From 2aaf84e425b01665665365c6565ce8c4f299f540 Mon Sep 17 00:00:00 2001
From: NotAShelf <raf@notashelf.dev>
Date: Fri, 6 Mar 2026 23:22:45 +0300
Subject: [PATCH] prober: fix unstable sort when latency within 10% and
 priorities equal

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I49fed694108cfb91ffe3ffad5c02c3a96a6a6964
---
 internal/prober/prober.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/internal/prober/prober.go b/internal/prober/prober.go
index f6dc6f1..3dddb48 100644
--- a/internal/prober/prober.go
+++ b/internal/prober/prober.go
@@ -177,9 +177,11 @@ func (p *Prober) SortedByLatency() []*UpstreamHealth {
 		if aDown != bDown {
 			return bDown // non-down first
 		}
-		// Within 10% latency difference: prefer lower priority number.
+		// Within 10% latency difference: prefer lower priority number, then lower latency.
 		if b.EMALatency > 0 && math.Abs(a.EMALatency-b.EMALatency)/b.EMALatency < 0.10 {
-			return a.Priority < b.Priority
+			if a.Priority != b.Priority {
+				return a.Priority < b.Priority
+			}
 		}
 		return a.EMALatency < b.EMALatency
 	})