Message

Purpose

The message as its author made it — identity, author, ancestry, and the writing — the whole of what travels sealed inside an EncryptedMessage. A Message exists only on a member's device: composed on the sender's side before sealing, recovered on a reader's side after unsealing; nothing of it — not even who wrote it — appears outside the seal. The message id is the message's own identity, minted once, owned by no platform; a correction is a later sealing carrying the same identity. The parents are the ids of the messages the author's device had seen when this message was made — the message's place in the conversation is carried inside the message itself, so no store anywhere is asked to keep order, and a per-recipient copy carries the same ancestry however its bytes were sealed.

Attributes

• message id: the message's identity, a MessageId such as "m-8001" — minted once, never re-minted
• author: the Member who wrote it
• author signature: is Text that carries the author's signature over the message, opaque; its verification belongs to the deferred trust layers
• parents: the MessageIds of the messages this one follows; empty for a conversation's opening message
• writing: the Writing the author wrote

Invariants

• A message names itself with a message id.

Scenarios

An opening message follows nothing

Given: the MessageId "m-8001", the Member anne.bruun, an author signature, no parents, and a Writing of "The hearing moved to Thursday." When: a Message is created Then: it is accepted with no parents — the conversation opens here

A message names what it follows

Given: the MessageId "m-8002", the Member sofie.lind, an author signature, a parent MessageId "m-8001", and a Writing of "I'll bring the file." When: a Message is created Then: it is accepted and reads back following "m-8001"

A correction carries the identity it corrects

Given: the MessageId "m-8001", the Member anne.bruun, an author signature, a parent MessageId "m-8002", and a Writing of "The hearing moved to Friday." When: a Message is created Then: it is accepted carrying id "m-8001" again — the same identity, a new writing, not a new message