Epic: Allow annual credit pre-commitments for usage-based

[jankeromnes]

Summary

In the context of usage-based, we would like to allow customers to pre-commit to a certain number of usage credits over (e.g.) the next 12 months.

Context

• RFC (internal)
• Slack thread (internal)

Acceptance Criteria

This likely implies creating a new BillingStrategy (e.g. "stripe-prepaid") for our CostCenters, which should:

• Grant an arbitrary number of prepaid credits that can be used over the next 12 months (after which they expire)
• Be linked to a unique OrderID that represents the unique pre-commitment
• Each month, create an invoice that:
  • Shows the CostCenter's actually-consumed credits during the month
  • Includes the unique OrderID of the pre-commitment
  • Does not require any payment or credit card (the actual payment happens outside of Stripe)
• Each month, the UsageLimit should be set to the total remaining prepaid credits (such that a customer is allowed to consume their entire yearly pre-commitment if they wish to, but not more)
  • Optionally, we can make this UsageLimit customizable by the customer (but it shall always remain between 0 and the total remaining prepaid credits)
  • Optionally, we may allow the customer to set a higher limit, by providing a credit card, such that any over-consumption gets paid at the regular pay-as-you-go rate
• Once all the prepaid credits are consumed, or at the end of the pre-commitment period:
  • Any remaining credits expire and are voided
  • A final invoice is created, which must also include the unique OrderID + recap all the previous invoice IDs

[svenefftinge]

Is this about self-served plans through stripe or high touch sales?
If the latter we can do this already today, by issuing a credit note in the admin dashboard.
Automatic expiration of credits is missing, though, but we can implement that later.

[jldec]

We can handle annual commits manually for now. Closing this issue.

• Invoicing done manually
• Apply credit grant in the admin dashboard
• Balance shown = grant + usage limit - actual usage (usage limit defaults to zero)
• No monthly invoicing required
• Teams should not receive free credits every month (@svenefftinge can you confirm that this is true)
• Credit expiration can be applied in the admin dashboard at the end if necessary, with a negative grant