VS Code: Session renames not persisted to JSONL files

Description

When renaming sessions in the VS Code sidebar, the custom titles are not written to the session JSONL files as {"type":"custom-title","customTitle":"..."} records. The sidebar displays the renamed titles correctly during the session, but the titles are lost and not accessible to the CLI or other tools that read the JSONL files.

Steps to Reproduce

1. Open a Claude Code session in VS Code
2. Rename the session in the sidebar (e.g., to "My Feature Work")
3. Check the session's JSONL file: grep "custom-title" ~/.claude/projects/<encoded-path>/<session-id>.jsonl
4. No custom-title record is found

Expected Behavior

Renaming a session should append a {"type":"custom-title","sessionId":"...","customTitle":"..."} record to the session's JSONL file, so that:

• The CLI (claude --resume) can display the custom name
• Third-party tools and skills can read session titles
• Titles persist across VS Code restarts

Actual Behavior

• The VS Code sidebar shows the renamed title correctly (likely cached in extension memory)
• The JSONL file contains no custom-title or ai-title records
• The extension source code (extension.js) has the renameSession function that should write these records, but it appears not to be called or to fail silently

Environment

• Claude Code VS Code Extension: 2.1.109
• macOS (darwin-arm64)
• Verified across 15+ sessions — zero had persisted title records