diff --git a/files/ansible-playbooks/ptsd-migrate.yml b/files/ansible-playbooks/ptsd-migrate.yml
index d22b7b7..797f475 100644
--- a/files/ansible-playbooks/ptsd-migrate.yml
+++ b/files/ansible-playbooks/ptsd-migrate.yml
@@ -635,6 +635,35 @@
       changed_when: false
       failed_when: false
 
+    - name: "PHASE 0 (LAST) | Detect mixed state: ppp0 present AND eth0.4000 present (should not happen)"
+      delegate_to: localhost
+      ansible.builtin.set_fact:
+        dev2_ppp_present: "{{ (dev2_ppp0_has_ipv4.stdout | default('') | trim) == 'YES' }}"
+        dev2_eth04000_present: "{{ (dev2_eth04000_exists.stdout | default('') | trim) == 'YES' }}"
+        dev2_mixed_state: >-
+          {{
+            ((dev2_ppp0_has_ipv4.stdout | default('') | trim) == 'YES')
+            and
+            ((dev2_eth04000_exists.stdout | default('') | trim) == 'YES')
+          }}
+      changed_when: false
+
+    - name: "PHASE 0 (LAST) | Graceful stop: DEV2 has BOTH ppp0 and eth0.4000 (mixed/partial migration)"
+      when: dev2_mixed_state | bool
+      delegate_to: localhost
+      ansible.builtin.debug:
+        msg:
+          - "We shall not continue: DEV2 is in mixed state (ppp0 present AND eth0.4000 present)."
+          - "This suggests partial/failed migration or unexpected config; manual inspection required."
+          - "ppp0_has_ipv4={{ dev2_ppp_present }}"
+          - "eth0.4000_exists={{ dev2_eth04000_present }}"
+          - "dev2_conn_final={{ dev2_conn_final }}"
+      changed_when: false
+
+    - name: "PHASE 0 (LAST) | End host: mixed/partial migration state"
+      when: dev2_mixed_state | bool
+      ansible.builtin.meta: end_host
+
     - name: "PHASE 0 (LAST) | Summarize DEV2 pre-migration eligibility"
       delegate_to: localhost
       ansible.builtin.set_fact: