Bot Mode group rooms were slow by construction: the round engine ran every
member's turn one after another, and each turn found out its bot had finished
by re-reading session.resume on a fixed 2s timer. A 4-bot room paid
4 x (model latency + up to 2s) per round, serially.
- group-rounds: members of a round now take their turns concurrently
(Promise.all). Rounds stay serial so bots still build on each other's
replies. Each member's delta is computed at its own turn start and its
watermark advances only to the pre-turn log length, so sibling replies
that land while it thinks are delivered next round exactly once; a
member's own replies are excluded from its delta by author (they are
already in its session). Message cap enforced per round; stop path
interrupts every member mid-turn (room.turn -> room.turns map).
- group-turns: the poll wakes on the member session's terminal frame
(message.complete / error via host.onEvent), then re-checks at 250ms
until session.running clears. The timer poll stays as a 5s backstop for
hosts without the event tap. Feature-detected; node test harness unaffected.
- group-chat-view: "X is thinking..." lists every member mid-turn.
- docs: bot-mode.md describes concurrent rounds + push-woken replies.
Live A/B (real tui_gateway over WS, 4 members, one round, same model):
serial+2s poll 35.0s -> concurrent+push 8.6s; every turn woke on the event.
Refs #92760
Teknium
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