diff --git a/django_admin_react/conf.py b/django_admin_react/conf.py
index 20e82d4..80d47ca 100644
--- a/django_admin_react/conf.py
+++ b/django_admin_react/conf.py
@@ -62,19 +62,20 @@
     # falls back to this default, since the value is written into a
     # ``<style>`` block and must not be able to inject CSS.
     "PRIMARY_COLOR": "#2563eb",
-    # ``REACT_LOGIN`` — opt-in React-rendered login (Issue #167).
-    # Default ``False`` keeps today's behavior: ``SpaIndexView``
-    # redirects anonymous / unauthorized users to Django's HTML login
-    # (or the package's own ``<mount>/login/`` page). When ``True``,
-    # the SPA shell is served to anonymous users (with the CSRF cookie
-    # set) so the React app can render its own login form, which POSTs
-    # to ``/api/v1/login/``. The auth *mechanism* is unchanged — still
-    # Django's ``authenticate``/``login`` behind the JSON endpoint
-    # (`api/views/auth.py`); only the UI surface differs. The shell
-    # carries no user data, so serving it to anonymous users discloses
-    # nothing the static bundle wouldn't, and every data API call still
-    # returns 403 until the user authenticates.
-    "REACT_LOGIN": False,
+    # ``REACT_LOGIN`` — React-rendered login is the **default** so the
+    # SPA fully replaces the Django admin URL surface end-to-end (owner
+    # directive 2026-05-28). ``SpaIndexView`` serves the React shell to
+    # anonymous users (with the CSRF cookie set) and the in-SPA login
+    # form POSTs to the API package's ``/api/v1/login/``. A consumer
+    # who wants the legacy HTML-admin login back can opt out with
+    # ``"REACT_LOGIN": False`` — the package's own ``<mount>/login/``
+    # endpoint is still mounted in either mode. The auth *mechanism* is
+    # unchanged in both modes (Django's ``authenticate``/``login``
+    # behind the JSON endpoint); only the UI surface differs. The
+    # shell carries no user data — serving it to anonymous users
+    # discloses nothing the static bundle wouldn't, and every data API
+    # call still returns 403 until the user authenticates.
+    "REACT_LOGIN": True,
     # PWA (Issue #86) — all optional; sane defaults make the manifest
     # work with zero config. See ``django_admin_react/pwa.py`` +
     # ``docs/ux/pwa.md``.
diff --git a/tests/test_login.py b/tests/test_login.py
index 41daf9f..05f59d6 100644
--- a/tests/test_login.py
+++ b/tests/test_login.py
@@ -66,8 +66,10 @@ def test_non_staff_rejected_at_login(client: Client, make_user) -> None:
     # Re-renders the form with an error; never establishes a staff session.
     assert response.status_code == 200
     assert "staff account" in response.content.decode().lower()
-    # The SPA still bounces them.
-    assert client.get(SPA_URL).status_code in (302,)
+    # Under the post-2026-05-28 default (`REACT_LOGIN=True`), the SPA
+    # shell serves to a non-staff session and the React app re-renders
+    # the login form. Every wire call still 403s, so no data leaks.
+    assert client.get(SPA_URL).status_code == 200
 
 
 @pytest.mark.django_db
@@ -75,7 +77,10 @@ def test_bad_password_rejected(client: Client, make_user) -> None:
     make_user("boss", staff=True)
     response = client.post(LOGIN_URL, {"username": "boss", "password": "wrong"})
     assert response.status_code == 200
-    assert client.get(SPA_URL).status_code == 302
+    # Anonymous (login failed) gets the React shell under the new
+    # `REACT_LOGIN=True` default; the in-SPA login form posts to the
+    # API.
+    assert client.get(SPA_URL).status_code == 200
 
 
 @pytest.mark.django_db
@@ -109,19 +114,37 @@ def test_logout_returns_to_login(client: Client, make_user) -> None:
     response = client.post(LOGOUT_URL)
     assert response.status_code == 302
     assert response["Location"] == LOGIN_URL
-    # Session cleared — SPA bounces again.
-    assert client.get(SPA_URL).status_code == 302
+    # Session cleared — under `REACT_LOGIN=True` (default) the SPA shell
+    # serves to the now-anonymous user; the in-SPA login form re-renders.
+    assert client.get(SPA_URL).status_code == 200
 
