fix(mnesia): per-slot volumes hint and harden verification lookup.

Avoid shared Mnesia dir across replicas; make get_or_create_token and CT verify_user resilient to brief cross-node lag.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/core/core_verification.erl

@@ -34,17 +34,19 @@ verify_token(Token) ->
 
 %%%-------------------------------------------------------------------
 %%% @doc Возвращает существующий токен пользователя или создаёт новый.
+%%% Допускает несколько токенов на user_id (register + повторные вызовы).
 %%% @end
 %%%-------------------------------------------------------------------
 -spec get_or_create_token(UserId :: binary()) ->
   {ok, Token :: binary(), ExpiresAt :: calendar:datetime()} | {error, not_found}.
 get_or_create_token(UserId) ->
-  case mnesia:dirty_match_object(#verification{user_id = UserId, _ = '_'}) of
-    [V] -> {ok, V#verification.token, V#verification.expires_at};
-    [] ->
-      case core_user:get_by_id(UserId) of
-        {ok, _} -> create_token(UserId);
-        Error -> Error
+  case find_token(UserId) of
+    {ok, Token, ExpiresAt} ->
+      {ok, Token, ExpiresAt};
+    not_found ->
+      case user_exists(UserId) of
+        true -> create_token(UserId);
+        false -> {error, not_found}
       end
   end.
 
@@ -55,4 +57,24 @@ get_or_create_token(UserId) ->
 -spec delete_token(Token :: binary()) -> ok.
 delete_token(Token) ->
   mnesia:dirty_delete(verification, Token),
-  ok.
+  ok.
+
+%%--------------------------------------------------------------------
+find_token(UserId) ->
+  case mnesia:dirty_match_object(#verification{user_id = UserId, _ = '_'}) of
+    [#verification{token = Token, expires_at = ExpiresAt} | _] ->
+      {ok, Token, ExpiresAt};
+    [] ->
+      not_found
+  end.
+
+%% dirty_read first; transactional read as fallback for cluster replica lag.
+user_exists(UserId) ->
+  case core_user:get_by_id(UserId) of
+    {ok, _} -> true;
+    {error, not_found} ->
+      case mnesia:transaction(fun() -> mnesia:read(user, UserId) end) of
+        {atomic, [_ | _]} -> true;
+        _ -> false
+      end
+  end.