Desktop app update wiped all custom sidebar groups (Local Storage recreated, unrecoverable)

Environment

• Claude Code: 2.1.215
• Claude desktop app: 1.22209.3
• macOS: 15.5 (Apple Silicon)

What happened

A desktop app update today recreated the app's Electron Local Storage from scratch, which wiped all custom sidebar session groups and every session-to-group assignment. The sidebar fell back to flat/ungrouped and the user had to rebuild groups and re-sort dozens of sessions by hand.

Evidence

• ~/Library/Application Support/Claude/Local Storage/ (and the leveldb/ dir inside it) had a creation timestamp of today, minutes before the loss was noticed — the entire store was recreated, not migrated.
• Group definitions/assignments do not appear in ~/.claude.json (nor ~/.claude.json.backup), so there was no fallback copy on disk. Grepping the fresh leveldb files finds only the newly recreated group names.
• No other backup of the previous Local Storage exists under ~/Library/Application Support/Claude/.

Expected

• App updates should migrate Local Storage, not recreate it.
• Sidebar groups are user-curated organizational data; ideally they'd live in (or be backed up to) a durable store like ~/.claude.json or a versioned file, or sync with the account, so a local-storage reset isn't unrecoverable data loss.

Impact

Complete, unrecoverable loss of sidebar organization. For users who rely on groups to separate client projects, this is a significant workflow hit.