Each job gets its own message thread, accessible directly from the job card. The builder invites internal staff AND external subbie companies as participants from inside the job, controlling which trades sit in which threads (per-thread permissions within the job). All messages are stored permanently on the job as its communication record — not in a separate inbox, not in WhatsApp, not in email. When someone opens the job, the full conversation history is right there alongside the scope, photos and timesheets.