feat: add agent cycling and tab wheel switching

fixes #92

4 files changed, 318 insertions, 10 deletions

diff --git a/src/app/actions.rs b/src/app/actions.rs
index 317bbff7..6263679c 100644
--- a/src/app/actions.rs
+++ b/src/app/actions.rs
@@ -323,6 +323,80 @@ impl AppState {
         }
     }
 
+    pub fn next_agent(&mut self) {
+        self.cycle_agent_entry(true);
+    }
+
+    pub fn previous_agent(&mut self) {
+        self.cycle_agent_entry(false);
+    }
+
+    fn cycle_agent_entry(&mut self, forward: bool) {
+        let entries = crate::ui::agent_panel_entries(self);
+        if entries.is_empty() {
+            return;
+        }
+
+        let focused = self
+            .active
+            .and_then(|idx| self.workspaces.get(idx))
+            .and_then(crate::workspace::Workspace::focused_pane_id);
+        let current_idx =
+            focused.and_then(|pane_id| entries.iter().position(|entry| entry.pane_id == pane_id));
+        let target_idx = match (current_idx, forward) {
+            (Some(idx), true) => (idx + 1) % entries.len(),
+            (Some(0), false) => entries.len() - 1,
+            (Some(idx), false) => idx - 1,
+            (None, true) => 0,
+            (None, false) => entries.len() - 1,
+        };
+
+        let target = &entries[target_idx];
+        let ws_idx = target.ws_idx;
+        let tab_idx = target.tab_idx;
+        let pane_id = target.pane_id;
+
+        self.switch_workspace(ws_idx);
+        self.switch_tab(tab_idx);
+        if let Some(tab) = self
+            .workspaces
+            .get_mut(ws_idx)
+            .and_then(|ws| ws.tabs.get_mut(tab_idx))
+        {
+            if tab.panes.contains_key(&pane_id) {
+                tab.layout.focus_pane(pane_id);
+                self.mark_session_dirty();
+            }
+        }
+        self.ensure_agent_panel_entry_visible(target_idx);
+    }
+
+    fn ensure_agent_panel_entry_visible(&mut self, idx: usize) {
+        if self.sidebar_collapsed {
+            return;
+        }
+
+        let (_, detail_area) = crate::ui::expanded_sidebar_sections(
+            self.view.sidebar_rect,
+            self.sidebar_section_split,
+        );
+        let metrics = crate::ui::agent_panel_scroll_metrics(self, detail_area);
+        let visible = metrics.viewport_rows;
+        if visible == 0 {
+            return;
+        }
+
+        if idx < self.agent_panel_scroll {
+            self.agent_panel_scroll = idx;
+        } else if idx >= self.agent_panel_scroll.saturating_add(visible) {
+            self.agent_panel_scroll = idx.saturating_add(1).saturating_sub(visible);
+        }
+
+        let max_scroll =
+            crate::ui::agent_panel_scroll_metrics(self, detail_area).max_offset_from_bottom;
+        self.agent_panel_scroll = self.agent_panel_scroll.min(max_scroll);
+    }
+
     pub fn close_selected_workspace(&mut self) {
         if self.workspaces.is_empty() {
             return;
@@ -871,6 +945,99 @@ mod tests {
         assert_eq!(toast.context, "detach, then run `herdr update`");
     }
 
