duplicateTargetIds property
Duplicated step targetIds within one tour — a tour-authoring error (one tour at a time, a duplicated target is ambiguous). The check is cheap and lazy; used by the controller's start-validation.
Implementation
Set<String> get duplicateTargetIds {
final seen = <String>{};
final duplicates = <String>{};
for (final step in steps) {
if (!seen.add(step.targetId)) {
duplicates.add(step.targetId);
}
}
return duplicates;
}