[BUG] 百度网盘 31034 频控暂停结束后请求风暴导致熔断反复升级 / BaiduNetdisk 31034 pause stampede #3254

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OpenList Version (required)

自建镜像（基于近期 main，含百度驱动观测日志）；现象在官方驱动逻辑下可复现：冷却结束后等待请求一起放行。

Storage Driver Used (required)

百度网盘（baidu_netdisk），经内置 S3 服务被 Velero/Kopia 等高并发删除/列举客户端访问。

Bug Description (required)

百度 filemanager 在突发请求时会返回外层 errno=12，info[] 里带 31034（频控）。驱动会进入暂停/冷却。原先冷却一结束，所有等待中的请求会一起发出；若百度仍在限流，它们再次全部收到 31034，暂停被反复拉长，吞吐长时间起不来。

复现步骤

1. 添加百度网盘存储，开启 S3。
2. 用备份工具或脚本对同一前缀做大量并发删除/列举（例如 Velero/Kopia 全量清理窗口）。
3. 日志出现大量 31034；冷却结束后请求再次扎堆，熔断时间被反复拉长。

预期： 冷却结束时应半开探测（只放行少量请求），确认百度恢复后再放行其余等待者；限流错误应对客户端可见（S3 侧宜为 503 SlowDown），而不是静默成功或无限拉长暂停。
实际： 冷却到期后等待请求风暴式重放，31034 再次命中并升级暂停。

与 #3207 / #3208（写后 List 缓存可见性）正交：那边是 Put 后 Head 404；本 issue 是百度频控与冷却放行策略。

Logs (required)

生产观察（自建镜像，经内置 S3 → 百度网盘，含多次 Velero/Kopia 全量备份窗口）：

• 约 2026-10-22～10-23 轮转日志：检出 31034 ×494；冷却/暂停多次升级。
• 2026-10-24 日备窗口：kine-percona 经 OpenList→百度备份成功；Velero daily-full-clean-20261023190013 PartiallyFailed 的唯一错误是 Alertmanager PVB readiness 超时，与百度频控无关。
• 冷却结束后若不做半开探测，等待请求会扎堆再次打出 31034。

Configuration File Content (required)

"s3": { "enable": true, "port": 5246, "ssl": false }

存储：百度网盘，S3 bucket 映射到其中一个目录。密钥已省略。

Reproduction Link (optional)

（PR 将附单元测试：breaker open / probe success / probe still 31034 / probe handoff / wait budget）

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Grok Bot