@startuml uc-12-level-up
autonumber
title UC-12 Level Up at Review Board (design sequence)
actor Player
participant "ReviewBoundary\n«/api/characters/{id}/level-up»" as boundary <<boundary>>
participant "ReviewBoard\nsb-core::character::level_up" as control <<control>>
participant "Progression\nxp_for_level + level_up_cost" as entity <<entity>>

== Level up ==
Player -> boundary : POST level-up
boundary -> control : level_up(character)
control -> entity : xp_for_level(next) = 18*100*level^2
control -> entity : cost = 500 * next level
alt at max level 100
  control --> boundary : 422 (DomainError)
else XP below threshold
  control --> boundary : 422 (DomainError)
else gold < cost
  control --> boundary : 422 (DomainError)
else ok
  control -> entity : level += 1, gold -= cost
  control -> entity : recompute + fully restore\nHP/energy/nerve/max SP, persist
  control --> boundary : {success, message, character}
  boundary --> Player : {success, message, character}
end
@enduml