feat: add manual sidebar resizing

4 files changed, 168 insertions, 31 deletions

diff --git a/src/app/input.rs b/src/app/input.rs
index a45b8e42..0c901be5 100644
--- a/src/app/input.rs
+++ b/src/app/input.rs
@@ -8,7 +8,9 @@ use tracing::warn;
 use crate::layout::{NavDirection, PaneInfo, SplitBorder};
 use crate::selection::Selection;
 
-use super::state::{key_matches, AppState, ContextMenuKind, ContextMenuState, DragState, Mode};
+use super::state::{
+    key_matches, AppState, ContextMenuKind, ContextMenuState, DragState, DragTarget, Mode,
+};
 use super::App;
 
 // ---------------------------------------------------------------------------
@@ -95,6 +97,22 @@ impl App {
     }
 
     pub(super) fn handle_mouse(&mut self, mouse: MouseEvent) {
+        if matches!(mouse.kind, MouseEventKind::Down(MouseButton::Left))
+            && self.state.on_sidebar_divider(mouse.column, mouse.row)
+        {
+            let now = std::time::Instant::now();
+            let is_double_click = self
+                .last_sidebar_divider_click
+                .is_some_and(|last| now.duration_since(last) <= super::SIDEBAR_DOUBLE_CLICK_WINDOW);
+            self.last_sidebar_divider_click = Some(now);
+
+            if is_double_click {
+                self.state.sidebar_width_auto = true;
+                self.state.drag = None;
+                return;
+            }
+        }
+
         if let Some(action) = self.state.handle_mouse(mouse) {
             match action {
                 SettingsAction::SaveTheme(name) => self.save_theme(&name),
@@ -857,12 +875,23 @@ impl AppState {
                     return None;
                 }
 
+                if self.on_sidebar_divider(mouse.column, mouse.row) {
+                    self.drag = Some(DragState {
+                        target: DragTarget::SidebarDivider,
+                    });
+                    self.sidebar_width_auto = false;
+                    self.set_manual_sidebar_width(mouse.column);
+                    return None;
+                }
+
                 if !in_sidebar {
                     if let Some(border) = self.find_border_at(mouse.column, mouse.row) {
                         self.drag = Some(DragState {
-                            path: border.path.clone(),
-                            direction: border.direction,
-                            area: border.area,
+                            target: DragTarget::PaneSplit {
+                                path: border.path.clone(),
+                                direction: border.direction,
+                                area: border.area,
+                            },
                         });
                         return None;
                     }
@@ -927,20 +956,32 @@ impl AppState {
 
             MouseEventKind::Drag(MouseButton::Left) => {
                 if let Some(drag) = &self.drag {
-                    let ratio = match drag.direction {
-                        Direction::Horizontal => {
-                            (mouse.column.saturating_sub(drag.area.x)) as f32
-                                / drag.area.width.max(1) as f32
+                    match &drag.target {
+                        DragTarget::PaneSplit {
+                            path,
+                            direction,
+                            area,
+                        } => {
+                            let ratio = match direction {
+                                Direction::Horizontal => {
+                                    (mouse.column.saturating_sub(area.x)) as f32
+                                        / area.width.max(1) as f32
+                                }
+                                Direction::Vertical => {
+                                    (mouse.row.saturating_sub(area.y)) as f32
+                                        / area.height.max(1) as f32
+                                }
+                            };
+                            let ratio = ratio.clamp(0.1, 0.9);
+                            let path = path.clone();
+                            if let Some(ws) = self.active.and_then(|i| self.workspaces.get_mut(i)) {
+                                ws.layout.set_ratio_at(&path, ratio);
+                            }
                         }
-                        Direction::Vertical => {
-                            (mouse.row.saturating_sub(drag.area.y)) as f32
-                                / drag.area.height.max(1) as f32
+                        DragTarget::SidebarDivider => {
+                            self.sidebar_width_auto = false;
+                            self.set_manual_sidebar_width(mouse.column);
                         }
-                    };
-                    let ratio = ratio.clamp(0.1, 0.9);
-                    let path = drag.path.clone();
-                    if let Some(ws) = self.active.and_then(|i| self.workspaces.get_mut(i)) {
-                        ws.layout.set_ratio_at(&path, ratio);
                     }
                 } else if let Some(sel) = &mut self.selection {
                     sel.drag(mouse.column, mouse.row);
@@ -1034,6 +1075,24 @@ impl AppState {
         None
     }
 
