Upgrade Scala 3.8.2 and sbt 1.11.6

.github/workflows/core-tests.yml

@@ -17,7 +17,7 @@ jobs:
 
       - name: Install sbt
         run: |
-          curl -fsSL "https://github.com/sbt/sbt/releases/download/v1.10.7/sbt-1.10.7.tgz" | sudo tar xz -C /usr/local
+          curl -fsSL "https://github.com/sbt/sbt/releases/download/v1.11.6/sbt-1.11.6.tgz" | sudo tar xz -C /usr/local
           echo "/usr/local/sbt/bin" >> "$GITHUB_PATH"
 
       - name: Check formatting

build.sbt

@@ -1,4 +1,4 @@
-val scala3Version = "3.5.2"
+val scala3Version = "3.8.2"
 
 lazy val root = project
   .in(file("."))

project/build.properties

@@ -1 +1 @@
-sbt.version=1.10.6
+sbt.version=1.11.6

src/main/scala/sfc/agents/Banking.scala

@@ -1,7 +1,6 @@
 package sfc.agents
 
 import sfc.config.SimParams
-import sfc.engine.*
 import sfc.engine.mechanisms.{Macroprudential, YieldCurve}
 import sfc.types.*
 import sfc.util.KahanSum.*

src/main/scala/sfc/agents/Household.scala

@@ -690,14 +690,14 @@ object Household:
   /** Base income, benefit, and updated status for one HH. */
   private def computeIncome(hh: State)(using SimParams): (PLN, PLN, HhStatus) =
     hh.status match
-      case HhStatus.Employed(firmId, sectorIdx, wage)    =>
+      case HhStatus.Employed(firmId, sectorIdx, wage) =>
         (wage, PLN.Zero, hh.status)
-      case HhStatus.Unemployed(months)                   =>
+      case HhStatus.Unemployed(months)                =>
         val benefit = computeBenefit(months)
         (benefit, benefit, HhStatus.Unemployed(months + 1))
-      case HhStatus.Retraining(monthsLeft, target, cost) =>
+      case HhStatus.Retraining(monthsLeft, _, cost)   =>
         (PLN.Zero, PLN.Zero, hh.status)
-      case HhStatus.Bankrupt                             =>
+      case HhStatus.Bankrupt                          =>
         (PLN.Zero, PLN.Zero, HhStatus.Bankrupt)
 
   /** Skill decay for long-term unemployed (onset after scarringOnset months).

src/main/scala/sfc/agents/Immigration.scala

@@ -23,7 +23,7 @@ object Immigration:
   /** Monthly immigration inflow. Exogenous: fixed rate × workingAgePop.
     * Endogenous: responds to (domesticWage / foreignWage − 1) × elasticity.
     */
-  def computeInflow(workingAgePop: Int, wage: PLN, unempRate: Double, month: Int)(using p: SimParams): Int =
+  def computeInflow(workingAgePop: Int, wage: PLN, unempRate: Double, @scala.annotation.unused month: Int)(using p: SimParams): Int =
     if !p.flags.immigration then 0
     else if p.flags.immigEndogenous then
       val wageGap = (wage.toDouble / p.immigration.foreignWage.toDouble - 1.0).max(0.0)

src/main/scala/sfc/agents/Nbfi.scala

@@ -121,16 +121,16 @@ object Nbfi:
     */
   def step(
       prev: State,
-      employed: Int,       // employed workers
-      wage: PLN,           // average monthly wage
-      priceLevel: Double,  // CPI price level (unused in current spec, kept for interface stability)
-      unempRate: Ratio,    // unemployment rate
-      bankNplRatio: Ratio, // aggregate bank NPL ratio (tightness signal)
-      govBondYield: Rate,  // government bond yield (annualised)
-      corpBondYield: Rate, // corporate bond yield (annualised)
-      equityReturn: Rate,  // equity monthly return
-      depositRate: Rate,   // bank deposit rate (TFI opportunity cost)
-      domesticCons: PLN,   // domestic consumption (NBFI credit base)
+      employed: Int,                               // employed workers
+      wage: PLN,                                   // average monthly wage
+      @scala.annotation.unused priceLevel: Double, // CPI price level (unused in current spec, kept for interface stability)
+      unempRate: Ratio,                            // unemployment rate
+      bankNplRatio: Ratio,                         // aggregate bank NPL ratio (tightness signal)
+      govBondYield: Rate,                          // government bond yield (annualised)
+      corpBondYield: Rate,                         // corporate bond yield (annualised)
+      equityReturn: Rate,                          // equity monthly return
+      depositRate: Rate,                           // bank deposit rate (TFI opportunity cost)
+      domesticCons: PLN,                           // domestic consumption (NBFI credit base)
   )(using p: SimParams): State =
     // TFI: inflow + investment income + rebalance
     val netInflow = tfiInflow(employed, wage, equityReturn, govBondYield, depositRate)

