Covers the conversation transcript: rendering and parsing round-trip with multi-line replies intact, a message body or transport name can never forge another message, unsafe run ids never become paths, turns read back oldest-first even under overlapping appends, and older installs get their ignore rules upgraded without touching a foreign file.

## Before writing SPEC.md files

Read https://raw.githubusercontent.com/brillout/sdd/refs/heads/main/sdd.md
