Preserve custom thread titles in archived threads

Problem

I use archived threads as a working memory system. I manually rename threads very carefully so I can find them again later. Once a thread is archived, that custom title is not preserved or surfaced in the archived threads list, so I can no longer reliably recover the thread by the name I gave it.

Expected behavior

Archived threads should:

• retain the custom title I assigned
• display that title in the archived threads view

Actual behavior

After archiving, I can’t reliably find renamed threads anymore because the custom title is either not preserved or not shown in the archive list view.

Why this matters

This breaks a common archive-and-recover workflow. I archive most inactive threads to keep the workspace clean, but that only works if I can trust that the thread name I chose will still appear later in the archived list.

Suggested fix

Use the user-assigned thread title as the visible title in the archived threads list.