Storage-Rent Aware Contract (Long-Lived State)

{
  // State box that anyone can refresh
  val stateNFT = SELF.tokens(0)._1  // Unique identifier
  val stateData = SELF.R4[Coll[Byte]].get
  val lastRefresh = SELF.R5[Int].get
  
  // Minimum ERG to survive rent (conservative estimate)
  val minRentReserve = 10000000L  // 0.01 ERG
  
  // State operations by owner
  val ownerPK = SELF.R6[SigmaProp].get
  val ownerUpdate = {
    val newState = OUTPUTS(0)
    newState.tokens(0)._1 == stateNFT &&
    newState.value >= minRentReserve &&
    ownerPK
  }
  
  // Anyone can refresh (preserves state, resets rent timer)
  val anyoneRefresh = {
    val refreshedBox = OUTPUTS(0)
    
    // State must be preserved exactly
    val statePreserved = 
      refreshedBox.tokens(0)._1 == stateNFT &&
      refreshedBox.R4[Coll[Byte]].get == stateData &&
      refreshedBox.R6[SigmaProp].get == ownerPK &&
      refreshedBox.propositionBytes == SELF.propositionBytes
    
    // Value must be maintained or increased
    val valueOk = refreshedBox.value >= SELF.value
    
    // Update refresh timestamp
    val timestampUpdated = refreshedBox.R5[Int].get == HEIGHT
    
    statePreserved && valueOk && timestampUpdated
  }
  
  ownerUpdate || anyoneRefresh
}