docs: explain backpressure rationale for PTY event channel in

src/main.rs

@@ -3622,6 +3622,10 @@ impl Application for App {
                 stream::channel(
                     100,
                     |mut output: iced::futures::channel::mpsc::Sender<Message>| async move {
+                        // Bounded: when the GUI can't drain fast enough, alacritty's PTY reader
+                        // blocks on send → kernel pipe fills → producing program is throttled by
+                        // the OS. Capacity 1024 caps the queue depth; per-event memory depends on
+                        // payload (Wakeup is ~100 B; Title/PtyWrite carry owned Strings).
                         let (event_tx, mut event_rx) = mpsc::channel(1024);
                         output.send(Message::TermEventTx(event_tx)).await.unwrap();
 

src/terminal.rs

@@ -104,7 +104,10 @@ pub struct EventProxy(
 
 impl EventListener for EventProxy {
     fn send_event(&self, event: Event) {
-        //TODO: handle error
+        // Bounded channel; blocking_send propagates backpressure to alacritty's
+        // PTY reader instead of letting events accumulate. Called from alacritty's
+        // std::thread PTY reader (not a tokio worker), so blocking is safe and
+        // blocking_send won't panic.
         let _ = self.2.blocking_send((self.0, self.1, event));
     }
 }