Function assemble 

pub(crate) fn assemble(
    seat: &HandoffSeat<'_>,
    messages: &[Message],
    git: &HandoffGitState,
    board: &[Task],
    memory_roots: &[PathBuf],
    live: Vec<HandoffSection>,
) -> GroundTruth

The deterministic half, pure over its inputs: what the tests drive.