Covers the live feed: per-session addressing and resubscribing on a switch, loss-and-retry versus a deliberate close, the atomic replay swap on reconnect (never showing less than before, partial replays dropped), and keeping a resumed session's whole transcript while the project-wide fallback trims to the newest session.

## Before writing SPEC.md files

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