WASM: batch keystrokes per animation frame to prevent cumulative state duplication

cmd/mosh-wasm/main.go

@@ -85,13 +85,28 @@ func newSession(url, key string) (*session, error) {
 func (s *session) jsObject() js.Value {
 	obj := js.Global().Get("Object").New()
 
+	// Batch keystrokes: queue actions, flush once per animation frame.
+	// This prevents cumulative state from creating new sequence numbers
+	// for every keystroke, which causes duplicates on high-latency paths.
+	var pendingFlush bool
+	flushFn := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		pendingFlush = false
+		s.client.Tick()
+		return nil
+	})
+	scheduleFlush := func() {
+		if !pendingFlush {
+			pendingFlush = true
+			js.Global().Call("requestAnimationFrame", flushFn)
+		}
+	}
+
 	obj.Set("send", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
 		if len(args) < 1 {
 			return nil
 		}
-		data := args[0].String()
-		s.client.Send([]byte(data))
-		s.client.Tick()
+		s.client.Send([]byte(args[0].String()))
+		scheduleFlush()
 		return nil
 	}))
 
@@ -99,10 +114,8 @@ func (s *session) jsObject() js.Value {
 		if len(args) < 2 {
 			return nil
 		}
-		cols := args[0].Int()
-		rows := args[1].Int()
-		s.client.Resize(uint16(cols), uint16(rows))
-		s.client.Tick()
+		s.client.Resize(uint16(args[0].Int()), uint16(args[1].Int()))
+		scheduleFlush()
 		return nil
 	}))