C7/C8: employees.last_login_ip 列补全（ALTER TABLE 迁移）+ redis decode 兼容修复 7 处（wecom_service×2/employee_directory×3/auth_wecom_sso×2，统一 isinstance 保护模式）

backend/app/services/employee_directory.py

@@ -62,7 +62,9 @@ async def get_org_directory(
             raw = await redis.get(ORG_DIRECTORY_CACHE_KEY)
             if raw:
                 logger.debug("命中组织目录缓存")
-                return json.loads(raw.decode("utf-8")), True
+                # v4.0 C8 修复：兼容 str/bytes
+                raw = raw if isinstance(raw, str) else raw.decode("utf-8")
+                return json.loads(raw), True
         except Exception as e:
             logger.warning(f"读取组织目录缓存失败（降级）: {e}")
 
@@ -306,7 +308,9 @@ async def get_cached_dept_list(
         try:
             raw = await redis.get(DEPT_LIST_CACHE_KEY)
             if raw:
-                return json.loads(raw.decode("utf-8"))
+                # v4.0 C8 修复：兼容 str/bytes
+                raw = raw if isinstance(raw, str) else raw.decode("utf-8")
+                return json.loads(raw)
         except Exception as e:
             logger.warning(f"读取部门列表缓存失败: {e}")
 
@@ -607,7 +611,9 @@ async def get_org_tree_cached(
         try:
             raw = await redis.get(cache_key)
             if raw:
-                tree = json.loads(raw.decode("utf-8"))
+                # v4.0 C8 修复：兼容 str/bytes
+                raw = raw if isinstance(raw, str) else raw.decode("utf-8")
+                tree = json.loads(raw)
                 logger.debug(f"命中组织架构树缓存: {endpoint}")
         except Exception as e:
             logger.warning(f"读取组织架构树缓存失败: {e}")

backend/app/services/wecom_service.py

@@ -78,7 +78,8 @@ class WecomService:
                 cached_token = await self.redis.get(cache_key)
                 if cached_token:
                     logger.debug("从缓存获取 access_token")
-                    return cached_token.decode("utf-8")
+                    # v4.0 C8 修复：decode_responses=True 时返回 str，兼容 bytes
+                    return cached_token if isinstance(cached_token, str) else cached_token.decode("utf-8")
             except Exception as e:
                 logger.warning(f"Redis 读取失败（降级）: {e}")
 
@@ -1134,7 +1135,8 @@ class WecomService:
                 cached = await self.redis.get(cache_key)
                 if cached:
                     logger.debug("从缓存获取 jsapi_ticket")
-                    return cached.decode("utf-8")
+                    # v4.0 C8 修复：兼容 str/bytes
+                    return cached if isinstance(cached, str) else cached.decode("utf-8")
             except Exception as e:
                 logger.warning(f"Redis 读取 jsapi_ticket 失败（降级）: {e}")