This is a one-to-one note thread, not live chat — your coach reviews and replies on their schedule (usually within a day), same as it works today over WhatsApp, just kept in one place tied to your actual data instead of scattered across apps. You'll get an email when there's a new note. Keeping it async like this avoids the always-on chat expectation and keeps the build simple — real-time messaging is something we can add later if it's actually needed.