Subscription & Usage-Based Billing Engine Selection

Helps choose and operate a recurring-billing engine — the system that turns subscriptions and usage into invoices, retries failed payments (dunning), handles proration, and (optionally) does revenue recognition — running on top of your own payment gateway so you stay the seller of record. This is a different decision from a Merchant of Record (who absorbs global tax liability — see /sales-merchant-of-record).

Step 1 — Gather context

If references/learnings.md exists, read it first for accumulated knowledge.

Ask the user (lead with a best-effort answer if they've already told you most of this):