From 67603b72dafcb548f65fc1108310de468b4b4e6b Mon Sep 17 00:00:00 2001
From: John <john.davies@diamond.ac.uk>
Date: Fri, 11 Sep 2026 18:57:47 +0100
Subject: [PATCH] Fix primary MAC lookup for shared MAC addresses

---
 netbox_agent/network.py |  9 ++++++++-
 tests/network.py        | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/netbox_agent/network.py b/netbox_agent/network.py
index c2706108..9a844ae9 100644
--- a/netbox_agent/network.py
+++ b/netbox_agent/network.py
@@ -309,6 +309,13 @@ def update_interface_macs(self, nic, macs):
                     }
                 )
 
+    def set_netbox_interface_primary_mac(self, interface, mac):
+        primary_mac = self.nb_net.mac_addresses.get(
+            interface_id=interface.id,
+            mac_address=mac,
+        )
+        interface.primary_mac_address = primary_mac.id
+
     def create_netbox_nic(self, nic, mgmt=False):
         # TODO: add Optic Vendor, PN and Serial
         nic_type = self.get_netbox_type_for_nic(nic)
@@ -551,7 +558,7 @@ def batched(it, n):
                 if version.parse(nb.version) < version.parse("4.2"):
                     interface.mac_address = nic["mac"]
                 else:
-                    interface.primary_mac_address = {"mac_address": nic["mac"]}
+                    self.set_netbox_interface_primary_mac(interface, nic["mac"])
                 nic_update += 1
 
             if hasattr(interface, "mtu"):
diff --git a/tests/network.py b/tests/network.py
index 99c42d4c..1d37af8f 100644
--- a/tests/network.py
+++ b/tests/network.py
@@ -1,4 +1,8 @@
+from types import SimpleNamespace
+from unittest.mock import MagicMock
+
 from netbox_agent.lldp import LLDP
+from netbox_agent.network import Network
 from tests.conftest import parametrize_with_fixtures
 
 
@@ -34,3 +38,18 @@ def test_lldp_parse_with_vlan(fixture):
     lldp = LLDP(fixture)
     assert lldp.get_switch_vlan("eth0") == {"300": {"pvid": True}}
     assert lldp.get_switch_vlan("eth1") == {"300": {}}
+
+
+def test_set_netbox_interface_primary_mac_scopes_lookup_to_interface():
+    network = object.__new__(Network)
+    network.nb_net = SimpleNamespace(mac_addresses=MagicMock())
+    network.nb_net.mac_addresses.get.return_value = SimpleNamespace(id=123)
+    interface = SimpleNamespace(id=456, primary_mac_address=None)
+
+    network.set_netbox_interface_primary_mac(interface, "AA:BB:CC:DD:EE:FF")
+
+    network.nb_net.mac_addresses.get.assert_called_once_with(
+        interface_id=456,
+        mac_address="AA:BB:CC:DD:EE:FF",
+    )
+    assert interface.primary_mac_address == 123