trying to avoid slam on startup

src/lerobot/policies/rtc/action_queue.py

@@ -236,11 +236,21 @@ class ActionQueue:
         if action_index_before_inference is not None:
             indexes_diff = max(0, self.last_index - action_index_before_inference)
             if indexes_diff != real_delay:
+                # The latency estimate (`real_delay`) and the number of actions the robot
+                # actually consumed during inference (`indexes_diff`) disagree. This happens
+                # when the queue starved (robot idle) or on the first chunk (nothing consumed
+                # yet). Discarding `real_delay` here would drop actions the arm never executed
+                # and splice the queue `real_delay` steps ahead of the physical pose — a hard
+                # jump/slam, worst on slow policies where `real_delay` is large. Never discard
+                # more than was actually consumed.
+                resolved = min(real_delay, indexes_diff)
                 logger.warning(
-                    "Indexes diff is not equal to real delay. indexes_diff=%d, real_delay=%d",
+                    "Indexes diff != real delay (indexes_diff=%d, real_delay=%d); "
+                    "clamping discard to %d to avoid a queue-splice jump.",
                     indexes_diff,
                     real_delay,
+                    resolved,
                 )
-                return real_delay
+                return resolved
 
         return effective_delay