Published versions are immutable and a rollback is a new version

Context

A saved decision or pin must retain the meaning of the release it used.

Decision

Edit only the draft, assign a new permanent number at publication, and restore old logic by publishing another release.

Alternatives Considered

Modify released expressions: Existing decisions and pins would change meaning.

Reactivate an old release number: History would no longer describe releases in their publication order.

Consequences

Decisions and pins can identify the expression evaluated. Disjoint effective periods support scheduled releases. Publication compares the validated draft fingerprint before committing.