fix(tui): keep focus sweep visible on borders

crates/cli/src/ui.rs

@@ -15124,11 +15124,12 @@ fn pane_border_style(theme: &Theme, focused: bool) -> Style {
     }
 }
 
-/// Paint the moving bright band for a newly focused pane after that pane and
-/// its title chrome are fully composited. The overlay temporarily draws all
-/// four edges even when the steady pane chrome hides some of them. `(x + y) /
-/// 2` supplies the phase, so the band intersects the top/left edges first and
-/// the bottom/right edges last: a diagonal top-left → bottom-right sweep.
+/// Paint the moving band for a newly focused pane after that pane and its
+/// title chrome are fully composited. The overlay toggles each border glyph:
+/// an already-visible rule is erased while a hidden rule is drawn brightly.
+/// `(x + y) / 2` supplies the phase, so the band intersects the top/left edges
+/// first and the bottom/right edges last: a diagonal top-left → bottom-right
+/// sweep.
 fn render_focus_border_sweep(f: &mut Frame, app: &mut App, now: Instant) {
     let target = app.focused_border_target();
     let rect = match target {
@@ -15206,12 +15207,21 @@ fn paint_focus_border_sweep(f: &mut Frame, rect: Rect, progress: f32, highlight:
                     (_, _, true, _) | (_, _, _, true) => "─",
                     _ => "│",
                 };
-                cell.set_symbol(symbol);
-                cell.set_style(highlight);
-                // `Cell::set_style` patches the existing cell and therefore
-                // cannot clear a modifier inherited from the pane beneath it.
-                // The focus cue is the glyph foreground, never reverse video.
-                cell.modifier.remove(Modifier::DIM | Modifier::REVERSED);
+                if cell.symbol() == symbol {
+                    // Compose like an XOR mask: a bright foreground repaint is
+                    // easy to lose on the pane's always-visible top rule, a
+                    // rolled-down Playbook frame, or a `/border` full frame.
+                    // Removing the glyph makes the same moving band legible on
+                    // all three without consulting pane-specific state.
+                    cell.set_symbol(" ");
+                } else {
+                    cell.set_symbol(symbol);
+                    cell.set_style(highlight);
+                    // `Cell::set_style` patches the existing cell and therefore
+                    // cannot clear a modifier inherited from the pane beneath
+                    // it. The drawn cue is foreground-only, never reverse video.
+                    cell.modifier.remove(Modifier::DIM | Modifier::REVERSED);
+                }
             }
         }
     }
@@ -15244,15 +15254,21 @@ mod focus_border_paint_tests {
     }
 
