Annual creative credits and prorated refunds with Fincra checkout

We are evaluating Fincra as an additional checkout option for ai video generator, a browser-based image and video creation service that offers annual subscriptions and one-time credit packs. Our current checkout uses another provider; we have not integrated Fincra.

1. If an annual plan issues its credits up front, which Fincra payment event should trigger the initial credit grant, and what identifier should deduplicate retried webhooks?

2. For a partial refund months later, can the original transaction be referenced when refunding the unused portion, while already-consumed generation credits remain in our own ledger?

3. If a payment is disputed after some credits have been used, which webhook events should we use to pause remaining credits and reconcile the final outcome?

We would appreciate pointers to the relevant API and sandbox events before designing this integration.