Local: browse a folder in the background with progress; keep picked folders in the sidebar

Browse Folder listed, probed and imported the whole folder on the UI thread, so a
network share froze the window with no feedback. It now lists and reads on a worker
(progress window with Cancel), then adds the photos in small batches reusing the
scan's probes. Folders picked with Browse Folder… stay in the Local list after
browsing elsewhere.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/library.rs

@@ -735,7 +735,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Add Photos…",
             ["File"],
             Some("Cmd+Shift+I"),
-            "{paths: [file or folder (recursive)], mode?: add|copy (add = reference the files in place; copy = into the library's Originals/YYYY/YYYY-MM-DD/), destination?: folder for copies, organize?: date|month|flat, rename?: file-name template for copies ({name} {seq:N} {date:%Y%m%d} {camera} {title}), renameStart?: 1, metadataPreset?: name, dng?: bool (copy raws as DNG), album?: albumId, albumName?: new album, preset?: presetId, keywords?: [..]} → {imported, duplicates, failed, album?}",
+            "{paths: [file or folder (recursive)], mode?: add|copy (add = reference the files in place; copy = into the library's Originals/YYYY/YYYY-MM-DD/), destination?: folder for copies, organize?: date|month|flat, rename?: file-name template for copies ({name} {seq:N} {date:%Y%m%d} {camera} {title}), renameStart?: 1, metadataPreset?: name, dng?: bool (copy raws as DNG), local?: bool (browsing: the photos stay out of the library, like library.browse), album?: albumId, albumName?: new album, preset?: presetId, keywords?: [..]} → {imported, duplicates, failed, album?}",
             always,
             |s, p| {
                 let paths = strs(p, "paths");
@@ -781,6 +781,7 @@ pub fn specs() -> Vec<CommandSpec> {
                     rename_start: p.get("renameStart").and_then(Value::as_u64).unwrap_or(1) as usize,
                     metadata_preset,
                     convert_dng: super::bool_or(p, "dng", false),
+                    local: super::bool_or(p, "local", false),
                     ..Default::default()
                 };
                 let undo0 = s.undo.len();

crates/engine/src/import.rs

@@ -528,7 +528,12 @@ pub fn import_with(s: &mut Session, paths: &[String], opts: &ImportOptions) -> c
         }
     }
 
-    let probed = probe_all(s.media.file_probe.as_ref(), &todo, &ScanProgress::default());
+    // files a preceding scan already probed are not read again (a network share is slow to read)
+    let cached: Vec<Option<ProbeInfo>> = todo.iter().map(|f| s.import_probes.remove(f)).collect();
+    let missing: Vec<String> = todo.iter().zip(&cached).filter(|(_, c)| c.is_none()).map(|(f, _)| f.clone()).collect();
+    let mut fresh = probe_all(s.media.file_probe.as_ref(), &missing, &ScanProgress::default()).into_iter();
+    let probed: Vec<Result<ProbeInfo, String>> =
+        cached.into_iter().map(|c| c.map(Ok).unwrap_or_else(|| fresh.next().unwrap_or_else(|| Err("not probed".into())))).collect();
     crate::memory::release();
     let now = (s.clock)();
     let mut ops = promote;

crates/ui-egui/src/headless.rs

@@ -767,7 +767,12 @@ mod tests {
         }
         let library_before = h.app.session.catalog.photos().filter(|p| !p.local).count();
         let r = h.request("engine.execute", json!({"command": "library.browse", "params": {"path": dir.to_string_lossy()}}), t);
-        assert_eq!(r["result"]["photos"], 1, "{r}");
+        // the folder is read in the background: the view switches at once, the photos follow
+        assert_eq!(r["result"]["scanning"], true, "{r}");
+        assert_eq!(h.app.session.source, lightcraft_engine::LibrarySource::Folder);
+        h.settle(SETTLE);
+        assert!(h.app.scan.is_none() && h.app.import.is_none());
+        assert_eq!(h.app.session.visible_cloned().len(), 1);
         assert!(h.settle(SETTLE), "a thumbnail that can't load must not keep the renderer busy");
         // this test session has no file hooks: the thumbnail fails once, is remembered, and isn't retried
         let id = h.app.session.visible_cloned()[0];

crates/ui-egui/src/import.rs

@@ -78,6 +78,9 @@ pub struct ImportTask {
     pub failed: usize,
     undo0: usize,
     first: Option<u64>,
+    /// Reading a folder for the Local view: the photos stay out of the library, and nothing is
+    /// selected or announced as added.
+    browse: bool,
 }
 
 /// A folder scan running on a worker thread (a network share can take minutes to read; the
@@ -87,6 +90,8 @@ pub struct ScanTask {
     rx: std::sync::mpsc::Receiver<ScanOutput>,
     /// Open the review with "copy into the library" checked (a camera / card).
     pub copy: bool,
+    /// Browsing a folder (Local): the photos are read in place instead of opening the review.
+    browse: bool,
 }
 
