[BUG] named sessions don't get the name displayed on chat box

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When I start a named session the little "title" on the chat box does not get rendered, it does show if I /rename inside the session.

What Should Happen?

Claude should always show the name passed in from --name with the same style as running /rename inside a chat

Error Messages/Logs

Steps to Reproduce

1. Start a session with a name: claude --name test-123
2. Notice no name shows up
3. Run /rename test-123-renamed
4. Notice the session name is displayed

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.85

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

Passing in name and no floating name displayed:

<img width="500" alt="Image" src="https://github.com/user-attachments/assets/49eef313-9920-4c8b-9f6c-9839ad4e30df" />

After rename:

<img width="500" alt="Image" src="https://github.com/user-attachments/assets/28c97133-a84a-4c03-b6f2-e211833a2a28" />

Based on session logs, it seems that a customTitle entry is needed for the name to be displayed, maybe claude should emit this when --name is provided?

{"type":"custom-title","customTitle":"test-123-renamed","sessionId":"a238b5db-1dd4-42fc-b4cd-ac9dab579de0"}
{"type":"agent-name","agentName":"test-123-renamed","sessionId":"a238b5db-1dd4-42fc-b4cd-ac9dab579de0"}