[VS Code] Renaming a session in Session History panel does not persist (reverts to auto-generated title)

Environment

• Claude Code (VS Code extension): v2.1.159 (latest on Marketplace)
• OS: Windows 11 (win32 x64)

Description
Renaming a session via the Session History panel (hover -> rename button) does not persist. After typing a new name and pressing Enter, the new name shows briefly but reverts to the original auto-generated title as soon as the session is clicked or the window is reloaded. Reproduces for both the active session and past/closed sessions.

Steps to reproduce

1. Open the Session History panel in the VS Code extension
2. Hover a session -> click the rename button
3. Type a new name -> press Enter
4. Click the session (or reload the window)
5. Name reverts to the original auto-generated title

Expected: Custom name persists across clicks/reloads/restarts.
Actual: Custom name is discarded; original auto-generated title returns.

Investigation (where the renamed title is NOT stored)
The renamed title does not appear to be written to disk anywhere:

• Transcript JSONL: no summary/title line
• ~/.claude/sessions/*.json: runtime PID state only
• ~/.claude/history.jsonl: input prompt history only
• VS Code globalStorage state.vscdb: no session-name entry

This suggests the rename updates UI state only and is never persisted.

Additional note
The /rename slash command is unavailable in this version ("/rename isn't available in this environment"), so there is no CLI workaround.