 /// Scan `paths` in the background, then open the review dialog (see [`poll_scan`]).
@@ -105,10 +110,66 @@ pub fn open(app: &mut LightcraftApp, paths: Vec<String>) -> Result<Value, String
     std::thread::spawn(job);
     #[cfg(target_arch = "wasm32")]
     job();
-    app.scan = Some(ScanTask { progress, rx, copy: false });
+    app.scan = Some(ScanTask { progress, rx, copy: false, browse: false });
     Ok(json!({"scanning": true}))
 }
 
+/// Show a folder's photos in the Local view (`library.browse` from the UI): the view switches at
+/// once, the folder is listed and read on a worker thread (a network share can take minutes),
+/// and the photos then join the view in small batches under a progress window. A browse already
+/// running is replaced; the import review's scan is not.
+pub fn browse(app: &mut LightcraftApp, path: &str, subfolders: Option<bool>) -> Result<Value, String> {
+    let dir = std::path::absolute(std::path::Path::new(path)).map_err(|e| e.to_string())?;
+    if !dir.is_dir() {
+        return Err(format!("{path}: not a folder"));
+    }
+    if app.scan.as_ref().is_some_and(|t| !t.browse) || app.import.as_ref().is_some_and(|t| !t.browse) {
+        return Err("an import is running".into());
+    }
+    if let Some(t) = app.scan.take() {
+        t.progress.cancel.store(true, Ordering::Relaxed);
+    }
+    app.import = None;
+    let dir_s = dir.to_string_lossy().trim_end_matches(['/', '\\']).to_string();
+    let subfolders = subfolders.unwrap_or_else(|| app.session.browse.as_ref().is_some_and(|b| b.subfolders));
+    app.session.browse = Some(lightcraft_engine::Browse { path: dir_s.clone(), subfolders });
+    app.session.source = lightcraft_engine::LibrarySource::Folder;
+    let (input, _) = ScanInput::new(&mut app.session, std::slice::from_ref(&dir_s));
+    let progress = std::sync::Arc::new(ScanProgress::default());
+    let (tx, rx) = std::sync::mpsc::channel();
+    let p = progress.clone();
+    let root = dir_s.clone();
+    let job = move || {
+        let files: Vec<String> = if subfolders {
+            lightcraft_engine::import::expand(&[root], None)
+        } else {
+            let mut v: Vec<String> = std::fs::read_dir(&root)
+                .map(|rd| {
+                    rd.flatten()
+                        .map(|e| e.path())
+                        .filter(|f| {
+                            f.is_file()
+                                && lightcraft_engine::import::is_supported(f)
+                                && !f.file_name().is_some_and(|n| n.to_string_lossy().starts_with('.'))
+                        })
+                        .map(|f| f.to_string_lossy().to_string())
+                        .collect()
+                })
+                .unwrap_or_default();
+            v.sort();
+            v
+        };
+        let _ = tx.send(scan_with(input, &files, &p));
+    };
+    #[cfg(not(target_arch = "wasm32"))]
+    std::thread::spawn(job);
+    #[cfg(target_arch = "wasm32")]
+    job();
+    app.scan = Some(ScanTask { progress, rx, copy: false, browse: true });
+    app.renderer.forget_imports();
+    Ok(json!({"path": dir_s, "subfolders": subfolders, "scanning": true}))
+}
+
 /// Collect a finished scan and open the review (called every frame).
 pub fn poll_scan(app: &mut LightcraftApp, ctx: &egui::Context) {
     let Some(task) = app.scan.as_ref() else { return };
@@ -127,6 +188,17 @@ pub fn poll_scan(app: &mut LightcraftApp, ctx: &egui::Context) {
         return;
     }
     app.session.import_probes = out.probes;
+    if task.browse {
+        // what the library doesn't know yet joins the Local view
+        let queue: Vec<String> =
+            out.candidates.iter().filter(|c| c.duplicate != Some("path".into()) && c.error.is_none()).map(|c| c.path.clone()).collect();
+        if !queue.is_empty() {
+            let undo0 = app.session.undo.len();
+            let total = queue.len();
+            app.import = Some(ImportTask { queue, total, params: json!({"mode": "add", "local": true}), undo0, browse: true, ..Default::default() });
+        }
+        return;
+    }
     if out.candidates.is_empty() {
         app.toast(ctx, "No photos found");
         return;
@@ -143,7 +215,11 @@ pub fn scan_progress(app: &mut LightcraftApp, ctx: &egui::Context) {
     let t = Tokens::get(ctx);
     let total = task.progress.total.load(Ordering::Relaxed);
     let done = task.progress.done.load(Ordering::Relaxed);
-    let text = if total == 0 { "Looking for photos…".to_string() } else { format!("Reading photos… {done} of {total}") };
+    let text = if total == 0 {
+        if task.browse { "Reading folder…" } else { "Looking for photos…" }.to_string()
+    } else {
+        format!("Reading photos… {done} of {total}")
+    };
     let mut cancel = false;
     egui::Window::new("Scanning").title_bar(false).resizable(false).anchor(Align2::CENTER_BOTTOM, [0.0, -80.0]).fixed_size([340.0, 80.0]).show(
         ctx,
@@ -249,6 +325,12 @@ pub fn tick(app: &mut LightcraftApp, ctx: &egui::Context) {
     let steps = app.session.undo.len().saturating_sub(task.undo0);
     let label = format!("Add {} Photo{}", task.imported, if task.imported == 1 { "" } else { "s" });
     app.session.merge_undo(steps, &label);
+    if task.browse {
+        if task.failed > 0 {
+            app.toast(ctx, format!("{} photo{} not readable", task.failed, if task.failed == 1 { "" } else { "s" }));
+        }
+        return;
+    }
     if let Some(f) = task.first {
         let _ = app.run("library.select", json!({"ids": [f]}));
     }
@@ -267,7 +349,7 @@ pub fn progress(app: &mut LightcraftApp, ctx: &egui::Context) {
     let Some(task) = &app.import else { return };
     let t = Tokens::get(ctx);
     let frac = task.done as f32 / task.total.max(1) as f32;
-    let text = format!("Adding photos… {} of {}", task.done, task.total);
+    let text = format!("{} photos… {} of {}", if task.browse { "Reading" } else { "Adding" }, task.done, task.total);
     egui::Window::new("Importing").title_bar(false).resizable(false).anchor(Align2::CENTER_BOTTOM, [0.0, -80.0]).fixed_size([340.0, 60.0]).show(
         ctx,
         |ui| {

