diff --git a/scripts/lib-hosts.sh b/scripts/lib-hosts.sh
index 3cc0dd9..46dbba5 100644
--- a/scripts/lib-hosts.sh
+++ b/scripts/lib-hosts.sh
@@ -43,6 +43,27 @@
 # Mirrors the surviving juju/lxd/tailscale virsh machines' live config (read
 # 2026-06-26). power_id is set per host to the hostname by the caller.
 VIRSH_POWER_ADDRESS="qemu+ssh://logxen@10.12.64.1/system"
+# VR1 NODE NIC -> PLANE ORDER (MEASURED 2026-07-30; D-133 flat per-NIC carve).
+# The substrate roots pin six MACs per node, and the module attaches them in list
+# order, so macs[i] IS enp<i+1>s0. Verified end-to-end on vr1-dc0-control-01:
+#   main.tf macs[0..5] = be:69:c5, 29:e5:2b, 05:98:c4, 96:e8:36, 5a:dc:91, 35:cc:01
+#   live carve         = enp1s0 be:69:c5 metal-admin      (fabric-4, PXE)
+#                        enp2s0 29:e5:2b provider-public  (br-ex inherits this MAC)
+#                        enp3s0 05:98:c4 metal-internal
+#                        enp4s0 96:e8:36 data-tenant
+#                        enp5s0 5a:dc:91 storage
+#                        enp6s0 35:cc:01 replication
+#
+# !! THIS IS NOT lib-net.sh's PLANE_CIDRS ORDER. !! PLANE_CIDRS starts with
+# provider-public; the NIC order starts with METAL-ADMIN. Anything that walks
+# PLANE_CIDRS positionally to assign NICs swaps enp1s0 and enp2s0 and puts the
+# PXE/metal-admin leg on provider-public -- which would strand commissioning on a
+# plane with no DHCP. Iterate THIS array for NIC placement, never PLANE_CIDRS.
+NIC_PLANE_ORDER=( metal-admin provider-public metal-internal data-tenant storage replication )
+# The provider-public NIC is the OVS br-ex parent (Pattern A): the node's static
+# lands on br-ex, and the member NIC itself carries no L3 link.
+BREX_PARENT_NIC="enp2s0"
+
 # The per-region forms exist only for the VR1 DCs (D-132 q1). Declared EMPTY at
 # the flat/VR0 layer so a shell that never selects a VR1 DC cannot pick up a
 # neighbouring DC's address -- an empty value fails loud; a stale one powers off
diff --git a/tests/dc-selector/run-tests.sh b/tests/dc-selector/run-tests.sh
index bf413e3..2ac5d5e 100644
--- a/tests/dc-selector/run-tests.sh
+++ b/tests/dc-selector/run-tests.sh
@@ -249,6 +249,29 @@
 H0_N="$(lib_hosts_select_dc vr1-dc0 >/dev/null 2>&1; echo "${#HOSTS[@]}")"
 chk "hosts vr1-dc0 fleet count 10 (D-121 Option C 9 role + D-104 juju-01)" "$H0_N" "10"
 
+# --- VR1 NODE NIC -> PLANE ORDER (MEASURED 2026-07-30) ---------------------
+# macs[i] in the substrate root IS enp<i+1>s0, verified against the live carve on
+# vr1-dc0-control-01. The load-bearing assertion is the LAST one: this order is
+# NOT PLANE_CIDRS order, and anything that walks PLANE_CIDRS positionally to
+# place NICs puts the PXE/metal-admin leg on provider-public -- stranding
+# commissioning on a plane with no DHCP.
+chk "nic order [0] is metal-admin (the PXE leg)" "${NIC_PLANE_ORDER[0]}" "metal-admin"
+chk "nic order [1] is provider-public"           "${NIC_PLANE_ORDER[1]}" "provider-public"
+chk "nic order [5] is replication"               "${NIC_PLANE_ORDER[5]}" "replication"
+chk "nic order has six entries"                  "${#NIC_PLANE_ORDER[@]}" "6"
+chk "br-ex parent NIC is enp2s0 (provider-public)" "$BREX_PARENT_NIC" "enp2s0"
+# every NIC-order entry must be a real space name
+NIC_BAD=0
+for _n in "${NIC_PLANE_ORDER[@]}"; do
+  _found=0; for _s in "${SPACES6[@]}"; do [ "$_n" = "$_s" ] && _found=1; done
+  [ "$_found" = 1 ] || NIC_BAD=$((NIC_BAD+1))
+done
+chk "every nic-order entry is one of the six spaces" "$NIC_BAD" "0"
+# THE TRAP ASSERTION: the two orders must DIFFER at position 0.
+NIC0="${NIC_PLANE_ORDER[0]}"; PC0="${PLANE_NAME[${PLANE_CIDRS[0]}]}"
+[ "$NIC0" != "$PC0" ] && ok "nic order DIFFERS from PLANE_CIDRS order at [0] (the enp1s0/enp2s0 trap)" \
+  || no "nic order DIFFERS from PLANE_CIDRS order at [0] -- both read '$NIC0', so the trap guard is vacuous"
+
 # --- ONE SELECTION PER SHELL (stale cross-DC guard, lib-net precedent) ---
 ( lib_hosts_select_dc vr1-dc0 >/dev/null 2>&1; lib_hosts_select_dc vr1-dc1 2>/dev/null ); \
   chk "hosts dc0->dc1 re-select REFUSED (stale cross-DC values)" "$?" 1