+    fn mark_agent(state: &mut AppState, ws_idx: usize, tab_idx: usize, pane_id: PaneId) {
+        state.workspaces[ws_idx].tabs[tab_idx]
+            .panes
+            .get_mut(&pane_id)
+            .unwrap()
+            .set_detected_state(Some(Agent::Pi), AgentState::Idle);
+    }
+
+    #[test]
+    fn next_agent_cycles_agent_panel_entries_in_all_scope() {
+        let mut first = Workspace::test_new("one");
+        let first_root = first.tabs[0].root_pane;
+        let first_second = first.test_split(Direction::Horizontal);
+        first.tabs[0].layout.focus_pane(first_root);
+        let second = Workspace::test_new("two");
+        let second_root = second.tabs[0].root_pane;
+
+        let mut state = AppState::test_new();
+        state.workspaces = vec![first, second];
+        state.active = Some(0);
+        state.selected = 0;
+        state.mode = Mode::Terminal;
+        state.agent_panel_scope = crate::app::state::AgentPanelScope::AllWorkspaces;
+        mark_agent(&mut state, 0, 0, first_root);
+        mark_agent(&mut state, 0, 0, first_second);
+        mark_agent(&mut state, 1, 0, second_root);
+
+        state.next_agent();
+        assert_eq!(state.active, Some(0));
+        assert_eq!(state.workspaces[0].focused_pane_id(), Some(first_second));
+
+        state.next_agent();
+        assert_eq!(state.active, Some(1));
+        assert_eq!(state.workspaces[1].focused_pane_id(), Some(second_root));
+
+        state.previous_agent();
+        assert_eq!(state.active, Some(0));
+        assert_eq!(state.workspaces[0].focused_pane_id(), Some(first_second));
+    }
+
+    #[test]
+    fn next_agent_cycles_only_current_scope_entries() {
+        let mut first = Workspace::test_new("one");
+        let first_root = first.tabs[0].root_pane;
+        let first_second = first.test_split(Direction::Horizontal);
+        first.tabs[0].layout.focus_pane(first_second);
+        let second = Workspace::test_new("two");
+        let second_root = second.tabs[0].root_pane;
+
+        let mut state = AppState::test_new();
+        state.workspaces = vec![first, second];
+        state.active = Some(0);
+        state.selected = 0;
+        state.mode = Mode::Terminal;
+        state.agent_panel_scope = crate::app::state::AgentPanelScope::CurrentWorkspace;
+        mark_agent(&mut state, 0, 0, first_root);
+        mark_agent(&mut state, 0, 0, first_second);
+        mark_agent(&mut state, 1, 0, second_root);
+
+        state.next_agent();
+
+        assert_eq!(state.active, Some(0));
+        assert_eq!(state.workspaces[0].focused_pane_id(), Some(first_root));
+    }
+
+    #[test]
+    fn previous_agent_keeps_wrapped_target_visible_in_agent_panel() {
+        let mut workspace = Workspace::test_new("one");
+        let root = workspace.tabs[0].root_pane;
+        for idx in 1..8 {
+            workspace.test_add_tab(Some(&format!("tab-{idx}")));
+        }
+
+        let mut state = AppState::test_new();
+        state.workspaces = vec![workspace];
+        state.active = Some(0);
+        state.selected = 0;
+        state.mode = Mode::Terminal;
+        state.agent_panel_scope = crate::app::state::AgentPanelScope::CurrentWorkspace;
+        for tab_idx in 0..state.workspaces[0].tabs.len() {
+            let pane_id = state.workspaces[0].tabs[tab_idx].root_pane;
+            mark_agent(&mut state, 0, tab_idx, pane_id);
+        }
+        state.workspaces[0].tabs[0].layout.focus_pane(root);
+        crate::ui::compute_view(&mut state, ratatui::layout::Rect::new(0, 0, 80, 14));
+
+        state.previous_agent();
+
+        let last_idx = state.workspaces[0].tabs.len() - 1;
+        assert_eq!(state.workspaces[0].active_tab, last_idx);
+        assert!(state.agent_panel_scroll > 0);
+    }
+
     #[test]
     fn switch_workspace_updates_active_and_selected() {
         let mut state = app_with_workspaces(&["a", "b", "c"]);
diff --git a/src/app/input/mouse.rs b/src/app/input/mouse.rs
index 99157d0d..779af3ed 100644
--- a/src/app/input/mouse.rs
+++ b/src/app/input/mouse.rs
@@ -581,19 +581,24 @@ impl AppState {
                 }
             }
 
-            MouseEventKind::ScrollUp | MouseEventKind::ScrollDown if !in_sidebar => {
-                if self.on_tab_bar(mouse.column, mouse.row) {
-                    match mouse.kind {
-                        MouseEventKind::ScrollUp => self.scroll_tabs_left(),
-                        MouseEventKind::ScrollDown => self.scroll_tabs_right(),
-                        _ => {}
-                    }
-                } else if !self.scroll_selection_with_wheel(mouse) {
-                    self.selection = None;
-                    self.handle_terminal_wheel(mouse);
+            MouseEventKind::ScrollUp | MouseEventKind::ScrollDown
+                if self.on_tab_bar(mouse.column, mouse.row) =>
+            {
+                match mouse.kind {
+                    MouseEventKind::ScrollUp => self.previous_tab(),
+                    MouseEventKind::ScrollDown => self.next_tab(),
+                    _ => {}
                 }
             }
 