src/main/scala/sfc/config/SimParams.scala

@@ -47,6 +47,7 @@ case class SectorDef(
   * Polish GDP (~3.5 bln PLN). Do NOT construct SimParams directly with unscaled
   * values — always start from `defaults` and use `.copy()`.
   */
+@annotation.nowarn("msg=unused private member") // Scala 3.8 false positive: defaults used via copy()
 case class SimParams private (
     flags: FeatureFlags = FeatureFlags(),
     pop: PopulationConfig = PopulationConfig(),

src/main/scala/sfc/engine/Simulation.scala

@@ -3,7 +3,6 @@ package sfc.engine
 import sfc.accounting.*
 import sfc.agents.*
 import sfc.config.*
-import sfc.types.*
 
 import scala.util.Random
 

src/main/scala/sfc/engine/markets/IntermediateMarket.scala

@@ -1,6 +1,6 @@
 package sfc.engine.markets
 
-import sfc.agents.{Firm, TechState}
+import sfc.agents.Firm
 import sfc.config.SimParams
 import sfc.types.*
 import sfc.util.KahanSum.*

src/main/scala/sfc/engine/markets/LaborMarket.scala

@@ -83,7 +83,7 @@ object LaborMarket:
       households: Vector[Household.State],
       firms: Vector[Firm.State],
       marketWage: PLN,
-      rng: Random,
+      @scala.annotation.unused rng: Random,
   )(using p: SimParams): JobSearchResult =
     val vacancies = computeVacancies(households, firms)
     if vacancies.isEmpty then JobSearchResult(households, 0)

src/main/scala/sfc/engine/mechanisms/Macroprudential.scala

@@ -105,7 +105,7 @@ object Macroprudential:
 
   private[engine] def withinConcentrationLimitImpl(
       bankLoans: Double,
-      bankCapital: Double,
+      @scala.annotation.unused bankCapital: Double,
       totalSystemLoans: Double,
   )(using p: SimParams): Boolean =
     if totalSystemLoans <= 0 then true

src/main/scala/sfc/engine/mechanisms/SectoralMobility.scala

@@ -83,7 +83,7 @@ object SectoralMobility:
       matrix: Vector[Vector[Double]],
       vacancyWeight: Double,
       rng: Random,
-  )(using p: SimParams): Int =
+  )(using @scala.annotation.unused p: SimParams): Int =
     val scores = gravityScores(from, wages, vacancies, matrix, vacancyWeight)
     val total  = scores.sum
     if total <= 0.0 then uniformFallback(from, rng)

src/main/scala/sfc/montecarlo/McRunner.scala

@@ -20,7 +20,7 @@ object McRunner:
   /** Run one simulation with given seed. Throws [[Sfc.SfcViolationException]]
     * on any SFC identity violation.
     */
-  def runSingle(seed: Long, rc: McRunConfig)(using p: SimParams): RunResult =
+  def runSingle(seed: Long, @scala.annotation.unused rc: McRunConfig)(using p: SimParams): RunResult =
     val init  = WorldInit.initialize(seed)
     var state = Simulation.SimState(init.world, init.firms, init.households)
 

src/main/scala/sfc/types.scala

@@ -6,11 +6,9 @@ object types:
   // === Entity IDs ===
   opaque type BankId = Int
   object BankId:
-    inline def apply(i: Int): BankId = i
-    val NoBank: BankId               = -1
-    extension (b: BankId)
-      inline def toInt: Int              = b
-      inline def ==(other: Int): Boolean = b == other
+    inline def apply(i: Int): BankId            = i
+    val NoBank: BankId                          = -1
+    extension (b: BankId) inline def toInt: Int = b
 
   opaque type FirmId = Int
   object FirmId:

src/test/scala/sfc/accounting/SfcSpec.scala

@@ -109,6 +109,7 @@ class SfcSpec extends AnyFlatSpec with Matchers:
       )
     }.toVector
 
