A Nexus workflow's shape — its nodes, its edges, its types — is frozen at publish. Logic inside nodes can keep evolving. The result: workflows you can version, diff, replay, and reason about like code.
Other platforms freeze the whole workflow or freeze nothing. Both are wrong. We freeze the contract — the shape callers depend on — and let everything else evolve.
Every version is replayable, diffable, auditable. No tribal knowledge. No "is this the version that broke?" — the answer is in the run record.