Point
HEAD carries one coherent contract
The supported repository state contains one internally aligned format, while a separate archive preserves discarded models without making them runtime obligations.
- Posture
- asserted
- Lifecycle
- active
The current branch is expected to explain and execute one meaning without requiring a reader to reconstruct compatibility from old proposals or retired applications. Normative documents, schemas, fixtures, processors, self-hosting records, and release gates must agree at HEAD.
The separate dated archive retains intermediate models and removed code. That archive does not require aliases, migration scaffolding, dormant implementations, or current prose for unsupported behavior. Reintroducing any such surface is a new maintenance decision that needs present evidence and explicit scope.
Contract changeOnly the aligned HEAD contract governs current changes; historical models stay outside runtime behavior.
Lifecycle and reversibilityThe separate archive preserves discarded choices without forcing compatibility or migration obligations into current lifecycle.