feat: add hidden collapsed sidebar mode

refs #842

8 files changed, 115 insertions, 8 deletions

diff --git a/src/app/input/sidebar.rs b/src/app/input/sidebar.rs
index fd631cd4..39affc83 100644
--- a/src/app/input/sidebar.rs
+++ b/src/app/input/sidebar.rs
@@ -497,6 +497,7 @@ mod tests {
     use super::super::{app_for_mouse_test, capture_snapshot, mouse, unique_temp_path};
     use crate::{
         app::state::{AgentPanelSort, DragTarget, Mode},
+        config::SidebarCollapsedModeConfig,
         detect::Agent,
         workspace::Workspace,
     };
@@ -969,6 +970,19 @@ mod tests {
     }
 
     #[test]
+    fn hidden_collapsed_sidebar_has_no_mouse_expand_hotspot() {
+        let mut app = app_for_mouse_test();
+        app.state.sidebar_collapsed = true;
+        app.state.sidebar_collapsed_mode = SidebarCollapsedModeConfig::Hidden;
+        app.state.view.sidebar_rect = Rect::new(0, 0, 0, 20);
+        app.state.view.terminal_area = Rect::new(0, 0, 80, 20);
+
+        app.handle_mouse(mouse(MouseEventKind::Down(MouseButton::Left), 0, 19));
+
+        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;
diff --git a/src/app/mod.rs b/src/app/mod.rs
index 2860664f..05518134 100644
--- a/src/app/mod.rs
+++ b/src/app/mod.rs
@@ -588,6 +588,7 @@ impl App {
             sidebar_width_source,
             sidebar_width_auto: false,
             sidebar_collapsed: false,
+            sidebar_collapsed_mode: config.ui.sidebar_collapsed_mode,
             sidebar_section_split,
             agent_panel_sort,
             next_agent_state_change_seq: 0,
@@ -1340,6 +1341,7 @@ impl App {
                 }
                 self.state.sidebar_min_width = config.ui.sidebar_min_width;
                 self.state.sidebar_max_width = config.ui.sidebar_max_width;
+                self.state.sidebar_collapsed_mode = config.ui.sidebar_collapsed_mode;
                 self.state.mobile_width_threshold = config.ui.mobile_width_threshold;
                 // Re-clamp the live width to the new bounds. No source guard — bounds
                 // always apply, including to widths owned by Persisted or Manual.
@@ -2500,6 +2502,31 @@ mod tests {
     }
 
