Usage meters records aggregation CONSUMPTION
Billing Lifecycle periods clock invoice-gen WHEN — the clock
Credits ledger credit-notes adjustments TRUTH
Customer identity payment-methods health WHO — shared context
Collection charge provider-api reconciliation HOW
Stripe payment-intents webhooks External
Dunning escalation retry-logic consequences FAILURE
Entitlements derivation enforcement ACCESS
usage.aggregated invoice.generated invoice.finalized payment.execute payment.failed payment.succeeded retry.triggered context.read segment.applied

As long as Stripe owns the clock, the domain can't decide WHEN to bill — and WHEN gates everything else.

stripe.Subscription decides when periods start and end, when invoices are created, when charges fire. changes_calculator already solves WHAT — plans, quantities, prices, line items. Take over the clock and the rest falls into place.

Seven domains. For each: what already exists in production (backed by graph mechanisms), what Q2 is building, and what remains after Q2. The "Remains" column is shorter than you'd expect.

DomainAlready existsQ2 buildsRemains after Q2
Billing Lifecyclechanges_calculator solves WHAT. fakestripe encodes the clock rules. 216 graph nodes.Registrar proves invoicing beyond subscriptions.Domain clock — BillingSchedule, domain invoice generation.
CollectionPaymentIntent execution. On/off-session. 637 graph nodes — largest domain.Live payment on all 5 paths. Deferred collection. UC for 10 products.CollectionRequest abstraction. Provider routing beyond Stripe.
DunningRecompute engine. Consequence orchestration. 374 graph nodes.Brain sole decision-maker. Clean pipe. Segment rules.Policy engine — segment-based escalation, revenue-aware retry.
Credits3 credit note creation paths. Role-based approval. 127 graph nodes.Honest Invoicing builds credit note pipeline. First domain-level accounting.Domain credit ledger. Pre-charge application during invoice generation.
CustomerBrain reads all 6 stores. subs_customer + subs_account. 59 graph nodes.Brain expansion = unified state in implementation. State API designs interface.Unified BillingCustomer model. Queryable health for all consumers.
UsagePer-product metering for Workers, R2, Stream. 19 graph nodes.—Unified meter registry. Single ingestion pipeline.
Entitlements~50 product services check entitlements. 29 graph nodes.Smart Checkout gates entitlements on confirmation.Event-derived entitlements. Decoupled from Stripe subscription state.

Five of seven domains get direct Q2 investment. The two that don't — Usage and Entitlements — already have working implementations that improve as the others mature. Usage needs the domain clock before it can land on domain invoices. Entitlements improve automatically as payment ordering and dunning become reliable.

The "Remains after Q2" column is the real roadmap. Notice what it asks for: a domain clock, a collection abstraction, a policy engine, a credit ledger, a unified customer model, a usage pipeline, event-derived entitlements. These are incremental additions to infrastructure that Q2 puts in place — not rewrites of what exists.