diff --git a/crates/ui-egui/src/control.rs b/crates/ui-egui/src/control.rs
index 1b9d22bb..1a6abdde 100644
--- a/crates/ui-egui/src/control.rs
+++ b/crates/ui-egui/src/control.rs
@@ -334,9 +334,16 @@ pub fn handle(app: &mut LightcraftApp, ctx: &egui::Context, req: &ControlRequest
     }
 }
 
-/// Default export folder: `~/Pictures/LightCraft Exports` (falls back to the working directory).
+/// Shown when an export has nowhere to go (no folder typed or chosen, and no home folder to default to).
+pub const NO_EXPORT_FOLDER: &str = "Choose an export folder first.";
+
+/// Default export folder: `~/Pictures/LightCraft Exports` (`%USERPROFILE%\Pictures\LightCraft Exports`
+/// on Windows, where `HOME` usually isn't set). Empty when no home folder is known.
 pub fn default_export_dir() -> String {
-    std::env::var("HOME").map(|h| format!("{h}/Pictures/LightCraft Exports")).unwrap_or_default()
+    let home = if cfg!(windows) { std::env::var_os("USERPROFILE").or_else(|| std::env::var_os("HOME")) } else { std::env::var_os("HOME") };
+    home.filter(|h| !h.is_empty())
+        .map(|h| std::path::PathBuf::from(h).join("Pictures").join("LightCraft Exports").to_string_lossy().into_owned())
+        .unwrap_or_default()
 }
 
 /// Export the selected photos (UI command `app.export`). Params: see
@@ -365,10 +372,23 @@ pub fn export_active(app: &mut LightcraftApp, p: &Value) -> Result<Value, String
     if ids.is_empty() {
         return Err("no photo selected".into());
     }
-    // no folder given (e.g. File → Export with Preset): the last export's, else the default
-    let last_dir = app.session.last_export.as_ref().and_then(|l| l.get("dir")).and_then(Value::as_str).map(str::to_string);
-    let dir = p.get("dir").and_then(Value::as_str).map(str::to_string).or(last_dir).filter(|d| !d.is_empty()).unwrap_or_else(default_export_dir);
-    let to = Destination { dir: dir.clone(), exact: p.get("path").and_then(Value::as_str).map(str::to_string) };
+    // An exact output file needs no folder. A folder given but left blank (the Export dialog's Folder
+    // field cleared) is an error, like Lightroom refusing to export to an unspecified folder, rather
+    // than a silent write into the working directory. No folder at all (e.g. File → Export with
+    // Preset): the last export's, else the default.
+    let exact = p.get("path").and_then(Value::as_str).filter(|s| !s.trim().is_empty()).map(str::to_string);
+    let dir = match p.get("dir").and_then(Value::as_str) {
+        Some(d) => d.trim().to_string(),
+        None => {
+            let last_dir =
+                app.session.last_export.as_ref().and_then(|l| l.get("dir")).and_then(Value::as_str).map(str::trim).filter(|d| !d.is_empty());
+            last_dir.map(str::to_string).unwrap_or_else(default_export_dir)
+        }
+    };
+    if dir.is_empty() && exact.is_none() {
+        return Err(NO_EXPORT_FOLDER.into());
+    }
+    let to = Destination { dir: dir.clone(), exact };
     let background = p.get("background").and_then(Value::as_bool).unwrap_or(false) && app.services.write_shared.is_some();
     let out = if background {
         let items = lightcraft_engine::export::prepare_batch(&mut app.session, &ids, &opts)?;
diff --git a/crates/ui-egui/src/menubar.rs b/crates/ui-egui/src/menubar.rs
index f5c23bb4..8012a26b 100644
--- a/crates/ui-egui/src/menubar.rs
+++ b/crates/ui-egui/src/menubar.rs
@@ -753,7 +753,13 @@ pub fn show_in_window(app: &mut LightcraftApp, ui: &mut egui::Ui, max_width: f32
         });
     }
     if let Some((id, params)) = clicked {
-        let _ = run_item(app, &id, params);
+        let r = run_item(app, &id, params);
+        // an export that can't start (e.g. no folder) says why instead of doing nothing
+        if let Err(e) = r
+            && matches!(id.as_str(), "app.export" | "app.exportPrevious")
+        {
+            app.toast(ui.ctx(), e);
+        }
     }
     ui.cursor().left() - start
 }
@@ -999,6 +1005,13 @@ mod tests {
         // remembered (expanded) for Export with Previous, folder included
         let last = app.session.last_export.clone().unwrap();
         assert_eq!((last["format"].as_str(), last["width"].as_u64(), last.get("preset")), (Some("png"), Some(40), None));
+        // a blank folder (the Export dialog's Folder field cleared) is refused with a clear message
+        // instead of writing into the working directory
+        let n = w.len();
+        drop(w);
+        let r = run_item(&mut app, "app.export", json!({"preset": "Tiny PNG", "dir": "  "}));
+        assert_eq!(r.unwrap_err(), crate::control::NO_EXPORT_FOLDER);
+        assert_eq!(written.lock().unwrap().len(), n, "nothing written without a folder");
     }
 
