Journey Version: definition and contract

A Journey Version is an immutable revision of a Product Journey's intent, steps, branches, checkpoints, ownership, and context policy. Editing a Journey creates a new attributable version instead of rewriting the definition used by earlier Runs and Decisions.

Why versions must be immutable

Evidence is only meaningful when it can resolve to the exact contract that produced it. If a step or checkpoint could change underneath an old Run, the same Run might appear to prove a different outcome later. Immutability prevents that reinterpretation.

A Journey Version therefore anchors:

• the State Capsules selected for execution;
• every Run and Observation produced from it;
• the Decision made from that evidence;
• every downstream Rendition and Publication;
• the Release Book that includes the change.

What creates a new version

Changes to outcome, actor, path, branch logic, checkpoints, context policy, target identity, side-effect rules, or protected source constructs require a new version. Editorial changes to a Rendition do not create a Journey Version because they change explanation rather than source truth.

Example: a billing upgrade changes its confirmation

Version 7 may define success as an active subscription plus a visible receipt. If the product later introduces an approval step and delayed activation, the old outcome cannot be edited in place. Version 8 records the new branch, state transition, checkpoint, and downstream impact. Runs against Version 7 remain valid evidence of the earlier contract.

Version versus revision number

A database revision or optimistic-lock counter prevents conflicting writes. A Journey Version carries product meaning. It identifies the immutable definition against which execution, evidence, and downstream freshness are judged.

See Product Journey for the durable object and the open Product Journey Contract for the current machine-readable identity envelope.