# IDF System revision history

Append-only Arc G field-change log. Forward-only honesty: events accrue from Arc G adoption.

Model: [IDF System](/models/idf-system.md)

_No events on file. Arc G is forward-only; the recorded event log accrues from Arc G adoption (2026-06-04) and records material changes as they flow through the updateEntityField chokepoint. For the current state of this model, see the model page._

## Forward-only note

Arc G is forward-only. The event log accrues from the Arc G adoption point. Fields with no events post-baseline equal the current cached value and are not independently verified at any prior date. To restate a recorded change, write a new event through the updateEntityField chokepoint.

_Canonical URL: /models/idf-system/history. REST: /v1/models/3d99f233-1f2a-4df8-9f04-bfa1d3261574/history. HTML: [/models/idf-system/history](/models/idf-system/history)._