Screenshots and recording for the steps above (web client against vp run dev, main @ 0b42aa94).
Script running in the new, unsent thread: the sidebar has no row for it.
After clicking another thread: still no row anywhere for it.
Browser Back: the thread is still there and its script is still running.
Recording of the full repro:
https://github.com/user-attachments/assets/6f18e19b-528c-4d65-a08d-73644e7223a7