Grace periods and past due - our current default behavior is: - when the first charge fails, we block access - when the n+1th charge fails, we continue grant access until you cancel their subscription

There's a lot of work to do to make that behavior more configurable, because every merchant has a different policy.

For 3DS we're working on getting more explicit coverage for. Not quite 3DS but related: we currently have it set up so that if your customer successfully adds a payment method but the first charge fails, we also won't grant entitlements in that case.

Lots of weird payments edge cases to work through still.