feat: pass the provider's finish reason to outlet filters (#32079)

Outlet filters see the finished reply with its content and token usage, but had no way to tell whether the model ended on its own, ran into the token limit or stopped to call a tool, short of reading every chunk in a stream filter. For OpenAI-compatible and Ollama models, the assistant message handed to outlet now carries finish_reason with the value the provider reported on the last model call of the turn, for streaming and non-streaming replies. Ollama replies cut off by the token limit now report length as well, where they always said stop before.

backend/open_webui/utils/middleware.py

@@ -3689,6 +3689,8 @@ def update_assistant_message_from_stream(assistant_message, raw):
             assistant_message['usage'] = merge_usage(assistant_message.get('usage'), raw_usage)
 
         for choice in data.get('choices', []):
+            if choice.get('finish_reason'):
+                assistant_message['finish_reason'] = choice['finish_reason']
             delta = choice.get('delta', {}) or {}
             content = delta.get('content')
             reasoning_content = delta.get('reasoning_content') or delta.get('reasoning') or delta.get('thinking')
@@ -4066,6 +4068,7 @@ async def outlet_filter_handler(ctx):
             if not message_list:
                 return
 
+        finish_reason = (ctx.get('assistant_message') or {}).get('finish_reason')
         outlet_data = {
             'model': model_id,
             'messages': [
@@ -4079,6 +4082,7 @@ async def outlet_filter_handler(ctx):
                     **({'output': copy.deepcopy(m['output'])} if m.get('output') else {}),
                     **({'usage': m['usage']} if m.get('usage') else {}),
                     **({'sources': m['sources']} if m.get('sources') else {}),
+                    **({'finish_reason': finish_reason} if finish_reason and m.get('id') == message_id else {}),
                 }
                 for m in message_list
             ],
@@ -4307,6 +4311,7 @@ async def non_streaming_chat_response_handler(response, ctx):
 
                     # Save message in the database
                     usage = normalize_usage(response_data.get('usage', {}) or {})
+                    finish_reason = choices[0].get('finish_reason') if choices else None
 
                     if save_to_chat:
                         await Chats.upsert_message_to_chat_by_id_and_message_id(
@@ -4326,6 +4331,7 @@ async def non_streaming_chat_response_handler(response, ctx):
                         'content': content,
                         'output': response_output,
                         **({'usage': usage} if usage else {}),
+                        **({'finish_reason': finish_reason} if finish_reason else {}),
                     }
                     await outlet_filter_handler(ctx)
                     await background_tasks_handler(ctx)
@@ -4361,10 +4367,12 @@ async def non_streaming_chat_response_handler(response, ctx):
     content = choices[0].get('message', {}).get('content') if choices else ''
     if ENABLE_API_OUTLET_FILTERS and (content or output):
         usage = normalize_usage(response_data.get('usage', {}) or {})
+        finish_reason = choices[0].get('finish_reason') if choices else None
         ctx['assistant_message'] = {
             **({'content': content} if content else {}),
             **({'output': output} if output else {}),
             **({'usage': usage} if usage else {}),
+            **({'finish_reason': finish_reason} if finish_reason else {}),
         }
         await outlet_filter_handler(ctx)
 
@@ -4768,6 +4776,7 @@ async def streaming_chat_response_handler(response, ctx):
                 content_parts = []
 
             usage = None
+            finish_reason = None
             last_response_id = None
 
             def full_output():
@@ -4867,6 +4876,7 @@ async def streaming_chat_response_handler(response, ctx):
 
                 async def stream_body_handler(response, form_data):
                     nonlocal usage
+                    nonlocal finish_reason
                     nonlocal output
                     nonlocal prior_output
                     nonlocal last_response_id
@@ -5211,6 +5221,9 @@ async def streaming_chat_response_handler(response, ctx):
                                             )
                                         continue
 
+                                    if choices[0].get('finish_reason'):
+                                        finish_reason = choices[0]['finish_reason']
+
                                     delta = choices[0].get('delta', {})
                                     delta_type = 'content'
 
@@ -6513,6 +6526,7 @@ async def streaming_chat_response_handler(response, ctx):
                     else ''.join(content_parts) or get_output_text(current_output),
                     'output': current_output,
                     **({'usage': usage} if usage else {}),
+                    **({'finish_reason': finish_reason} if finish_reason else {}),
                 }
                 await outlet_filter_handler(ctx)
                 await background_tasks_handler(ctx)

backend/open_webui/utils/response.py

@@ -224,6 +224,8 @@ def convert_response_ollama_to_openai(ollama_response: dict) -> dict:
     response = openai_chat_completion_message_template(
         model, message_content, reasoning_content, openai_tool_calls, usage
     )
+    if not openai_tool_calls and ollama_response.get('done_reason'):
+        response['choices'][0]['finish_reason'] = ollama_response['done_reason']
     return response
 
 
@@ -247,6 +249,7 @@ async def convert_streaming_response_ollama_to_openai(ollama_streaming_response)
             has_tool_calls = True
 
         done = data.get('done', False)
+        done_reason = data.get('done_reason')
 
         usage = None
         if done:
@@ -263,6 +266,8 @@ async def convert_streaming_response_ollama_to_openai(ollama_streaming_response)
 
         if done and has_tool_calls:
             data['choices'][0]['finish_reason'] = 'tool_calls'
+        elif done_reason:
+            data['choices'][0]['finish_reason'] = done_reason
 
         line = f'data: {JSONCodec.dumps(data)}\n\n'
         yield line