diff --git a/netx_api/app_startup.py b/netx_api/app_startup.py
index 42bd032..7e2f82e 100644
--- a/netx_api/app_startup.py
+++ b/netx_api/app_startup.py
@@ -10,6 +10,7 @@ from .db import Base, SessionLocal, engine
 from .schema_patches import (
     apply_all_legacy_startup_ddl,
     apply_auth_schema_patches,
+    apply_topology_schema_safety_net,
     run_alembic_upgrade_to_head,
 )
 from .security_bootstrap import assert_secure_defaults_or_exit
@@ -54,8 +55,11 @@ def run_api_startup() -> None:
     try:
         with engine.begin() as conn:
             apply_auth_schema_patches(conn)
+            # Critical topology columns even when full legacy DDL is skipped
+            # (e.g. alembic stamped head without applying domain patches).
+            apply_topology_schema_safety_net(conn)
     except Exception:
-        _log.exception("startup: auth schema patches failed")
+        _log.exception("startup: auth/topology schema safety patches failed")
     if skip_ddl and alembic_ok:
         _log.info("startup: schema via Alembic (legacy inline DDL skipped)")
     else:
diff --git a/netx_api/schema_patches.py b/netx_api/schema_patches.py
index 192e23e..d073e8e 100644
--- a/netx_api/schema_patches.py
+++ b/netx_api/schema_patches.py
@@ -123,6 +123,28 @@ def apply_auth_schema_patches(conn: Connection) -> None:
     )
 
 
+def apply_topology_schema_safety_net(conn: Connection) -> None:
+    """Always-on topology columns (Alembic stamp-without-upgrade must not skip these)."""
+    _run_sql(
+        conn,
+        "ALTER TABLE topo_folder ADD COLUMN IF NOT EXISTS external_ref VARCHAR(128) DEFAULT ''",
+    )
+    _run_sql(
+        conn,
+        "CREATE INDEX IF NOT EXISTS ix_topo_folder_external_ref ON topo_folder (external_ref)",
+    )
+    _run_sql(conn, "ALTER TABLE topo_fabric_node ADD COLUMN IF NOT EXISTS world_x DOUBLE PRECISION")
+    _run_sql(conn, "ALTER TABLE topo_fabric_node ADD COLUMN IF NOT EXISTS world_y DOUBLE PRECISION")
+    _run_sql(
+        conn,
+        "CREATE INDEX IF NOT EXISTS ix_topo_fabric_node_world_x ON topo_fabric_node (world_x)",
+    )
+    _run_sql(
+        conn,
+        "CREATE INDEX IF NOT EXISTS ix_topo_fabric_node_world_y ON topo_fabric_node (world_y)",
+    )
+
+
 def apply_key_alert_schema_patches(
     engine: Engine | None = None,
     *,