Workflow Versioning Prevents Silent Behavior Swaps Mid-Flight

Deployments change workflow definitions while instances are running, and versioning is what keeps an in-flight workflow finishing under the rules it started with.

An in-flight workflow that silently adopts new step definitions is running a program nobody wrote. Version pinning is the difference between deploying software and mutating it.

Versioning rules

• Instances record their definition version at start.
• Steps resolve against the pinned version, not the latest.
• Migration between versions is an explicit, audited operation.

Use the architecture guide, changelog, and blackboard schema to let deployments ship without mutating work already in flight.