Middleware

Place a _.middleware.ts file in any routes/ subdirectory to intercept requests and responses for that subtree. Middleware applies from the root down — a _.middleware.ts at the root runs for every request.

// routes/_.middleware.ts
import type { Middleware } from "../types/_.middleware.js";

export const middleware: Middleware = async ($, respondTo) => {
  if (!$.context.isAuthorized($.auth?.apiKey)) {
    return $.response[401].json({ error: "Unauthorized" });
  }

  return respondTo($);
};

respondTo($) passes the request to the next middleware layer or the route handler, and returns the response. You can modify $ before calling respondTo, modify the response after, or both.

Counterfact generates a _.middleware.ts type file for every directory in the routes tree. Import the matching type from the mirrored directory under types/. For example, routes/admin/_.middleware.ts imports Middleware from types/admin/_.middleware.ts. The generated type automatically uses the nearest _.context.ts file for $.context.

Middleware

See also