Contracts that are created without an expiry date should switch to ongoing immediately after being activated
Contracts will transition to ongoing when their latest open billing period exceeds the expiry date minus the default termination period
Any contracts that get left behind by the above 2 points (should be all of them) or where previously incorrectly set to Active will transition to ongoing when the 'generate pending billings' background task runs.
To prevent transitioning to ongoing, Contracts should have a termination scheduled before expiry date is within the default termination period from now.