Agents you can replay, fork and trust.

import { agent, sqlite, tool } from "@threads/core";
import { anthropic } from "@threads/anthropic";
import { z } from "zod";

const getWeather = tool({
  name: "get_weather",
  description: "Get the weather for a city.",
  input: z.object({ city: z.string() }),
  runs: "host",
  effect: "read_only",
  execute: async ({ city }) => `It is sunny in ${city}.`,
});

const weather = agent({
  name: "weather",
  instructions: "Answer questions about the weather.",
  model: anthropic({
    model: "claude-sonnet-5",
    maxTokens: 8192,
    contextWindow: 200_000,
    maxOutputTokens: 8192,
  }),
  tools: [getWeather],
});

const result = await weather.run("What is the weather in Paris?", {
  store: sqlite(".threads"),
});
if (result.status === "completed") console.log(result.output);