Status check: can the stale mutable state fallback logic in ndc_task_util.go be removed?

Summary

service/history/ndc_task_util.go (line ~158) contains a TODO
suggesting that fallback logic for stale mutable state can be
removed once the team is confident, based on monitoring the
StaleMutableStateCounter metric:

// TODO: With validateTaskByClock check above, we should never run into 
// the situation where mutable state cache is stale. This is based on 
// the assumption that shard context will never re-acquire the shard 
// after it has been stolen.
// We should monitor the StaleMutableStateCounter metric and remove 
// the logic below once we are confident.

Question

Has the team had a chance to monitor StaleMutableStateCounter
in production since this was written? If the counter has
remained at zero (or near-zero) for a sufficient period, this
might be ready for removal/simplification.

I don't have access to production metrics, so I'm filing this
as a check-in rather than attempting the change myself — removing
this fallback without confidence could introduce correctness
issues.

References

• service/history/ndc_task_util.go:158-180
• common/metrics/metric_defs.go:986 (StaleMutableStateCounter definition)