The ledger is no longer the system of record

The event log is.

The general ledger has been the system of record for five hundred years. CAST inverts that: the event log is the system of record, and the ledger is a projection of it.

The inversion

In conventional accounting, the ledger is authoritative. Everything else — supporting documents, approvals, correspondence — exists to justify the entries in it. When a question arises, you start from the ledger entry and work backward, reconstructing the context that produced it.

CAST reverses the dependency. The authoritative artifact is the append-only event log. Postings are derived from completed work orders, which are derived from events. The ledger is no longer the thing you reconstruct toward — it is a thing you project from the events that already hold the truth.

If every table but the event log were deleted and the log replayed, every posting would reconstruct exactly. The ledger is a view, not the source.

Why this matters

Question	Ledger-first answer	Event-log-first answer
Who approved this?	Reconstruct from email and memory	Read the decision event
What policy applied?	Infer from the date	Read the pinned policy version
Has it been altered?	Hard to prove	Verify the lineage hash
Did both parties agree?	No record of the counterparty	Read the bilateral event

Intellectual lineage

This is not invented from scratch. It builds on Sorter’s events theory of accounting — the idea that the basic data of accounting should be events, not pre-aggregated balances — and on Ijiri’s triple-entry bookkeeping, given a bilateral, cryptographically bound form. CAST is the application of these ideas to commercial payments at the moment AI makes verification the scarce resource.

Deterministic commerce

The consequence: reconciliation should not exist.