@tysel/sdk

Typed definition helpers for Tysel applications. This npm package is not the Tysel CLI or native runtime; install those through the Tysel installer.

tysel init adds the matching package version automatically. For a manual installation, pin it to the native toolchain version:

version="$(tysel --version | awk '{print $2}')"
npm install --save-dev "@tysel/sdk@$version" "@tysel/types@$version"

Use defineApp when an application needs cross-property inference, notably for MCP input schemas:

import type { TyselEnv } from "./tysel-env.js";
import { defineApp } from "@tysel/sdk";

export default defineApp<TyselEnv>()({
  tasks: {
    lookup: {
      kind: "mcp",
      description: "Look up a customer",
      input: { customerId: "string" },
      async handler(input) {
        return { customerId: input.customerId };
      },
    },
  },
});

The package also exports cron, queue, mcp, and durableTask, plus public types from @tysel/types. Helpers return plain objects; the native runtime provides execution APIs. Applications that do not need helper inference can use satisfies TyselApp directly.

See the runtime API and durable execution guide.