+  @annotation.nowarn("msg=unused private member") // defaults used by callers
   private def makeHouseholds(n: Int, savings: Double = 15000.0, debt: Double = 0.0): Vector[Household.State] =
     (0 until n).map { i =>
       Household.State(

src/test/scala/sfc/agents/BankingSectorPropertySpec.scala

@@ -20,6 +20,7 @@ class BankingSectorPropertySpec extends AnyFlatSpec with Matchers with ScalaChec
 
   private val configs = Banking.DefaultConfigs
 
+  @annotation.nowarn("msg=unused private member") // defaults used by callers
   private def mkBank(
       id: Int = 0,
       deposits: PLN = PLN(1e6),

src/test/scala/sfc/agents/HouseholdSpec.scala

@@ -136,9 +136,9 @@ class HouseholdSpec extends AnyFlatSpec with Matchers:
   // --- Variable-rate debt service + deposit interest ---
 
   "Household.step with bankRates" should "use variable lending rate for debt service" in {
-    val rng                = new Random(42)
-    val debt               = PLN(100000.0)
-    val hhs                = Vector(
+    val rng              = new Random(42)
+    val debt             = PLN(100000.0)
+    val hhs              = Vector(
       mkHousehold(
         0,
         HhStatus.Employed(FirmId(0), SectorIdx(0), PLN(8000.0)),
@@ -155,16 +155,16 @@ class HouseholdSpec extends AnyFlatSpec with Matchers:
       ),
     )
     // Bank 0: 6% annual lending rate, Bank 1: 10% annual
-    val br                 = BankRates(
+    val br               = BankRates(
       lendingRates = Vector(Rate(0.06), Rate(0.10)),
       depositRates = Vector(Rate(0.04), Rate(0.04)),
     )
-    val (_, agg, maybePbf) =
+    val (_, _, maybePbf) =
       Household.step(hhs, mkWorld(), PLN(8000.0), PLN(4666.0), 0.4, rng, nBanks = 2, bankRates = Some(br))
-    val pbf                = maybePbf.get
+    val pbf              = maybePbf.get
     // Expected debt service: debt * (HhBaseAmortRate + lendingRate/12)
-    val expectedDs0        = debt.toDouble * (p.household.baseAmortRate.toDouble + 0.06 / 12.0)
-    val expectedDs1        = debt.toDouble * (p.household.baseAmortRate.toDouble + 0.10 / 12.0)
+    val expectedDs0      = debt.toDouble * (p.household.baseAmortRate.toDouble + 0.06 / 12.0)
+    val expectedDs1      = debt.toDouble * (p.household.baseAmortRate.toDouble + 0.10 / 12.0)
     pbf(0).debtService shouldBe PLN(expectedDs0) +- PLN(0.01)
     pbf(1).debtService shouldBe PLN(expectedDs1) +- PLN(0.01)
     // Bank 1's higher rate should mean higher debt service
@@ -271,25 +271,25 @@ class HouseholdSpec extends AnyFlatSpec with Matchers:
   // --- Immigration: remittance deduction ---
 
