input: total keyboard routing + per-terminal discipline (ADR 0006 ph1)

wm: FOCUSED is now a plain window id — window 0 (home terminal) is an
ordinary focusable window in the z-order.  The CONSOLE sentinel
(usize::MAX) and the focused()==0 special cases are gone; focus_console()
is an alias for focus(0).  Desktop clicks focus window 0.  The WM input
pump routes every key unconditionally: IRQ ring -> pump -> focused
window's owner; nothing polls the scancode rings directly any more.

tty: read_line() reads from the calling task's message queue (the old
global-ring read_line and the duplicate read_line_from_queue are merged);
raw mode (read_byte/try_read_byte) consumes the same queue;
interrupt_pressed drains the queue instead of the ring.

shell: task 0 owns home terminal window 0 and blocks on its queue like a
windowed shell; cat/hexdump stdin paths pass the home terminal handle.

sched: watchdog comments updated (shell parks on recv_blocking).

Verified in QEMU: F1 spawns terminals, F2 cycles focus home->term1->
term2, keystrokes land only in the focused window, ^C cancels a line,
edit runs raw over the queue and exits to a working prompt; test-disk
regression PASS.

1 files changed, 7 insertions, 6 deletions

diff --git a/rsnix/src/sched.rs b/rsnix/src/sched.rs
index 39ecb65..0c4938e 100644
--- a/rsnix/src/sched.rs
+++ b/rsnix/src/sched.rs
@@ -201,7 +201,7 @@ const WATCHDOG_SPIN_TICKS: u32 = 1500;
 const WATCHDOG_BOOT_SPIN_TICKS: u32 = 750;
 
 /// True once the shell REPL is live (set by main.rs before shell::run()).
-/// The shell legitimately parks in poll_key with a fixed frame when it is;
+/// The shell legitimately blocks on its message queue once live;
 /// before that, task 0 running boot code must not sit in a fixed frame.
 static SHELL_RUNNING: AtomicBool = AtomicBool::new(false);
 
@@ -264,16 +264,17 @@ pub fn on_tick(cur: usize) -> usize {
         TASKS[CURRENT].ticks += 1;
         // Spin detection: a task whose interrupted frame never moves
         // (identical RSP on every tick) is stuck in a hot loop — no yield,
-        // no sleep, no block.  The shell (id 0) legitimately parks in
-        // poll_key with a fixed frame, and idle (id 1) hlt's; both exempt.
+        // no sleep, no block.  The shell (id 0) legitimately blocks on
+        // recv_blocking with a fixed frame, and idle (id 1) hlt's; both
+        // exempt.
         let id = CURRENT;
         let w = &mut SPIN_WATCH[id];
         if w.last_rsp == cur {
             w.same += 1;
             // Background tasks (id >= 2): spinning is never legitimate.
-            // Task 0 (shell): exempt once the REPL is live (poll_key parks
-            // with a fixed frame); during the boot phase a fixed frame
-            // means usb/ehci init is wedged on real hardware.
+            // Task 0 (shell): exempt once the REPL is live (recv_blocking
+            // parks with a fixed frame); during the boot phase a fixed
+            // frame means usb/ehci init is wedged on real hardware.
             let threshold = if id == SHELL_TID && !SHELL_RUNNING.load(Ordering::Relaxed) {
                 WATCHDOG_BOOT_SPIN_TICKS
             } else if id >= 2 {