Run
Document-level overrides for the model's baked-in simulation run parameters. Each field is optional; null means "inherit whatever the model author set" (the substrate's default behaviour). When non-null, the value replaces the model's setting on every design point's effective run parameters.
Per-design-point replications (ReplicationSpec.Uniform / ReplicationSpec.PerPoint) are deliberately NOT here — they live on the document's ReplicationSpec field because design- point replication count is a per-point concept (CCD centre points conventionally have higher reps than corners). The Experiment app's Model tab cross-links the Uniform-replications case for discoverability without duplicating storage.
This block currently carries two knobs; reserved as the home for additional model-level run-parameter overrides if needed (e.g. clearDataBeforeReplication, startTime).