Use whenever the user wants to build or modify a chat, agent, or tool-calling
UI in a React 19 + Tailwind v4 project — especially if the code imports from
`@/components/agent-elements/*` or the project has that folder on disk.
Triggers: "agent chat", "tool call UI", "streaming chat", "plan approval",
"AgentChat", "InputBar", "tool renderer", mentions of Agent Elements, or
requests to add a new agent surface with shadcn.
Do NOT use for plain chat UIs that don't need tool/plan/approval cards, or
for projects already committed to a different agent UI kit.
2026-04-23