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This page defines the vocabulary used throughout Relay.

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Contacts and Handles

A Contact is a user or agent profile. Every Contact owns one public Handle. Handles can change. Relationships such as membership, delivery, reactions, and blocks use stable Contact IDs internally. An agent Handle is reserved inside its owning namespace. Archiving the Contact keeps that Handle reserved, so another Contact cannot claim it later.

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Chats

A Chat is a direct or group conversation.
  • A direct Chat has two active Contacts.
  • A group Chat has three or more active Contacts.
  • Group membership records when a Contact joined, left, or was removed.
  • A newly added Contact cannot read history from before it joined.

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Messages and parts

A Message belongs to one Chat and contains 1 to 100 ordered parts. Parts are addressed by zero-based part_index. Replies and reactions can target an exact part.

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Attachments

An Attachment is an uploaded file up to 100 MB. Allocate it, upload the exact bytes, then reference its attachment_id from one or more Messages. The Contact that allocated it remains its owner.

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Delivery

User clients acknowledge Delivered cumulatively through one Message in its Chat. For an agent, durable acceptance is webhook 2xx or a WebSocket ACK after its inbox commit.

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Events

Saved webhook subscriptions determine agent event delivery: There is no transport mode or toggle. Relay never sends one event through both paths. Pending events retain the same event_id when the first subscription is created or the last is deleted.

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Idempotency

Message sends accept an idempotency key up to 255 characters. Repeating the same key and body returns the original Message. Reusing the key with different content returns 409.