@mottyjs/core

The core of the Motty SDK: all a motty needs to work and a plugin needs to be written. It holds the motty builder, model, the combinators fallback, race, retry and timeout, answer, reroute, think, said, the error classes and the types. It has no dependencies, and only what is imported ends up in a motty's bundle. said(message) is what a message says, whether it came as text or as parts.

bun add @mottyjs/core

import { fallback, model, motty, race, retry, reroute } from "@mottyjs/core";

A motty that answers a request without tools with the first of two small models to reply, and any other with a strong model, retried twice, with a second one behind it:

import { fallback, model, motty, race, retry, reroute } from "@mottyjs/core";

const luna = model("openai/gpt-6-luna");
const sol = model("openai/gpt-6.1-sol");
const haiku = model("anthropic/claude-haiku-5-5");
const sonnet = model("anthropic/claude-sonnet-5-5");

export default motty({ name: "coder" })
  .route(({ request }) => (request.tools.length === 0 ? "quick" : "standard"), {
    // A quick question still gets an answer when both small models are down
    quick: ({ prompt }) => race(luna, haiku).complete(prompt).catch(() => reroute("standard")),
    standard: ({ prompt }) => fallback(retry(sonnet, 2), sol).complete(prompt),
  });

A call may state headers in its options for the request that answers it. They are sent only where the host's connection allows the name, and a header with no value is skipped:

const session = request.headers.get("x-session");
prompt.options = { ...prompt.options, headers: { "x-session": session } };
return sonnet.complete(prompt);

A plugin reaches the host through the import path @mottyjs/core/host.

The SDK as a whole is described in the root README, and the reasons behind its design in ARCHITECTURE.md.