🔒️(backend) enhance scope manipulation

Enhance scope manipulation by normalizing and sanitizing
scope values before processing.

Scopes are now converted to lowercase to ensure consistent behavior,
deduplicated while preserving their original order, and handled in a
deterministic way aligned with the intended authorization model.

src/backend/core/external_api/permissions.py

@@ -57,6 +57,9 @@ class BaseScopePermission(permissions.BasePermission):
         if isinstance(token_scopes, str):
             token_scopes = token_scopes.split()
 
+        # Ensure scopes is a deduplicated list (preserving order) and lowercase all scopes
+        token_scopes = list(dict.fromkeys(scope.lower() for scope in token_scopes))
+
         if settings.OIDC_RS_SCOPES_PREFIX:
             token_scopes = [
                 scope.removeprefix(f"{settings.OIDC_RS_SCOPES_PREFIX}:")

src/backend/core/tests/test_external_api_rooms.py

@@ -660,6 +660,37 @@ def test_api_rooms_response_no_telephony(settings):
     assert response.data["id"] == str(room.id)
 
 
+def test_api_rooms_token_scope_case_insensitive(settings):
+    """Token's scope should be case-insensitive."""
+    settings.APPLICATION_JWT_SECRET_KEY = "devKey"
+    user = UserFactory()
+
+    # Generate token with mixed-case scope "Rooms:List" to verify that scope
+    # validation is case-insensitive (should match "rooms:list")
+    now = datetime.now(timezone.utc)
+    payload = {
+        "iss": settings.APPLICATION_JWT_ISSUER,
+        "aud": settings.APPLICATION_JWT_AUDIENCE,
+        "iat": now,
+        "exp": now + timedelta(hours=1),
+        "client_id": "test-client",
+        "scope": "Rooms:List",  # Mixed case - should be accepted as "rooms:list"
+        "user_id": str(user.id),
+        "delegated": True,
+    }
+    token = jwt.encode(
+        payload,
+        settings.APPLICATION_JWT_SECRET_KEY,
+        algorithm=settings.APPLICATION_JWT_ALG,
+    )
+
+    client = APIClient()
+    client.credentials(HTTP_AUTHORIZATION=f"Bearer {token}")
+    response = client.get("/external-api/v1.0/rooms/")
+
+    assert response.status_code == 200
+
+
 def test_api_rooms_token_without_delegated_flag(settings):
     """Token without delegated flag should be rejected."""
     settings.APPLICATION_JWT_SECRET_KEY = "devKey"