fix(macos): default droplets to a writable user directory (#4746)

crates/ui-egui/src/file_ui.rs

@@ -22,6 +22,22 @@ fn default_dir(app: &PhotocraftApp) -> String {
     app.session.active().and_then(|d| d.path.as_deref()).and_then(|p| p.rfind(['/', '\\']).map(|i| p[..i].to_string())).unwrap_or_else(|| ".".into())
 }
 
+/// A packaged macOS app does not start in a useful writable working directory. A saved
+/// document keeps its own folder; otherwise prefer the user's Documents folder.
+fn droplet_default_dir(app: &PhotocraftApp) -> String {
+    let dir = default_dir(app);
+    if dir != "." {
+        return dir;
+    }
+    #[cfg(target_os = "macos")]
+    if let Some(home) = std::env::var_os("HOME") {
+        let home = std::path::PathBuf::from(home);
+        let documents = home.join("Documents");
+        return if documents.is_dir() { documents } else { home }.to_string_lossy().into_owned();
+    }
+    dir
+}
+
 fn doc_stem(app: &PhotocraftApp) -> String {
     app.session.active().map(|d| d.doc.name.rsplit_once('.').map_or(d.doc.name.clone(), |(a, _)| a.to_string())).unwrap_or_else(|| tl!("Untitled").into())
 }
@@ -71,6 +87,7 @@ pub fn invoke(app: &mut PhotocraftApp, ctx: &egui::Context, id: &str, params: &V
             json!({"units": ["inches", "cm", "pixels"], "mode": ["rgb", "gray", "cmyk", "lab"]}),
         ),
         "file.automate.createDroplet" => {
+            let dir = droplet_default_dir(app);
             let Some(action) = crate::actions::selected_action(app) else {
                 return Some(Err("record an action in the Actions panel first".into()));
             };
@@ -1064,6 +1081,20 @@ mod tests {
         (app, egui::Context::default())
     }
 
+    #[test]
+    fn droplet_folder_follows_the_document_or_uses_a_safe_fallback() {
+        let (mut app, _) = app();
+        let fallback = droplet_default_dir(&app);
+        #[cfg(target_os = "macos")]
+        if std::env::var_os("HOME").is_some() {
+            assert!(std::path::Path::new(&fallback).is_absolute());
+        }
+        #[cfg(not(target_os = "macos"))]
+        assert_eq!(fallback, ".");
+        app.session.active_mut().unwrap().path = Some("/tmp/photocraft/drawing.pcraft".into());
+        assert_eq!(droplet_default_dir(&app), "/tmp/photocraft");
+    }
+
     #[test]
     fn save_for_web_dialog_runs_the_command() {
         let (mut app, ctx) = app();