Cannot delete 'Untitled' sessions in conversation history

Description

When switching between past conversations in the Claude Code VS Code extension, some sessions appear as "Untitled" in the conversation history list. Clicking the X (delete) icon on these sessions does nothing — the session remains in the list and cannot be removed.

Steps to Reproduce

1. Open the Claude Code panel in VS Code
2. Switch between multiple past conversations
3. Observe that some sessions are labeled "Untitled"
4. Hover over an "Untitled" session to reveal the X (delete) icon
5. Click the X icon

Expected Behavior

The "Untitled" session is removed from the conversation history list.

Actual Behavior

Nothing happens. The session remains in the list and cannot be deleted.

Environment

• Claude Code version: 2.1.41
• VS Code version: 1.109.5
• OS: macOS 26.3

Notes

The issue appears to only affect sessions labeled "Untitled". Named sessions can be deleted normally.