[BUG] Agent session temp files use Dropbox-incompatible filenames (multiple dots), causing persistent sync errors

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?

I am syncing all my claude directories and there seems to be naming convention that is causing Dropbox issues.

<img width="552" height="268" alt="Image" src="https://github.com/user-attachments/assets/09cae29a-b405-40ee-87b5-1ff0208eb2b3" />

What Should Happen?

No complaints from Dropbox client

Error Messages/Logs

s.OapGweUlug.agent.cHSH8gx76Y
Couldn't upload this file. Remove emojis or special characters like /\."<>:|?* from filename.

Steps to Reproduce

Install Dropbox and have .claude directory point to a directory inside Dropbox directory

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.92 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_