diff --git a/openupgrade_scripts/scripts/ptplus_edi/18.0.2.0.0/pre-migration.py b/openupgrade_scripts/scripts/ptplus_edi/18.0.2.0.0/pre-migration.py
new file mode 100644
index 00000000000..adea79fb447
--- /dev/null
+++ b/openupgrade_scripts/scripts/ptplus_edi/18.0.2.0.0/pre-migration.py
@@ -0,0 +1,82 @@
+import logging
+
+from openupgradelib import openupgrade
+
+_logger = logging.getLogger(__name__)
+
+LEGACY_MODULE = "__ptplus_legacy__"
+
+
+@openupgrade.migrate()
+def migrate(env, version):
+    """Retire the legacy CIUS-PT edi format xmlid before base's orphan GC.
+
+    At 18.0 the vendor rebuilt ptplus_edi (18.0.2.0.0) on account.move.send
+    and stopped declaring the legacy account_edi framework record
+    ``account.edi.format`` ``cius_pt_211``. base's _process_end orphan
+    cleanup (inside -u all) then tries ``DELETE FROM account_edi_format``,
+    which FK-RESTRICT-blocked by historical account_edi_document rows and
+    the journal m2m -> a benign but RED-flagged "bad query" on EVERY fresh
+    run. A hop-close SQL surrogate cannot cure it: it runs after -u all, so
+    the first firing always happens. Same casuistry and same fix as ptplus's
+    PT-RF CD tax tags at 16.0 (PR#20): minimal retirement, in the module's
+    own namespace, BEFORE the GC.
+
+    If the record is still referenced by ANY FK (row existence from the DB
+    catalog -- immune to ON DELETE CASCADE masking), move its xmlid to the
+    __ptplus_legacy__ namespace: the row, its links and its provenance
+    survive, and the GC no longer owns it. If nothing references it, leave
+    it for the GC to delete cleanly.
+    """
+    env.cr.execute(
+        """
+        SELECT res_id
+        FROM ir_model_data
+        WHERE module = 'ptplus_edi'
+          AND model = 'account.edi.format'
+          AND name = 'cius_pt_211'
+        """
+    )
+    row = env.cr.fetchone()
+    if not row:
+        return
+    rec_id = row[0]
+
+    env.cr.execute(
+        """
+        SELECT c.conrelid::regclass::text, a.attname
+        FROM pg_constraint c
+        JOIN pg_attribute a
+          ON a.attrelid = c.conrelid AND a.attnum = ANY (c.conkey)
+        WHERE c.contype = 'f'
+          AND c.confrelid = 'account_edi_format'::regclass
+        """
+    )
+    referenced = False
+    for table, column in env.cr.fetchall():
+        env.cr.execute(
+            f"SELECT 1 FROM {table} WHERE {column} = %s LIMIT 1",
+            (rec_id,),
+        )
+        if env.cr.fetchone():
+            referenced = True
+            break
+
+    if referenced:
+        openupgrade.logged_query(
+            env.cr,
+            """
+            UPDATE ir_model_data
+            SET module = %s, noupdate = true
+            WHERE module = 'ptplus_edi'
+              AND model = 'account.edi.format'
+              AND name = 'cius_pt_211'
+            """,
+            (LEGACY_MODULE,),
+        )
+        _logger.info(
+            "cius_pt_211 (account.edi.format id %s) still referenced: "
+            "xmlid retired to %s",
+            rec_id,
+            LEGACY_MODULE,
+        )