Module reference

Everything a function declares, it declares in its own file, read at deploy time. One surface export — http, mcp, or app (never more than one) — plus config for runtime capabilities.

export const http

Deploys the default export as an HTTP endpoint at /f/<name>. The whole export is optional — a bare default handler deploys with the defaults below.

export const http = { name: "hook", methods: ["POST"], path: "/repos/{repo}", access: "public" };

export default async function handler(request, context) {
  const payload = await request.json().catch(() => ({}));
  return context.json({ repo: request.params.repo, ok: true });
}

Script mode

A file with no export or import statement is a script: its statements run top to bottom as the body of a GET handler, and its return is the response. Quick calculations and one-off scripts need nothing else.

const t = 1;
const b = 2;

return t + b;

request, context, fetch, console.log and top-level await are all in scope. The return value picks the content type: an object or array is JSON, a string is text unless it starts with a tag (then HTML), a number or boolean is text, no return is a null body, and context.json/text/html/redirect work as in a handler. A script declares nothing, so it has no capabilities — no context.db, secrets, state or objects — and takes its name and access from the push: rusted push calc.js --name calc --access public, or inline with no file at all: rusted push --script 'return 1 + 2' --name calc. --method and --path still override. Script mode is JavaScript: TypeScript goes through the bundler, which rejects a top-level return.

export const mcp

Deploys the module as an MCP server at /f/<name> — tools are the interface, so an mcp module must not have a default export. Arguments are validated against each tool's schema before its handler runs. See MCP.

export const mcp = {
  name: "calculator",
  tools: {
    add: {
      description: "Add two numbers",
      inputSchema: { type: "object", properties: { a: { type: "number" }, b: { type: "number" } }, required: ["a", "b"] },
      async handler({ a, b }) { return a + b; },
    },
  },
};

export const app

The third surface: Express-style routes, middleware, and path parameters under one function's URL, built with the rusted.app() chain. Routes are the interface — an app module has no default export, and the route table is inspected and validated at deploy time like mcp tools. See Web apps.

export const app = rusted
  .app({ name: "todo-app", access: "public" })
  .use(loggingMiddleware)
  .get("/", homeHandler)
  .post("/todos/{id}/toggle", toggleHandler);

export const config

Runtime capabilities. Nothing is on by default — a function gets exactly what it declares, and the console shows what each function asked for.

export const config = {
  secrets: ["GITHUB_TOKEN"],
  state: true,
  objects: {
    UPLOADS: {
      endpoint: "https://<account>.r2.cloudflarestorage.com",
      bucket: "uploads",
      maxObjectBytes: 5_000_000,
      accessKeyIdSecret: "R2_KEY_ID",
      secretAccessKeySecret: "R2_KEY_SECRET",
    },
  },
};