feat(access): derive authenticated baseline roles

src/govoplan_access/backend/admin/service.py

@@ -56,7 +56,7 @@ def ensure_default_roles(session: Session, tenant: Tenant | None = None) -> dict
         query = query.filter(Role.tenant_id == tenant.id) if tenant is not None else query.filter(Role.tenant_id.is_(None))
         role = query.one_or_none()
         is_builtin = _template_is_builtin(template_managed=template.managed, protected=template.protected, tenant_role=tenant is not None)
-        is_assignable = True
+        is_assignable = not template.default_authenticated
         if role is None:
             role = Role(
                 tenant_id=tenant.id if tenant is not None else None,
@@ -200,7 +200,24 @@ def set_user_groups(session: Session, *, user: User, group_ids: Iterable[str]) -
 
 
 def set_user_roles(session: Session, *, user: User, role_ids: Iterable[str]) -> None:
-    ids = sorted(set(role_ids))
+    default_slugs = {
+        template.slug
+        for template in role_templates_for_level("tenant")
+        if template.default_authenticated
+    }
+    default_roles = (
+        session.query(Role)
+        .filter(
+            Role.tenant_id == user.tenant_id,
+            Role.slug.in_(default_slugs),
+        )
+        .all()
+        if default_slugs
+        else []
+    )
+    default_role_ids = {role.id for role in default_roles}
+    requested_ids = set(role_ids) - default_role_ids
+    ids = sorted(requested_ids)
     roles = (
         session.query(Role)
         .filter(Role.tenant_id == user.tenant_id, Role.id.in_(ids), Role.is_assignable.is_(True))