The team lead Shipped
Sequences the run and holds the roster. It is the only actor that knows who else is running, and it deliberately never forms an opinion about the code.
The lead is the run's orchestrator: it resolves the scope, runs selection, dispatches the pillars under a concurrency cap, and sequences everything after. It is the one actor that holds the whole roster in view — and precisely because of that, it does not review. A lead that also reviewed would be a single model whose reading of the diff quietly outranks everyone else's.
The one place it uses judgment
Lane selection in the build loop is deterministic in the normal case; only a genuine tie escalates to exactly one team-lead dispatch. Even there, a failure degrades loudly to a null lane with the candidates listed rather than a silent guess.