 
 # --------------------------------------------------------------------------- #
 # Fallback when the legacy admin is OFF                                        #
 # --------------------------------------------------------------------------- #
-@override_settings(ROOT_URLCONF="tests.test_project.urls_no_admin", LOGIN_URL="/accounts/login/")
+@override_settings(
+    ROOT_URLCONF="tests.test_project.urls_no_admin",
+    LOGIN_URL="/accounts/login/",
+    DJANGO_ADMIN_REACT={"REACT_LOGIN": False},
+)
 @pytest.mark.django_db
 def test_spa_falls_back_to_package_login_when_admin_off(client: Client) -> None:
-    # No admin mounted + LOGIN_URL is Django's untouched default → the
-    # package login must be the redirect target.
-    response = client.get(SPA_URL)
-    assert response.status_code == 302
-    assert response["Location"].startswith(LOGIN_URL)
-    assert "next=" in response["Location"]
+    """Legacy fallback path (`REACT_LOGIN=False`): with no admin mounted
+    and a default `LOGIN_URL`, the SPA index view redirects to the
+    package's own `<mount>/login/`. Preserved for consumers who opt out
+    of the React-rendered login (the post-2026-05-28 default is
+    `REACT_LOGIN=True`, which serves the shell to anon instead — that
+    path is covered in `test_spa_index.py`)."""
+    import django_admin_react.conf as _conf
+    import importlib
+    import django_admin_react.views as _views
+    importlib.reload(_conf)
+    importlib.reload(_views)
+    try:
+        response = client.get(SPA_URL)
+        assert response.status_code == 302
+        assert response["Location"].startswith(LOGIN_URL)
+        assert "next=" in response["Location"]
+    finally:
+        importlib.reload(_conf)
+        importlib.reload(_views)
diff --git a/tests/test_spa_index.py b/tests/test_spa_index.py
index f17799e..ddac522 100644
--- a/tests/test_spa_index.py
+++ b/tests/test_spa_index.py
@@ -59,29 +59,30 @@ def fake_manifest(tmp_path: Path) -> Path:
 # Auth gate                                                                   #
 # --------------------------------------------------------------------------- #
 @pytest.mark.django_db
-def test_anonymous_user_redirected_to_login(anon_client: Client) -> None:
+def test_anonymous_user_gets_shell_under_react_login_default(anon_client: Client) -> None:
+    """Default mode (`REACT_LOGIN=True`, the post-2026-05-28 default):
+    anonymous users get the React shell so the in-SPA login form renders
+    — replacing the legacy admin login URL surface end-to-end. The shell
+    carries no user data; every API call still 403s until the user is
+    authenticated."""
     response = anon_client.get(ROOT_URL)
-    assert response.status_code == 302
-    # The package leaves LOGIN_URL up to the consumer's settings — only
-    # assert that the redirect carries the SPA path as the ``next``
-    # parameter so the user lands back here after login. The ``next``
-    # value is percent-encoded (CodeQL py/url-redirection fix), so the
-    # raw path appears encoded in Location; decode the query to compare.
-    location = response["Location"]
-    assert "next=" in location
-    query = parse_qs(urlsplit(location).query)
-    assert query["next"][0].startswith(ROOT_URL)
+    assert response.status_code == 200
+    body = response.content.decode("utf-8")
+    # The shell is what's served (not a redirect).
+    assert 'name="dar-mount"' in body
 
 
 @pytest.mark.django_db
-def test_authenticated_non_staff_redirected(user_client: Client) -> None:
-    """Non-staff users do not see the SPA, even if logged in."""
+def test_authenticated_non_staff_gets_shell_under_react_login_default(user_client: Client) -> None:
+    """Non-staff users get the React shell under the new `REACT_LOGIN=True`
+    default; the in-SPA login form re-renders for them and the API still
+    403s every wire call so no data leaks. (The shell is purely chrome —
+    serving it to a non-staff session discloses nothing the static bundle
+    wouldn't.)"""
     response = user_client.get(ROOT_URL)
-    # The package treats them like anonymous for the SPA — same redirect
-    # path. (The API returns 403, but the SPA shell is a UI surface and
-    # bouncing through login is the friendlier flow.)
-    assert response.status_code == 302
-    assert "next=" in response["Location"]
+    assert response.status_code == 200
+    body = response.content.decode("utf-8")
+    assert 'name="dar-mount"' in body
 
 
 @pytest.mark.django_db
@@ -340,13 +341,20 @@ def test_invalid_theme_cookie_is_ignored(superuser_client: Client) -> None:
 # --------------------------------------------------------------------------- #
 # REACT_LOGIN — serve the shell to anonymous users (Issue #167)               #
 # --------------------------------------------------------------------------- #
-def test_react_login_off_anon_still_redirected(anon_client: Client) -> None:
-    """Default (REACT_LOGIN unset): anonymous → 302 to the login page."""
-    with override_settings(DJANGO_ADMIN_REACT={}):
+def test_react_login_off_anon_redirected(anon_client: Client) -> None:
+    """Opt-out (`REACT_LOGIN=False`): anonymous users are redirected to
+    the legacy login page with a `?next=` round-trip back to the SPA.
+    Preserved as the escape hatch for consumers who don't want the
+    React-rendered login (the default is `True` since 2026-05-28)."""
+    with override_settings(DJANGO_ADMIN_REACT={"REACT_LOGIN": False}):
         _reload_conf()
         try:
             response = anon_client.get(ROOT_URL)
             assert response.status_code == 302
+            location = response["Location"]
+            assert "next=" in location
+            query = parse_qs(urlsplit(location).query)
+            assert query["next"][0].startswith(ROOT_URL)
         finally:
             _reload_conf()