When a chat is auto-named, also rename the parent session if it is still on its default 'New session' label. UPDATE is gated by an atomic WHERE clause so user renames and prior propagations are not clobbered. Publishes session_renamed via broker.publishUser; useSidebar already listens. Closes the gap where sessions auto-created from the sidebar would stay 'New session' forever. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>