T33: the sessions and right columns resize by a drag on their border toward the terminal, 160 to 960 pixels, kept in the settings once a drag rests; Ely 5c2822c's resizable ShellColumn, whose handle occludes the header so the drag moves no window, and Ely 005faef's handle line, a filled hairline, since gpui paints a border no wider than half its box

src/settings/mod.rs

@@ -75,6 +75,9 @@ pub struct Settings {
     pub show_sessions: bool,
     pub show_panel: bool,
     pub panel: PanelTab,
+    /// The sessions and right columns' widths, in pixels, as their borders were dragged.
+    pub sessions_width: f32,
+    pub panel_width: f32,
     /// The main window's size, unmaximized, in pixels.
     pub window_width: f32,
     pub window_height: f32,
@@ -103,6 +106,8 @@ impl Default for Settings {
             show_sessions: true,
             show_panel: true,
             panel: PanelTab::Git,
+            sessions_width: 240.0,
+            panel_width: 240.0,
             window_width: 1200.0,
             window_height: 760.0,
         }
@@ -114,6 +119,7 @@ pub const LINE_HEIGHT: RangeInclusive<f32> = 1.0..=2.0;
 pub const OPACITY: RangeInclusive<f32> = 0.3..=1.0;
 pub const PADDING: RangeInclusive<f32> = 0.0..=64.0;
 pub const SCROLLBACK: RangeInclusive<u32> = 0..=100_000;
+pub const COLUMN: RangeInclusive<f32> = 160.0..=960.0;
 pub const WINDOW: RangeInclusive<f32> = 100.0..=16384.0;
 
 impl Settings {
@@ -125,6 +131,8 @@ impl Settings {
         within("padding_x", self.padding_x, &PADDING)?;
         within("padding_y", self.padding_y, &PADDING)?;
         within("scrollback", self.scrollback, &SCROLLBACK)?;
+        within("sessions_width", self.sessions_width, &COLUMN)?;
+        within("panel_width", self.panel_width, &COLUMN)?;
         within("window_width", self.window_width, &WINDOW)?;
         within("window_height", self.window_height, &WINDOW)?;
         for (field, id) in [
@@ -242,6 +250,12 @@ mod tests {
             error.to_string(),
             "window_width is 50, outside 100 to 16384"
         );
+        let settings = Settings {
+            panel_width: 1000.0,
+            ..Settings::default()
+        };
+        let error = settings.validate().expect_err("too wide");
+        assert_eq!(error.to_string(), "panel_width is 1000, outside 160 to 960");
     }
 
     #[test]