Claude Code silently deletes sessions older than 30 days

Claude Code stores each session as a .jsonl file under ~/.claude/projects/ and by default deletes files untouched for 30 days with no warning. Users can disable cleanup by setting cleanupPeriodDays: 3650 in ~/.claude/settings.json; a value of 0 fails validation.

• Default cleanupPeriodDays is 30; old sessions are removed on startup
• Sessions started in the Claude desktop app are exempt since v2.1.248
• Setting the value to 0 does not keep sessions forever — it fails validation
• Deleted session files cannot be recovered, so raise the limit in advance