Update wiped full user state (sessions + memory) — user now permanently afraid to update

What happened

After updating Claude Code to a new version, all local user state was destroyed — prior sessions, memory files, and configuration were all wiped. Recovery took ~11 hours of manually rebuilding state.

Impact

As a direct result, user will not update Claude Code again. That means they're stuck on an old version indefinitely, which creates two cascading problems:

1. They miss out on every future fix and feature (including, ironically, any fix for this bug).
2. Any issues they hit on the old version get harder to support because the version drifts further from current.

What the bug likely is

Whatever migration step runs on upgrade either:

• Fails silently and destroys the previous state instead of preserving it, or
• Assumes a new directory/schema that isn't backwards-compatible and wipes the old location

What would fix this

1. Back up user state before any destructive migration. Zip \~/.claude/\ (or equivalent per platform) into a timestamped archive before touching it.
2. Abort and restore on migration failure instead of proceeding with partial/empty state.
3. Version-gate the migration so re-running the updater on an already-migrated install is a no-op.
4. Surface an explicit prompt before any data-touching upgrade step so the user knows it's about to happen.

Environment

• Claude Code (Windows 11)
• Data loss occurred on an update some time ago; user has refused to update since.