+    fn on_sidebar_divider(&self, col: u16, row: u16) -> bool {
+        if self.sidebar_collapsed {
+            return false;
+        }
+        let sidebar = self.view.sidebar_rect;
+        sidebar.width > 0
+            && col == sidebar.x + sidebar.width.saturating_sub(1)
+            && row >= sidebar.y
+            && row < sidebar.y + sidebar.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);
+        self.sidebar_width =
+            width.clamp(crate::ui::MIN_SIDEBAR_WIDTH, crate::ui::MAX_SIDEBAR_WIDTH);
+    }
+
     /// Find which workspace index a sidebar row belongs to (two-section layout).
     fn workspace_at_row(&self, row: u16) -> Option<usize> {
         let sidebar = self.view.sidebar_rect;
@@ -1197,8 +1256,9 @@ impl AppState {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::workspace::Workspace;
-    use crossterm::event::KeyModifiers;
+    use crate::{config::Config, workspace::Workspace};
+    use crossterm::event::{KeyModifiers, MouseEvent};
+    use ratatui::layout::Rect;
 
     fn state_with_workspaces(names: &[&str]) -> AppState {
         let mut state = AppState::test_new();
@@ -1211,6 +1271,30 @@ mod tests {
         state
     }
 
+    fn app_for_mouse_test() -> App {
+        let (_api_tx, api_rx) = std::sync::mpsc::channel();
+        let mut app = App::new(
+            &Config::default(),
+            true,
+            None,
+            api_rx,
+            crate::api::EventHub::default(),
+        );
+        app.state.mode = Mode::Terminal;
+        app.state.view.sidebar_rect = Rect::new(0, 0, 26, 20);
+        app.state.view.terminal_area = Rect::new(26, 0, 80, 20);
+        app
+    }
+
+    fn mouse(kind: MouseEventKind, col: u16, row: u16) -> MouseEvent {
+        MouseEvent {
+            kind,
+            column: col,
+            row,
+            modifiers: KeyModifiers::empty(),
+        }
+    }
+
     #[test]
     fn custom_rename_key_enters_rename_mode() {
         let mut state = state_with_workspaces(&["test"]);
@@ -1365,4 +1449,29 @@ mod tests {
         assert!(state.sound.enabled);
         assert_eq!(state.mode, Mode::Settings);
     }
+
+    #[test]
+    fn dragging_sidebar_divider_sets_manual_width() {
+        let mut app = app_for_mouse_test();
+
+        app.handle_mouse(mouse(MouseEventKind::Down(MouseButton::Left), 25, 5));
+        app.handle_mouse(mouse(MouseEventKind::Drag(MouseButton::Left), 30, 5));
+
+        assert!(!app.state.sidebar_width_auto);
+        assert_eq!(app.state.sidebar_width, 31);
+    }
+
+    #[test]
+    fn double_clicking_sidebar_divider_resets_auto_width() {
+        let mut app = app_for_mouse_test();
+        app.state.sidebar_width_auto = false;
+        app.state.sidebar_width = 30;
+
+        app.handle_mouse(mouse(MouseEventKind::Down(MouseButton::Left), 25, 5));
+        app.handle_mouse(mouse(MouseEventKind::Up(MouseButton::Left), 25, 5));
+        app.handle_mouse(mouse(MouseEventKind::Down(MouseButton::Left), 25, 5));
+
+        assert!(app.state.sidebar_width_auto);
+        assert!(app.state.drag.is_none());
+    }
 }
diff --git a/src/app/mod.rs b/src/app/mod.rs
index f352f97c..15ae2b9b 100644
--- a/src/app/mod.rs
+++ b/src/app/mod.rs
@@ -12,6 +12,7 @@ use std::io;
 use std::time::{Duration, Instant};
 
 const GIT_REMOTE_STATUS_REFRESH_INTERVAL: Duration = Duration::from_millis(1500);
+const SIDEBAR_DOUBLE_CLICK_WINDOW: Duration = Duration::from_millis(350);
 
 use crossterm::event::{self, Event, KeyEventKind};
 use ratatui::layout::Rect;
@@ -37,6 +38,7 @@ pub struct App {
     config_diagnostic_deadline: Option<Instant>,
     toast_deadline: Option<Instant>,
     last_git_remote_status_refresh: Instant,
+    last_sidebar_divider_click: Option<Instant>,
 }
 
 /// Resolve the palette from config: base theme + optional custom overrides.
@@ -135,6 +137,7 @@ impl App {
             prefix_code,
             prefix_mods,
             sidebar_width: config.ui.sidebar_width,
+            sidebar_width_auto: true,
             sidebar_collapsed: false,
             confirm_close: config.ui.confirm_close,
             confirm_close_selected_confirm: true,
@@ -184,6 +187,7 @@ impl App {
             event_tx,
             event_rx,
             last_git_remote_status_refresh: Instant::now(),
+            last_sidebar_divider_click: None,
             api_rx,
             event_hub,
             last_focus,
diff --git a/src/app/state.rs b/src/app/state.rs
index fcde6bff..b1350e48 100644
--- a/src/app/state.rs
+++ b/src/app/state.rs
@@ -389,11 +389,18 @@ pub struct SettingsState {
     pub original_theme: Option<String>,
 }
 
