diff --git a/backend/app/gateway/auth_disabled.py b/backend/app/gateway/auth_disabled.py
index 396de7129..ef8e6e78c 100644
--- a/backend/app/gateway/auth_disabled.py
+++ b/backend/app/gateway/auth_disabled.py
@@ -6,9 +6,11 @@ import logging
 import os
 from types import SimpleNamespace
 
+from deerflow.runtime.user_context import DEFAULT_USER_ID
+
 AUTH_DISABLED_ENV_VAR = "DEER_FLOW_AUTH_DISABLED"
-AUTH_DISABLED_USER_ID = "e2e-user"
-AUTH_DISABLED_USER_EMAIL = "e2e@test.local"
+AUTH_DISABLED_USER_ID = DEFAULT_USER_ID
+AUTH_DISABLED_USER_EMAIL = "default@test.local"
 
 AUTH_SOURCE_SESSION = "session"
 AUTH_SOURCE_INTERNAL = "internal"
diff --git a/backend/tests/test_auth_middleware.py b/backend/tests/test_auth_middleware.py
index 489159709..ab2e817eb 100644
--- a/backend/tests/test_auth_middleware.py
+++ b/backend/tests/test_auth_middleware.py
@@ -185,7 +185,7 @@ def _make_auth_csrf_app():
 
 @pytest.fixture
 def client(monkeypatch):
-    monkeypatch.delenv("DEER_FLOW_AUTH_DISABLED", raising=False)
+    monkeypatch.setenv("DEER_FLOW_AUTH_DISABLED", "")
     return TestClient(_make_app())
 
 
@@ -223,7 +223,7 @@ def test_auth_disabled_allows_protected_path_without_cookie(monkeypatch):
     assert res.json() == {"models": []}
 
 
-def test_auth_disabled_stamps_e2e_admin_user_without_cookie(monkeypatch):
+def test_auth_disabled_stamps_default_admin_user_without_cookie(monkeypatch):
     monkeypatch.setenv("DEER_FLOW_AUTH_DISABLED", "1")
     client = TestClient(_make_app())
 
@@ -231,10 +231,10 @@ def test_auth_disabled_stamps_e2e_admin_user_without_cookie(monkeypatch):
 
     assert res.status_code == 200
     assert res.json() == {
-        "id": "e2e-user",
-        "email": "e2e@test.local",
+        "id": "default",
+        "email": "default@test.local",
         "system_role": "admin",
-        "context_user_id": "e2e-user",
+        "context_user_id": "default",
     }
 
 
@@ -246,8 +246,8 @@ def test_auth_disabled_auth_me_reuses_middleware_user_without_cookie(monkeypatch
 
     assert res.status_code == 200
     assert res.json() == {
-        "id": "e2e-user",
-        "email": "e2e@test.local",
+        "id": "default",
+        "email": "default@test.local",
         "system_role": "admin",
         "needs_setup": False,
     }
@@ -331,7 +331,7 @@ def test_auth_disabled_startup_warning_when_effective(monkeypatch, caplog):
         warn_if_auth_disabled_enabled()
 
     assert "authentication is bypassed" in caplog.text
-    assert "e2e-user" in caplog.text
+    assert "default" in caplog.text
 
 
 def test_auth_disabled_startup_warning_suppressed_in_explicit_production_env(monkeypatch, caplog):
@@ -350,7 +350,8 @@ def test_protected_path_with_junk_cookie_rejected(client):
     """Junk cookie → 401. Middleware strictly validates the JWT now
     (AUTH_TEST_PLAN test 7.5.8); it no longer silently passes bad
     tokens through to the route handler."""
-    res = client.get("/api/models", cookies={"access_token": "some-token"})
+    client.cookies.set("access_token", "some-token")
+    res = client.get("/api/models")
     assert res.status_code == 401
 
 
diff --git a/frontend/src/core/auth/auth-disabled-user.ts b/frontend/src/core/auth/auth-disabled-user.ts
index 2e26a8911..1601aed15 100644
--- a/frontend/src/core/auth/auth-disabled-user.ts
+++ b/frontend/src/core/auth/auth-disabled-user.ts
@@ -1,8 +1,8 @@
 import type { User } from "./types";
 
 export const AUTH_DISABLED_USER: User = {
-  id: "e2e-user",
-  email: "e2e@test.local",
+  id: "default",
+  email: "default@test.local",
   system_role: "admin",
   needs_setup: false,
 };