[BUG] Session index doesn't survive reinstall, even though transcript files remain on disk

Preflight Checklist

• [x] I have searched existing issues 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?

After reinstalling Claude Code, my previous sessions no longer appeared in the session list / history. However, the raw session transcript files (.jsonl) were still present on disk under ~/.claude/projects/<project-hash>/, fully intact with all messages and tool calls. The session index/registry appears to have been reset by the reinstall, even though the underlying data was never deleted.

What Should Happen?

The session index should be rebuilt from the transcript files already present on disk after a reinstall, so users don't have to manually locate session UUIDs from the filesystem to recover their history.

Error Messages/Logs

Steps to Reproduce

1. Have existing Claude Code sessions in a project directory.
2. Reinstall Claude Code (uninstall + reinstall, or fresh install).
3. Open Claude Code in the same project directory.
4. Previous sessions are missing from the session list, even though the .jsonl files are still present in ~/.claude/projects/.

Workaround found: manually locating the .jsonl file in ~/.claude/projects/<project-hash>/ and running claude --resume <session-uuid-from-filename> successfully restores the full session.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.218

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_