feat(iced): make toolbox expandable/collapsible to 2 columns

hcie-iced-app/crates/hcie-iced-gui/src/app.rs

@@ -264,6 +264,8 @@ pub struct HcieIcedApp {
     pub bool_shape_a: Option<usize>,
     /// Boolean operation shape B selector index (geometry panel).
     pub bool_shape_b: Option<usize>,
+    /// Whether the toolbox is expanded to 2 columns (false = single column 36px, true = 2 columns 72px).
+    pub sidebar_expanded: bool,
 }
 
 /// A recently opened file entry.
@@ -779,6 +781,9 @@ pub enum Message {
     ViewerPrev,
     ViewerNext,
     ViewerEnter,
+
+    // ── Toolbox expand/collapse ─────────────────────────
+    SidebarToggleExpanded,
 }
 
 /// Convert a FilterType enum to the engine's string filter ID.
@@ -1113,6 +1118,7 @@ impl HcieIcedApp {
             vector_drag_last: None,
             bool_shape_a: None,
             bool_shape_b: None,
+            sidebar_expanded: false,
         };
 
         // Apply saved settings to tool state
@@ -5147,6 +5153,10 @@ impl HcieIcedApp {
                 }
             }
 
+            Message::SidebarToggleExpanded => {
+                self.sidebar_expanded = !self.sidebar_expanded;
+            }
+
             Message::NoOp => {}
 
             Message::TabletTouch { x, y, pressed } => {
@@ -5257,7 +5267,7 @@ impl HcieIcedApp {
             self.active_menu,
         );
 
-        // Toolbox — fixed 36px strip on the left edge (outside dock)
+        // Toolbox — 36px strip (single column) or 72px (2 columns) on the left edge
         let toolbox = crate::sidebar::view(
             &self.tool_state,
             &self.fg_color,
@@ -5266,6 +5276,7 @@ impl HcieIcedApp {
             self.active_tool_slot,
             self.sub_tools_open,
             &self.slot_last_used,
+            self.sidebar_expanded,
         );
 
         // Merged toolbar: icon buttons + tool options in one row

hcie-iced-app/crates/hcie-iced-gui/src/sidebar/mod.rs

@@ -63,7 +63,10 @@ pub const TOOL_SLOTS: &[ToolSlot] = &[
     },
 ];
 
-/// Build the Photopea-style fixed 36px sidebar element.
+/// Build the Photopea-style sidebar element.
+///
+/// When `expanded` is false, renders a single 36px column (default).
+/// When `expanded` is true, renders a 2-column grid (72px) showing more tools.
 pub fn view<'a>(
     tool_state: &'a ToolState,
     fg_color: &'a [u8; 4],
@@ -72,12 +75,30 @@ pub fn view<'a>(
     active_slot: usize,
     sub_tools_open: bool,
     slot_last_used: &'a [usize],
+    expanded: bool,
 ) -> Element<'a, Message> {
-    // Tool buttons — single column, with sub-tools popup support
+    let sidebar_width = if expanded { 72 } else { 36 };
+
+    // Tool buttons — single column or 2-column grid depending on expanded state
     let mut tool_list = column![].spacing(1);
-    for (idx, slot) in TOOL_SLOTS.iter().enumerate() {
-        let btn = tool_button(slot, tool_state, colors, idx, active_slot, sub_tools_open, slot_last_used);
-        tool_list = tool_list.push(btn);
+    if expanded {
+        // 2-column layout: show tools in pairs
+        let mut row_children = iced::widget::Row::new().spacing(1);
+        for (idx, slot) in TOOL_SLOTS.iter().enumerate() {
+            let btn = tool_button(slot, tool_state, colors, idx, active_slot, sub_tools_open, slot_last_used);
+            row_children = row_children.push(btn);
+            // Every 2 tools, start a new row
+            if idx % 2 == 1 || idx == TOOL_SLOTS.len() - 1 {
+                tool_list = tool_list.push(row_children);
+                row_children = iced::widget::Row::new().spacing(1);
+            }
+        }
+    } else {
+        // Single column layout (default)
+        for (idx, slot) in TOOL_SLOTS.iter().enumerate() {
+            let btn = tool_button(slot, tool_state, colors, idx, active_slot, sub_tools_open, slot_last_used);
+            tool_list = tool_list.push(btn);
+        }
     }
 
     // Color swatches at bottom (Photopea-style: diagonal overlapping)
@@ -173,7 +194,7 @@ pub fn view<'a>(
             )
     )
     .padding([4, 2])
-    .width(36)
+    .width(sidebar_width)
     .height(32);
 
     // Separator line
@@ -182,13 +203,37 @@ pub fn view<'a>(
         ..Default::default()
     };
 
+    // Toggle expand/collapse button (arrow icon)
+    let toggle_label = if expanded { "◀" } else { "▶" };
+    let toggle_btn = button(text(toggle_label).size(10).color(colors.text_secondary))
+        .on_press(Message::SidebarToggleExpanded)
+        .padding(2)
+        .width(sidebar_width)
+        .style(move |_theme: &iced::Theme, status: iced::widget::button::Status| {
+            match status {
+                iced::widget::button::Status::Hovered => iced::widget::button::Style {
+                    background: Some(iced::Background::Color(colors.bg_hover)),
+                    text_color: colors.text_primary,
+                    border: iced::Border::default(),
+                    ..Default::default()
+                },
+                _ => iced::widget::button::Style {
+                    background: Some(iced::Background::Color(iced::Color::from_rgba(0.0, 0.0, 0.0, 0.0))),
+                    text_color: colors.text_secondary,
+                    border: iced::Border::default(),
+                    ..Default::default()
+                },
+            }
+        });
+
     let sidebar = column![
         container(tool_list).padding([2, 0]),
         container(text("").height(1)).width(Length::Fill).style(sep_style),
         color_section,
         container(reset_btn).padding([2, 4]),
+        container(toggle_btn).padding([2, 0]),
     ]
-    .width(36)
+    .width(sidebar_width)
     .spacing(0);
 
     container(sidebar)