Fix walked_roots to only include recursively walked directories

crates/memofs/src/lib.rs

@@ -50,6 +50,11 @@ pub struct PrefetchCache {
     /// Populated during prefetch so that `get_dir_middleware` can skip
     /// per-file VFS metadata probes entirely.
     pub dir_init: HashMap<PathBuf, Option<(String, PathBuf)>>,
+    /// Directories that were recursively walked during prefetch. A metadata
+    /// cache miss is only treated as NotFound if the queried path falls
+    /// under one of these roots. Paths outside walked roots fall through
+    /// to the backend (they may exist but weren't covered by the walk).
+    pub walked_roots: Vec<PathBuf>,
 }
 
 mod sealed {
@@ -288,11 +293,17 @@ impl VfsInner {
             if let Some(&is_file) = cache.is_file.get(path) {
                 return Ok(Metadata { is_file });
             }
+            if cache
+                .walked_roots
+                .iter()
+                .any(|root| path.starts_with(root))
+            {
                 return Err(io::Error::new(
                     io::ErrorKind::NotFound,
                     "not in prefetch cache",
                 ));
             }
+        }
 
         self.backend.metadata(path)
     }
@@ -754,6 +765,7 @@ mod test {
             is_file: HashMap::new(),
             children: HashMap::new(),
             dir_init: HashMap::new(),
+            walked_roots: Vec::new(),
         }
     }
 
@@ -891,6 +903,7 @@ mod test {
             is_file: HashMap::new(),
             children: HashMap::new(),
             dir_init: HashMap::new(),
+            walked_roots: Vec::new(),
         });
 
         let result = vfs.read(&file_path).unwrap();
@@ -937,6 +950,7 @@ mod test {
             is_file: HashMap::new(),
             children: HashMap::new(),
             dir_init: HashMap::new(),
+            walked_roots: Vec::new(),
         });
 
         let handles: Vec<_> = (0..100)
@@ -978,6 +992,7 @@ mod test {
             is_file: HashMap::new(),
             children: HashMap::new(),
             dir_init: HashMap::new(),
+            walked_roots: Vec::new(),
         });
 
         for i in 0..50 {

src/serve_session.rs

@@ -156,6 +156,7 @@ fn prefetch_project_files(project: &Project, sync_scripts_only: bool) -> io::Res
             is_file: HashMap::new(),
             children: HashMap::new(),
             dir_init: HashMap::new(),
+            walked_roots: Vec::new(),
         });
     }
 
@@ -181,11 +182,15 @@ fn prefetch_project_files(project: &Project, sync_scripts_only: bool) -> io::Res
     // Recursive walk of each $path root. Canonicalize to resolve ".."
     // before the equality/starts_with checks.
     let canonical_folder = std::fs::canonicalize(folder).unwrap_or_else(|_| folder.to_path_buf());
+    let mut walked_roots: Vec<PathBuf> = Vec::new();
     for root in &roots {
         if !root.exists() {
             continue;
         }
         let canonical_root = std::fs::canonicalize(root).unwrap_or_else(|_| root.to_path_buf());
+        if canonical_root != canonical_folder {
+            walked_roots.push(canonical_root.clone());
+        }
         if canonical_root == canonical_folder {
             // $path points to the project folder itself -- shallow walk
             // already covers depth 0-1, fill in the subtree.
@@ -286,6 +291,7 @@ fn prefetch_project_files(project: &Project, sync_scripts_only: bool) -> io::Res
         is_file: is_file_map,
         children: children_map,
         dir_init: dir_init_map,
+        walked_roots,
     })
 }
 

tests/tests/build.rs

@@ -269,6 +269,7 @@ fn parallel_snapshot_with_prefetch_cache() {
         is_file,
         children: children_map,
         dir_init: std::collections::HashMap::new(),
+        walked_roots: Vec::new(),
     });
 
     let snap_cached = librojo::snapshot_from_vfs(&ctx, &vfs_cached, &project_path)
@@ -375,6 +376,7 @@ fn overlapping_path_roots_no_duplicate_children() {
         is_file,
         children: children_map,
         dir_init: std::collections::HashMap::new(),
+        walked_roots: Vec::new(),
     });
 
     let snap = librojo::snapshot_from_vfs(&ctx, &vfs, &project_path)