The old startup-only entry point startDirSyncApply is gone; the module now exports startWorkerDirSync, which still arms that apply step and then adds beforeTurn (pull and apply incoming files) and afterTurn (push locally changed files, republish the record of what the worker holds).
The module is loaded on demand; if the import fails the session logs dir_sync_worker_import_failed and simply runs with no syncing.
Evidence
startWorkerDirSync
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
