fix: do not navigate out to the right

viewport/viewport.go

@@ -331,9 +331,23 @@ func (m *Model) MoveLeft() {
 
 // MoveRight moves all lines to set runes right.
 func (m *Model) MoveRight() {
+	// prevents over scrolling to the right
+	if m.indent >= m.longestLineWidth()-m.Width {
+		return
+	}
 	m.indent += m.horizontalStep
 }
 
+func (m Model) longestLineWidth() int {
+	w := 0
+	for _, l := range m.lines {
+		if ww := ansi.StringWidth(l); ww > w {
+			w = ww
+		}
+	}
+	return w
+}
+
 // Resets lines indent to zero.
 func (m *Model) ResetIndent() {
 	m.indent = 0