+            MouseEventKind::ScrollUp | MouseEventKind::ScrollDown
+                if !in_sidebar && self.scroll_selection_with_wheel(mouse) => {}
+
+            MouseEventKind::ScrollUp | MouseEventKind::ScrollDown if !in_sidebar => {
+                self.selection = None;
+                self.handle_terminal_wheel(mouse);
+            }
+
             MouseEventKind::ScrollUp if in_sidebar => {
                 let agent_area = self.agent_panel_rect();
                 let over_agent_panel = agent_area != Rect::default()
@@ -1568,6 +1573,90 @@ mod tests {
     }
 
     #[test]
+    fn wheel_over_tab_bar_switches_tabs() {
+        let mut app = app_for_mouse_test();
+        let mut ws = Workspace::test_new("one");
+        ws.test_add_tab(Some("two"));
+        ws.test_add_tab(Some("three"));
+        app.state.workspaces = vec![ws];
+        app.state.active = Some(0);
+        app.state.selected = 0;
+        app.state.mode = Mode::Terminal;
+
+        crate::ui::compute_view(&mut app.state, Rect::new(0, 0, 106, 20));
+        let tab_bar = app.state.view.tab_bar_rect;
+
+        app.handle_mouse(mouse(MouseEventKind::ScrollDown, tab_bar.x + 1, tab_bar.y));
+        assert_eq!(app.state.workspaces[0].active_tab, 1);
+
+        app.handle_mouse(mouse(MouseEventKind::ScrollUp, tab_bar.x + 1, tab_bar.y));
+        assert_eq!(app.state.workspaces[0].active_tab, 0);
+
+        app.handle_mouse(mouse(MouseEventKind::ScrollUp, tab_bar.x + 1, tab_bar.y));
+        assert_eq!(app.state.workspaces[0].active_tab, 2);
+
+        app.handle_mouse(mouse(
+            MouseEventKind::ScrollDown,
+            tab_bar.x + tab_bar.width.saturating_sub(1),
+            tab_bar.y,
+        ));
+        assert_eq!(app.state.workspaces[0].active_tab, 0);
+    }
+
+    #[test]
+    fn wheel_over_overflowing_tab_bar_switches_tabs() {
+        let mut app = app_for_mouse_test();
+        let mut ws = Workspace::test_new("one");
+        ws.tabs[0].set_custom_name("very-long-one".into());
+        ws.test_add_tab(Some("very-long-two"));
+        ws.test_add_tab(Some("very-long-three"));
+        app.state.workspaces = vec![ws];
+        app.state.active = Some(0);
+        app.state.selected = 0;
+        app.state.mode = Mode::Terminal;
+
+        crate::ui::compute_view(&mut app.state, Rect::new(0, 0, 65, 20));
+        assert!(app.state.view.tab_scroll_right_hit_area.width > 0);
+        let tab_bar = app.state.view.tab_bar_rect;
+
+        app.handle_mouse(mouse(
+            MouseEventKind::ScrollDown,
+            tab_bar.x + tab_bar.width.saturating_sub(2),
+            tab_bar.y,
+        ));
+        assert_eq!(app.state.workspaces[0].active_tab, 1);
+
+        app.handle_mouse(mouse(
+            MouseEventKind::ScrollDown,
+            tab_bar.x + tab_bar.width.saturating_sub(2),
+            tab_bar.y,
+        ));
+        assert_eq!(app.state.workspaces[0].active_tab, 2);
+    }
+
+    #[test]
+    fn wheel_outside_tab_bar_does_not_switch_tabs() {
+        let mut app = app_for_mouse_test();
+        let mut ws = Workspace::test_new("one");
+        ws.test_add_tab(Some("two"));
+        app.state.workspaces = vec![ws];
+        app.state.active = Some(0);
+        app.state.selected = 0;
+        app.state.mode = Mode::Terminal;
+
+        crate::ui::compute_view(&mut app.state, Rect::new(0, 0, 106, 20));
+        let terminal = app.state.view.terminal_area;
+
+        app.handle_mouse(mouse(
+            MouseEventKind::ScrollDown,
+            terminal.x + 1,
+            terminal.y + 1,
+        ));
+
+        assert_eq!(app.state.workspaces[0].active_tab, 0);
+    }
+
+    #[test]
     fn mobile_switch_button_opens_switcher_and_workspace_row_switches_workspace() {
         let mut app = app_for_mouse_test();
         app.state.workspaces = vec![Workspace::test_new("one"), Workspace::test_new("two")];
diff --git a/src/app/input/navigate.rs b/src/app/input/navigate.rs
index ce3d9cf4..6dfaf475 100644
--- a/src/app/input/navigate.rs
+++ b/src/app/input/navigate.rs
@@ -31,6 +31,18 @@ pub(crate) fn terminal_direct_navigation_action(
         return Some(NavigateAction::NextWorkspace);
     }
     if kb
+        .previous_agent
+        .is_some_and(|(code, mods)| key_matches(key, code, mods))
+    {
+        return Some(NavigateAction::PreviousAgent);
+    }
+    if kb
+        .next_agent
+        .is_some_and(|(code, mods)| key_matches(key, code, mods))
+    {
+        return Some(NavigateAction::NextAgent);
+    }
+    if kb
         .previous_tab
         .is_some_and(|(code, mods)| key_matches(key, code, mods))
     {
@@ -363,6 +375,8 @@ pub(crate) enum NavigateAction {
     CloseWorkspace,
     PreviousWorkspace,
     NextWorkspace,
+    PreviousAgent,
+    NextAgent,
     NewTab,
     RenameTab,
     PreviousTab,
@@ -407,6 +421,18 @@ fn navigate_action_for_key(state: &AppState, key: &KeyEvent) -> Option<NavigateA
     {
         return Some(NavigateAction::NextWorkspace);
     }
+    if kb
+        .previous_agent
+        .is_some_and(|(code, mods)| key_matches(key, code, mods))
+    {
+        return Some(NavigateAction::PreviousAgent);
+    }
+    if kb
+        .next_agent
+        .is_some_and(|(code, mods)| key_matches(key, code, mods))
+    {
+        return Some(NavigateAction::NextAgent);
+    }
     if key_matches(key, kb.new_tab.0, kb.new_tab.1) {
         return Some(NavigateAction::NewTab);
     }
@@ -508,6 +534,14 @@ pub(super) fn execute_navigate_action(state: &mut AppState, action: NavigateActi
             state.next_workspace();
             leave_navigate_mode(state);
         }
+        NavigateAction::PreviousAgent => {
+            state.previous_agent();
+            leave_navigate_mode(state);
+        }
+        NavigateAction::NextAgent => {
+            state.next_agent();
+            leave_navigate_mode(state);
+        }
         NavigateAction::NewTab => super::modal::open_new_tab_dialog(state),
         NavigateAction::RenameTab => super::modal::open_rename_active_tab(state, false),
         NavigateAction::PreviousTab => {
@@ -730,6 +764,20 @@ mod tests {
     }
 