   "Household.step" should "not deduct remittances from non-immigrant HH" in {
-    val rng               = new Random(42)
-    val wage              = 8000.0
-    val hhs               = Vector(
+    val rng         = new Random(42)
+    val wage        = 8000.0
+    val hhs         = Vector(
       mkHousehold(0, HhStatus.Employed(FirmId(0), SectorIdx(2), PLN(wage)), savings = PLN(50000.0))
         .copy(isImmigrant = false),
     )
-    val (updated, agg, _) = Household.step(hhs, mkWorld(), PLN(wage), PLN(4666.0), 0.4, rng)
+    val (_, agg, _) = Household.step(hhs, mkWorld(), PLN(wage), PLN(4666.0), 0.4, rng)
     agg.totalRemittances shouldBe PLN.Zero
   }
 
   it should "not deduct remittances from immigrant HH when disabled" in {
-    val rng               = new Random(42)
-    val wage              = 8000.0
-    val hhs               = Vector(
+    val rng         = new Random(42)
+    val wage        = 8000.0
+    val hhs         = Vector(
       mkHousehold(0, HhStatus.Employed(FirmId(0), SectorIdx(2), PLN(wage)), savings = PLN(50000.0))
         .copy(isImmigrant = true),
     )
     // ImmigEnabled is false by default → no remittance deduction
-    val (updated, agg, _) = Household.step(hhs, mkWorld(), PLN(wage), PLN(4666.0), 0.4, rng)
+    val (_, agg, _) = Household.step(hhs, mkWorld(), PLN(wage), PLN(4666.0), 0.4, rng)
     agg.totalRemittances shouldBe PLN.Zero
   }
 

src/test/scala/sfc/engine/HousingMarketPropertySpec.scala

@@ -35,6 +35,7 @@ class HousingMarketPropertySpec extends AnyFlatSpec with Matchers with ScalaChec
     PLN.Zero,
   )
 
+  @annotation.nowarn("msg=unused private member") // defaults used by callers
   private def mkFlows(
       interest: Double = 0.0,
       principal: Double = 0.0,

src/test/scala/sfc/engine/HousingMarketSpec.scala

@@ -35,6 +35,7 @@ class HousingMarketSpec extends AnyFlatSpec with Matchers:
   ): HousingMarket.StepInput =
     HousingMarket.StepInput(prev, Rate(mortgageRate), Rate(inflation), Rate(incomeGrowth), employed, Rate(prevMortgageRate))
 
+  @annotation.nowarn("msg=unused private member") // defaults used by callers
   private def mkFlows(
       interest: Double = 0.0,
       principal: Double = 0.0,

src/test/scala/sfc/engine/IntermediateMarketSpec.scala

@@ -52,6 +52,7 @@ class IntermediateMarketSpec extends AnyFlatSpec with Matchers:
       greenCapital = PLN.Zero,
     )
 
+  @annotation.nowarn("msg=unused private member") // default used by callers
   private def makeFirmsAllSectors(perSector: Int = 10): Vector[Firm.State] =
     (0 until 6).flatMap { s =>
       (0 until perSector).map(i => makeFirm(s * perSector + i, s))

src/test/scala/sfc/engine/KnfBfgSpec.scala

@@ -15,6 +15,7 @@ class KnfBfgSpec extends AnyFlatSpec with Matchers:
   given SimParams          = SimParams.defaults
   private val p: SimParams = summon[SimParams]
 
+  @annotation.nowarn("msg=unused private member") // defaults used by callers
   private def mkBank(
       id: Int = 0,
       deposits: PLN = PLN(1e6),

src/test/scala/sfc/engine/OpenEconomyPropertySpec.scala

@@ -19,6 +19,7 @@ class OpenEconomyPropertySpec extends AnyFlatSpec with Matchers with ScalaCheckP
 
   private val defaultSectorOutputs = Vector.fill(6)(PLN(1e8))
 
+  @annotation.nowarn("msg=unused private member") // default used by callers
   private def makeForex(er: Double = p.forex.baseExRate): OpenEconomy.ForexState =
     OpenEconomy.ForexState(er, PLN(1e8), PLN(1e8), PLN.Zero, PLN(1e7))
 

src/test/scala/sfc/engine/PhysicalCapitalSpec.scala

@@ -11,6 +11,7 @@ class PhysicalCapitalSpec extends AnyFlatSpec with Matchers:
   given SimParams          = SimParams.defaults
   private val p: SimParams = summon[SimParams]
 
+  @annotation.nowarn("msg=unused private member") // defaults used by callers
   private def mkFirm(
       sector: Int = 1,
       workers: Int = 10,