crates/ui-egui/src/menus.rs

@@ -842,6 +842,11 @@ pub fn run_ui_command(app: &mut LightcraftApp, id: &str, p: &Value) -> Option<Re
             app.ui.dialog = Some(Dialog::Shortcuts);
             Ok(Value::Null)
         }
+        "library.browse" if !cfg!(target_arch = "wasm32") => {
+            // listed and read in the background (see `import::browse`)
+            let Some(path) = p.get("path").and_then(Value::as_str) else { return None };
+            crate::import::browse(app, path, p.get("subfolders").and_then(Value::as_bool))
+        }
         "file.addPhotos" => {
             let paths = match p.get("paths").and_then(Value::as_array) {
                 Some(a) => a.iter().filter_map(Value::as_str).map(str::to_string).collect(),

crates/ui-egui/src/panels/left.rs

@@ -182,11 +182,13 @@ fn local_section(app: &mut LightcraftApp, ui: &mut egui::Ui) {
         }
     }
     let browsing = app.session.browse.clone().filter(|_| app.session.source == LibrarySource::Folder);
-    if let Some(b) = &browsing
-        && !places.iter().any(|(_, p)| *p == b.path)
-    {
-        let name = std::path::Path::new(&b.path).file_name().map(|n| n.to_string_lossy().to_string()).unwrap_or_else(|| b.path.clone());
-        places.push((name, b.path.clone()));
+    // picked folders stay listed; the folder being browsed is listed even when it wasn't picked
+    let roots = app.ui.local_roots.iter().cloned().chain(browsing.iter().map(|b| b.path.clone()));
+    for path in roots {
+        if !places.iter().any(|(_, p)| *p == path) {
+            let name = std::path::Path::new(&path).file_name().map(|n| n.to_string_lossy().to_string()).unwrap_or_else(|| path.clone());
+            places.push((name, path));
+        }
     }
     let current = browsing.as_ref().map(|b| b.path.clone());
     for (name, path) in places {
@@ -194,10 +196,16 @@ fn local_section(app: &mut LightcraftApp, ui: &mut egui::Ui) {
     }
     if app.services.pick_folder.is_some() && row(app, ui, "local:browse", Icon::Plus, "Browse Folder…", None, false, 0.0).clicked() {
         let picked = app.services.pick_folder.as_mut().and_then(|f| f());
-        if let Some(path) = picked
-            && let Err(e) = app.run("library.browse", json!({"path": path}))
-        {
-            app.toast(ui.ctx(), e);
+        if let Some(path) = picked {
+            match app.run("library.browse", json!({"path": path})) {
+                Ok(r) => {
+                    let dir = r["path"].as_str().unwrap_or(&path).to_string();
+                    if !app.ui.local_roots.contains(&dir) {
+                        app.ui.local_roots.push(dir);
+                    }
+                }
+                Err(e) => app.toast(ui.ctx(), e),
+            }
         }
     }
     ui.add_space(10.0);

crates/ui-egui/src/state.rs

@@ -287,6 +287,8 @@ pub struct UiState {
     pub spots_threshold: f32,
     /// The library filter bar above the grid.
     pub filter_bar: bool,
+    /// Folders picked with Local → Browse Folder…, kept in the sidebar after browsing elsewhere.
+    pub local_roots: Vec<String>,
     /// Culling: after a rating, flag or colour-label key, move to the next photo.
     pub auto_advance: bool,
     /// Full-screen preview (F): the photo alone on black, no chrome.
@@ -538,6 +540,7 @@ impl Default for UiState {
             settings: AppSettings::default(),
             window_fullscreen: None,
             filter_bar: false,
+            local_roots: Vec::new(),
             compare: None,
             reference: None,
             toast: None,