Covers the session lifecycle journeys: starting a session and watching it live through to the archived row (worktree retired, record on the run's own branch), two sessions running concurrently each in its own checkout, and publishing a finished session's branch to a real remote — even when the click lands mid-teardown.

## Before writing SPEC.md files

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