feat: add expanded sidebar collapse control (#291)

* feat: add expanded sidebar collapse control

refs #278

* fix: place sidebar collapse control inside content

refs #278

---------

Co-authored-by: Can Celik <ogulcancelik@gmail.com>

src/app/input/mouse.rs

@@ -449,12 +449,12 @@ impl AppState {
                 }
 
                 if in_sidebar {
-                    if self.sidebar_collapsed {
-                        if self.on_collapsed_sidebar_toggle(mouse.column, mouse.row) {
-                            self.sidebar_collapsed = false;
-                            return None;
-                        }
+                    if self.on_sidebar_toggle(mouse.column, mouse.row) {
+                        self.sidebar_collapsed = !self.sidebar_collapsed;
+                        return None;
+                    }
 
+                    if self.sidebar_collapsed {
                         if let Some(idx) = self.collapsed_workspace_at_row(mouse.row) {
                             self.switch_workspace(idx);
                             self.mode = Mode::Terminal;

src/app/input/sidebar.rs

@@ -238,17 +238,25 @@ impl AppState {
             return false;
         }
         let sidebar = self.view.sidebar_rect;
+        let toggle = crate::ui::expanded_sidebar_toggle_rect(sidebar);
+        let on_toggle = toggle.width > 0
+            && col >= toggle.x
+            && col < toggle.x + toggle.width
+            && row >= toggle.y
+            && row < toggle.y + toggle.height;
         sidebar.width > 0
+            && !on_toggle
             && col == sidebar.x + sidebar.width.saturating_sub(1)
             && row >= sidebar.y
             && row < sidebar.y + sidebar.height
     }
 
-    pub(super) fn on_collapsed_sidebar_toggle(&self, col: u16, row: u16) -> bool {
-        if !self.sidebar_collapsed {
-            return false;
-        }
-        let rect = crate::ui::collapsed_sidebar_toggle_rect(self.view.sidebar_rect);
+    pub(super) fn on_sidebar_toggle(&self, col: u16, row: u16) -> bool {
+        let rect = if self.sidebar_collapsed {
+            crate::ui::collapsed_sidebar_toggle_rect(self.view.sidebar_rect)
+        } else {
+            crate::ui::expanded_sidebar_toggle_rect(self.view.sidebar_rect)
+        };
         rect.width > 0
             && col >= rect.x
             && col < rect.x + rect.width
@@ -969,6 +977,24 @@ mod tests {
         assert!(!app.state.sidebar_collapsed);
     }
 
+    #[test]
+    fn clicking_expanded_sidebar_toggle_collapses_sidebar() {
+        let mut app = app_for_mouse_test();
+        app.state.sidebar_collapsed = false;
+        app.state.view.sidebar_rect = Rect::new(0, 0, 26, 20);
+        app.state.view.terminal_area = Rect::new(26, 0, 80, 20);
+
+        let toggle = crate::ui::expanded_sidebar_toggle_rect(app.state.view.sidebar_rect);
+        app.handle_mouse(mouse(
+            MouseEventKind::Down(MouseButton::Left),
+            toggle.x,
+            toggle.y,
+        ));
+
+        assert!(app.state.sidebar_collapsed);
+        assert!(app.state.drag.is_none());
+    }
+
     #[test]
     fn clicking_workspace_switches_on_mouse_up() {
         let mut app = app_for_mouse_test();
@@ -1454,6 +1480,26 @@ mod tests {
         assert_eq!(snapshot.sidebar_width, Some(31));
     }
 
+    #[test]
+    fn dragging_sidebar_bottom_divider_still_sets_manual_width() {
+        let mut app = app_for_mouse_test();
+        let divider_col = app.state.view.sidebar_rect.x + app.state.view.sidebar_rect.width - 1;
+        let bottom_row = app.state.view.sidebar_rect.y + app.state.view.sidebar_rect.height - 1;
+
+        app.handle_mouse(mouse(
+            MouseEventKind::Down(MouseButton::Left),
+            divider_col,
+            bottom_row,
+        ));
+        app.handle_mouse(mouse(
+            MouseEventKind::Drag(MouseButton::Left),
+            divider_col + 5,
+            bottom_row,
+        ));
+
+        assert_eq!(app.state.sidebar_width, 31);
+    }
+
     #[test]
     fn dragging_past_max_clamps_to_configured_max() {
         let mut app = app_for_mouse_test();