     #[test]
+    fn reload_config_updates_sidebar_collapsed_mode() {
+        let _guard = config_env_lock().lock().unwrap();
+        let path = temp_config_path("reload-config-sidebar-collapsed-mode");
+        std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+        std::env::set_var(crate::config::CONFIG_PATH_ENV_VAR, &path);
+
+        let mut app = test_app();
+        assert_eq!(
+            app.state.sidebar_collapsed_mode,
+            crate::config::SidebarCollapsedModeConfig::Compact
+        );
+
+        std::fs::write(&path, "[ui]\nsidebar_collapsed_mode = \"hidden\"\n").unwrap();
+        let report = app.reload_config();
+        assert_eq!(report.status, crate::config::ConfigReloadStatus::Applied);
+        assert_eq!(
+            app.state.sidebar_collapsed_mode,
+            crate::config::SidebarCollapsedModeConfig::Hidden
+        );
+
+        std::env::remove_var(crate::config::CONFIG_PATH_ENV_VAR);
+        let _ = std::fs::remove_dir_all(path.parent().unwrap());
+    }
+
+    #[test]
     fn reload_config_updates_sidebar_bounds_and_reclamps() {
         let _guard = config_env_lock().lock().unwrap();
         let path = temp_config_path("reload-config-sidebar-bounds");
diff --git a/src/app/state.rs b/src/app/state.rs
index 9e5dbed1..694ff252 100644
--- a/src/app/state.rs
+++ b/src/app/state.rs
@@ -1349,6 +1349,7 @@ pub struct AppState {
     pub sidebar_width_source: SidebarWidthSource,
     pub sidebar_width_auto: bool,
     pub sidebar_collapsed: bool,
+    pub sidebar_collapsed_mode: crate::config::SidebarCollapsedModeConfig,
     /// Ratio of sidebar height allocated to the workspaces section.
     pub sidebar_section_split: f32,
     pub agent_panel_sort: AgentPanelSort,
@@ -1708,6 +1709,7 @@ impl AppState {
             sidebar_width_source: SidebarWidthSource::ConfigDefault,
             sidebar_width_auto: false,
             sidebar_collapsed: false,
+            sidebar_collapsed_mode: crate::config::SidebarCollapsedModeConfig::Compact,
             sidebar_section_split: 0.5,
             agent_panel_sort: AgentPanelSort::Spaces,
             next_agent_state_change_seq: 0,
diff --git a/src/config.rs b/src/config.rs
index 12e9cf1c..5ddc4c60 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -19,9 +19,9 @@ pub use self::{
     },
     model::{
         validated_sidebar_bounds, AgentPanelSortConfig, Config, ConfigReloadReport,
-        ConfigReloadStatus, NewTerminalCwdConfig, ShellModeConfig, ToastClipboardPosition,
-        ToastConfig, ToastDelivery, ToastHerdrPosition, UpdateChannelConfig,
-        MAX_TOAST_DELAY_SECONDS,
+        ConfigReloadStatus, NewTerminalCwdConfig, ShellModeConfig, SidebarCollapsedModeConfig,
+        ToastClipboardPosition, ToastConfig, ToastDelivery, ToastHerdrPosition,
+        UpdateChannelConfig, MAX_TOAST_DELAY_SECONDS,
     },
     sound::SoundConfig,
     theme::{parse_color, CustomThemeColors, ThemeConfig},
diff --git a/src/config/model.rs b/src/config/model.rs
index 92192c26..301b58ca 100644
--- a/src/config/model.rs
+++ b/src/config/model.rs
@@ -106,6 +106,14 @@ impl AgentPanelSortConfig {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Deserialize, Serialize)]
+#[serde(rename_all = "lowercase")]
+pub enum SidebarCollapsedModeConfig {
+    #[default]
+    Compact,
+    Hidden,
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub struct RightClickPassthroughModifierConfig(Option<KeyModifiers>);
 
@@ -763,6 +771,8 @@ pub struct UiConfig {
     pub sidebar_min_width: u16,
     /// Maximum sidebar width (columns) when expanded. Default: 36.
     pub sidebar_max_width: u16,
+    /// Collapsed sidebar presentation. Default: compact.
+    pub sidebar_collapsed_mode: SidebarCollapsedModeConfig,
     /// Terminal width at or below which Herdr uses the mobile single-column layout. Default: 64.
     pub mobile_width_threshold: u16,
     /// Capture mouse input for Herdr's mouse UI. Default: true.
@@ -963,6 +973,7 @@ impl Default for UiConfig {
             sidebar_width: 26,
             sidebar_min_width: 18,
             sidebar_max_width: 36,
+            sidebar_collapsed_mode: SidebarCollapsedModeConfig::Compact,
             mobile_width_threshold: DEFAULT_MOBILE_WIDTH_THRESHOLD,
             mouse_capture: true,
             right_click_passthrough_modifier: RightClickPassthroughModifierConfig::default(),
@@ -1311,6 +1322,25 @@ mobile_width_threshold = 96
     }
 
     #[test]
+    fn sidebar_collapsed_mode_defaults_compact_and_parses_hidden() {
+        let default_config = Config::default();
+        assert_eq!(
+            default_config.ui.sidebar_collapsed_mode,
+            SidebarCollapsedModeConfig::Compact
+        );
+
+        let toml = r#"
+[ui]
+sidebar_collapsed_mode = "hidden"
+"#;
+        let config: Config = toml::from_str(toml).unwrap();
+        assert_eq!(
+            config.ui.sidebar_collapsed_mode,
+            SidebarCollapsedModeConfig::Hidden
+        );
+    }
+
+    #[test]
     fn validated_sidebar_bounds_rejects_inverted() {
         assert_eq!(validated_sidebar_bounds(18, 36), Some((18, 36)));
         assert_eq!(validated_sidebar_bounds(20, 20), Some((20, 20)));
diff --git a/src/main.rs b/src/main.rs
index ea46585f..6a44131c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -244,6 +244,9 @@ const DEFAULT_CONFIG: &str = r##"# herdr configuration
 # Maximum sidebar width when expanded (columns)
 # sidebar_max_width = 36
 
