Add batch queue with slide-out side panel

Queue panel with OverlaySplitView sidebar. Users can add batches
from the results page via "Add to Queue" action. Queue shows
pending/active/completed batches with status icons. Toggle via
header bar button. Batches can be removed while pending.

pixstrip-gtk/src/app.rs

@@ -96,6 +96,31 @@ pub struct AppState {
     pub output_dir: Rc<RefCell<Option<std::path::PathBuf>>>,
     pub job_config: Rc<RefCell<JobConfig>>,
     pub detailed_mode: bool,
+    pub batch_queue: Rc<RefCell<BatchQueue>>,
+}
+
+/// A queued batch of images with their processing settings
+#[derive(Clone, Debug)]
+pub struct QueuedBatch {
+    pub name: String,
+    pub files: Vec<std::path::PathBuf>,
+    pub output_dir: std::path::PathBuf,
+    pub job_config: JobConfig,
+    pub status: BatchStatus,
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub enum BatchStatus {
+    Pending,
+    Processing,
+    Completed,
+    Failed(String),
+}
+
+/// Batch queue holding pending, active, and completed batches
+#[derive(Clone, Debug, Default)]
+pub struct BatchQueue {
+    pub batches: Vec<QueuedBatch>,
 }
 
 #[derive(Clone)]
@@ -107,6 +132,8 @@ struct WizardUi {
     title: adw::WindowTitle,
     pages: Vec<adw::NavigationPage>,
     toast_overlay: adw::ToastOverlay,
+    queue_button: gtk::ToggleButton,
+    queue_list_box: gtk::ListBox,
     state: AppState,
 }
 
@@ -221,6 +248,7 @@ fn build_ui(app: &adw::Application) {
         excluded_files: Rc::new(RefCell::new(std::collections::HashSet::new())),
         output_dir: Rc::new(RefCell::new(None)),
         detailed_mode: app_cfg.skill_level.is_advanced(),
+        batch_queue: Rc::new(RefCell::new(BatchQueue::default())),
         job_config: Rc::new(RefCell::new(JobConfig {
             resize_enabled: if remember { sess_state.resize_enabled.unwrap_or(true) } else { true },
             resize_width: if remember { sess_state.resize_width.unwrap_or(1200) } else { 1200 },
@@ -306,6 +334,15 @@ fn build_ui(app: &adw::Application) {
     let title = adw::WindowTitle::new("Pixstrip", "Batch Image Processor");
     header.set_title_widget(Some(&title));
 
+    // Queue toggle button
+    let queue_button = gtk::ToggleButton::builder()
+        .icon_name("view-list-symbolic")
+        .tooltip_text("Batch Queue")
+        .visible(false)
+        .build();
+    queue_button.add_css_class("flat");
+    header.pack_start(&queue_button);
+
     // Help button for per-step contextual help
     let help_button = gtk::Button::builder()
         .icon_name("help-about-symbolic")
@@ -368,10 +405,31 @@ fn build_ui(app: &adw::Application) {
     content_box.append(step_indicator.widget());
     content_box.append(&nav_view);
 
+    // Queue side panel
+    let (queue_panel, queue_list_box) = build_queue_panel(&app_state);
+
+    // Overlay split view: queue sidebar + main content
+    let split_view = adw::OverlaySplitView::builder()
+        .sidebar(&queue_panel)
+        .sidebar_position(gtk::PackType::End)
+        .show_sidebar(false)
+        .max_sidebar_width(300.0)
+        .min_sidebar_width(250.0)
+        .build();
+
+    // Wire queue toggle button to show/hide sidebar
+    {
+        let sv = split_view.clone();
+        queue_button.connect_toggled(move |btn| {
+            sv.set_show_sidebar(btn.is_active());
+        });
+    }
+
     // Toolbar view with header and bottom bar
     let toolbar_view = adw::ToolbarView::new();
     toolbar_view.add_top_bar(&header);
-    toolbar_view.set_content(Some(&content_box));
+    split_view.set_content(Some(&content_box));
+    toolbar_view.set_content(Some(&split_view));
     toolbar_view.add_bottom_bar(&bottom_bar);
 
