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-      × No solution found when resolving dependencies for split (python_full_version == '3.8.*'):
+      × No solution found when resolving dependencies for split (markers: python_full_version == '3.8.*'):
       ╰─▶ Because the requested Python version (>=3.8) does not satisfy Python>=3.9 and sphinx==7.2.6 depends on Python>=3.9, we can conclude that sphinx==7.2.6 cannot be used.
           And because only sphinx<=7.2.6 is available, we can conclude that sphinx>=7.2.6 cannot be used.
           And because pharaohs-tomp:mygroup depends on sphinx>=7.2.6 and your project requires pharaohs-tomp:mygroup, we can conclude that your project's requirements are unsatisfiable.