Decision replay and model monitoring answer different questions.

Monitoring observes the engine.

Monitoring can detect drift, latency, errors, unusual outputs and changes in service performance. Those controls remain necessary for the model or application.

Replay reconstructs the governed decision.

A decision can depend on model output, operational evidence, a policy version, human authority and an action performed elsewhere. Replay keeps those dependencies attached to the decision identity.

When a required dependency is missing or has changed, a trustworthy replay process should report the mismatch instead of presenting a false success.

The controls complement one another.

Monitoring helps operators understand current system behavior. Replay helps assurance, audit and operations teams reconstruct a past enterprise decision. DTF does not replace the monitoring stack that owns the model itself.