Chat Message Flow

Overview

Message sending in Harmony flows through CoreMessageService, which handles encryption decisions, database insertion, and relies on Supabase Realtime for delivery to other clients. Federation of messages is handled asynchronously by database triggers.

Sending a Message

Receiving a Message

Encryption Key Sharing

When a user joins an encrypted channel, they need the Megolm session key:

Thread Messages

Thread messages use ThreadService and bypass encryption entirely — they are always sent as plaintext directly to the database.

DM Messages

DM (direct message) flow is similar to channel messages but uses the useDM store:

Message Display

MessageDisplay renders the message list with:

• Virtual scrolling for performance (only visible messages rendered)
• Markdown/rich content rendering via MessageContent / UnifiedMessageContent
• Inline embeds (links, server invites, media)
• Reactions display and interaction
• Reply context and threading indicators
• Encryption status indicator per message

Realtime Subscription

The chat store subscribes to messages via RealtimeConnectionManager:

Server Encryption Modes

Mode	Behavior
disabled	All messages plaintext, encryption UI hidden
optional	Encrypt if keys available, fall back to plaintext
required	Block send if encryption not set up

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See also: Authentication Flow for how sessions work, and Real-time Updates for subscription management.