tlc: start_line plumbing + buttonbar in editor/viewer

Editor gains goto_line(), viewer gains jump_to_line() + open_file(start_line). Both editor and viewer now render the F-key buttonbar at the bottom (1Help 2Save... / 1Help 2Wrap...).

local/recipes/tui/tlc/source/src/editor/mod.rs

@@ -299,7 +299,18 @@ bracket_flash: None,
          }
      }
 
-     /// Borrow the underlying buffer.
+    /// Jump cursor to a 1-based line number and scroll the
+    /// viewport so the line is visible.
+    pub fn goto_line(&mut self, line: u32) {
+        if line >= 1 {
+            if let Ok(off) = crate::editor::goto::line_to_offset(&self.buffer, line) {
+                self.buffer.set_cursor(off);
+                self.cursor.set_position(self.buffer.cursor(), &self.buffer);
+            }
+        }
+    }
+
+    /// Borrow the underlying buffer.
     #[must_use]
     pub fn buffer(&self) -> &Buffer {
         &self.buffer

local/recipes/tui/tlc/source/src/editor/render.rs

@@ -609,8 +609,24 @@ impl Editor {
             }
         }
 
-        // Status line (last line of the editor area).
-        if area.height >= 2 {
+        // Status line + buttonbar.
+        if area.height >= 3 {
+            let status_y = area.y + area.height - 2;
+            let status = Paragraph::new(Line::from(Span::styled(
+                self.status_string(),
+                Style::default().fg(linestate_fg).bg(linestate_bg),
+            )));
+            frame.render_widget(status, Rect::new(area.x, status_y, area.width, 1));
+
+            let bar_y = area.y + area.height - 1;
+            let bar_area = Rect::new(area.x, bar_y, area.width, 1);
+            let labels: [(&str, &str); 10] = [
+                ("1", "Help"), ("2", "Save"), ("3", "Mark"), ("4", "Repl"),
+                ("5", "Copy"), ("6", "Move"), ("7", "Search"), ("8", "Delete"),
+                ("9", "PullDn"), ("10", "Quit"),
+            ];
+            crate::widget::buttonbar::render_buttonbar(frame, bar_area, theme, &labels);
+        } else if area.height >= 2 {
             let status_y = area.y + area.height - 1;
             let status = Paragraph::new(Line::from(Span::styled(
                 self.status_string(),

local/recipes/tui/tlc/source/src/viewer/mod.rs

@@ -255,6 +255,14 @@ impl Viewer {
         }
     }
 
+    /// Jump to a 1-based line number.
+    pub fn jump_to_line(&mut self, line: u64) {
+        if line >= 1 {
+            self.top = line.saturating_sub(1);
+            self.sync_cursor_to_top();
+        }
+    }
+
     fn current_line(&self) -> u64 {
         self.goto
             .resolve(self.cursor, goto::GotoKind::Offset)
@@ -406,17 +414,26 @@ impl Viewer {
         let selected_fg = viewer_selected.map(|p| p.fg).unwrap_or(theme.cursor_fg);
         let selected_bg = viewer_selected.map(|p| p.bg).unwrap_or(theme.cursor_bg);
 
-        let constraints = if area.height >= 3 {
+        let constraints = if area.height >= 4 {
             [
                 Constraint::Length(1),
                 Constraint::Min(1),
                 Constraint::Length(1),
+                Constraint::Length(1),
+            ]
+        } else if area.height >= 3 {
+            [
+                Constraint::Length(1),
+                Constraint::Min(1),
+                Constraint::Length(1),
+                Constraint::Length(0),
             ]
         } else {
             [
                 Constraint::Length(0),
                 Constraint::Min(1),
                 Constraint::Length(0),
+                Constraint::Length(0),
             ]
         };
         let chunks = Layout::default()
@@ -465,6 +482,15 @@ impl Viewer {
             );
         }
 
+        if chunks[3].height > 0 {
+            let labels: [(&str, &str); 10] = [
+                ("1", "Help"), ("2", "Wrap"), ("3", ""), ("4", "Hex"),
+                ("5", ""), ("6", ""), ("7", "Search"), ("8", "Magic"),
+                ("9", ""), ("10", "Quit"),
+            ];
+            crate::widget::buttonbar::render_buttonbar(frame, chunks[3], theme, &labels);
+        }
+
         // Prompt overlay: rendered on the top row so it doesn't
         // collide with the footer area below. The body's border
         // block still owns the central chunk.
@@ -740,13 +766,16 @@ impl Viewer {
 }
 
 /// Backwards-compat shim: `open_file` was the Phase 0 stub.
-pub fn open_file(file: &str) -> Result<()> {
+pub fn open_file(file: &str, start_line: Option<u64>) -> Result<()> {
     use crate::terminal::event::translate_key;
     use crate::terminal::color::DEFAULT_THEME;
     use termion::event::Event as TermEvent;
     use termion::input::TermReadEventsAndRaw;
 
     let mut v = Viewer::open(file)?;
+    if let Some(line) = start_line {
+        v.jump_to_line(line);
+    }
 
     let mut tui = crate::terminal::Tui::new()?;
     let stdin = std::io::stdin();