Enum SessionState 

pub enum SessionState {
    Idle,
    Offered {
        pending: PendingOffer,
    },
    OfferReceived {
        bundle: PreKeyBundle,
    },
    AwaitingAck {
        ratchet: Ratchet,
    },
    Established {
        ratchet: Ratchet,
    },
    Rejected,
    Closed,
}

How far a conversation has got towards being encrypted.

Only SessionState::Established carries a ratchet that will decrypt content, which is what makes “an accept does not mean established” a property of the type.

Deliberately not Debug: two of these variants hold key material, and a derived formatter would put it in whatever log the caller happens to write.

Variants

Idle

Nothing has been offered yet.

Offered

We sent init and are waiting for an answer.

Fields

pending: PendingOffer

The keys we offered, kept until the answer arrives.

OfferReceived

They sent init and we have not answered yet.

Fields

bundle: PreKeyBundle

What they offered.

AwaitingAck

We answered and are waiting for the ack that proves they can decrypt.

An accept can be lost, so showing a lock here would tell the user something untrue. This state deliberately exposes no way to decrypt content.

Fields

ratchet: Ratchet

The ratchet, held but not yet trusted to carry content.

Established

The session works in both directions.

Fields

ratchet: Ratchet

The live ratchet.

Rejected

They refused.

Closed

The session ended.