Mediator

Mediator is the typed execution gateway for handlers inside a module. It uses handler contracts to provide type-safe execute(...) calls.

What Mediator does

• resolves handlers registered in the current module
• enforces contract key/payload/response types at compile time
• applies pre-handlers and scenarios during execution

Injecting Mediator

class UserController {
  constructor(private readonly queryMediator: Deps["queryMediator"]) {}
}

Executing a query

const user = await this.queryMediator.execute("users/get-user", {
  userId: req.params.id,
});

If handler contract changes, execute(...) typing updates automatically.

Scenarios and middleware

Mediator accepts execution options for scenarios with selecting proper return type by used scenario:

const result = await this.queryMediator.execute(
  "users/get",
  { userId: "u-1" },
  {
    executionContext: req.context,
    scenario: "auth-only",
    includePreHandlerKeys: ["auth"],
  },
);

This keeps controller code simple while preserving strict types for payload and return type of handlers.