[BUG] VS Code extension: renaming a session tab reverts to old name on Enter

### Preflight Checklist

- [x] I have searched existing issues and this hasn't been reported yet
- [x] This is a single bug report
- [x] I am using the latest version of Claude Code

### What's Wrong?

Renaming a session tab in the Claude Code VS Code extension's sidebar does not work. After typing a new name into the rename field and pressing Enter, the field resets back to the old name instead of committing the new one.

### What Should Happen?

Pressing Enter after typing a new session name should commit the rename and show the new name in the sidebar.

### Steps to Reproduce

1. Open the Claude Code sidebar in VS Code with at least one active session.
2. Click the rename (pencil) icon on a session tab.
3. Type a new name into the field.
4. Press Enter.
5. Observe: the field reverts to the original name instead of keeping the new one.

### Claude Model

Not sure / Multiple models

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

Unknown

### Claude Code Version

2.1.268 (Claude Code)

### Platform

Anthropic API

### Operating System

macOS

### Terminal/Shell

VS Code integrated terminal

### Additional Information

- VS Code version: 1.131.0
- Claude Code VS Code extension version: anthropic.claude-code 2.1.270
- OS: macOS 15.7.3 (Build 24G419)

Reproduce the rename flow in the Claude Code VS Code extension's sidebar using the listed steps, then trace the session-tab rename handling for the Enter key. Confirm that the new name is retained and shown after submission, including for the reported macOS and extension versions.

Written by the indexing model from the issue text.