From 4e9c75be508a151dc1ed1148e3aec20c21b7b42f Mon Sep 17 00:00:00 2001
From: Timothy Jaeryang Baek <tim@openwebui.com>
Date: Sat, 9 Aug 2025 23:49:56 +0400
Subject: [PATCH] enh: CHAT_RESPONSE_STREAM_DELTA_CHUNK_SIZE

---
 backend/open_webui/env.py              | 19 +++++++++++++++++++
 backend/open_webui/utils/middleware.py |  3 ++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/backend/open_webui/env.py b/backend/open_webui/env.py
index c3f8f637ee..7719ea421a 100644
--- a/backend/open_webui/env.py
+++ b/backend/open_webui/env.py
@@ -487,6 +487,25 @@ else:
         MODELS_CACHE_TTL = 1
 
 
+####################################
+# CHAT
+####################################
+
+CHAT_RESPONSE_STREAM_DELTA_CHUNK_SIZE = os.environ.get(
+    "CHAT_RESPONSE_STREAM_DELTA_CHUNK_SIZE", "1"
+)
+
+if CHAT_RESPONSE_STREAM_DELTA_CHUNK_SIZE == "":
+    CHAT_RESPONSE_STREAM_DELTA_CHUNK_SIZE = 1
+else:
+    try:
+        CHAT_RESPONSE_STREAM_DELTA_CHUNK_SIZE = int(
+            CHAT_RESPONSE_STREAM_DELTA_CHUNK_SIZE
+        )
+    except Exception:
+        CHAT_RESPONSE_STREAM_DELTA_CHUNK_SIZE = 1
+
+
 ####################################
 # WEBSOCKET SUPPORT
 ####################################
diff --git a/backend/open_webui/utils/middleware.py b/backend/open_webui/utils/middleware.py
index 7ef911ea42..a433ef3a0c 100644
--- a/backend/open_webui/utils/middleware.py
+++ b/backend/open_webui/utils/middleware.py
@@ -95,6 +95,7 @@ from open_webui.config import (
 from open_webui.env import (
     SRC_LOG_LEVELS,
     GLOBAL_LOG_LEVEL,
+    CHAT_RESPONSE_STREAM_DELTA_CHUNK_SIZE,
     BYPASS_MODEL_ACCESS_CONTROL,
     ENABLE_REALTIME_CHAT_SAVE,
 )
@@ -1819,7 +1820,7 @@ async def process_chat_response(
 
                     delta_count = 0
                     delta_chunk_size = max(
-                        1,
+                        CHAT_RESPONSE_STREAM_DELTA_CHUNK_SIZE,
                         int(
                             metadata.get("params", {}).get("stream_delta_chunk_size")
                             or 1