Conversation Memory — References

Specifications that already solved threading, ordering, and history replication for message-based systems, plus the obligations that attach to a retained record of what was said.

Threading and message identity

• RFC 5322: Internet Message Format — the Message-ID, In-Reply-To and References fields, which are the long-standing answer to giving every message a stable identity and reconstructing a reply tree from it.
• Message Threading — Jamie Zawinski. The widely reimplemented algorithm for assembling a thread tree from reply references, including what to do when the references are missing, wrong, or circular.

Ordering and history replication

• Matrix Specification — a conversation history modelled as a directed acyclic graph of events replicated between servers, with explicit resolution rules when concurrent events arrive. Linked at its root; per-version paths move.
• Time, Clocks, and the Ordering of Events in a Distributed System — Leslie Lamport, Communications of the ACM, 1978. Why wall-clock timestamps cannot order events produced by independent writers, and what to use instead. Cited by name.

Retaining a record of what was said

• Regulation (EU) 2016/679 (GDPR) — in particular Article 5(1)(e) on storage limitation, Article 15 on the right of access, and Article 20 on data portability: the obligations that turn "we keep the transcript" into export, retention, and disclosure requirements.

No verified reference is recorded for conversation branching semantics in assistant products, for summary nodes attached to message ranges, or for thread merge and split. These are product conventions and are not standardised anywhere.