WASM: tick immediately when idle, batch when ack pending

cmd/mosh-wasm/main.go

@@ -85,14 +85,19 @@ func newSession(url, key string) (*session, error) {
 func (s *session) jsObject() js.Value {
 	obj := js.Global().Get("Object").New()
 
-	// Keystrokes are queued via Send(). The JS interval flushes them.
-	// Do NOT tick from send — the WebTransport ack round-trip is ~50ms,
-	// and ticking per-keystroke creates duplicate sequence numbers.
+	// Tick immediately when idle (no unacked states). When busy (ack
+	// pending), queue keystrokes and let the interval flush them.
+	// This gives instant feel for the first key while preventing
+	// cumulative state duplication during rapid typing.
 	obj.Set("send", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
 		if len(args) < 1 {
 			return nil
 		}
 		s.client.Send([]byte(args[0].String()))
+		t := s.client.Transport()
+		if t.AckedByRemote() >= t.SentNum() {
+			s.client.Tick()
+		}
 		return nil
 	}))
 
@@ -101,6 +106,10 @@ func (s *session) jsObject() js.Value {
 			return nil
 		}
 		s.client.Resize(uint16(args[0].Int()), uint16(args[1].Int()))
+		t := s.client.Transport()
+		if t.AckedByRemote() >= t.SentNum() {
+			s.client.Tick()
+		}
 		return nil
 	}))