Branching logic for engagement-based paths

A linear sequence sends the same follow-up to a contact who clicked your demo link and a contact who never opened the first email. That equivalence wastes the engaged contact's attention — they receive content calibrated for cold prospects — and misses the conversion window when intent is highest. iso-25010:2011 functional-suitability.functional-completeness treats this as a completeness failure: the system claims to run campaigns but cannot differentiate its behavior based on the core input it tracks. At the business level, a branching gap means every click and reply is detected but never acted on, turning your engagement data into a vanity metric.

Add step_on_engage and step_on_no_engage fields to step records, then resolve the next step at advancement time rather than at sequence design time.

interface SequenceStep {
  id: string
  action: 'send_email' | 'wait' | 'condition'
  delayDays: number
  templateId: string | null
  stepOnEngage: string | null    // jump here if contact opened or clicked
  stepOnNoEngage: string | null  // use if not engaged (null = continue linear)
}

async function resolveNextStep(enrollment: Enrollment, step: SequenceStep): Promise<string | null> {
  if (step.stepOnEngage) {
    const engaged = await checkEngagement(enrollment.contactId, step.emailId)
    return engaged ? step.stepOnEngage : step.stepOnNoEngage
  }
  return step.defaultNextStepId
}

At minimum, treat clicks and replies as the engagement signals — opens alone are unreliable under Apple Mail Privacy Protection.