     #[test]
diff --git a/crates/ui-egui/src/panels/dialogs.rs b/crates/ui-egui/src/panels/dialogs.rs
index bc23383b..c2c3d267 100644
--- a/crates/ui-egui/src/panels/dialogs.rs
+++ b/crates/ui-egui/src/panels/dialogs.rs
@@ -824,8 +824,9 @@ pub fn show(app: &mut LightcraftApp, ctx: &egui::Context) {
     }
     if confirm {
         match confirm_dialog(app, &dlg) {
-            // the import review stays open on an error (e.g. an unusable folder template)
-            Err(e) if matches!(dlg, Dialog::Import { .. }) => app.toast(ctx, e),
+            // the import review stays open on an error (e.g. an unusable folder template), and so
+            // does Export (e.g. no folder chosen) so the choices aren't lost
+            Err(e) if matches!(dlg, Dialog::Import { .. } | Dialog::Export { .. }) => app.toast(ctx, e),
             // the SAM 3 dialog stays open to show the download (or why it can't start)
             Err(e) if matches!(dlg, Dialog::SamModel { .. }) => {
                 if let Dialog::SamModel { error, .. } = &mut dlg {
diff --git a/crates/ui-egui/src/shortcuts.rs b/crates/ui-egui/src/shortcuts.rs
index c5d2ce16..f76757e0 100644
--- a/crates/ui-egui/src/shortcuts.rs
+++ b/crates/ui-egui/src/shortcuts.rs
@@ -158,8 +158,11 @@ pub fn handle(app: &mut LightcraftApp, ctx: &egui::Context) {
                 o.remove("advance");
             }
             cull(app, id, params, advance);
-        } else {
-            let _ = app.run(id, params);
+        } else if let Err(e) = app.run(id, params)
+            && matches!(id, "app.export" | "app.exportPrevious")
+        {
+            // an export that can't start (e.g. no folder) says why instead of doing nothing
+            app.toast(ctx, e);
         }
     }
     for f in fire {
@@ -255,7 +258,12 @@ pub fn handle(app: &mut LightcraftApp, ctx: &egui::Context) {
                     continue;
                 }
             }
-            let _ = app.run(&f, json!({}));
+            // an export that can't start (e.g. no folder) says why instead of doing nothing
+            if let Err(e) = app.run(&f, json!({}))
+                && matches!(f.as_str(), "app.export" | "app.exportPrevious")
+            {
+                app.toast(ctx, e);
+            }
             match f.as_str() {
                 "photo.pick" => app.toast(ctx, "Flagged as Pick"),
                 "photo.reject" => app.toast(ctx, "Flagged as Reject"),