Distill v2.0.39

What's new

• New /side command opens a temporary side chat forked from the current session. The side session is hidden from /resume and the roster, and it is deleted when you close it.
• x.ai/session/fork is now idempotent. The same new session id returns the existing fork instead of creating a duplicate.
• Stale side sessions older than 24 hours are cleaned up at startup.
• /btw and /fork are unchanged.