Wiring the whole application in one file

Nothing in this codebase imports its own dependencies. Modules are factory functions taking a plain object, and the container decides what goes in it — which is what makes the services testable without mocking module loaders.

This is an excerpt; the real file is roughly 500 lines of exactly this shape:

// IMPERSONATION (generic — shared by every future impersonable actor type)
import { makeImpersonationSessionsRepo } from "./modules/impersonation/impersonationSessions.repo.js";

// LANDLORD_ADMIN RATE LIMITERS
import { makeLandlordadminRateLimiters } from "./modules/landlord_admin/middlewares/landlordadminRateLimiters.js";

const container = createContainer();

// -------------------------------------
// GLOBAL DEPENDENCIES
// -------------------------------------
container.register({
  db: asValue(db),
  redis: asValue(redis),
  env: asValue(env),
  logger: asValue(logger)
});

// -------------------------------------
// GLOBAL UTILITIES
// -------------------------------------
container.register({
  passwordService: asFunction(makePasswordService).singleton(),
  tokenService: asFunction(makeTokenService).singleton(),
  linkService: asFunction(makeLinkService).singleton()
});

// -------------------------------------
// HQLEAD MIDDLEWARES
// -------------------------------------
container.register({
  verifyHQLeadJWT: asFunction(makeVerifyHQLeadJWT).singleton(),
  verifyHQLeadRole: asFunction(makeVerifyHQLeadRole).singleton(),
  verifyHQLeadCSRF: asFunction(makeVerifyHQLeadCSRF).singleton(),
  getHQLeadActor: asFunction(makeGetHQLeadActor).singleton()
});

// -------------------------------------
// HQLEAD REPO / SERVICE / CONTROLLER
// -------------------------------------
container.register({

asValue registers something already constructed — the database pool, the Redis client, the logger. asFunction registers a factory the container calls, resolving each parameter by name.

So a service declaring { redis, landlordadminIdentityRepo } receives them without naming a file path. In tests it receives fakes instead, with no module interception and no framework. The cost is real and worth stating: resolution happens by string name, so a typo surfaces at runtime rather than when the file is compiled.