question: AI 回复内容出现大规模乱码式重复文本，导致输出完全不可读。

### 你想完成什么 / What are you trying to do

AI 助手返回的内容出现严重的文本渲染异常：输出被海量重复的 zzBrain 字符串完全淹没，仅残留极少量可读的正常文本片段，导致回复内容完全无法使用。

### 已尝试的步骤 / What you have tried

尝试新开对话和压缩对话后大概率会是同样的问题

### 环境 / Environment

- Cindy 版本或 commit / version or commit:0.1.51
- 平台与版本 / platform & OS version:Windows

Reproduce the issue on Cindy 0.1.51 on Windows by starting a new conversation and compressing an existing one, as described in the report. Trace where the assistant response becomes dominated by repeated “zzBrain” text; done means the response remains readable in both reported cases.

Written by the indexing model from the issue text.