feat(events): waitlist and capacity enforcement

[BrunaDomingues]

Summary

Completes atomic capacity enforcement and waitlist (FIFO) on top of the RSVP flow (#275): when an event is full, participants are waitlisted if the policy allows, or rejected with 422 otherwise. Occupied seats count confirmed, checked_in, and attended enrollments; audit trail and domain events are emitted on enroll.

Capacity & waitlist (EnrollUserAction)

• scopeActive() on Enrollment: confirmed + checked_in + attended occupy capacity (replaces counting only confirmed in capacity resolution)
• Inside DB::transaction, lockForUpdate() on event and enrollment policy (unchanged from feat(events): rsvp enrollment end-to-end #275; ensures fresh state under concurrent enrollments)
• If capacity is null → always confirmed
• If active count < capacity → confirmed + EnrollmentConfirmed
• If active count >= capacity and has_waitlist=true → waitlisted with waitlist_position = max(position) + 1 + EnrollmentWaitlisted (no EnrollmentConfirmed)
• If active count >= capacity and has_waitlist=false → EnrollmentException::eventFull() (HTTP 422)
• EnrollmentTransition recorded for every enroll (from_status=null, to_status=<initial>, triggered_by=user)

Domain event

• EnrollmentWaitlisted: implements ShouldDispatchAfterCommit (payload: enrollment_id, event_id, user_id, waitlist_position) — no listener in this slice

App panel (participant)

• Event detail: persistent copy “You are on the waitlist (position X)” when waitlisted
• Event detail: “This event is full” when at capacity without waitlist (no Confirm Presence button)
• Success notification uses waitlist message with position after RSVP
• canConfirmPresence / isEventFull use active() scope (aligned with backend)

Admin

• Enrollments relation manager: waitlist_position column (toggleable)
• Status filter unchanged (confirmed, waitlisted, etc.)

Scopes (Enrollment model)

• scopeConfirmed(), scopeWaitlisted(), scopeActive() — active = capacity-occupying statuses only

Architecture

Events module └── Enrollment domain ├── EnrollUserAction (capacity via active() + lockForUpdate) ├── EnrollmentWaitlisted (domain event) └── Enrollment ├── scopeConfirmed / scopeWaitlisted / scopeActive

App panel └── EventDetail (+ waitlist copy, event full state)

Admin panel └── EnrollmentsRelationManager (+ waitlist_position column)

Files (high level)

Area	Count / notes
Actions	EnrollUserAction (active count, dispatch EnrollmentWaitlisted)
Domain events	EnrollmentWaitlisted
Models	Enrollment (scopeActive fix)
Enums	EnrollmentStatus::getResponseMessage(?waitlistPosition)
Lang	en / pt_BR pages (waitlist position, event full)
App panel	EventDetail, event-detail.blade.php
Admin	EnrollmentsRelationManager
Tests	EnrollmentScopeTest, EnrollUserActionTest (+ capacity/FIFO/422/unlimited), RsvpEnrollmentTest (+ UI)

Out of scope (future slices)

• Promote from waitlist on cancellation (FIFO promotion job/action)
• Notifications listener for EnrollmentWaitlisted
• True parallel-process concurrency test (race on last seat)
• Gamification listener for EnrollmentConfirmed

Closes #241
Parent: #237
Blocked by / builds on: #240, #275

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Test plan

• php artisan test --filter=EnrollmentScopeTest
• php artisan test --filter=EnrollUserActionTest
• php artisan test --filter=RsvpEnrollmentTest
• ./vendor/bin/pint --test

Admin

• Edit event with RSVP policy → set capacity and has_waitlist
• Open Enrollments tab → confirm Waitlist column and filter by waitlisted

App — capacity / waitlist

• Event without capacity limit → Confirm Presence → Confirmed
• Fill to capacity with waitlist → next enroll → Waitlisted badge + “position X” on detail + success notification with position
• Fill to capacity without waitlist → “This event is full”, no Confirm Presence button
• Existing enrollment in checked_in occupies last seat → new user → waitlisted (validates active() scope)

App — API / action edge cases

• Enroll when full without waitlist → EnrollmentException / 422 (event_full)
• Multiple enrollments beyond capacity with waitlist → positions 1, 2, … (FIFO)

[GabrielFVDev]

LGTM