fix: httpx 0.28 AsyncClient multipart compat — pass all fields via files= list

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/sync/paperless.py

@@ -116,23 +116,26 @@ class PaperlessClient:
         self, file_bytes: bytes, filename: str, metadata: dict
     ) -> str:
         """Upload a document; returns the Celery task_id UUID string."""
-        form: list[tuple[str, str]] = []
+        # Build multipart as a list of tuples so all parts go through a single
+        # AsyncByteStream — required for httpx >= 0.28 with AsyncClient.
+        parts: list[tuple[str, tuple]] = [
+            ("document", (filename, file_bytes, "application/octet-stream")),
+        ]
         for key in ("title", "created", "archive_serial_number"):
             val = metadata.get(key)
             if val is not None:
-                form.append((key, str(val)))
+                parts.append((key, (None, str(val), "text/plain")))
         if metadata.get("correspondent") is not None:
-            form.append(("correspondent", str(metadata["correspondent"])))
+            parts.append(("correspondent", (None, str(metadata["correspondent"]), "text/plain")))
         if metadata.get("document_type") is not None:
-            form.append(("document_type", str(metadata["document_type"])))
+            parts.append(("document_type", (None, str(metadata["document_type"]), "text/plain")))
         for tag_id in metadata.get("tags", []):
-            form.append(("tags", str(tag_id)))
+            parts.append(("tags", (None, str(tag_id), "text/plain")))
 
         r = await self._request(
             "POST",
             "/api/documents/post_document/",
-            files={"document": (filename, file_bytes, "application/octet-stream")},
-            data=form,
+            files=parts,
         )
         result = r.json()
         # API returns a plain task UUID string