feat(command-palette): add grouped suggestions, history tracking, and model/provider fuzzy matching

- Export `PaletteGroup` and `PaletteSuggestion` to represent suggestion metadata.
- Implement command history with deduplication, capacity limit, and recent‑command suggestions.
- Enhance dynamic suggestion logic to include history, commands, models, and providers with fuzzy ranking.
- Add UI rendering for grouped suggestions, header with command palette label, and footer instructions.
- Update help text with new shortcuts (Ctrl+P, layout save/load) and expose new agent/layout commands.

crates/owlen-tui/src/ui.rs

@@ -12,7 +12,8 @@ use unicode_width::UnicodeWidthStr;
 
 use crate::chat_app::{ChatApp, HELP_TAB_COUNT, MessageRenderContext, ModelSelectorItemKind};
 use crate::state::{
-    CodePane, EditorTab, FileFilterMode, LayoutNode, PaneId, RepoSearchRowKind, SplitAxis,
+    CodePane, EditorTab, FileFilterMode, LayoutNode, PaletteGroup, PaneId, RepoSearchRowKind,
+    SplitAxis,
 };
 use owlen_core::model::DetailedModelInfo;
 use owlen_core::theme::Theme;
@@ -1696,6 +1697,18 @@ fn render_status(frame: &mut Frame<'_>, area: Rect, app: &ChatApp) {
         InputMode::SymbolSearch => ("SYMBOLS", theme.mode_command),
     };
 
+    let mode_badge_style = if app.mode_flash_active() {
+        Style::default()
+            .bg(theme.selection_bg)
+            .fg(theme.selection_fg)
+            .add_modifier(Modifier::BOLD)
+    } else {
+        Style::default()
+            .bg(mode_color)
+            .fg(theme.background)
+            .add_modifier(Modifier::BOLD)
+    };
+
     let (op_label, op_fg, op_bg) = match app.get_mode() {
         owlen_core::mode::Mode::Chat => ("CHAT", theme.operating_chat_fg, theme.operating_chat_bg),
         owlen_core::mode::Mode::Code => ("CODE", theme.operating_code_fg, theme.operating_code_bg),
@@ -1710,13 +1723,7 @@ fn render_status(frame: &mut Frame<'_>, area: Rect, app: &ChatApp) {
     };
 
     let mut left_spans = vec![
-        Span::styled(
-            format!(" {} ", mode_label),
-            Style::default()
-                .bg(mode_color)
-                .fg(theme.background)
-                .add_modifier(Modifier::BOLD),
-        ),
+        Span::styled(format!(" {} ", mode_label), mode_badge_style),
         Span::styled(
             " │ ",
             Style::default()
@@ -2868,6 +2875,7 @@ fn render_help(frame: &mut Frame<'_>, app: &ChatApp) {
             Line::from("  Tab           → autocomplete suggestion"),
             Line::from("  ↑/↓           → navigate suggestions"),
             Line::from("  Backspace     → delete character"),
+            Line::from("  Ctrl+P        → open command palette"),
             Line::from(""),
             Line::from(vec![Span::styled(
                 "GENERAL",
@@ -2878,6 +2886,7 @@ fn render_help(frame: &mut Frame<'_>, app: &ChatApp) {
             Line::from("  :h, :help          → show this help"),
             Line::from("  :q, :quit          → quit application"),
             Line::from("  :reload          → reload configuration and themes"),
+            Line::from("  :layout save/load  → persist or restore pane layout"),
             Line::from(""),
             Line::from(vec![Span::styled(
                 "CONVERSATION",
@@ -2909,6 +2918,16 @@ fn render_help(frame: &mut Frame<'_>, app: &ChatApp) {
             Line::from("  :load, :o          → browse and load saved sessions"),
             Line::from("  :sessions, :ls     → browse saved sessions"),
             Line::from(""),
+            Line::from(vec![Span::styled(
+                "AGENT",
+                Style::default()
+                    .add_modifier(Modifier::BOLD)
+                    .fg(theme.user_message_role),
+            )]),
+            Line::from("  :agent start       → arm the agent for the next request"),
+            Line::from("  :agent stop        → stop or disarm the agent"),
+            Line::from("  :agent status      → show current agent state"),
+            Line::from(""),
             Line::from(vec![Span::styled(
                 "CODE VIEW",
                 Style::default()
@@ -3361,57 +3380,181 @@ fn render_theme_browser(frame: &mut Frame<'_>, app: &ChatApp) {
 fn render_command_suggestions(frame: &mut Frame<'_>, app: &ChatApp) {
     let theme = app.theme();
     let suggestions = app.command_suggestions();
+    let buffer = app.command_buffer();
+    let area = frame.area();
 
