diff --git a/src/app/input.rs b/src/app/input.rs
index 17f283c8..e483029b 100644
--- a/src/app/input.rs
+++ b/src/app/input.rs
@@ -1971,6 +1971,11 @@ 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 let Some(idx) = self.collapsed_workspace_at_row(mouse.row) {
                             self.switch_workspace(idx);
                             self.mode = Mode::Terminal;
@@ -2316,6 +2321,18 @@ impl AppState {
             && row < sidebar.y + sidebar.height
     }
 
+    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);
+        rect.width > 0
+            && col >= rect.x
+            && col < rect.x + rect.width
+            && row >= rect.y
+            && row < rect.y + rect.height
+    }
+
     fn set_manual_sidebar_width(&mut self, divider_col: u16) {
         let sidebar = self.view.sidebar_rect;
         let width = divider_col.saturating_sub(sidebar.x).saturating_add(1);
@@ -3620,6 +3637,23 @@ mod tests {
         assert_eq!(app.state.mode, Mode::Terminal);
     }
 
+    #[test]
+    fn clicking_collapsed_sidebar_toggle_expands_sidebar() {
+        let mut app = app_for_mouse_test();
+        app.state.sidebar_collapsed = true;
+        app.state.view.sidebar_rect = Rect::new(0, 0, 4, 20);
+        app.state.view.terminal_area = Rect::new(4, 0, 80, 20);
+
+        let toggle = crate::ui::collapsed_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);
+    }
+
     #[test]
     fn clicking_workspace_switches_on_mouse_up() {
         let mut app = app_for_mouse_test();
diff --git a/src/ui.rs b/src/ui.rs
index 3783dd5c..4a734d0d 100644
--- a/src/ui.rs
+++ b/src/ui.rs
@@ -1054,6 +1054,16 @@ fn render_agent_detail(app: &AppState, frame: &mut Frame, area: Rect) {
     }
 }
 
+pub(crate) fn collapsed_sidebar_toggle_rect(area: Rect) -> Rect {
+    let bottom_y = area.y + area.height.saturating_sub(1);
+    let content_w = area.width.saturating_sub(1);
+    if content_w == 0 || area.height == 0 {
+        return Rect::default();
+    }
+    let x = area.x + content_w / 2;
+    Rect::new(x, bottom_y, 1, 1)
+}
+
 fn render_sidebar_toggle(
     app: &AppState,
     frame: &mut Frame,
@@ -1066,9 +1076,8 @@ fn render_sidebar_toggle(
     if !collapsed {
         return;
     }
-    let bottom_y = area.y + area.height.saturating_sub(1);
-    let content_w = area.width.saturating_sub(1);
-    if content_w == 0 || area.height == 0 {
+    let toggle_area = collapsed_sidebar_toggle_rect(area);
+    if toggle_area == Rect::default() {
         return;
     }
     let icon_style = if app.update_available.is_some() {
@@ -1076,8 +1085,6 @@ fn render_sidebar_toggle(
     } else {
         Style::default().fg(p.overlay0)
     };
-    let x = area.x + content_w / 2;
-    let toggle_area = Rect::new(x, bottom_y, 1, 1);
     frame.render_widget(Paragraph::new(Span::styled("»", icon_style)), toggle_area);
 }