diff --git a/docs/spa-cutover-flag.md b/docs/spa-cutover-flag.md
new file mode 100644
index 0000000..a0f5801
--- /dev/null
+++ b/docs/spa-cutover-flag.md
@@ -0,0 +1,18 @@
+# SPA cutover feature flag (`USE_SPA_UI`)
+
+## Formål
+`USE_SPA_UI` styrer om host/player UI routes serverer Angular SPA shell eller legacy Django templates.
+
+## Miljø-toggle (uden kodeændring)
+Sæt env var pr. miljø:
+
+- `USE_SPA_UI=true` -> `/lobby/ui/host` og `/lobby/ui/player` returnerer SPA shell
+- `USE_SPA_UI=false` (default) -> legacy template-flow bruges uændret
+
+Backward compatibility under cutover:
+- Hvis `USE_SPA_UI` ikke er sat, bruges `WPP_SPA_ENABLED` som fallback.
+
+## Verifikation
+- Flag OFF: `UiScreenTests.test_legacy_templates_are_used_when_spa_flag_is_off`
+- Flag ON (host): `UiScreenTests.test_host_screen_can_render_angular_shell_when_feature_flag_enabled`
+- Flag ON (player): `UiScreenTests.test_player_screen_can_render_angular_shell_when_feature_flag_enabled`
diff --git a/lobby/feature_flags.py b/lobby/feature_flags.py
new file mode 100644
index 0000000..83ae495
--- /dev/null
+++ b/lobby/feature_flags.py
@@ -0,0 +1,6 @@
+from django.conf import settings
+
+
+def use_spa_ui() -> bool:
+    """Central read-point for SPA cutover flag."""
+    return bool(getattr(settings, "USE_SPA_UI", False))
diff --git a/lobby/templates/lobby/spa_shell.html b/lobby/templates/lobby/spa_shell.html
new file mode 100644
index 0000000..c57da0a
--- /dev/null
+++ b/lobby/templates/lobby/spa_shell.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<html lang="da">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <title>WPP SPA</title>
+</head>
+<body>
+  <app-root data-wpp-shell-route="{{ shell_route }}"></app-root>
+  <script type="module" src="{{ spa_asset_base }}/main.js"></script>
+</body>
+</html>
diff --git a/lobby/tests.py b/lobby/tests.py
index 84fefca..896b596 100644
--- a/lobby/tests.py
+++ b/lobby/tests.py
@@ -5,7 +5,7 @@ from pathlib import Path
 
 from django.contrib.auth import get_user_model
 from django.core.management import call_command
-from django.test import TestCase
+from django.test import TestCase, override_settings
 from django.urls import reverse
 from django.utils import timezone
 
@@ -973,6 +973,38 @@ class UiScreenTests(TestCase):
         self.assertContains(response, "player_shell_runtime_error")
         self.assertContains(response, "window.addEventListener(\"error\"")
 
+    @override_settings(USE_SPA_UI=False)
+    def test_legacy_templates_are_used_when_spa_flag_is_off(self):
+        self.client.login(username="host_ui", password="secret123")
+
+        host_response = self.client.get(reverse("lobby:host_screen"))
+        player_response = self.client.get(reverse("lobby:player_screen"))
+
+        self.assertContains(host_response, "Host panel")
+        self.assertContains(player_response, "Player panel")
+        self.assertNotContains(host_response, "<app-root")
+        self.assertNotContains(player_response, "<app-root")
+
+    @override_settings(USE_SPA_UI=True)
+    def test_host_screen_can_render_angular_shell_when_feature_flag_enabled(self):
+        self.client.login(username="host_ui", password="secret123")
+
+        response = self.client.get(reverse("lobby:host_screen"))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "<app-root")
+        self.assertContains(response, "data-wpp-shell-route=\"/host\"")
+        self.assertContains(response, "/static/frontend/angular/browser/main.js")
+
+    @override_settings(USE_SPA_UI=True)
+    def test_player_screen_can_render_angular_shell_when_feature_flag_enabled(self):
+        response = self.client.get(reverse("lobby:player_screen"))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "<app-root")
+        self.assertContains(response, "data-wpp-shell-route=\"/player\"")
+        self.assertContains(response, "/static/frontend/angular/browser/main.js")
+
 
 class SessionDetailRoundQuestionTests(TestCase):
     def setUp(self):
diff --git a/lobby/ui_views.py b/lobby/ui_views.py
index 21e9c65..89a66d2 100644
--- a/lobby/ui_views.py
+++ b/lobby/ui_views.py
@@ -1,14 +1,34 @@
+from django.conf import settings
 from django.contrib.auth.decorators import login_required
 from django.shortcuts import render
 
 from fupogfakta.models import Category
 
+from .feature_flags import use_spa_ui
+
+
+def _render_spa_shell(request, shell_route: str):
+    return render(
+        request,
+        "lobby/spa_shell.html",
+        {
+            "shell_route": shell_route,
+            "spa_asset_base": settings.WPP_SPA_ASSET_BASE,
+        },
+    )
+
 
 @login_required
 def host_screen(request, spa_path=None):
+    if use_spa_ui():
+        return _render_spa_shell(request, "/host")
+
     categories = Category.objects.filter(is_active=True).order_by("name")
     return render(request, "lobby/host_screen.html", {"categories": categories})
 
 
 def player_screen(request):
+    if use_spa_ui():
+        return _render_spa_shell(request, "/player")
+
     return render(request, "lobby/player_screen.html")
diff --git a/partyhub/settings.py b/partyhub/settings.py
index c808d03..1e73568 100644
--- a/partyhub/settings.py
+++ b/partyhub/settings.py
@@ -99,6 +99,14 @@ STATIC_ROOT = BASE_DIR / 'staticfiles'
 
 DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'
 
+
+USE_SPA_UI_RAW = env('USE_SPA_UI')
+if USE_SPA_UI_RAW is None:
+    # Backward-compatible fallback while cutover is rolling out.
+    USE_SPA_UI_RAW = env('WPP_SPA_ENABLED', 'false')
+USE_SPA_UI = USE_SPA_UI_RAW.lower() == 'true'
+WPP_SPA_ASSET_BASE = env('WPP_SPA_ASSET_BASE', '/static/frontend/angular/browser').rstrip('/')
+
 CHANNEL_REDIS_HOST = env('CHANNEL_REDIS_HOST', '127.0.0.1')
 CHANNEL_REDIS_PORT = int(env('CHANNEL_REDIS_PORT', '6379'))
 CHANNEL_LAYERS = {