+# Collapsed sidebar presentation: "compact" keeps the narrow status rail, "hidden" uses zero width.
+# sidebar_collapsed_mode = "compact"
+
 # Terminal width at or below which Herdr uses the mobile single-column layout.
 # Increase this for foldables, tablets, or wide phone terminals.
 # mobile_width_threshold = 64
diff --git a/src/ui.rs b/src/ui.rs
index 041cb232..a48ded04 100644
--- a/src/ui.rs
+++ b/src/ui.rs
@@ -182,7 +182,10 @@ fn compute_view_internal(
     }
 
     let sidebar_w = if app.sidebar_collapsed {
-        COLLAPSED_WIDTH
+        match app.sidebar_collapsed_mode {
+            crate::config::SidebarCollapsedModeConfig::Compact => COLLAPSED_WIDTH,
+            crate::config::SidebarCollapsedModeConfig::Hidden => 0,
+        }
     } else {
         app.sidebar_width
             .clamp(app.sidebar_min_width, app.sidebar_max_width)
@@ -385,10 +388,12 @@ pub fn render_with_runtime_registry(
 
     if app.view.layout == ViewLayout::Mobile {
         render_mobile_header(app, terminal_runtimes, frame, app.view.mobile_header_rect);
-    } else if app.sidebar_collapsed {
-        render_sidebar_collapsed(app, frame, sidebar_area);
-    } else {
-        render_sidebar(app, terminal_runtimes, frame, sidebar_area);
+    } else if sidebar_area.width > 0 {
+        if app.sidebar_collapsed {
+            render_sidebar_collapsed(app, frame, sidebar_area);
+        } else {
+            render_sidebar(app, terminal_runtimes, frame, sidebar_area);
+        }
     }
     if app.view.layout != ViewLayout::Mobile {
         render_tab_bar(app, frame, tab_bar_area);
@@ -791,6 +796,28 @@ mod tests {
     }
 
     #[test]
+    fn hidden_collapsed_sidebar_uses_full_width_terminal_area() {
+        let mut app = crate::app::state::AppState::test_new();
+        app.sidebar_collapsed = true;
+        app.sidebar_collapsed_mode = crate::config::SidebarCollapsedModeConfig::Hidden;
+        app.workspaces = vec![Workspace::test_new("one")];
+        app.active = Some(0);
+        app.selected = 0;
+        app.mode = Mode::Terminal;
+
+        compute_view(&mut app, Rect::new(0, 0, 80, 20));
+
+        assert_eq!(app.view.sidebar_rect, Rect::new(0, 0, 0, 20));
+        assert_eq!(app.view.tab_bar_rect, Rect::new(0, 0, 80, 1));
+        assert_eq!(app.view.terminal_area, Rect::new(0, 1, 80, 19));
+        assert!(app.view.workspace_card_areas.is_empty());
+
+        let backend = TestBackend::new(80, 20);
+        let mut terminal = Terminal::new(backend).unwrap();
+        terminal.draw(|frame| render(&app, frame)).unwrap();
+    }
+
+    #[test]
     fn collapsed_sidebar_keeps_active_workspace_highlight_in_terminal_mode() {
         let mut app = crate::app::state::AppState::test_new();
         app.sidebar_collapsed = true;
diff --git a/src/ui/sidebar.rs b/src/ui/sidebar.rs
index a7b0ca92..72b344fb 100644
--- a/src/ui/sidebar.rs
+++ b/src/ui/sidebar.rs
@@ -636,6 +636,10 @@ pub(crate) fn collapsed_sidebar_sections(area: Rect) -> (Rect, Option<u16>, Rect
 
 /// Collapsed sidebar: workspace glance on top, compact agent list below.
 pub(super) fn render_sidebar_collapsed(app: &AppState, frame: &mut Frame, area: Rect) {
+    if area.width == 0 || area.height == 0 {
+        return;
+    }
+
     let is_navigating = matches!(app.mode, Mode::Navigate);
 
     let p = &app.palette;