fix(fuse): a new file closed empty reaches Drive at once (B192)

crates/pdfs-fuse/src/lib.rs

@@ -3334,6 +3334,12 @@ impl Core {
         if !h.dirty {
             self.cache.clear_scratch_durable(&h.path);
             let _ = std::fs::remove_file(&h.path);
+            // A new file's create waits for this release to wake the drain
+            // (`Core::queue_local_node`). Closed empty, it attached nothing
+            // that would, and sat until the idle poll (`docs/BUGS.md` B192).
+            if is_local_uid(&h.uid) {
+                self.wake_drain();
+            }
             return Ok(());
         }
         preserve_on_access_denied(self.require_uid_writable(&h.uid), h.dirty, || {
@@ -3828,7 +3834,7 @@ impl Core {
         debug!(%uid, %parent_uid, name, is_dir, "created node offline; queued");
         // A folder is due now; without this the workers slept through it to
         // the idle poll (B160). A file is not: its bytes ride on the create, and
-        // the release that attaches them wakes the drain.
+        // its release wakes the drain, with bytes or without (B192).
         if is_dir {
             self.wake_drain();
         }

crates/pdfs-fuse/src/sim/daemon.rs

@@ -383,6 +383,34 @@ mod tests {
         let _ = std::fs::remove_dir_all(&dir);
     }
 
+    #[test]
+    #[ignore = "mounts FUSE: run with `cargo test -p pdfs-fuse sim:: -- --ignored`"]
+    fn a_file_made_empty_while_the_drain_is_idle_reaches_drive_at_once() {
+        // A new file's create waits for the release that attaches its bytes
+        // to wake the drain. A file closed without any attached none, so it
+        // sat until the workers' 30 s idle poll (B192).
+        let drive = FakeDrive::new();
+        let dir = scratch("idle-empty-create");
+        let daemon = Daemon::start(&dir, drive.client(1, Faults::lan())).unwrap();
+        assert!(wait_until(Duration::from_secs(30), || {
+            daemon.pending().is_ok_and(|items| items.is_empty())
+        }));
+
+        std::fs::write(daemon.mountpoint.join("e.md"), b"").unwrap();
+        assert!(
+            wait_until(Duration::from_secs(10), || {
+                daemon.pending().is_ok_and(|items| items.is_empty())
+                    && drive.lookup("e.md").is_some()
+            }),
+            "{:?} {:?}",
+            daemon.pending(),
+            drive.tree()
+        );
+
+        assert!(matches!(daemon.stop(), Ok(MountOutcome::Shutdown)));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     #[test]
     #[ignore = "mounts FUSE: run with `cargo test -p pdfs-fuse sim:: -- --ignored`"]
     fn a_file_whose_upload_was_not_read_back_takes_two_writes_at_once() {