-    // Only show suggestions if there are any
-    if suggestions.is_empty() {
+    if area.width == 0 || area.height == 0 {
         return;
     }
 
-    // Create a small popup near the status bar (bottom of screen)
-    let frame_height = frame.area().height;
-    let suggestion_count = suggestions.len().min(8); // Show max 8 suggestions
-    let popup_height = (suggestion_count as u16) + 2; // +2 for borders
+    let visible_count = suggestions.len().clamp(1, 8) as u16;
+    let mut height = visible_count.saturating_mul(2).saturating_add(6);
+    height = height.clamp(6, area.height);
 
-    // Position the popup above the status bar
-    let popup_area = Rect {
-        x: 1,
-        y: frame_height.saturating_sub(popup_height + 3), // 3 for status bar height
-        width: 40.min(frame.area().width - 2),
-        height: popup_height,
-    };
+    let mut width = area.width.saturating_sub(10);
+    if width < 50 {
+        width = area.width.saturating_sub(4);
+    }
+    if width == 0 {
+        width = area.width;
+    }
+    let width = width.min(area.width);
+
+    let x = area.x + (area.width.saturating_sub(width)) / 2;
+    let y = area.y + (area.height.saturating_sub(height)) / 3;
+    let popup_area = Rect::new(x, y, width, height);
 
     frame.render_widget(Clear, popup_area);
 
-    let items: Vec<ListItem> = suggestions
-        .iter()
-        .enumerate()
-        .map(|(idx, cmd)| {
-            let is_selected = idx == app.selected_suggestion();
-            let style = if is_selected {
-                Style::default()
-                    .fg(theme.selection_fg)
-                    .bg(theme.selection_bg)
-                    .add_modifier(Modifier::BOLD)
-            } else {
-                Style::default().fg(theme.text)
-            };
+    let header = Line::from(vec![
+        Span::styled(
+            " Command Palette ",
+            Style::default().fg(theme.info).add_modifier(Modifier::BOLD),
+        ),
+        Span::styled(
+            "Ctrl+P",
+            Style::default()
+                .fg(theme.placeholder)
+                .add_modifier(Modifier::DIM),
+        ),
+    ]);
 
-            ListItem::new(Span::styled(cmd.to_string(), style))
-        })
-        .collect();
+    let block = Block::default()
+        .title(header)
+        .borders(Borders::ALL)
+        .border_style(Style::default().fg(theme.info))
+        .style(Style::default().bg(theme.background).fg(theme.text));
 
-    let list = List::new(items).block(
-        Block::default()
-            .title(Span::styled(
-                " Commands (Tab to complete) ",
-                Style::default().fg(theme.info).add_modifier(Modifier::BOLD),
-            ))
-            .borders(Borders::ALL)
-            .border_style(Style::default().fg(theme.info))
-            .style(Style::default().bg(theme.background).fg(theme.text)),
-    );
+    let inner = block.inner(popup_area);
+    frame.render_widget(block, popup_area);
 
