diff --git a/backend/open_webui/utils/middleware.py b/backend/open_webui/utils/middleware.py
index 8bd0b175b0..13597731b4 100644
--- a/backend/open_webui/utils/middleware.py
+++ b/backend/open_webui/utils/middleware.py
@@ -157,6 +157,29 @@ def output_id(prefix: str) -> str:
     return f'{prefix}_{uuid4().hex[:24]}'
 
 
+def merge_streamed_reasoning_details(target: list, details) -> None:
+    items = details if isinstance(details, list) else [details]
+    for item in items:
+        if not isinstance(item, dict):
+            continue
+
+        index = item.get('index')
+        existing = (
+            next((detail for detail in target if detail.get('index') == index), None)
+            if isinstance(index, int)
+            else None
+        )
+        if existing is None:
+            target.append(dict(item))
+            continue
+
+        for key, value in item.items():
+            if key in ('text', 'summary') and isinstance(value, str) and isinstance(existing.get(key), str):
+                existing[key] += value
+            else:
+                existing[key] = value
+
+
 def _split_tool_calls(
     tool_calls: list[dict],
 ) -> list[dict]:
@@ -4282,21 +4305,35 @@ async def streaming_chat_response_handler(response, ctx):
                                     )
                                     reasoning_details = delta.get('reasoning_details')
                                     if reasoning_content or reasoning_details:
-                                        if not output or output[-1].get('type') != 'reasoning':
-                                            reasoning_item = {
-                                                'type': 'reasoning',
-                                                'id': output_id('r'),
-                                                'status': 'in_progress',
-                                                'start_tag': '<think>',
-                                                'end_tag': '</think>',
-                                                'attributes': {'type': 'reasoning_content'},
-                                                'content': [],
-                                                'summary': None,
-                                                'started_at': time.time(),
-                                            }
-                                            output.append(reasoning_item)
-                                        else:
-                                            reasoning_item = output[-1]
+                                        reasoning_item = (
+                                            next(
+                                                (
+                                                    item
+                                                    for item in reversed(output)
+                                                    if item.get('type') == 'reasoning'
+                                                ),
+                                                None,
+                                            )
+                                            if reasoning_details and not reasoning_content
+                                            else None
+                                        )
+
+                                        if reasoning_item is None:
+                                            if not output or output[-1].get('type') != 'reasoning':
+                                                reasoning_item = {
+                                                    'type': 'reasoning',
+                                                    'id': output_id('r'),
+                                                    'status': 'in_progress',
+                                                    'start_tag': '<think>',
+                                                    'end_tag': '</think>',
+                                                    'attributes': {'type': 'reasoning_content'},
+                                                    'content': [],
+                                                    'summary': None,
+                                                    'started_at': time.time(),
+                                                }
+                                                output.append(reasoning_item)
+                                            else:
+                                                reasoning_item = output[-1]
 
                                         if reasoning_content:
                                             # Append to reasoning content
@@ -4317,11 +4354,14 @@ async def streaming_chat_response_handler(response, ctx):
                                             delta_type = 'content'
 
                                         if reasoning_details:
-                                            reasoning_item.setdefault('reasoning_details', []).extend(
-                                                reasoning_details
-                                                if isinstance(reasoning_details, list)
-                                                else [reasoning_details]
+                                            merge_streamed_reasoning_details(
+                                                reasoning_item.setdefault('reasoning_details', []),
+                                                reasoning_details,
                                             )
+                                            data = {
+                                                'output': full_output(),
+                                            }
+                                            delta_type = 'content'
 
                                     if value:
                                         if (