Allow users to configure how many conversations appear in Recents

What variant of Codex are you using?

Codex Desktop / App

What feature would you like to see?

Please let users choose how many conversations are shown in the Recents section of the sidebar.

A useful setting could offer values such as 5, 10, 20, 50, or All, with a Show more action for anything beyond the chosen initial count.

I use projectless conversations for recurring tasks such as daily briefs. These create many short-lived threads, so showing 50 recent conversations makes the Recents section very long and pushes my Projects too far down the sidebar. Moving Recents below Projects only reverses the problem: Recents then becomes too far down to reach conveniently.

The visible Recents count should be a presentation preference, separate from conversation retention and loading. Choosing a small number must not hide conversations from search, remove history, or limit the full paginated history available inside each project.

Expected behavior

• Users can configure the number of conversations initially visible under Recents.
• A small selection such as 5 or 10 keeps Projects easy to reach.
• Older conversations remain available through search and a Show more / full-history view.
• Project conversation history continues to load independently of the global Recents display count.

Related issue

This is related to #25761, but it addresses a different need. That issue asks for complete access to older project conversations beyond the global recent-50 window. This request asks for control over how many recent conversations are visibly expanded in the sidebar, without reducing access to any saved history.