Finance — Core concepts

Concept	Meaning
Billing	Charge context created from booking/subscription; owns payment option and split context.
BillingPeriod	Financial period used to group lines, especially for subscription schedules.
Invoice	Receivable document sent to the customer/account.
InvoiceLine	A concrete fee, discount, add-on, adjustment, or booking-linked line.
CreditNote	Negative/adjustment document that balances a reduction after invoicing.
FinanceTransaction	Search/read projection over invoice, credit note, and payment state.
InvoiceScheduler	Job/scheduler that processes or issues invoices.
Preview Billing Difference	Read-only computation for financial deltas during booking edits.
Accounting Provider	External accounting system such as Xero.

Billing vs Invoice

Billing is the charging context. Invoice is the financial document users and finance operations see. One billing context can produce multiple invoices when split rules apply.

Invoice vs FinanceTransaction

Invoice and CreditNote are source records. FinanceTransaction is a projection for search/list/sync behavior. If they drift, trust the source records and refresh or reconcile the projection.

Ownership summary

Owner	Owns
Billing	Payment option, split context, invoice preparation data.
Invoice	Header, lines, status, lock/processing state.
CreditNote	Header, lines, allocation links.
FinanceTransaction	Projection/search state.
Payment	Provider transaction and payment batch state, not invoice lifecycle.