src/ui.rs

@@ -68,9 +68,10 @@ pub(crate) use self::{
         agent_panel_body_rect, agent_panel_entries, agent_panel_scroll_metrics,
         agent_panel_scrollbar_rect, agent_panel_toggle_rect, collapsed_sidebar_sections,
         collapsed_sidebar_toggle_rect, compute_workspace_card_areas, expanded_sidebar_sections,
-        normalized_workspace_scroll, sidebar_section_divider_rect, workspace_drop_indicator_row,
-        workspace_list_entries, workspace_list_rect, workspace_list_scroll_metrics,
-        workspace_list_scrollbar_rect, workspace_parent_group_state, WorkspaceListEntry,
+        expanded_sidebar_toggle_rect, normalized_workspace_scroll, sidebar_section_divider_rect,
+        workspace_drop_indicator_row, workspace_list_entries, workspace_list_rect,
+        workspace_list_scroll_metrics, workspace_list_scrollbar_rect, workspace_parent_group_state,
+        WorkspaceListEntry,
     },
 };
 pub(crate) use self::{

src/ui/sidebar.rs

@@ -1179,6 +1179,18 @@ pub(crate) fn collapsed_sidebar_toggle_rect(area: Rect) -> Rect {
     Rect::new(x, bottom_y, 1, 1)
 }
 
+pub(crate) fn expanded_sidebar_toggle_rect(area: Rect) -> Rect {
+    if area.width <= 1 || area.height == 0 {
+        return Rect::default();
+    }
+    Rect::new(
+        area.x + area.width.saturating_sub(2),
+        area.y + area.height.saturating_sub(1),
+        1,
+        1,
+    )
+}
+
 fn render_sidebar_toggle(
     app: &AppState,
     frame: &mut Frame,
@@ -1186,25 +1198,55 @@ fn render_sidebar_toggle(
     collapsed: bool,
     p: &Palette,
 ) {
-    if !collapsed {
-        return;
-    }
-    let toggle_area = collapsed_sidebar_toggle_rect(area);
+    let toggle_area = if collapsed {
+        collapsed_sidebar_toggle_rect(area)
+    } else {
+        expanded_sidebar_toggle_rect(area)
+    };
     if toggle_area == Rect::default() {
         return;
     }
-    let icon_style = if app.global_menu_attention_badge_visible() {
+    let icon = if collapsed { "»" } else { "«" };
+    let icon_style = if collapsed && app.global_menu_attention_badge_visible() {
         Style::default().fg(p.accent).add_modifier(Modifier::BOLD)
     } else {
         Style::default().fg(p.overlay0)
     };
-    frame.render_widget(Paragraph::new(Span::styled("»", icon_style)), toggle_area);
+    frame.render_widget(Paragraph::new(Span::styled(icon, icon_style)), toggle_area);
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::{detect::Agent, workspace::Workspace};
+    use ratatui::{backend::TestBackend, Terminal};
+
+    #[test]
+    fn render_sidebar_toggle_draws_expanded_collapse_icon() {
+        let app = crate::app::state::AppState::test_new();
+        let area = Rect::new(0, 0, 26, 20);
+        let mut terminal =
+            Terminal::new(TestBackend::new(26, 20)).expect("test terminal should initialize");
+
+        terminal
+            .draw(|frame| render_sidebar_toggle(&app, frame, area, false, &app.palette))
+            .expect("sidebar toggle should render");
+
+        let toggle = expanded_sidebar_toggle_rect(area);
+        assert_eq!(
+            terminal.backend().buffer()[(toggle.x, toggle.y)].symbol(),
+            "«"
+        );
+    }
+
+    #[test]
+    fn expanded_sidebar_toggle_sits_inside_sidebar_content() {
+        let area = Rect::new(0, 0, 26, 20);
+        let toggle = expanded_sidebar_toggle_rect(area);
+
+        assert_eq!(toggle.x, area.x + area.width - 2);
+        assert_eq!(toggle.y, area.y + area.height - 1);
+    }
 
     #[test]
     fn all_workspaces_agent_panel_entries_use_workspace_and_optional_tab_labels() {