Fix freeze on file/folder picker dialogs: use the non-blocking dialog API instead of blocking_pick_files()/blocking_pick_folder(), which deadlock when called from a command handler

Cargo.lock

@@ -2536,6 +2536,7 @@ dependencies = [
  "tauri",
  "tauri-build",
  "tauri-plugin-dialog",
+ "tokio",
  "walkdir",
 ]
 

src-tauri/Cargo.toml

@@ -18,3 +18,4 @@ tauri-plugin-dialog = "2"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 walkdir = "2"
+tokio = { version = "1", features = ["sync"] }

src-tauri/src/files.rs

@@ -71,9 +71,23 @@ fn expand(paths: &[String]) -> Vec<FileEntry> {
 }
 
 /// Native "Select Files" dialog, mirroring the original's Load Files button.
+///
+/// Uses the non-blocking callback API (not `blocking_pick_files()`): the blocking
+/// variant must never be called from a Tauri command handler, because on macOS it has
+/// to hand off to the main thread to actually show the panel and then wait for a
+/// response - if the command itself is occupying the thread the dialog needs, the app
+/// deadlocks the moment the dialog tries to close (this is exactly what "froze after I
+/// hit Cancel" looked like). The callback form lets the dialog signal completion
+/// asynchronously instead, which we bridge back into an `async fn` with a oneshot
+/// channel.
 #[tauri::command]
-pub fn pick_files(app: AppHandle) -> Vec<FileEntry> {
-    let selection = app.dialog().file().blocking_pick_files();
+pub async fn pick_files(app: AppHandle) -> Vec<FileEntry> {
+    let (tx, rx) = tokio::sync::oneshot::channel();
+    app.dialog().file().pick_files(move |result| {
+        let _ = tx.send(result);
+    });
+    let selection = rx.await.unwrap_or(None);
+
     let paths: Vec<String> = selection
         .into_iter()
         .flatten()
@@ -84,9 +98,16 @@ pub fn pick_files(app: AppHandle) -> Vec<FileEntry> {
 }
 
 /// Native "Select Folders" dialog; the folder's contents are expanded recursively.
+/// See `pick_files` above for why this uses the callback API instead of
+/// `blocking_pick_folder()`.
 #[tauri::command]
-pub fn pick_folder(app: AppHandle) -> Vec<FileEntry> {
-    let selection = app.dialog().file().blocking_pick_folder();
+pub async fn pick_folder(app: AppHandle) -> Vec<FileEntry> {
+    let (tx, rx) = tokio::sync::oneshot::channel();
+    app.dialog().file().pick_folder(move |result| {
+        let _ = tx.send(result);
+    });
+    let selection = rx.await.unwrap_or(None);
+
     let paths: Vec<String> = selection
         .into_iter()
         .filter_map(|f| f.into_path().ok())
@@ -96,7 +117,11 @@ pub fn pick_folder(app: AppHandle) -> Vec<FileEntry> {
 }
 
 /// Expands paths dropped onto the window (files and/or folders) into their files.
+/// Runs off the main thread too - not for a deadlock reason like the dialogs above,
+/// just so recursively walking a very large dropped folder doesn't stall the UI.
 #[tauri::command]
-pub fn expand_dropped_paths(paths: Vec<String>) -> Vec<FileEntry> {
-    expand(&paths)
+pub async fn expand_dropped_paths(paths: Vec<String>) -> Vec<FileEntry> {
+    tauri::async_runtime::spawn_blocking(move || expand(&paths))
+        .await
+        .unwrap_or_default()
 }