From 4300e0d674aec2174c70ca0cde53506a8b0d657f Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Mon, 21 Sep 2026 18:58:52 +0000
Subject: [PATCH 1/2] Initial plan


From 4aed45fa4dd11dbb612b93112f78a60f1dc59647 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Mon, 21 Sep 2026 19:04:39 +0000
Subject: [PATCH 2/2] Wait for ring convergence in zoneAwareSharding test to
 fix flakiness

Co-authored-by: CharlieTLe <3375195+CharlieTLe@users.noreply.github.com>
---
 pkg/alertmanager/multitenant_test.go | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/pkg/alertmanager/multitenant_test.go b/pkg/alertmanager/multitenant_test.go
index 93dcc769c3e..63a388d06c9 100644
--- a/pkg/alertmanager/multitenant_test.go
+++ b/pkg/alertmanager/multitenant_test.go
@@ -860,6 +860,15 @@ func TestMultitenantAlertmanager_zoneAwareSharding(t *testing.T) {
 	am2ZoneA := createInstance(2, "zoneA", registriesZoneA)
 	am1ZoneB := createInstance(3, "zoneB", registriesZoneB)
 
+	// Wait until every instance's ring client sees all the instances, otherwise
+	// ownership is computed against a partial ring view and tenants may get
+	// double-counted.
+	for _, am := range []*MultitenantAlertmanager{am1ZoneA, am2ZoneA, am1ZoneB} {
+		test.Poll(t, 5*time.Second, 3, func() any {
+			return am.ring.InstancesCount()
+		})
+	}
+
 	{
 		require.NoError(t, alertStore.SetAlertConfig(ctx, alertspb.AlertConfigDesc{
 			User:      user1,