chat proxy: multipart через files-only — data+files list ломает httpx

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

apps/mattermost_connector/chat_proxy.py

@@ -62,24 +62,31 @@ def _upstream_request_args(request, token: str) -> tuple[dict, HttpResponse | No
         return {'headers': headers}, None
 
     if _is_multipart(request):
-        data = []
+        # list+list data/files в httpx ломает multipart (TypeError: tuple in join).
+        # Текстовые поля тоже через files=(None, value).
+        multipart = []
+        total = 0
         for key in request.POST:
             for value in request.POST.getlist(key):
-                data.append((key, value))
-        files = []
-        total = 0
+                multipart.append((key, (None, str(value))))
         for key in request.FILES:
             for uploaded in request.FILES.getlist(key):
                 total += uploaded.size
                 if total > _MAX_BODY:
                     return {}, HttpResponse(status=413)
                 content = uploaded.read()
-                files.append((
+                if isinstance(content, str):
+                    content = content.encode('utf-8')
+                multipart.append((
                     key,
-                    (uploaded.name, content, uploaded.content_type or 'application/octet-stream'),
+                    (
+                        uploaded.name or 'file',
+                        content,
+                        uploaded.content_type or 'application/octet-stream',
+                    ),
                 ))
-        # Content-Type с boundary выставит httpx сам — исходный boundary уже «съеден».
-        return {'headers': headers, 'data': data or None, 'files': files or None}, None
+        # Content-Type с boundary выставит httpx сам.
+        return {'headers': headers, 'files': multipart or None}, None
 
     content_type = request.headers.get('Content-Type')
     if content_type:

apps/mattermost_connector/tests.py

@@ -5,6 +5,7 @@
 from datetime import date
 from unittest import mock
 
+import httpx
 from django.contrib.auth import get_user_model
 from django.test import TestCase
 from mattermostautodriver.exceptions import ResourceNotFound
@@ -456,8 +457,13 @@ class ChatApiProxyTests(TestCase):
         self.assertEqual(_args[0], 'POST')
         self.assertTrue(_args[1].endswith('/api/v4/files'))
         self.assertIn('files', kwargs)
-        self.assertIn('data', kwargs)
+        self.assertNotIn('data', kwargs)
         self.assertNotIn('content', kwargs)
-        # httpx сам ставит multipart boundary
         self.assertNotIn('Content-Type', kwargs['headers'])
         self.assertEqual(kwargs['headers']['Authorization'], 'Bearer user-pat-token')
+        # httpx реально умеет закодировать этот формат
+        built = httpx.Request('POST', 'https://mm.test.local/api/v4/files', files=kwargs['files'])
+        self.assertIn('multipart/form-data', built.headers['content-type'])
+        body = built.read()
+        self.assertIn(b'channel_id', body)
+        self.assertIn(b'hello', body)