feat(redis): implement Redis integration for game state management and websocket communication

.idea/gradle.xml

@@ -17,6 +17,7 @@
             <option value="$PROJECT_DIR$/modules/io" />
             <option value="$PROJECT_DIR$/modules/json" />
             <option value="$PROJECT_DIR$/modules/rule" />
+            <option value="$PROJECT_DIR$/modules/ws" />
           </set>
         </option>
       </GradleProjectSettings>

.idea/scala_compiler.xml

@@ -5,7 +5,7 @@
       <option name="deprecationWarnings" value="true" />
       <option name="uncheckedWarnings" value="true" />
     </profile>
-    <profile name="Gradle 2" modules="NowChessSystems.modules.account.integrationTest,NowChessSystems.modules.account.main,NowChessSystems.modules.account.native-test,NowChessSystems.modules.account.quarkus-generated-sources,NowChessSystems.modules.account.quarkus-test-generated-sources,NowChessSystems.modules.account.scoverage,NowChessSystems.modules.account.test,NowChessSystems.modules.bot.main,NowChessSystems.modules.bot.scoverage,NowChessSystems.modules.bot.test,NowChessSystems.modules.core.integrationTest,NowChessSystems.modules.core.main,NowChessSystems.modules.core.native-test,NowChessSystems.modules.core.quarkus-generated-sources,NowChessSystems.modules.core.quarkus-test-generated-sources,NowChessSystems.modules.core.scoverage,NowChessSystems.modules.core.test,NowChessSystems.modules.io.integrationTest,NowChessSystems.modules.io.main,NowChessSystems.modules.io.native-test,NowChessSystems.modules.io.quarkus-generated-sources,NowChessSystems.modules.io.quarkus-test-generated-sources,NowChessSystems.modules.io.scoverage,NowChessSystems.modules.io.test,NowChessSystems.modules.json.main,NowChessSystems.modules.json.scoverage,NowChessSystems.modules.json.test,NowChessSystems.modules.rule.integrationTest,NowChessSystems.modules.rule.main,NowChessSystems.modules.rule.native-test,NowChessSystems.modules.rule.quarkus-generated-sources,NowChessSystems.modules.rule.quarkus-test-generated-sources,NowChessSystems.modules.rule.scoverage,NowChessSystems.modules.rule.test,NowChessSystems.modules.ui.main,NowChessSystems.modules.ui.scoverage,NowChessSystems.modules.ui.test">
+    <profile name="Gradle 2" modules="NowChessSystems.modules.account.integrationTest,NowChessSystems.modules.account.main,NowChessSystems.modules.account.native-test,NowChessSystems.modules.account.quarkus-generated-sources,NowChessSystems.modules.account.quarkus-test-generated-sources,NowChessSystems.modules.account.scoverage,NowChessSystems.modules.account.test,NowChessSystems.modules.bot.main,NowChessSystems.modules.bot.scoverage,NowChessSystems.modules.bot.test,NowChessSystems.modules.core.integrationTest,NowChessSystems.modules.core.main,NowChessSystems.modules.core.native-test,NowChessSystems.modules.core.quarkus-generated-sources,NowChessSystems.modules.core.quarkus-test-generated-sources,NowChessSystems.modules.core.scoverage,NowChessSystems.modules.core.test,NowChessSystems.modules.io.integrationTest,NowChessSystems.modules.io.main,NowChessSystems.modules.io.native-test,NowChessSystems.modules.io.quarkus-generated-sources,NowChessSystems.modules.io.quarkus-test-generated-sources,NowChessSystems.modules.io.scoverage,NowChessSystems.modules.io.test,NowChessSystems.modules.json.main,NowChessSystems.modules.json.scoverage,NowChessSystems.modules.json.test,NowChessSystems.modules.rule.integrationTest,NowChessSystems.modules.rule.main,NowChessSystems.modules.rule.native-test,NowChessSystems.modules.rule.quarkus-generated-sources,NowChessSystems.modules.rule.quarkus-test-generated-sources,NowChessSystems.modules.rule.scoverage,NowChessSystems.modules.rule.test,NowChessSystems.modules.ui.main,NowChessSystems.modules.ui.scoverage,NowChessSystems.modules.ui.test,NowChessSystems.modules.ws.integrationTest,NowChessSystems.modules.ws.main,NowChessSystems.modules.ws.native-test,NowChessSystems.modules.ws.quarkus-generated-sources,NowChessSystems.modules.ws.quarkus-test-generated-sources,NowChessSystems.modules.ws.scoverage,NowChessSystems.modules.ws.test">
       <option name="deprecationWarnings" value="true" />
       <option name="uncheckedWarnings" value="true" />
       <parameters>