-/// Active mouse drag on a split border.
+pub(crate) enum DragTarget {
+    PaneSplit {
+        path: Vec<bool>,
+        direction: Direction,
+        area: Rect,
+    },
+    SidebarDivider,
+}
+
+/// Active mouse drag on a split border or sidebar divider.
 pub(crate) struct DragState {
-    pub path: Vec<bool>,
-    pub direction: Direction,
-    pub area: Rect,
+    pub target: DragTarget,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -464,6 +471,7 @@ pub struct AppState {
     pub prefix_code: KeyCode,
     pub prefix_mods: KeyModifiers,
     pub sidebar_width: u16,
+    pub sidebar_width_auto: bool,
     pub sidebar_collapsed: bool,
     pub confirm_close: bool,
     pub confirm_close_selected_confirm: bool,
@@ -554,6 +562,7 @@ impl AppState {
             prefix_code: KeyCode::Char('b'),
             prefix_mods: KeyModifiers::CONTROL,
             sidebar_width: 26,
+            sidebar_width_auto: true,
             sidebar_collapsed: false,
             confirm_close: true,
             confirm_close_selected_confirm: true,
diff --git a/src/ui.rs b/src/ui.rs
index 2b5b8a4a..5e58159a 100644
--- a/src/ui.rs
+++ b/src/ui.rs
@@ -13,8 +13,8 @@ use crate::detect::AgentState;
 use crate::layout::PaneInfo;
 
 const COLLAPSED_WIDTH: u16 = 4; // num + space + dot + separator
-const MIN_SIDEBAR_WIDTH: u16 = 18;
-const MAX_SIDEBAR_WIDTH: u16 = 36;
+pub(crate) const MIN_SIDEBAR_WIDTH: u16 = 18;
+pub(crate) const MAX_SIDEBAR_WIDTH: u16 = 36;
 
 // Braille spinner frames — smooth rotation
 const SPINNERS: &[&str] = &["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"];
@@ -32,8 +32,11 @@ use crate::app::state::Palette;
 pub fn compute_view(app: &mut AppState, area: Rect) {
     let sidebar_w = if app.sidebar_collapsed {
         COLLAPSED_WIDTH
-    } else {
+    } else if app.sidebar_width_auto {
         compute_sidebar_width(app)
+    } else {
+        app.sidebar_width
+            .clamp(MIN_SIDEBAR_WIDTH, MAX_SIDEBAR_WIDTH)
     };
 
     let [sidebar_area, main_area] =
@@ -159,7 +162,9 @@ fn compute_pane_infos(app: &AppState, area: Rect) -> Vec<PaneInfo> {
 /// Auto-scale sidebar width based on workspace identity + agent summary.
 fn compute_sidebar_width(app: &AppState) -> u16 {
     if app.workspaces.is_empty() {
-        return app.sidebar_width;
+        return app
+            .sidebar_width
+            .clamp(MIN_SIDEBAR_WIDTH, MAX_SIDEBAR_WIDTH);
     }
     let max_line = app
         .workspaces
@@ -570,11 +575,11 @@ fn render_sidebar_toggle(frame: &mut Frame, area: Rect, collapsed: bool, p: &Pal
 
 fn render_panes(app: &AppState, frame: &mut Frame, area: Rect) {
     let Some(ws_idx) = app.active else {
-        render_empty(frame, area, &app.palette);
+        render_empty(app, frame, area);
         return;
     };
     let Some(ws) = app.workspaces.get(ws_idx) else {
-        render_empty(frame, area, &app.palette);
+        render_empty(app, frame, area);
         return;
     };
 
@@ -690,19 +695,29 @@ fn render_selection_highlight(
     }
 }
 
-fn render_empty(frame: &mut Frame, area: Rect, p: &Palette) {
+fn render_empty(app: &AppState, frame: &mut Frame, area: Rect) {
+    let p = &app.palette;
     let lines = vec![
         Line::from(""),
         Line::from(""),
         Line::from(Span::styled(
-            "  No active workspace",
+            "  No workspaces yet",
             Style::default().fg(p.overlay0),
         )),
         Line::from(""),
+        Line::from(Span::styled(
+            "  A workspace is one project context.",
+            Style::default().fg(p.overlay1),
+        )),
+        Line::from(Span::styled(
+            "  Its root pane (top-left) sets the default repo or folder name.",
+            Style::default().fg(p.overlay1),
+        )),
+        Line::from(""),
         Line::from(vec![
             Span::styled("  Press ", Style::default().fg(p.overlay0)),
             Span::styled(
-                "new",
+                format!("{}", app.keybinds.new_workspace_label),
                 Style::default().fg(p.accent).add_modifier(Modifier::BOLD),
             ),
             Span::styled(" to create one", Style::default().fg(p.overlay0)),