diff --git a/temporal/api/worker/v1/message.proto b/temporal/api/worker/v1/message.proto
index a87142c78..b8e06c904 100644
--- a/temporal/api/worker/v1/message.proto
+++ b/temporal/api/worker/v1/message.proto
@@ -22,6 +22,11 @@ message WorkerPollerInfo {
 
   // Set true if the number of concurrent pollers is auto-scaled
   bool is_autoscaling = 3;
+
+  // Counts of poller autoscaler scale decisions since the last heartbeat, keyed by
+  // reason (e.g. "server_up", "server_up_suppressed", "empty_poll_down", "re_halve").
+  // Only set when the poller count is auto-scaled.
+  map<string, int64> scale_decisions = 4;
 }
 
 message WorkerSlotsInfo {