[BUG] Session history silently wiped after app update — no server-side backup, no export, no warning

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?

Summary
Months of Claude Code session history were permanently lost after a desktop app update. Sessions are stored only in Electron's IndexedDB — which can be cleared during app updates — with no server-side sync, no automatic export, and no user warning.

What happened
App updated, all session history prior to ~March 2026 was gone
No warning shown before or after the update
Sessions are not recoverable — Anthropic has no server-side copy
Investigation findings
Session metadata stored in Electron IndexedDB: ~/Library/Application Support/Claude/IndexedDB/
Transcripts stored locally as .jsonl files in ~/.claude/projects/
After update: only 5 transcript files remained, 15 session titles in UI, all older sessions gone completely
App version: 2.1.156
Why this matters
Claude Code is a paid product marketed as a long-term coding partner. Losing months of work silently due to an Electron IndexedDB purge is serious data loss, not a minor UX issue.

Requests
Server-side session sync (parity with claude.ai)
Automatic local export before updates
Clear warning that sessions are local-only
Session export feature (JSON/Markdown)

What Should Happen?

Requests
Server-side session sync (parity with claude.ai)
Automatic local export before updates
Clear warning that sessions are local-only
Session export feature (JSON/Markdown)

Error Messages/Logs

The conversations and code data is lost

Steps to Reproduce

Don't know but after upgrades the data is lost

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.9659.2

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_