[BUG] [VS Code / Cursor extension] Manual session tab rename reverts after ~150 ms (regression in 2.1.269)

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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?

**Summary**
The first manual rename of a session works. Every rename after that shows the new name for about 150 ms, then reverts to the previous name.

**Actual**
- Editing works: the field activates, the cursor goes in, and the text changes.
- The new name appears in the session sidebar and on the editor tab for about 150 ms.
- Both then revert to the name from before the edit.
- This happens on every rename after the first.

**Suspected cause (not verified)**
Something in 2.1.269 overwrites the stored title after a manual edit. Two possibilities: the automatic title is re-applied, or stale state gets written back. The "user set this title" flag may only be honored for the first rename.

**Impact**
With many parallel sessions open, you can no longer label them by hand, and tab names are how you tell them apart.

### What Should Happen?

The new name stays in the session sidebar and on the editor tab.

### Error Messages/Logs

```shell

```

### Steps to Reproduce

1. Open a Claude Code session in the extension.
2. Rename the session with the editable title field. The new name sticks.
3. Keep working until the automatic title has been applied.
4. Rename the session again. Click the field, place the cursor, change the text, confirm.

### Claude Model

Other

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

2.1.268

### Claude Code Version

every release above 2.1.268 as of today , including 2.1.274

### Platform

Other

### Operating System

Windows

### Terminal/Shell

Cursor

### Additional Information

_No response_

Start by reproducing the session-title edit flow in the VS Code/Cursor extension on Windows, comparing 2.1.268 with 2.1.269 or later. Trace what runs after the automatic title is applied and after the second manual rename, then verify that the chosen name remains in both the session sidebar and editor tab across repeated renames.

Written by the indexing model from the issue text.