Where Do Domain Events Get Created? | Domain Driven Design w/ TypeScript

class User {
  // factory method to create users, yep
  public static create (props): User { }  

  // yup, also a valid domain operation
  public deactivate (): void {}       
  
  // ❌ No. A client shouldn't need to use this operation.
  // Use a Value Object to encapsulate validation logic instead: 
  // https://khalilstemmler.com/articles/typescript-value-object/  
  public validateFirstName (firstName): boolean {}            
}

export type OfferState = 'initial' | 'accepted'  | 'declined'

interface OfferProps {
  ...
  state: OfferState;
}

export class Offer extends AggregateRoot<OfferProps> {
  ...

  get offerId (): OfferId {
    return OfferId.create(this._id);
  }

  get offerState (): OfferState {
    return this.props.state;
  }

  public acceptOffer (): Result<any> {
    switch (this.offerState) {
      case 'initial':
        // Notice how there is not a public setter for the
        // 'state' attribute. That's because it's important that
        // we intercept changes to state so that we can create and add
        // a Domain Event to the "observable subject" when it's
        // appropriate to do so.
        this.props.state = 'accepted';
        // And then we create the domain event.
        this.addDomainEvent(new OfferAcceptedEvent(this.offerId));
        return Result.ok<any>();
      case 'accepted':
        return Result.fail<any>(new Error('Already accepted this offer'));
      case 'declined':
        return Result.fail<any>(new Error("Can't accept an offer already declined"));
      default:
        return Result.fail<any>(new Error("Offer was in an invalid state"));
    }
  }

  public declineOffer (): Result<any> {
    switch (this.offerState) {
      case 'initial':
        // Same deal is going on here.
        this.props.state = 'declined';
        this.addDomainEvent(new OfferDeclinedEvent(this.offerId));
        return Result.ok<any>();
      case 'accepted':
        return Result.fail<any>(new Error('Already accepted this offer'));
      case 'declined':
        return Result.fail<any>(new Error("Can't decline an offer already declined"));
      default:
        return Result.fail<any>(new Error("Offer was in an invalid state"));
    }
  }

  private constructor (props: OfferProps, id?: UniqueEntityId) {
    super(props, id);
  }
}

export class AcceptOfferUseCase implements UseCase<AcceptOfferDTO, Result<Offer>> {
  private offerRepo: IOfferRepo;
  private artistRepo: IArtistRepo;

  constructor (offerRepo: IOfferRepo) {
    this.offerRepo = offerRepo
  }

  public async execute (request: AcceptOfferDTO): Promise<Result<Offer>> {
    const { offerId } = request;
    const offer = this.offerRepo.findById(offerId);

    if (!!offer === false) {
      return Result.fail<Offer>(ErrorType.NOT_FOUND)
    }

    // Creates the domain event
    offer.acceptOffer();

    // Persists the offer and dispatches all created domain events
    this.offerRepo.save(offer);
    
    return Result.ok<Offer>(offer)
  }
}