Phantom Type State Machines for Privileged Security Workflows

interface Unverified {}
interface Verified {}
 
class SecurityPipeline<State = Unverified> {
  private constructor(private readonly payload: string) {}
 
  static create(payload: string): SecurityPipeline<Unverified> {
    return new SecurityPipeline<Unverified>(payload);
  }
 
  verify(this: SecurityPipeline<Unverified>, secret: string): SecurityPipeline<Verified> {
    if (secret !== "SECRET_KEY") throw new Error("Invalid key");
    return new SecurityPipeline<Verified>(this.payload);
  }
 
  execute(this: SecurityPipeline<Verified>): string {
    return `Executing payload: ${this.payload}`;
  }
}