feat(diagnostics): correlate movement acknowledgements with painted views

test/web/test_player_app.js

@@ -43,6 +43,25 @@ test("joystick repeat interval is monotonic and remains slower than cooldown", (
   assert.ok(player.JOYSTICK_FAST_REPEAT_MS > 150);
 });
 
+test("latency correlation is bounded and only completes matching authoritative views", () => {
+  let clock = 0;
+  const tracker = new player.LatencyTracker(() => clock);
+  tracker.sent("move-1");
+  clock = 12;
+  tracker.acknowledged("move-1", 41);
+  clock = 16;
+  tracker.painted(40);
+  assert.equal(tracker.snapshot().length, 0);
+  clock = 24;
+  tracker.painted(41);
+  assert.deepEqual(tracker.snapshot(), [{requestId: "move-1", commandToAckMs: 12,
+    commandToPaintMs: 24, ackToPaintMs: 12}]);
+  for (let index = 0; index < player.LATENCY_SAMPLE_LIMIT + 4; index++) {
+    tracker.sent(`move-${index + 2}`);
+  }
+  assert.ok(tracker.pending.size <= player.LATENCY_SAMPLE_LIMIT);
+});
+
 test("player map cells enlarge small projections without exceeding a readable bound", () => {
   const sevenBySeven = player.playerCellSize(396, 730, 7, 7);
   const fourByFour = player.playerCellSize(396, 730, 4, 4);