diff --git a/application/api/admin/routes.py b/application/api/admin/routes.py
index b921dd4e..5676679f 100644
--- a/application/api/admin/routes.py
+++ b/application/api/admin/routes.py
@@ -18,7 +18,6 @@ from datetime import datetime, timedelta, timezone
 from flask import jsonify, make_response, request
 from flask_restx import Namespace, Resource
 
-from application.api import api
 from application.api.oidc import denylist
 from application.api.user.authz import ROLE_ADMIN, admin_required
 from application.storage.db.repositories.admin_stats import AdminStatsRepository
@@ -374,10 +373,3 @@ class AdminDeviceAuditResource(Resource):
             ),
             200,
         )
-
-
-# Register here, in this import-cached module, rather than in app.py's body so a
-# re-import of application.app (coverage tests reload the module) doesn't re-fire
-# add_namespace against the already-initialized Api. app.py imports this module
-# for the side effect.
-api.add_namespace(admin_ns)
diff --git a/application/app.py b/application/app.py
index aec9f13f..ad9f0140 100644
--- a/application/app.py
+++ b/application/app.py
@@ -15,7 +15,7 @@ from application.core.logging_config import setup_logging
 setup_logging()
 
 from application.api import api  # noqa: E402
-from application.api.admin import routes as _admin_routes  # noqa: E402,F401  (registers admin_ns)
+from application.api.admin import admin_ns  # noqa: E402
 from application.api.answer import answer  # noqa: E402
 from application.api.devices import devices_bp  # noqa: E402
 from application.api.events.routes import events  # noqa: E402
@@ -69,6 +69,12 @@ app.register_blueprint(devices_bp)
 app.register_blueprint(oidc_bp)
 app.register_blueprint(scim_bp)
 app.register_blueprint(v1_bp)
+# Register the admin namespace once. The membership guard makes this idempotent
+# if application.app is re-imported (coverage tests reload the module): without
+# it, re-running add_namespace would re-register routes on the already-served
+# first app and raise "add_url_rule can no longer be called".
+if admin_ns not in api.namespaces:
+    api.add_namespace(admin_ns)
 app.config.update(
     UPLOAD_FOLDER="inputs",
     CELERY_BROKER_URL=settings.CELERY_BROKER_URL,