Ledger

Guidance for working with the OpenMeter ledger package (openmeter/ledger/).

Package Structure

• openmeter/ledger/ — core interfaces and primitives: Ledger, Account, SubAccount, Querier, routing, validation, account type definitions
• openmeter/ledger/historical/ — current concrete ledger implementation; books immutable transactions and computes balances by summing entries
• openmeter/ledger/account/ — account and sub-account domain types, posting addresses, route-backed sub-account identity
• openmeter/ledger/account/service/ — account service; New(repo, liveServices) self-wires SubAccountService into AccountLiveServices
• openmeter/ledger/account/adapter/ — ent repo adapter
• openmeter/ledger/resolvers/ — AccountResolver implementation; provisions per-customer accounts and shared business accounts
• openmeter/ledger/resolvers/adapter/ — ent repo for customer→account mapping
• openmeter/ledger/transactions/ — transaction templates, resolution, and prioritized customer-credit collection helpers

Business Domain Model

• customer_fbo currently means customer credit/stored value, not a literal regulated FBO bank account. It includes prepaid, promotional, externally purchased, and similar credit sources.
• customer_receivable tracks value the customer owes but has not yet paid.
• customer_accrued is a staging account for acknowledged usage/spend that is not yet recognized as earnings for reporting.
• Business accounts are namespace-scoped shared accounts:
  • wash represents the outside world / external cash boundary and is expected to run negative
  • earnings receives recognized revenue from accrued
  • brokerage is the business-side offset used in FX flows

Routing Model

• Accounts express ownership and business purpose; sub-accounts are the concrete posting addresses.
• Sub-accounts are identified by canonical route dimensions stored in ledger.Route and encoded into a routing key.
• Active route dimensions today:
  • currency for all account types
  • credit_priority for customer credit (customer_fbo) routing and collection order
  • cost_basis for FX-related routing
• tax_code and features are wired through routing and query code but are deferred from the current business flows.
• Use account-specific route params instead of constructing generic Route values in higher-level domain code:
  • CustomerFBORouteParams
  • CustomerReceivableRouteParams
  • CustomerAccruedRouteParams
  • BusinessRouteParams

Transaction Semantics

• Transaction templates in openmeter/ledger/transactions/ encode posting mechanics, not settlement-mode orchestration.
• Current customer/business posting flows:
  • IssueCustomerReceivableTemplate: customer credit +, customer receivable -
  • FundCustomerReceivableTemplate: wash -, customer receivable +
  • CoverCustomerReceivableTemplate: customer credit -, customer receivable +
  • TransferCustomerFBOToAccruedTemplate: collect from prioritized customer credit sub-accounts into accrued
  • TransferCustomerReceivableToAccruedTemplate: receivable -, accrued +
  • RecognizeEarningsFromAccruedTemplate: accrued -, earnings +
  • ConvertCurrencyTemplate: customer credit and brokerage postings on both source and target legs
• TransferCustomerFBOToAccruedTemplate currently supports partial collection. If no value can be collected it returns nil.
• Longer-term settlement logic is expected to live above templates; collection logic will likely move out of transactions/ into a dedicated package.

Wiring Notes

• account/service.New takes account.AccountLiveServices; Locker is required for customer-account locking and Querier is required for balance lookups.
• The usual composition is account repo + locker + lazy/historical querier + resolver repo + historical repo.
• historical.NewLedger(repo, accountService, locker) is the concrete runtime ledger.
• historical.Ledger.CommitGroup validates balanced transactions, locks affected customer accounts, creates a transaction group, then books transactions.
• Current account locking in CommitGroup applies to customer FBO and customer receivable accounts. Balance-consistency validation is still largely TODO territory.
• resolvers.AccountResolver provisions:
  • three per-customer accounts (customer_fbo, customer_receivable, customer_accrued)
  • three lazily created shared business accounts per namespace (wash, earnings, brokerage)

Testing Gotchas

• Ledger tests are Postgres-backed. Use real migrations, not bare schema creation, when tests rely on route/account/entry integrity.
• For direct go test runs, set POSTGRES_HOST=127.0.0.1 so Postgres-backed tests are not skipped.
• For ledger changes that affect customer credit balance, credit flows, or related API behavior, also run the credit package tests and any referenced end-to-end coverage. At minimum, include POSTGRES_HOST=127.0.0.1 go test -tags=dynamic ./test/credits so the legacy credit stack is covered too.
• openmeter/ledger/testutils/integration.go is the main integration fixture for the ledger domain. It sets up:
  • migrated Postgres schema
  • account service
  • account resolver
  • historical ledger
  • pre-created customer and business accounts
• Transaction tests in openmeter/ledger/transactions/ are a good source of business-domain examples and expected balances.
• Historical adapter tests in openmeter/ledger/historical/adapter/ledger_test.go are the best reference for query/filter behavior and migration-backed setup patterns.

Running Ledger Tests

Prefer direct command execution for ledger verification. Do not wrap commands in sh -lc, bash -lc, or similar helper shells when a direct invocation works. If a Nix shell is required, use nix develop --impure .#ci -c env POSTGRES_HOST=127.0.0.1 go test ... rather than an extra shell wrapper.

# Run all ledger tests
POSTGRES_HOST=127.0.0.1 go test -tags=dynamic -v ./openmeter/ledger/...

# Run specific sub-packages
POSTGRES_HOST=127.0.0.1 go test -tags=dynamic -v ./openmeter/ledger/historical/...
POSTGRES_HOST=127.0.0.1 go test -tags=dynamic -v ./openmeter/ledger/account/...
POSTGRES_HOST=127.0.0.1 go test -tags=dynamic -v ./openmeter/ledger/transactions/...