YA replication fix.

common/nfs-services-server.nix

@@ -121,8 +121,8 @@ in
             # Create readonly snapshot
             btrfs subvolume snapshot -r /persist/services "$SNAPSHOT_PATH"
 
-            # Find previous snapshot on sender
-            PREV_LOCAL=$(ls -t /persist/services@* 2>/dev/null | grep -v "^$SNAPSHOT_PATH$" | head -1 || true)
+            # Find previous snapshot on sender (sort by name since readonly snapshots have same mtime)
+            PREV_LOCAL=$(ls -1 /persist/services@* 2>/dev/null | grep -v "^$SNAPSHOT_PATH$" | sort -r | head -1 || true)
 
             # Try incremental send if we have a parent, fall back to full send if it fails
             if [ -n "$PREV_LOCAL" ]; then