     // Toast overlay wraps everything for in-app notifications
@@ -442,6 +500,8 @@ fn build_ui(app: &adw::Application) {
         title,
         pages,
         toast_overlay,
+        queue_button,
+        queue_list_box,
         state: app_state,
     };
 
@@ -1799,6 +1859,13 @@ fn wire_results_actions(
                         reset_wizard(&ui);
                     });
                 }
+                "Add to Queue" => {
+                    let ui = ui.clone();
+                    row.connect_activated(move |_| {
+                        add_current_batch_to_queue(&ui);
+                        reset_wizard(&ui);
+                    });
+                }
                 "Save as Preset" => {
                     row.set_action_name(Some("win.save-preset"));
                 }
@@ -2725,3 +2792,173 @@ fn format_duration(ms: u64) -> String {
         format!("{}m {}s", mins, secs)
     }
 }
+
+fn build_queue_panel(_state: &AppState) -> (gtk::Box, gtk::ListBox) {
+    let panel = gtk::Box::builder()
+        .orientation(gtk::Orientation::Vertical)
+        .spacing(0)
+        .width_request(260)
+        .build();
+
+    // Header
+    let header_box = gtk::Box::builder()
+        .orientation(gtk::Orientation::Horizontal)
+        .spacing(8)
+        .margin_top(12)
+        .margin_bottom(8)
+        .margin_start(12)
+        .margin_end(12)
+        .build();
+
+    let header_label = gtk::Label::builder()
+        .label("Batch Queue")
+        .css_classes(["heading"])
+        .hexpand(true)
+        .halign(gtk::Align::Start)
+        .build();
+    header_box.append(&header_label);
+
+    panel.append(&header_box);
+    panel.append(&gtk::Separator::new(gtk::Orientation::Horizontal));
+
+    // Empty state
+    let empty_label = gtk::Label::builder()
+        .label("No batches queued")
+        .css_classes(["dim-label"])
+        .vexpand(true)
+        .valign(gtk::Align::Center)
+        .halign(gtk::Align::Center)
+        .build();
+
+    let list_box = gtk::ListBox::builder()
+        .selection_mode(gtk::SelectionMode::None)
+        .css_classes(["boxed-list"])
+        .margin_start(8)
+        .margin_end(8)
+        .margin_top(8)
+        .visible(false)
+        .build();
+
+    let scrolled = gtk::ScrolledWindow::builder()
+        .hscrollbar_policy(gtk::PolicyType::Never)
+        .vexpand(true)
+        .build();
+
+    let inner = gtk::Box::builder()
+        .orientation(gtk::Orientation::Vertical)
+        .spacing(8)
+        .build();
+    inner.append(&empty_label);
+    inner.append(&list_box);
+    scrolled.set_child(Some(&inner));
+
+    panel.append(&scrolled);
+
+    (panel, list_box)
+}
+
+fn refresh_queue_list(ui: &WizardUi) {
+    let list_box = &ui.queue_list_box;
+
+    // Remove all existing rows
+    while let Some(child) = list_box.first_child() {
+        list_box.remove(&child);
+    }
+
+    let queue = ui.state.batch_queue.borrow();
+
+    // Toggle empty state visibility
+    if let Some(parent) = list_box.parent() {
+        // Find sibling empty label
+        if let Some(first_child) = parent.first_child() {
+            if let Some(label) = first_child.downcast_ref::<gtk::Label>() {
+                label.set_visible(queue.batches.is_empty());
+            }
+        }
+    }
+    list_box.set_visible(!queue.batches.is_empty());
+
+    for (i, batch) in queue.batches.iter().enumerate() {
+        let status_icon = match &batch.status {
+            BatchStatus::Pending => "content-loading-symbolic",
+            BatchStatus::Processing => "emblem-synchronizing-symbolic",
+            BatchStatus::Completed => "emblem-ok-symbolic",