-    frame.render_widget(list, popup_area);
+    if inner.width == 0 || inner.height == 0 {
+        return;
+    }
+
+    let layout = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([
+            Constraint::Length(3),
+            Constraint::Min(4),
+            Constraint::Length(2),
+        ])
+        .split(inner);
+
+    let input = Paragraph::new(Line::from(vec![
+        Span::styled(
+            ":",
+            Style::default()
+                .fg(theme.placeholder)
+                .add_modifier(Modifier::BOLD),
+        ),
+        Span::raw(buffer),
+    ]))
+    .style(Style::default().bg(theme.background).fg(theme.text));
+    frame.render_widget(input, layout[0]);
+
+    let selected_index = if suggestions.is_empty() {
+        None
+    } else {
+        Some(
+            app.selected_suggestion()
+                .min(suggestions.len().saturating_sub(1)),
+        )
+    };
+
+    if suggestions.is_empty() {
+        let placeholder = Paragraph::new(Line::from(Span::styled(
+            "No matches — keep typing",
+            Style::default()
+                .fg(theme.placeholder)
+                .add_modifier(Modifier::ITALIC),
+        )))
+        .alignment(Alignment::Center)
+        .style(Style::default().bg(theme.background).fg(theme.placeholder));
+        frame.render_widget(placeholder, layout[1]);
+    } else {
+        let highlight = Style::default()
+            .bg(theme.selection_bg)
+            .fg(theme.selection_fg);
+
+        let mut items: Vec<ListItem> = Vec::new();
+        let mut previous_group: Option<PaletteGroup> = None;
+
+        for (idx, suggestion) in suggestions.iter().enumerate() {
+            let mut lines: Vec<Line> = Vec::new();
+            if previous_group != Some(suggestion.group) {
+                lines.push(Line::from(Span::styled(
+                    palette_group_label(suggestion.group),
+                    Style::default()
+                        .fg(theme.placeholder)
+                        .add_modifier(Modifier::BOLD),
+                )));
+                previous_group = Some(suggestion.group);
+            }
+
+            let label_line = Line::from(vec![
+                Span::styled(
+                    if Some(idx) == selected_index {
+                        "›"
+                    } else {
+                        " "
+                    },
+                    Style::default().fg(theme.placeholder),
+                ),
+                Span::raw(" "),
+                Span::styled(
+                    suggestion.label.clone(),
+                    Style::default().add_modifier(Modifier::BOLD),
+                ),
+            ]);
+            lines.push(label_line);
+
+            if let Some(detail) = &suggestion.detail {
+                lines.push(Line::from(Span::styled(
+                    format!("    {}", detail),
+                    Style::default()
+                        .fg(theme.placeholder)
+                        .add_modifier(Modifier::DIM),
+                )));
+            }
+
+            let item = ListItem::new(lines);
+            items.push(item);
+        }
+
+        let mut list_state = ListState::default();
+        list_state.select(selected_index);
+
+        let list = List::new(items)
+            .highlight_style(highlight)
+            .style(Style::default().bg(theme.background).fg(theme.text));
+
+        frame.render_stateful_widget(list, layout[1], &mut list_state);
+    }
+
+    let instructions = "Enter: run · Tab: autocomplete · Esc: cancel";
+    let detail_text = selected_index
+        .and_then(|idx| suggestions.get(idx))
+        .and_then(|item| item.detail.as_deref())
+        .map(|detail| format!("{detail}  —  {instructions}"))
+        .unwrap_or_else(|| instructions.to_string());
+
+    let footer = Paragraph::new(Line::from(Span::styled(
+        detail_text,
+        Style::default().fg(theme.placeholder),
+    )))
+    .alignment(Alignment::Center)
+    .style(Style::default().bg(theme.background).fg(theme.placeholder));
+    frame.render_widget(footer, layout[2]);
+}
+
+fn palette_group_label(group: PaletteGroup) -> &'static str {
+    match group {
+        PaletteGroup::History => "History",
+        PaletteGroup::Command => "Commands",
+        PaletteGroup::Model => "Models",
+        PaletteGroup::Provider => "Providers",
+    }
 }
 
 fn render_repo_search(frame: &mut Frame<'_>, app: &mut ChatApp) {