diff --git a/crates/uv-installer/src/plan.rs b/crates/uv-installer/src/plan.rs
index 1941a8371..e79277bf3 100644
--- a/crates/uv-installer/src/plan.rs
+++ b/crates/uv-installer/src/plan.rs
@@ -126,6 +126,7 @@ impl<'a> Planner<'a> {
                             dist.name(),
                             installed,
                             &source,
+                            dist.version(),
                             installation,
                             tags,
                             config_settings,
diff --git a/crates/uv-installer/src/satisfies.rs b/crates/uv-installer/src/satisfies.rs
index 87c78bb33..351157e02 100644
--- a/crates/uv-installer/src/satisfies.rs
+++ b/crates/uv-installer/src/satisfies.rs
@@ -15,6 +15,7 @@ use uv_distribution_types::{
 };
 use uv_git_types::{GitLfs, GitOid};
 use uv_normalize::PackageName;
+use uv_pep440::Version;
 use uv_platform_tags::{IncompatibleTag, TagCompatibility, Tags};
 use uv_pypi_types::{DirInfo, DirectUrl, VcsInfo, VcsKind};
 
@@ -36,6 +37,7 @@ impl RequirementSatisfaction {
         name: &PackageName,
         distribution: &InstalledDist,
         source: &RequirementSource,
+        version: Option<&Version>,
         installation: InstallationStrategy,
         tags: &Tags,
         config_settings: &ConfigSettings,
@@ -358,6 +360,21 @@ impl RequirementSatisfaction {
             }
         }
 
+        // If a resolved version is provided, check that it matches the installed version.
+        // This is needed for sources that don't include explicit version specifiers (e.g.,
+        // directory dependencies with dynamic versioning), where the resolver may have determined
+        // a new version should be installed.
+        if let Some(version) = version {
+            if distribution.version() != version {
+                debug!(
+                    "Installed version does not match resolved version for {name}: {} vs. {}",
+                    distribution.version(),
+                    version
+                );
+                return Self::OutOfDate;
+            }
+        }
+
         // Otherwise, assume the requirement is up-to-date.
         Self::Satisfied
     }
diff --git a/crates/uv-installer/src/site_packages.rs b/crates/uv-installer/src/site_packages.rs
index 84dc7f66b..e6ef1c61d 100644
--- a/crates/uv-installer/src/site_packages.rs
+++ b/crates/uv-installer/src/site_packages.rs
@@ -485,6 +485,7 @@ impl SitePackages {
                             name,
                             distribution,
                             &requirement.source,
+                            None,
                             installation,
                             tags,
                             config_settings,
@@ -508,6 +509,7 @@ impl SitePackages {
                                 name,
                                 distribution,
                                 &constraint.source,
+                                None,
                                 installation,
                                 tags,
                                 config_settings,
diff --git a/crates/uv/tests/it/sync.rs b/crates/uv/tests/it/sync.rs
index d1f2cb0e8..7a95f6070 100644
--- a/crates/uv/tests/it/sync.rs
+++ b/crates/uv/tests/it/sync.rs
@@ -15376,3 +15376,113 @@ fn sync_fails_ambiguous_url() -> Result<()> {
 
     Ok(())
 }
+
+/// Test that when a local directory dependency's version changes, the planner reinstalls it
+/// even if the source directory content (cache info) hasn't changed.
+///
+/// Regression test for: <https://github.com/astral-sh/uv/issues/17370>
+#[test]
+fn sync_reinstalls_on_version_change() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    // Create a workspace with a local directory dependency.
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = ["child"]
+
+        [tool.uv.sources]
+        child = { path = "packages/child" }
+        "#,
+    )?;
+
+    // Create the child package with version 0.1.0.
+    let child = context.temp_dir.child("packages/child");
+    child.create_dir_all()?;
+    child.child("pyproject.toml").write_str(
+        r#"
+        [project]
+        name = "child"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+
+        [build-system]
+        requires = ["hatchling"]
+        build-backend = "hatchling.build"
+        "#,
+    )?;
+    child
+        .child("src")
+        .child("child")
+        .child("__init__.py")
+        .touch()?;
+
+    // Lock and sync (installs child v0.1.0).
+    uv_snapshot!(context.filters(), context.lock(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    ");
+
+    uv_snapshot!(context.filters(), context.sync(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + child==0.1.0 (from file://[TEMP_DIR]/packages/child)
+    ");
+
+    // Now bump the child's version to 0.1.1.
+    child.child("pyproject.toml").write_str(
+        r#"
+        [project]
+        name = "child"
+        version = "0.1.1"
+        requires-python = ">=3.12"
+
+        [build-system]
+        requires = ["hatchling"]
+        build-backend = "hatchling.build"
+        "#,
+    )?;
+
+    // Lock again; lockfile should show v0.1.1.
+    uv_snapshot!(context.filters(), context.lock(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    Updated child v0.1.0 -> v0.1.1
+    ");
+
+    // Sync should reinstall child with the new version. Before the fix for #17370,
+    // this would incorrectly say "Audited 2 packages" and not reinstall the child package.
+    uv_snapshot!(context.filters(), context.sync(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    Prepared 1 package in [TIME]
+    Uninstalled 1 package in [TIME]
+    Installed 1 package in [TIME]
+     - child==0.1.0 (from file://[TEMP_DIR]/packages/child)
+     + child==0.1.1 (from file://[TEMP_DIR]/packages/child)
+    ");
+
+    Ok(())
+}