Session history times get scrambled after updating the VS Code extension

Every time I update the Claude Code VS Code extension, a bunch of my old session transcripts show the wrong time in the history panel, and the list ends up out of order.

I dug into it a bit. The timestamp shown in the history panel seems to come from the transcript file's mtime on disk (~/.claude/projects/<project>/*.jsonl), not from anything stored inside the file. Each line in the JSONL actually has its own correct timestamp, so the data isn't lost, it's just that the displayed time is wrong.

What tipped me off: all the affected sessions had the exact same timestamp, and it matched the moment the extension restarted after the update. That's not what you'd expect from individual sessions getting touched for unrelated reasons, it looks like something on startup after an update is going through every transcript file and rewriting it (without preserving mtime), even ones that had nothing new happen in them.

Steps to reproduce:

1. Have a handful of existing sessions in ~/.claude/projects/<project>/
2. Check their mtimes with ls -la
3. Update the extension and let it restart
4. Check the mtimes again, old sessions now show the restart time instead of when they were last actually used
5. Session history panel shows the same scrambled times/order

Would expect old sessions to keep showing their real last-activity time after an extension update, not get bumped to "now."

Version: 2.1.217, VS Code extension, macOS.