test: stabilize distributed load verification

loadtest/im-pressure/recorder.go

@@ -165,6 +165,17 @@ func (r *deliveryRecorder) historyFound(mid string) bool {
 	return r.history[mid]
 }
 
+func (r *deliveryRecorder) historyFoundAll(messageIDs []string) bool {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	for _, mid := range messageIDs {
+		if !r.history[mid] {
+			return false
+		}
+	}
+	return true
+}
+
 func (r *deliveryRecorder) unackedObservedMessages(ledger []AcceptedMessage, scenario string) []AcceptedMessage {
 	accepted := make(map[string]bool, len(ledger))
 	for _, message := range ledger {
@@ -274,13 +285,17 @@ func (r *deliveryRecorder) summarize(base AgentSummary, ledger []AcceptedMessage
 	return base
 }
 
-func (r *deliveryRecorder) countRealtimeLostStored(ledger []AcceptedMessage) int64 {
+func (r *deliveryRecorder) countRealtimeLostStored(ledger []AcceptedMessage, storedMessageIDs []string) int64 {
 	runID, _ := r.runID.Load().(string)
+	stored := make(map[string]bool, len(storedMessageIDs))
+	for _, mid := range storedMessageIDs {
+		stored[mid] = true
+	}
 	r.mu.Lock()
 	defer r.mu.Unlock()
 	var count int64
 	for _, message := range ledger {
-		if message.RunID != runID || !r.history[message.ClientMid] {
+		if message.RunID != runID || !stored[message.ClientMid] {
 			continue
 		}
 		obs := r.observed[message.ClientMid]