Issue #3405: Auto Import waits for an import that starts during its listing

An import, sync or Lightroom migration that started while the watched folder was listed made the scan mark the new files as tried without importing them, so they were skipped until restart. The listing's result is now dropped in that case and the next listing imports them.

crates/ui-egui/src/app/frame.rs

@@ -97,6 +97,11 @@ impl LightcraftApp {
                         Ok(l) => l,
                         Err(e) => return log::debug!("auto import: {e}"),
                     };
+                    // an import, sync or Lightroom migration that started while the folder was listed: scanning
+                    // now would mark the new files as tried without importing them; the next listing picks them up
+                    if app.import.is_some() || app.sync_run.is_some() || app.lightroom.is_some() {
+                        return;
+                    }
                     let p = serde_json::json!({"listing": listing, "start": false});
                     let Ok(r) = app.session.execute("library.autoImportScan", &p) else { return };
                     let Some(mut params) = r.get("import").cloned().filter(|_| app.import.is_none()) else { return };

crates/ui-egui/src/tests/drop_import.rs

@@ -1107,3 +1107,22 @@ fn public_drop_take_preserves_reentered_barrier_order_and_clears_protection() {
         assert_eq!(photos(&h), 0, "neither taken handles nor refused arrivals replay");
     }
 }
+
+/// An import that starts while Auto Import lists its watched folder: the new photo isn't marked as
+/// tried and skipped, the next listing imports it once the other import is done.
+#[test]
+fn auto_import_waits_for_an_import_that_starts_during_its_listing() {
+    let dir = Scratch::new("auto-race");
+    let mut h = app(&dir);
+    write_png(&dir.path("watch/w.png"), 3);
+    h.app.session.import_defaults.auto_folder = Some(dir.path("watch"));
+    // the first listing notes the file's size, the second (size unchanged) imports it
+    assert!(h.step_until(T, |h| h.app.tasks.is_running("Auto Import")), "the watched folder is listed");
+    assert!(h.step_until(T, |h| !h.app.tasks.is_running("Auto Import")));
+    assert_eq!(photos(&h), 0);
+    assert!(h.step_until(T, |h| h.app.tasks.is_running("Auto Import")), "and listed again");
+    // the listing's result is applied on a later frame, after this import has started
+    h.app.import = Some(crate::import::ImportTask::new(vec![dir.path("trip")], json!({"mode": "add"}), 0, false));
+    assert!(h.step_until(T, |h| photos(h) == 3), "the trip's two photos and the watched one arrive: {}", photos(&h));
+    h.app.session.import_defaults.auto_folder = None;
+}