+            BatchStatus::Failed(_) => "dialog-error-symbolic",
+        };
+
+        let status_text = match &batch.status {
+            BatchStatus::Pending => "Pending".to_string(),
+            BatchStatus::Processing => "Processing...".to_string(),
+            BatchStatus::Completed => "Completed".to_string(),
+            BatchStatus::Failed(e) => format!("Failed: {}", e),
+        };
+
+        let row = adw::ActionRow::builder()
+            .title(&batch.name)
+            .subtitle(&format!("{} images - {}", batch.files.len(), status_text))
+            .build();
+        row.add_prefix(&gtk::Image::from_icon_name(status_icon));
+
+        // Add remove button for pending batches
+        if batch.status == BatchStatus::Pending {
+            let remove_btn = gtk::Button::builder()
+                .icon_name("user-trash-symbolic")
+                .tooltip_text("Remove from queue")
+                .valign(gtk::Align::Center)
+                .build();
+            remove_btn.add_css_class("flat");
+
+            let queue_ref = ui.state.batch_queue.clone();
+            let ui_clone = ui.clone();
+            let idx = i;
+            remove_btn.connect_clicked(move |_| {
+                queue_ref.borrow_mut().batches.remove(idx);
+                refresh_queue_list(&ui_clone);
+            });
+
+            row.add_suffix(&remove_btn);
+        }
+
+        list_box.append(&row);
+    }
+
+    // Show/hide queue button badge
+    let has_pending = queue.batches.iter().any(|b| b.status == BatchStatus::Pending);
+    ui.queue_button.set_visible(!queue.batches.is_empty() || has_pending);
+}
+
+fn add_current_batch_to_queue(ui: &WizardUi) {
+    let files: Vec<std::path::PathBuf> = {
+        let loaded = ui.state.loaded_files.borrow();
+        let excluded = ui.state.excluded_files.borrow();
+        loaded.iter().filter(|p| !excluded.contains(*p)).cloned().collect()
+    };
+
+    if files.is_empty() {
+        ui.toast_overlay.add_toast(adw::Toast::new("No images to queue"));
+        return;
+    }
+
+    let output_dir = ui.state.output_dir.borrow().clone()
+        .unwrap_or_else(|| {
+            files[0].parent()
+                .unwrap_or_else(|| std::path::Path::new("."))
+                .join("processed")
+        });
+
+    let config = ui.state.job_config.borrow().clone();
+    let batch_num = ui.state.batch_queue.borrow().batches.len() + 1;
+
+    let batch = QueuedBatch {
+        name: format!("Batch {}", batch_num),
+        files,
+        output_dir,
+        job_config: config,
+        status: BatchStatus::Pending,
+    };
+
+    ui.state.batch_queue.borrow_mut().batches.push(batch);
+    ui.queue_button.set_visible(true);
+    refresh_queue_list(ui);
+    ui.toast_overlay.add_toast(adw::Toast::new("Batch added to queue"));
+}

pixstrip-gtk/src/processing.rs

@@ -216,8 +216,17 @@ pub fn build_results_page() -> adw::NavigationPage {
     save_preset_row.add_prefix(&gtk::Image::from_icon_name("document-save-symbolic"));
     save_preset_row.add_suffix(&gtk::Image::from_icon_name("go-next-symbolic"));
 
+    let add_queue_row = adw::ActionRow::builder()
+        .title("Add to Queue")
+        .subtitle("Queue another batch with different images")
+        .activatable(true)
+        .build();
+    add_queue_row.add_prefix(&gtk::Image::from_icon_name("view-list-symbolic"));
+    add_queue_row.add_suffix(&gtk::Image::from_icon_name("go-next-symbolic"));
+
     action_group.add(&open_row);
     action_group.add(&process_more_row);
+    action_group.add(&add_queue_row);
     action_group.add(&save_preset_row);
     content.append(&action_group);