diff --git a/src/logic/logic_ai_transcribe.erl b/src/logic/logic_ai_transcribe.erl
index e5c95da..96b0a46 100644
--- a/src/logic/logic_ai_transcribe.erl
+++ b/src/logic/logic_ai_transcribe.erl
@@ -125,8 +125,9 @@ env_int(Name, Default) ->
 %%%===================================================================
 
 call_provider(xai, Url, Key, Audio, CType) ->
-  %% xAI: multipart; опциональные поля до поля file, file — последним.
-  Body = build_multipart([{<<"format">>, <<"true">>}], Audio, <<"voice.dat">>, CType),
+  %% xAI: multipart без опциональных полей — язык определяется авто
+  %% (format=true требует явный language и отключает автоопределение).
+  Body = build_multipart([], Audio, <<"voice.dat">>, CType),
   post_and_parse(xai, Url, Key, Body);
 call_provider(openai, Url, Key, Audio, CType) ->
   Model = case env_bin("STT_MODEL") of
diff --git a/test/unit/logic_ai_transcribe_tests.erl b/test/unit/logic_ai_transcribe_tests.erl
index f64f96c..31a9637 100644
--- a/test/unit/logic_ai_transcribe_tests.erl
+++ b/test/unit/logic_ai_transcribe_tests.erl
@@ -56,13 +56,10 @@ test_xai_success() ->
   ?assertEqual(?XAI_URL, Url),
   ?assertEqual([{"authorization", "Bearer test-key"}], Headers),
   ?assertMatch("multipart/form-data; boundary=" ++ _, ContentType),
-  ?assertMatch({_, _}, binary:match(Body, <<"name=\"format\"">>)),
   ?assertMatch({_, _}, binary:match(Body, <<"name=\"file\"">>)),
   ?assertMatch({_, _}, binary:match(Body, <<"audio-bytes">>)),
-  %% Поле file — последнее (требование xAI).
-  {PosFormat, _} = binary:match(Body, <<"name=\"format\"">>),
-  {PosFile, _} = binary:match(Body, <<"name=\"file\"">>),
-  ?assert(PosFormat < PosFile).
+  %% Без поля format — язык определяется авто (format=true требует language).
+  ?assertEqual(nomatch, binary:match(Body, <<"name=\"format\"">>)).
 
 test_openai_adapter() ->
   os:putenv("STT_PROVIDER", "openai"),