A pooled robot substituted into an ordinary (non-AI) game never opens the
chat, so a text message to it would linger unread forever — skewing the unread
count and the publish-to-read metric. Clear its recipient bit at PostMessage
time (robotRecipients via account.IsRobot), so the message is born read. The
human sender never had their own message unread, so this is invisible to them;
a nudge to a robot already self-clears when the robot answers by moving.
Persist per-message read state as a chat_messages.unread_seats bitmask
(migration 00008): a text message seeds every recipient seat's bit, a nudge
only the awaited seat's. A seat's bit clears when the player opens the move
history or chat (POST /games/:id/chat/read, sent only when something is
unread), and a nudge additionally clears when its recipient answers by moving
(a wired game NudgeClearer, dependency-inverted so game keeps off social).
UI shows a per-viewer unread dot in the lobby (next to the opponent) and the
game score bar — the unread_chat game-view flag seeds it from authoritative
REST views, live chat/nudge events raise it. Opening the move history counts
as reading (even without entering chat): the 💬 fade-blinks twice and the
client acks. Admin Messages gains an unread-only filter, a read/unread column,
and a per-message card with the per-seat read breakdown. Observability:
chat_read_duration histogram + chat_unread_messages gauge + social tracing.
Ilia Denisov