Waitlist Automation

[!NOTE] Waitlist assignment and promotion are active in production code paths.

How waitlist is triggered

A registration is placed on waitlist when:

• capacity is set, and
• confirmedCount is already at or above capacity

The registration is saved with:

• status: waitlist
• waitlistPosition: next queue number

FIFO promotion logic

When organiser increases capacity, EventSlot promotes in ascending waitlistPosition.

Attendee notifications on promotion

After promotion, EventSlot attempts to send slot-confirmed email per promoted registrant and records email diagnostics for support.

Waitlist position display

Attendees can see queue position via registration status surfaces that read waitlistPosition from their registration record.

Promotion pseudocode

on capacity increase(newCapacity):
  addedSlots = newCapacity - oldCapacity
  if addedSlots <= 0: reject

  queue = waitlist ordered by waitlistPosition asc
  promote = first min(addedSlots, queue.length)

  for each registration in promote:
    set status = confirmed
    clear waitlistPosition

  confirmedCount += promote.length
  waitlistCount  -= promote.length

Edge cases

Multiple cancellations

Cancellations free capacity pressure but direct cancellation flow and promotion flow are independent. Organisers can also increase capacity to trigger deterministic batch promotion.

Capacity reduction

Current capacity endpoint enforces increase-only behavior. Reducing capacity is intentionally blocked by this route to avoid forced demotions.