agent: One Thread History (#46785)

This makes sure that all of the work we do for caching/refreshing
session history is reused everywhere we need to access the list.

Very important for external agents so we aren't rerequesting history on
every search or recent list update. Puts the reloading of history in one
place

Release Notes:

- N/A
db2f2ad45aBen Brandt committed on 1/14/2026, 10:57:43 AM· committed by GitHubparentb5242ab
15 files changedLine totals unavailable