Added prefetch

furumi-common/proto/virtualfs.proto

@@ -29,13 +29,51 @@ message FileChunk {
   bytes data = 1;
 }
 
+// ── Snapshot & watch ──────────────────────────────────────────────
+
+// Request a pre-built snapshot of the directory tree up to `depth` levels.
+// depth = 0 means only the requested path itself; depth = 1 includes immediate children, etc.
+message SnapshotRequest {
+  string path = 1;
+  uint32 depth = 2;
+}
+
+// One directory's contents within a snapshot response.
+message SnapshotEntry {
+  string path = 1;
+  repeated DirEntry children = 2;
+}
+
+// Subscribe to live filesystem change notifications (no parameters needed).
+message WatchRequest {}
+
+enum ChangeKind {
+  CREATED = 0;
+  DELETED = 1;
+  MODIFIED = 2;
+}
+
+// Notifies the client that the contents of `path` have changed.
+message ChangeEvent {
+  string path = 1;
+  ChangeKind kind = 2;
+}
+
 service RemoteFileSystem {
   // Get file or directory attributes (size, permissions, timestamps). Maps to stat/getattr.
   rpc GetAttr (PathRequest) returns (AttrResponse);
-  
+
   // List directory contents. Uses Server Streaming to handle massively large directories efficiently.
   rpc ReadDir (PathRequest) returns (stream DirEntry);
-  
+
   // Read chunks of a file. Uses Server Streaming for efficient chunk delivery based on offset/size.
   rpc ReadFile (ReadRequest) returns (stream FileChunk);
+
+  // Return a pre-built in-memory snapshot of the directory tree rooted at `path`.
+  // The server walks `depth` levels deep on its side — one round-trip fills the client cache.
+  rpc GetSnapshot (SnapshotRequest) returns (stream SnapshotEntry);
+
+  // Subscribe to live filesystem change events. The server pushes a ChangeEvent whenever
+  // a directory's contents change, allowing the client to invalidate its cache immediately.
+  rpc WatchChanges (WatchRequest) returns (stream ChangeEvent);
 }