     #[test]
-    fn sweep_draws_full_foreground_border_over_hidden_edges() {
+    fn sweep_erases_visible_top_rule_and_draws_hidden_side_edge() {
         let backend = TestBackend::new(12, 12);
         let mut terminal = ratatui::Terminal::new(backend).expect("terminal");
         terminal
             .draw(|f| {
-                f.buffer_mut()
-                    .cell_mut(Position { x: 5, y: 0 })
-                    .expect("top rule")
-                    .set_symbol("─");
+                let rect = Rect::new(0, 0, 11, 11);
+                f.render_widget(
+                    Block::default()
+                        .borders(Borders::ALL)
+                        .border_style(Style::default().fg(Color::Green)),
+                    rect,
+                );
+                f.render_widget(Clear, Rect::new(0, 1, 1, 10));
+                f.render_widget(Clear, Rect::new(10, 1, 1, 10));
+                f.render_widget(Clear, Rect::new(0, 10, 11, 1));
                 f.buffer_mut()
                     .cell_mut(Position { x: 0, y: 5 })
                     .expect("left edge")
@@ -15264,20 +15280,47 @@ mod focus_border_paint_tests {
                     );
                 paint_focus_border_sweep(
                     f,
-                    Rect::new(0, 0, 11, 11),
+                    rect,
                     0.25,
                     Style::default().fg(Color::Blue),
                 );
             })
             .expect("draw");
         let buffer = terminal.backend().buffer();
-        assert_eq!(buffer[(5, 0)].symbol(), "─");
-        assert_eq!(buffer[(5, 0)].fg, Color::Blue);
+        assert_eq!(buffer[(5, 0)].symbol(), " ");
         assert_eq!(buffer[(0, 5)].symbol(), "│");
         assert_eq!(buffer[(0, 5)].fg, Color::Blue);
         assert_eq!(buffer[(0, 5)].bg, Color::Yellow);
         assert!(!buffer[(0, 5)].modifier.contains(Modifier::REVERSED));
-        assert_eq!(buffer[(0, 0)].symbol(), " ");
+        assert_eq!(buffer[(0, 0)].symbol(), "┌");
+    }
+
+    #[test]
+    fn sweep_erases_visible_full_frame_like_playbook_or_border_mode() {
+        let backend = TestBackend::new(12, 12);
+        let mut terminal = ratatui::Terminal::new(backend).expect("terminal");
+        terminal
+            .draw(|f| {
+                let rect = Rect::new(0, 0, 11, 11);
+                f.render_widget(
+                    Block::default()
+                        .borders(Borders::ALL)
+                        .border_style(Style::default().fg(Color::Cyan)),
+                    rect,
+                );
+                paint_focus_border_sweep(
+                    f,
+                    rect,
+                    0.25,
+                    Style::default().fg(Color::Blue),
+                );
+            })
+            .expect("draw");
+        let buffer = terminal.backend().buffer();
+        assert_eq!(buffer[(5, 0)].symbol(), " ");
+        assert_eq!(buffer[(0, 5)].symbol(), " ");
+        assert_eq!(buffer[(10, 0)].symbol(), "┐");
+        assert_eq!(buffer[(0, 10)].symbol(), "└");
     }
 
     #[test]
@@ -15315,11 +15358,15 @@ mod focus_border_paint_tests {
         let mut terminal = ratatui::Terminal::new(backend).expect("terminal");
         terminal
             .draw(|f| {
-                f.buffer_mut().set_string(
-                    1,
-                    0,
-                    " rename me ",
-                    Style::default().fg(Color::Yellow),
+                f.render_widget(
+                    Block::default()
+                        .borders(Borders::ALL)
+                        .border_style(Style::default().fg(Color::Green))
+                        .title(Line::from(Span::styled(
+                            " rename me ",
+                            Style::default().fg(Color::Yellow),
+                        ))),
+                    Rect::new(0, 0, 21, 11),
                 );
                 paint_focus_border_sweep(
                     f,

specs/0203-tui-focus-border-sweep.md

@@ -11,7 +11,7 @@ When keyboard focus moves to a different TUI pane or focusable sidebar section,
 
 Focus identity includes the session-list rows, the lineage section, and each split window independently. Moving between sibling split windows therefore retriggers the animation even though both use the same general view-focus route. The initial pane at TUI startup does not animate.
 
-The sweep temporarily draws all four border edges, including their corners, even when the pane's steady chrome hides its side and bottom borders or exposes only a header rule. The highlight changes the border line's foreground color and weight; it does not fill or reverse the cells' backgrounds. Embedded titles and live title-edit text remain readable and are not replaced by the sweep. Once the sweep passes, the pane immediately returns to its configured steady border visibility.
+The sweep temporarily traces all four border edges, including their corners, even when the pane's steady chrome hides its side and bottom borders or exposes only a header rule. Where no border line is visible, the moving segment draws a bright line; where a steady pane or Playbook border is already visible, the moving segment erases that portion of the line for the frame. It does not fill or reverse the cells' backgrounds. Embedded titles and live title-edit text remain readable and are not replaced by the sweep. Once the sweep passes, the pane immediately returns to its configured steady border visibility.
 
 The effect must not change pane geometry, content layout, terminal size, or input routing. Edge-to-edge borderless zoom views do not animate.