Names of the fields that were (or, in dry-run, would be) written.
The per-field diff (old → new) for every rule — the dry-run preview AND the applied record.
True when this was a dry-run (no write attempted).
Per-rule evaluation errors (condition/source/transform), if any. No write happens when present.
True when the entity was saved (always false in dry-run, on error, or when nothing changed).
OptionalSaveSave error detail, when a real apply failed to persist.
Outcome of EntityFieldRules.ApplyToEntity.