     #[test]
+    fn terminal_direct_agent_shortcut_maps_to_navigation_action() {
+        let mut state = state_with_workspaces(&["test"]);
+        state.keybinds.next_agent = Some((KeyCode::Char('a'), KeyModifiers::ALT));
+        state.keybinds.next_agent_label = Some("alt+a".into());
+
+        let action = terminal_direct_navigation_action(
+            &state,
+            &KeyEvent::new(KeyCode::Char('a'), KeyModifiers::ALT),
+        );
+
+        assert_eq!(action, Some(NavigateAction::NextAgent));
+    }
+
+    #[test]
     fn terminal_direct_focus_pane_shortcut_maps_to_navigation_action() {
         let mut state = state_with_workspaces(&["test"]);
         state.keybinds.focus_pane_left = Some((KeyCode::Left, KeyModifiers::ALT));
diff --git a/src/app/state.rs b/src/app/state.rs
index 3791f674..b350235a 100644
--- a/src/app/state.rs
+++ b/src/app/state.rs
@@ -903,6 +903,10 @@ impl AppState {
                 previous_workspace_label: None,
                 next_workspace: None,
                 next_workspace_label: None,
+                previous_agent: None,
+                previous_agent_label: None,
+                next_agent: None,
+                next_agent_label: None,
                 new_tab: (KeyCode::Char('c'), KeyModifiers::empty()),
                 new_tab_label: "c".into(),
                 rename_tab: None,