chat-agent-on-boot-hook.md

@trigger.dev/sdk	minor

Adds onBoot to chat.agent — a lifecycle hook that fires once per worker process picking up the chat. Runs for the initial run, preloaded runs, AND reactive continuation runs (post-cancel, crash, endRun, requestUpgrade, OOM retry), before any other hook. Use it to initialize chat.local, open per-process resources, or re-hydrate state from your DB on continuation — anywhere the SAME run picking up after suspend/resume isn't enough.

const userContext = chat.local<{ name: string; plan: string }>({ id: "userContext" });

export const myChat = chat.agent({
  id: "my-chat",
  onBoot: async ({ clientData, continuation }) => {
    const user = await db.user.findUnique({ where: { id: clientData.userId } });
    userContext.init({ name: user.name, plan: user.plan });
  },
  run: async ({ messages, signal }) =>
    streamText({ model: openai("gpt-4o"), messages, abortSignal: signal }),
});

Use onBoot (not onChatStart) for state setup that must run every time a worker picks up the chat — onChatStart fires once per chat and won't run on continuation, leaving chat.local uninitialized when run() tries to use it.