fix(users): admin can never strip their own admin permission

Both backend (PATCH /users/{id}) and frontend (Edit User modal) now block
an admin from changing their own primary role away from admin or removing
admin from their own extra_roles, closing off a self-lockout scenario.

backend/app/routers/users.py

@@ -17,6 +17,7 @@ from app.dependencies.auth import require_role, require_any_role_strict
 
 # Import UnitOfWork from app.domain.unit_of_work
 from app.domain.unit_of_work import UnitOfWork
+from app.domain.errors import BusinessRuleViolation
 
 # Import User from app.models.user
 from app.models.user import User
@@ -269,6 +270,16 @@ def update_user_route(
     """Update one or more fields of an existing user. **Requires admin role.**."""
     # Assign update_data = payload.model_dump(exclude_unset=True)
     update_data = payload.model_dump(exclude_unset=True)
+
+    # An admin can never strip their own admin permission — otherwise a
+    # careless self-edit (or a compromised session) could lock every admin
+    # out of the platform with no way back in.
+    if user_id == current_user.id and current_user.role == "admin":
+        final_role = update_data.get("role", current_user.role)
+        final_extra_roles = update_data.get("extra_roles", current_user.extra_roles or [])
+        if "admin" not in {final_role, *(final_extra_roles or [])}:
+            raise BusinessRuleViolation("You cannot remove your own admin permission.")
+
     # Open context manager
     with UnitOfWork(db) as uow:
         # Assign user = update_user(db, user_id, **update_data)

backend/tests/test_multi_role_switch.py

@@ -4,6 +4,42 @@ instead of ever mixing permissions from more than one.
 """
 
 
+def test_admin_cannot_remove_own_admin_role(api, auth_headers, admin_user):
+    resp = api(
+        "patch", f"/api/v1/users/{admin_user.id}", auth_headers,
+        json={"role": "viewer"},
+    )
+    assert resp.status_code == 400
+    assert "admin" in resp.text.lower()
+
+
+def test_admin_cannot_drop_admin_via_extra_roles_either(api, auth_headers, admin_user):
+    # Give themselves a second role first, then try to swap the primary
+    # role away from admin without admin anywhere in extra_roles.
+    resp = api(
+        "patch", f"/api/v1/users/{admin_user.id}", auth_headers,
+        json={"role": "red_lead", "extra_roles": ["viewer"]},
+    )
+    assert resp.status_code == 400
+
+
+def test_admin_can_switch_primary_role_if_admin_kept_in_extra_roles(api, auth_headers, admin_user):
+    resp = api(
+        "patch", f"/api/v1/users/{admin_user.id}", auth_headers,
+        json={"role": "red_lead", "extra_roles": ["admin"]},
+    )
+    assert resp.status_code == 200, resp.text
+
+
+def test_admin_can_edit_own_other_fields_without_touching_role(api, auth_headers, admin_user):
+    resp = api(
+        "patch", f"/api/v1/users/{admin_user.id}", auth_headers,
+        json={"full_name": "Renamed Admin"},
+    )
+    assert resp.status_code == 200, resp.text
+    assert resp.json()["role"] == "admin"
+
+
 def test_admin_can_grant_extra_roles(api, auth_headers):
     created = api(
         "post", "/api/v1/users", auth_headers,

frontend/src/pages/UsersPage.tsx

@@ -268,6 +268,7 @@ export default function UsersPage() {
       {editingUser && (
         <EditUserModal
           user={editingUser}
+          isSelfAdmin={editingUser.id === currentUser?.id && currentUser?.role === "admin"}
           onClose={() => setEditingUser(null)}
           onSubmit={(payload) =>
             updateMutation.mutate({ userId: editingUser.id, payload })
@@ -415,13 +416,16 @@ function CreateUserModal({ onClose, onSubmit, isSubmitting, error }: CreateUserM
 
 interface EditUserModalProps {
   user: UserOut;
+  /** True when the account being edited is the logged-in admin's own —
+   * an admin must never be able to strip their own admin permission. */
+  isSelfAdmin: boolean;
   onClose: () => void;
   onSubmit: (payload: Parameters<typeof updateUser>[1]) => void;
   isSubmitting: boolean;
   error: Error | null;
 }
 
-function EditUserModal({ user, onClose, onSubmit, isSubmitting, error }: EditUserModalProps) {
+function EditUserModal({ user, isSelfAdmin, onClose, onSubmit, isSubmitting, error }: EditUserModalProps) {
   const [formData, setFormData] = useState({
     full_name: user.full_name || "",
     email: user.email || "",
@@ -489,8 +493,9 @@ function EditUserModal({ user, onClose, onSubmit, isSubmitting, error }: EditUse
             <label className="block text-sm font-medium text-gray-300">Role</label>
             <select
               value={formData.role}
+              disabled={isSelfAdmin}
               onChange={(e) => setFormData({ ...formData, role: e.target.value })}
-              className="mt-1 w-full rounded-lg border border-gray-700 bg-gray-800 px-3 py-2 text-gray-200"
+              className="mt-1 w-full rounded-lg border border-gray-700 bg-gray-800 px-3 py-2 text-gray-200 disabled:cursor-not-allowed disabled:opacity-50"
             >
               {ROLES.map((role) => (
                 <option key={role.value} value={role.value}>
@@ -498,6 +503,11 @@ function EditUserModal({ user, onClose, onSubmit, isSubmitting, error }: EditUse
                 </option>
               ))}
             </select>
+            {isSelfAdmin && (
+              <p className="mt-1 text-xs text-gray-500">
+                You can't change your own role away from admin.
+              </p>
+            )}
           </div>
 
           <div>
@@ -505,7 +515,9 @@ function EditUserModal({ user, onClose, onSubmit, isSubmitting, error }: EditUse
               Additional Roles <span className="text-gray-500">(switchable via the top-bar role switcher)</span>
             </label>
             <div className="mt-1.5 grid grid-cols-2 gap-1.5">
-              {ROLES.filter((r) => r.value !== formData.role).map((role) => (
+              {ROLES.filter((r) => r.value !== formData.role).map((role) => {
+                const lockAdmin = isSelfAdmin && role.value === "admin" && formData.extra_roles.includes("admin");
+                return (
                   <label
                     key={role.value}
                     className="flex items-center gap-2 rounded-lg border border-gray-700 bg-gray-800 px-2.5 py-1.5 text-sm text-gray-300"
@@ -513,12 +525,14 @@ function EditUserModal({ user, onClose, onSubmit, isSubmitting, error }: EditUse
                     <input
                       type="checkbox"
                       checked={formData.extra_roles.includes(role.value)}
+                      disabled={lockAdmin}
                       onChange={() => toggleExtraRole(role.value)}
-                    className="h-3.5 w-3.5 rounded border-gray-600 bg-gray-900 text-cyan-500 focus:ring-cyan-500"
+                      className="h-3.5 w-3.5 rounded border-gray-600 bg-gray-900 text-cyan-500 focus:ring-cyan-500 disabled:cursor-not-allowed disabled:opacity-50"
                     />
                     {role.label}
                   </label>
-              ))}
+                );
+              })}
             </div>
           </div>