[BUG] Sidebar session history lost when disk reaches ENOSPC — no recovery path

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?

When the C drive fills to 0 GB free, Claude Desktop cannot write session
entries to its internal IndexedDB (ENOSPC errors logged in main.log).
After freeing disk space and restarting, the sidebar shows no past sessions —
only new sessions created after the fix appear. The sidebar is permanently
blank for all prior history.

What Should Happen?

On next launch after disk space is restored, the app should re-scan
~/.claude/projects/*.jsonl and rebuild the sidebar session list automatically.
Or provide a manual "Rescan sessions" option in the UI.

Error Messages/Logs

ENOSPC: no space left on device, write
{ errno: -4055, code: 'ENOSPC', syscall: 'write',
  at async lE.writeSessionToDisk (index.js:3278:4672) }

Steps to Reproduce

1. Fill C drive to near 0 GB free
2. Open Claude Desktop and start sessions — they fail to save silently
3. Free disk space (delete files)
4. Restart Claude Desktop
5. Sidebar shows no session history — blank

Note: JSONL transcript files in ~/.claude/projects/ are fully intact

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

unknown

Claude Code Version

2.1.177

Platform

Other

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

146 JSONL session files (345 MB) survive intact in ~/.claude/projects/
but the app's IndexedDB session index is not rebuilt from them on restart.
The session MCP can still read all sessions from disk, confirming the
content is not lost — only the sidebar index is broken.