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, 7 insertions, 3 deletions

diff --git a/rsnix/src/klog.rs b/rsnix/src/klog.rs
index 5da5094..2e1fc82 100644
--- a/rsnix/src/klog.rs
+++ b/rsnix/src/klog.rs
@@ -21,7 +21,11 @@ extern crate alloc;
 use alloc::string::String;
 
 pub const MAX_LINES: usize = 128;
-pub const MAX_LINE: usize = 128;
+/// Max bytes stored per line.  Wide enough that no real line truncates
+/// at any plausible terminal width (a 240-col 4K framebuffer row is
+/// still under this) — long lines flow in full and the terminal wraps
+/// them at the screen edge instead of cutting them off.
+pub const MAX_LINE: usize = 512;
 
 struct Ring {
     /// Sequence counter for the next line to be appended (total ever).
@@ -36,7 +40,7 @@ struct Ring {
     /// the timer is running (early-boot PIT reads are uninitialised).
     last_ms: u64,
     ms: [u64; MAX_LINES],
-    lens: [u8; MAX_LINES],
+    lens: [u16; MAX_LINES],
     bytes: [[u8; MAX_LINE]; MAX_LINES],
 }
 
@@ -74,7 +78,7 @@ pub fn append(line: &str, mut ms: u64) {
     }
     r.ms[r.next] = ms;
     r.bytes[r.next][..n].copy_from_slice(&b[..n]);
-    r.lens[r.next] = n as u8;
+    r.lens[r.next] = n as u16;
     r.next = (r.next + 1) % MAX_LINES;
     r.seq += 1;
 }