klog/tty/pager: no more truncated lines — full lines flow, terminal wraps

- klog: MAX_LINE 128 -> 512 (lens widened u8 -> u16) — long serial_println
  lines (panics, boot messages) are no longer cut at 128 bytes; they
  print in full and the terminal wraps them at the screen edge
- tty: LINE_BUF_SIZE 256 -> 1024 — typed command lines longer than 256
  chars were silently dropped at the buffer limit; now they echo and
  submit in full (the terminal already wraps the echo mid-typing)
- pager (-p): screenfuls now count wrapped rows, not lines — a line
  wider than the terminal occupies ceil(len/cols) rows, so the pause
  lands at a real screen boundary instead of overflowing it

1 files changed, 10 insertions, 2 deletions

diff --git a/shell/src/lib.rs b/shell/src/lib.rs
index 97fa6c2..617e5a4 100644
--- a/shell/src/lib.rs
+++ b/shell/src/lib.rs
@@ -365,6 +365,7 @@ enum StageState {
     Pause {
         shown: usize,
         screen: usize,
+        cols: usize,
     },
 }
 
@@ -433,6 +434,10 @@ impl Pipeline {
                 Filter::Pause => StageState::Pause {
                     shown: 0,
                     screen: rsnix::vt::size().0.saturating_sub(1).max(1),
+                    // Rows a screenful of *wrapped* output occupies: a
+                    // line wider than the terminal takes more than one
+                    // row, so the pager counts rows, not lines.
+                    cols: rsnix::vt::size().1.max(1),
                 },
             };
             stages.push((f.clone(), st));
@@ -510,14 +515,17 @@ impl Pipeline {
                     }
                 }
                 Filter::Pause => {
-                    let StageState::Pause { shown, screen } = st else {
+                    let StageState::Pause { shown, screen, cols } = st else {
                         unreachable!("stage state does not match filter")
                     };
                     for l in cur.drain(..) {
+                        // Rows this line occupies after terminal wrapping
+                        // (at least 1; an empty line is one row).
+                        let rows = l.len().div_ceil(*cols);
                         if *shown > 0 && *shown % *screen == 0 && !pager_wait() {
                             return false;
                         }
-                        *shown += 1;
+                        *shown += rows;
                         out.push(l);
                     }
                 }