Add final SSE error events for streaming endpoints when retries are exhausted

* Initial plan

* Add final SSE error events for all streaming services

Co-authored-by: bbbugg <80089841+bbbugg@users.noreply.github.com>

* revert openai

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: bbbugg <80089841+bbbugg@users.noreply.github.com>
Co-authored-by: bbbugg <daming20120101@163.com>

Enhance error handling by extracting nested JSON from error messages in SSE events

Enhance error handling for content generation and streaming endpoints

Enhance error handling for content generation and streaming endpoints

Enhance error handling for content generation and streaming endpoints

Enhance error handling for content generation and streaming endpoints

还原vertex和openai的更改，只保留gemini

app/service/chat/gemini_chat_service.py

@@ -470,6 +470,7 @@ class GeminiChatService:
         is_success = False
         status_code = None
         final_api_key = api_key
+        last_error_msg = None
 
         while retries < max_retries:
             request_datetime = datetime.datetime.now()
@@ -509,6 +510,7 @@ class GeminiChatService:
                 retries += 1
                 is_success = False
                 error_log_msg = str(e)
+                last_error_msg = error_log_msg
                 logger.warning(
                     f"Streaming API call failed with error: {error_log_msg}. Attempt {retries} of {max_retries}"
                 )
@@ -553,3 +555,26 @@ class GeminiChatService:
                     latency_ms=latency_ms,
                     request_time=request_datetime,
                 )
+
+        # Emit final error SSE event if all retries failed
+        if not is_success:
+            # 从错误消息中提取嵌套JSON
+            parsed_error = None
+            if last_error_msg:
+                try:
+                    # 查找JSON起始位置
+                    json_start = last_error_msg.find('{')
+                    if json_start != -1:
+                        json_str = last_error_msg[json_start:]
+                        parsed_error = json.loads(json_str)
+                except json.JSONDecodeError:
+                    pass
+
+            error_data = {
+                "error": {
+                    "code": parsed_error['error']['code'] if (parsed_error and 'error' in parsed_error and 'code' in parsed_error['error']) else (status_code or 500),
+                    "message": parsed_error['error']['message'] if (parsed_error and 'error' in parsed_error and 'message' in parsed_error['error']) else (last_error_msg or "Streaming failed"),
+                    "status": parsed_error['error']['status'] if (parsed_error and 'error' in parsed_error and 'status' in parsed_error['error']) else "INTERNAL"
+                }
+            }
+            yield json.dumps(error_data, ensure_ascii=False)

app/service/chat/openai_chat_service.py

@@ -740,4 +740,4 @@ class OpenAIChatService:
                 status_code=status_code,
                 latency_ms=latency_ms,
                 request_time=request_datetime,
-            )
+            )

app/service/chat/vertex_express_chat_service.py

@@ -400,4 +400,4 @@ class GeminiChatService:
                     status_code=status_code,
                     latency_ms=latency_ms,
                     request_time=request_datetime,
-                )
+                )