Ignore stale Dosh snapshots

src/bin/dosh-client.rs

@@ -725,6 +725,9 @@ struct FrameBuffer {
 impl FrameBuffer {
     fn accept(&mut self, frame: Frame, last_rendered_seq: &mut u64) -> Vec<Frame> {
         if frame.snapshot {
+            if frame.output_seq < *last_rendered_seq {
+                return Vec::new();
+            }
             self.pending.clear();
             *last_rendered_seq = frame.output_seq;
             return vec![frame];
@@ -939,4 +942,13 @@ mod tests {
         assert_eq!(last, 20);
         assert!(buffer.accept(test_frame(12, false), &mut last).is_empty());
     }
+
+    #[test]
+    fn frame_buffer_ignores_stale_snapshot() {
+        let mut buffer = FrameBuffer::default();
+        let mut last = 20;
+
+        assert!(buffer.accept(test_frame(19, true), &mut last).is_empty());
+        assert_eq!(last, 20);
+    }
 }