Stuck managed repeat after output-backend recovery

[malpern]

Summary

After a transient DriverKit output-backend failure (asio.system:55), managed repeat continues firing indefinitely for keys that were physically held at the moment of disconnection. The key repeats at ~30ms intervals and cannot be stopped by pressing other keys — requires killing kanata.

Root Cause

The recovery path in kanata/macos.rs:288-293 clears PRESSED_KEYS (input thread tracking) but does not clear the keyberon layout state. The processing thread's tick_managed_repeat() checks self.cur_keys (populated from self.layout.keycodes()), which still contains the stuck key because no Release event was ever delivered — the physical key-up happened while input was ungrabbed and went directly to macOS.

After re-grab, no release event arrives (key is no longer physically held), so the keyberon layout permanently retains the key as "pressed" and managed repeat loops forever.

Observed Behavior (2026-05-31)

14:29:05.392  — e key pressed during normal typing
14:29:05.424  — error_occurred asio.system:55
14:29:05.472  — "output backend unavailable during write — releasing input devices"
14:29:05.891  — managed repeat E starts firing (~30ms interval)
14:29:06.587  — output backend recovers, input re-grabbed
14:29:06.611+ — managed repeat E continues for 21+ seconds (928 total repeats)
              — user pressed Esc multiple times, no effect
              — had to emergency-stop kanata

Proposed Fix

After recovery, before re-grabbing input, also clear keyberon layout state and managed repeat timers — matching what the latency-soft-reset path already does (mod.rs:2612-2616):

// In macos.rs recovery path, after line 293:
{
    let mut kanata = kanata.lock();
    kanata.kbd_out.release_tracked_output_keys("output-backend-recovery");
    // ADD: clear keyberon layout state so no keys appear "stuck"
    release_normalkey_states(kanata.layout.bm());
    // ADD: clear managed repeat timers
    if let Some(ref mut mrs) = kanata.managed_repeat_state {
        mrs.timers.clear();
    }
}
PRESSED_KEYS.lock().clear();

Relevant Code

• src/kanata/macos.rs:247-293 — recovery path (missing layout clear)
• src/kanata/managed_repeat.rs:59-143 — tick_managed_repeat (checks cur_keys from layout)
• src/kanata/mod.rs:2612-2616 — latency-soft-reset (has the correct pattern)