Replace the new-chat <Select label="Agent role"> picker with colored role
cards rendered as the empty-state of a brand-new chat (centered in the window),
per docs/backlog/ai-chat-role-cards-empty-state.md. Clicking a card selects that
identity; sending without a pick falls back to the Universal assistant; the
cards disappear once the chat is non-empty. Purely client-side — the existing
selectedAiRoleIdAtom + roleId request wiring (server role fixation on chat
creation) is unchanged.
- new RoleCards rendered through the existing emptyState prop chain
(AiChatWindow -> ChatThread -> MessageList); MessageList already supported it.
- Universal assistant card (gray, value null, default-selected) + one card per
enabled role, color cycled from a 10-name Mantine palette via the pure
roleCardColor() helper; theme-aware CSS vars (light/-light-color/-filled).
- each card is an UnstyledButton with aria-pressed for a11y + testability.
- tests: role-card-color (palette cycling, negative-safe) + role-cards.test.tsx
(render, emoji/name, selection highlight, click -> onSelect). 9 tests green,
client tsc clean.
Verified live in-browser: cards (not a Select) show for a new chat; selecting
Пират binds the chat to that role end-to-end (badge + pirate reply); no pick =>
Universal; cards vanish after the first message.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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