Mobile: no horizontal overflow on any view (grid/flex min-width:0, wrapping for long names/URLs/code, responsive modals/tables, compact top bar, toasts moved above content); conversation-first chat (list default, All messages kept), composer removed, New message FAB/button with mandatory-recipient compose sheet (search, multi-select, reply prefill); scripts/overflow.mjs audit (npm run test:ui), richer seed data