wm: 1px focus-colored border + flush full window on focus change

- draw_window_border(): 1px border around every window except the root.
  Blue (TITLE_BG_FOCUS) when focused, grey (TITLE_BG) when not.
- focus() / focus_console(): composite the full window area + border pad
  on both the old and new focused windows (was title-bar-only before).
- flush(): include border pad in the damage rectangle.
- move_window(): redraw border area at old and new positions.
- Remove redundant term.flush() from tty Focus handler (focus() covers it).

2 files changed, 57 insertions, 11 deletions

diff --git a/rsnix/src/tty.rs b/rsnix/src/tty.rs
index ad33cb3..c44dca8 100644
--- a/rsnix/src/tty.rs
+++ b/rsnix/src/tty.rs
@@ -201,9 +201,6 @@ pub fn read_line_from_queue(term: &mut crate::vt::Terminal) -> Option<LineInput>
             crate::sched::TaskMsg::Focus(gained) => {
                 if gained {
                     crate::vt::set_active(term as *mut crate::vt::Terminal);
-                    // Re-composite the full window so content is visible
-                    // immediately (focus() only redraws the title bar).
-                    term.flush();
                 } else {
                     crate::vt::set_active(core::ptr::null_mut());
                 }
diff --git a/rsnix/src/wm.rs b/rsnix/src/wm.rs
index 71c310f..e5ae6ba 100644
--- a/rsnix/src/wm.rs
+++ b/rsnix/src/wm.rs
@@ -229,7 +229,11 @@ pub fn flush(id: usize) {
         return;
     };
     let outer_h = win.h + if win.chrome { TITLE_BAR_H } else { 0 };
-    composite_rect(win.x, win.y, win.w, outer_h);
+    let pad = if id != 0 { 1 } else { 0 };
+    composite_rect(
+        win.x.saturating_sub(pad), win.y.saturating_sub(pad),
+        win.w + 2 * pad, outer_h + 2 * pad,
+    );
 }
 
 pub fn destroy(id: usize) {
@@ -323,12 +327,22 @@ pub fn focus(id: usize) {
         && let Some(pw) = get(p)
     {
         let _ = crate::sched::send(pw.owner, TaskMsg::Focus(false));
-        composite_rect(pw.x, pw.y, pw.w, TITLE_BAR_H);
+        // Redraw old window: full content + border area.
+        let oh = pw.h + if pw.chrome { TITLE_BAR_H } else { 0 };
+        let pad = if p != 0 { 1 } else { 0 };
+        composite_rect(
+            pw.x.saturating_sub(pad), pw.y.saturating_sub(pad),
+            pw.w + 2 * pad, oh + 2 * pad,
+        );
     }
     let _ = crate::sched::send(win.owner, TaskMsg::Focus(true));
-    if win.chrome {
-        composite_rect(win.x, win.y, win.w, TITLE_BAR_H);
-    }
+    // Redraw new window: full content + border area.
+    let oh = win.h + if win.chrome { TITLE_BAR_H } else { 0 };
+    let pad = if id != 0 { 1 } else { 0 };
+    composite_rect(
+        win.x.saturating_sub(pad), win.y.saturating_sub(pad),
+        win.w + 2 * pad, oh + 2 * pad,
+    );
 }
 
 pub fn focus_console() {
@@ -338,7 +352,12 @@ pub fn focus_console() {
         && let Some(pw) = get(p)
     {
         let _ = crate::sched::send(pw.owner, TaskMsg::Focus(false));
-        composite_rect(pw.x, pw.y, pw.w, TITLE_BAR_H);
+        let oh = pw.h + if pw.chrome { TITLE_BAR_H } else { 0 };
+        let pad = if p != 0 { 1 } else { 0 };
+        composite_rect(
+            pw.x.saturating_sub(pad), pw.y.saturating_sub(pad),
+            pw.w + 2 * pad, oh + 2 * pad,
+        );
     }
 }
 
@@ -585,8 +604,9 @@ fn move_window(id: usize, nx: usize, ny: usize) {
         WINDOWS[id].x = nx;
         WINDOWS[id].y = ny;
     }
-    composite_rect(ox, oy, w.w, w.h + TITLE_BAR_H);
-    composite_rect(nx, ny, w.w, w.h + TITLE_BAR_H);
+    let pad = 1;
+    composite_rect(ox - pad, oy - pad, w.w + 2 * pad, w.h + TITLE_BAR_H + 2 * pad);
+    composite_rect(nx - pad, ny - pad, w.w + 2 * pad, w.h + TITLE_BAR_H + 2 * pad);
 }
 
 pub fn owner(id: usize) -> Option<usize> {
@@ -645,11 +665,40 @@ fn composite_rect(x: usize, y: usize, w: usize, h: usize) {
 }
 
 /// Blit the portion of a window that intersects `(rx, ry, rw, rh)`.
+/// 1px border drawn around every window except the root (id 0).
+/// Blue when focused, grey when not.
+fn draw_window_border(id: usize, rx: usize, ry: usize, rw: usize, rh: usize) {
+    if id == 0 { return; }
+    let win = unsafe { WINDOWS[id] };
+    if !win.used || win.state != WinState::Visible { return; }
+    let outer_h = win.h + if win.chrome { TITLE_BAR_H } else { 0 };
+    let bg = if focused() == Some(id) { TITLE_BG_FOCUS } else { TITLE_BG };
+    let bc = gop::rgb(bg.0, bg.1, bg.2);
+    // Border sits 1px outside the window's outer rect.
+    let bx = win.x.saturating_sub(1);
+    let by = win.y.saturating_sub(1);
+    let bw = win.w + 2;
+    let bh = outer_h + 2;
+    let ix = bx.max(rx);
+    let iy = by.max(ry);
+    let ix2 = (bx + bw).min(rx + rw);
+    let iy2 = (by + bh).min(ry + rh);
+    if ix >= ix2 || iy >= iy2 { return; }
+    // Four edges.
+    gop::shadow_fill_rect(ix, iy, ix2 - ix, 1, bc);               // top
+    gop::shadow_fill_rect(ix, iy2 - 1, ix2 - ix, 1, bc);          // bottom
+    gop::shadow_fill_rect(ix, iy + 1, 1, iy2 - iy - 2, bc);       // left
+    gop::shadow_fill_rect(ix2 - 1, iy + 1, 1, iy2 - iy - 2, bc);  // right
+}
+
+/// Blit the portion of a window that intersects `(rx, ry, rw, rh)`.
 fn draw_window_intersect(id: usize, rx: usize, ry: usize, rw: usize, rh: usize) {
     let win = unsafe { WINDOWS[id] };
     if !win.used || win.state != WinState::Visible || win.buf.is_null() {
         return;
     }
+    // Draw border first (under the window content).
+    draw_window_border(id, rx, ry, rw, rh);
     let outer_h = win.h + if win.chrome { TITLE_BAR_H } else { 0 };
     let wx = win.x;
     let wy = win.y;