diff --git a/backend/app/api/backtest.py b/backend/app/api/backtest.py
index 1350252..d27e42c 100644
--- a/backend/app/api/backtest.py
+++ b/backend/app/api/backtest.py
@@ -3,6 +3,7 @@ from __future__ import annotations
 
 import asyncio
 import json
+import logging
 import queue
 import threading
 from dataclasses import asdict
@@ -21,6 +22,8 @@ from app.services.backtest import (
     is_available,
 )
 
+logger = logging.getLogger(__name__)
+
 router = APIRouter(prefix="/api/backtest", tags=["backtest"])
 
 FACTOR_DEFAULT_DAYS = 180
@@ -664,10 +667,13 @@ async def optimize_stream(
                 try:
                     base_params = json.loads(params) if params else {}
                 except (json.JSONDecodeError, TypeError):
+                    # 静默降级会让"用户配置丢失"变成无声 bug: 至少 warn 供诊断 (前端应传合法 JSON)。
+                    logger.warning("optimize: params JSON 解析失败, 降级为空 params: %r", params)
                     base_params = {}
                 try:
                     ov = json.loads(overrides) if overrides else None
                 except (json.JSONDecodeError, TypeError):
+                    logger.warning("optimize: overrides JSON 解析失败, 降级为 None: %r", overrides)
                     ov = None
                 ocfg = OptimizeConfig(
                     strategy_id=strategy_id,
diff --git a/frontend/src/lib/optimizerTask.ts b/frontend/src/lib/optimizerTask.ts
index 5c6beae..f9c848e 100644
--- a/frontend/src/lib/optimizerTask.ts
+++ b/frontend/src/lib/optimizerTask.ts
@@ -174,6 +174,9 @@ function connectSSE(url: string): void {
       if (reconnectAttempts > MAX_RECONNECT) {
         es.close()
         eventSource = null
+        // 清 localStorage: 否则刷新页面 tryReconnect 会重连到这个已放弃的任务。
+        localStorage.removeItem(RECONNECT_KEY)
+        localStorage.removeItem(JOB_KEY_KEY)
         current = { ...current, isPending: false, error: '连接中断, 重连多次失败' }
         emit()
       }
@@ -244,9 +247,16 @@ export function stopOptimize(): void {
     localStorage.removeItem(RECONNECT_KEY)
     localStorage.removeItem(JOB_KEY_KEY)
   } else if (eventSource) {
-    // 保持连接等 job 事件; 兜底: 5s 后仍没 key 就强关
+    // 保持连接等 job 事件; 兜底: 5s 后仍没 key 就强关并清 localStorage,
+    // 避免刷新重连到未取消任务。(若期间 job 到达, handler 已清并置 null, 下面条件不成立跳过)
     const es = eventSource
-    setTimeout(() => { if (es === eventSource) { es.close(); eventSource = null } }, 5000)
+    setTimeout(() => {
+      if (es === eventSource) {
+        es.close(); eventSource = null
+        localStorage.removeItem(RECONNECT_KEY)
+        localStorage.removeItem(JOB_KEY_KEY)
+      }
+    }, 5000)
   }
   if (current?.isPending) {
     current = { ...current, isPending: false, error: '已取消' }