Check subdirectory existence after cache heal (#11719)

## Summary

Closes https://github.com/astral-sh/uv/issues/11703.

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

@@ -415,16 +415,6 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         let cache_shard = cache_shard.shard(revision.id());
         let source_dist_entry = cache_shard.entry(SOURCE);
 
-        // Validate that the subdirectory exists.
-        if let Some(subdirectory) = subdirectory {
-            if !source_dist_entry.path().join(subdirectory).is_dir() {
-                return Err(Error::MissingSubdirectory(
-                    url.clone(),
-                    subdirectory.to_path_buf(),
-                ));
-            }
-        }
-
         // If there are build settings, we need to scope to a cache shard.
         let config_settings = self.build_context.config_settings();
         let cache_shard = if config_settings.is_empty() {
@@ -456,6 +446,16 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             .await?
         };
 
+        // Validate that the subdirectory exists.
+        if let Some(subdirectory) = subdirectory {
+            if !source_dist_entry.path().join(subdirectory).is_dir() {
+                return Err(Error::MissingSubdirectory(
+                    url.clone(),
+                    subdirectory.to_path_buf(),
+                ));
+            }
+        }
+
         let task = self
             .reporter
             .as_ref()
@@ -528,16 +528,6 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         let cache_shard = cache_shard.shard(revision.id());
         let source_dist_entry = cache_shard.entry(SOURCE);
 
-        // Validate that the subdirectory exists.
-        if let Some(subdirectory) = subdirectory {
-            if !source_dist_entry.path().join(subdirectory).is_dir() {
-                return Err(Error::MissingSubdirectory(
-                    url.clone(),
-                    subdirectory.to_path_buf(),
-                ));
-            }
-        }
-
         // If the metadata is static, return it.
         let dynamic =
             match StaticMetadata::read(source, source_dist_entry.path(), subdirectory).await? {
@@ -586,6 +576,16 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             .await?
         };
 
+        // Validate that the subdirectory exists.
+        if let Some(subdirectory) = subdirectory {
+            if !source_dist_entry.path().join(subdirectory).is_dir() {
+                return Err(Error::MissingSubdirectory(
+                    url.clone(),
+                    subdirectory.to_path_buf(),
+                ));
+            }
+        }
+
         // If there are build settings, we need to scope to a cache shard.
         let config_settings = self.build_context.config_settings();
         let cache_shard = if config_settings.is_empty() {

crates/uv/tests/it/sync.rs

@@ -7808,3 +7808,54 @@ fn multiple_group_conflicts() -> Result<()> {
 
     Ok(())
 }
+
+/// See: <https://github.com/astral-sh/uv/issues/11703>
+#[test]
+fn prune_cache_url_subdirectory() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = [
+            "root",
+        ]
+
+        [tool.uv.sources]
+        root = { url = "https://github.com/user-attachments/files/18216295/subdirectory-test.tar.gz", subdirectory = "packages/root" }
+    "#})?;
+
+    // Lock the project.
+    uv_snapshot!(context.filters(), context.lock(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 5 packages in [TIME]
+    "###);
+
+    // Prune the cache.
+    context.prune().arg("--ci").assert().success();
+
+    // Install the project.
+    uv_snapshot!(context.filters(), context.sync(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 5 packages in [TIME]
+    Prepared 4 packages in [TIME]
+    Installed 4 packages in [TIME]
+     + anyio==4.3.0
+     + idna==3.6
+     + root==0.0.1 (from https://github.com/user-attachments/files/18216295/subdirectory-test.tar.gz#subdirectory=packages/root)
+     + sniffio==1.3.1
+    "###);
+
+    Ok(())
+}