[BUG] the teleport feature doesn't properly handle multi-byte UTF-8 characters in session context.

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 running claude --teleport <session_id> to resume a session, the CLI panics with a byte index boundary error during the "Checking out branch" step. The error indicates an attempt to slice a UTF-8 string at an invalid boundary (byte index 21, which falls inside a multi-byte Chinese character).

What Should Happen?

The --teleport command should successfully restore the session and check out the associated branch without crashing, even when the session contains non-ASCII characters (e.g., Chinese text in commit messages or branch descriptions).

Error Messages/Logs

claude --teleport session_01AsCge2trSdJiYokqip****
                                                          
 ◑ Teleporting session…                                   
                                                          
 session_01AsCge2trSdJiYokqip****                         
                                                          
   ✔ Validating session                                   
   ✔ Fetching session logs                                
   ✔ Getting branch info                                  
   ◑ Checking out branch                                  
                                                          

thread '<unnamed>' (418382) panicked at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/core/src/str/mod.rs:833:21:
byte index 21 is not a char boundary; it is inside '）' (bytes 19..22) of `實作 FilamentUser）`
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fatal runtime error: failed to initiate panic, error 5, aborting
[1]    32218 abort      claude --teleport session_01AsCge2trSdJiYokqip****

Steps to Reproduce

Simply execute claude --teleport session_01AsCge2trSdJiYokqip**** again
(The **** is mask by me because I don't think this should be published on the Internet)

<img width="627" height="371" alt="Image" src="https://github.com/user-attachments/assets/74b2a130-d196-4f8e-b8e4-4a8da90f6a5e" />

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.72

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

Terminal I used is PHPStorm Terminal