Communication — Overview

Communication delivers messages to users — email, push, SMS, in-app. It receives "work to send", renders content, selects recipients, sends through providers, and tracks delivery state.

How is Communication different from Platform?

The two parts are connected but have clear roles:

• Platform decides "when to send what" — creates NotificationJob (work to send) from events or direct commands.
• Communication handles "how to send it" — turns NotificationJob into real messages sent to the right people, with the right template, and tracks whether delivery succeeded.

Message types

Type	What it is	Example
Transactional / manual	One message for one specific event	Welcome email, booking confirmation
Reminder	Message based on schedule/threshold	Document expiring soon, invoice due
Campaign	Bulk send to many people	Holiday notice to all parents
Report subscription	Recurring report	Weekly report sent automatically
In-app (UserMessage)	Message displayed in the app	Notification inbox in the app

Main "objects"

Name	One sentence
NotificationJob	Work to send (input from Platform).
OutgoingMessage	One outbound message for each recipient, each channel; carries delivery state.
UserMessage	One in-app message per recipient (in-app inbox).
MessagingJob + Blob	Coordinates large campaign/report payloads.
SmsUsage	Ledger charging per accepted SMS provider (by BusinessUnit).
Template	Content template with {{...}} placeholders.

Suggested reading order

1. End-user view — which channels users receive messages through.
2. Core concepts — artifacts & send-once principles.
3. System architecture — send pipeline & key policy.
4. Automation & Reminders — scheduled/threshold reminders, AutomationScheduler.
5. Report Subscription — recurring automated reports.
6. Codebase flow — workers & files.
7. Data & read/write tables — artifacts in SQL/Table/Blob, tables by flow.
8. Common cases — template, suppress, seed recipient.