This walkthrough creates a thread through the FHIR API using MedplumClient. That matches how a real app (or Bot) writes messages. The Medplum App is useful as an inspector: confirm resources, references, and history—not as the primary authoring experience you ship to users.
In a healthcare context, messages are sent all the time and can include many scenarios (patient to physician, physician to physician, and more), so ensuring they are well organized is important. This guide explains how to model and organize threads in Medplum.
This guide explains how thread header Communication.status models open versus closed threads, how to manage participants on the header with recipient, and how FHIR access policies align with who should see a thread.