bruno/board/game/02 Get Game.bru

@@ -11,5 +11,5 @@ get {
 }
 
 vars:pre-request {
-  gameId: Yg200tOF
+  gameId: j0nPtcjl
 }

bruno/board/game/03 Stream Game.bru

@@ -11,12 +11,24 @@ ws {
 }
 
 body:ws {
-  name: message 1
+  name: move
   content: '''
-    {}
+    {
+      "type": "MOVE",
+      "uci": "b1c3"
+    }
+  '''
+}
+
+body:ws {
+  name: ping
+  content: '''
+    {
+      "type": "PING"
+    }
   '''
 }
 
 vars:pre-request {
-  gameId: uWm99efJ
+  gameId: j0nPtcjl
 }

bruno/environments/local.bru

@@ -1,5 +1,5 @@
 vars {
   baseUrl: http://localhost:8080
-  wsBaseUrl: ws://localhost:8080
+  wsBaseUrl: ws://localhost:8084
   ioBaseUrl: http://localhost:8081
 }

build.gradle.kts

@@ -46,7 +46,11 @@ val coverageExclusions = listOf(
     // AccountResource / ChallengeResource — REST integration layer; @QuarkusTest not instrumented by Scoverage
     "**/account/src/main/scala/de/nowchess/account/resource/**",
     // JacksonConfig / NativeReflectionConfig — Quarkus lifecycle hooks, no testable logic
-    "**/account/src/main/scala/de/nowchess/account/config/**"
+    "**/account/src/main/scala/de/nowchess/account/config/**",
+    // WebSocket service — infrastructure CDI beans (RedisConfig, RedissonProducer)
+    "**/ws/src/main/scala/de/nowchess/ws/config/**",
+    // GameWebSocketResource in core — replaced by ws module
+    "**/core/src/main/scala/de/nowchess/chess/resource/GameWebSocketResource.scala",
 )
 
 // Converts a Sonar-style glob to a scoverage regex (matched against full source path).
@@ -93,7 +97,8 @@ val versions = mapOf(
     "SCALA_PARSER_COMBINATORS" to "2.4.0",
     "FASTPARSE"             to "3.0.2",
     "JACKSON"               to "2.17.2",
-    "JACKSON_SCALA"         to "2.17.2"
+    "JACKSON_SCALA"         to "2.17.2",
+    "REDISSON"              to "3.32.0"
 )
 extra["VERSIONS"] = versions
 

modules/account/src/main/scala/de/nowchess/account/filter/AlreadyLoggedInFilter.scala

@@ -30,8 +30,10 @@ class AlreadyLoggedInFilter extends ContainerRequestFilter:
       )
 
   private def isAuthenticated: Boolean =
+    // scalafix:off DisableSyntax.null
     try jwt.getName != null
     catch case _ => false
+    // scalafix:on DisableSyntax.null
 
   private def isProtectedEndpoint(path: String, method: String): Boolean =
     (path.contains("/api/account") || path.contains("/account")) &&

modules/api/src/main/scala/de/nowchess/api/dto/GameStateDto.scala

@@ -10,4 +10,5 @@ final case class GameStateDto(
     undoAvailable: Boolean,
     redoAvailable: Boolean,
     clock: Option[ClockDto],
+    takebackRequestedBy: Option[String] = None,
 )

modules/core/build.gradle.kts

@@ -70,7 +70,7 @@ dependencies {
     implementation("io.quarkus:quarkus-websockets-next")
 
     implementation("com.fasterxml.jackson.module:jackson-module-scala_3:${versions["JACKSON_SCALA"]!!}")
-
+    implementation("org.redisson:redisson:${versions["REDISSON"]!!}")
 
     testImplementation(project(":modules:io"))
     testImplementation(project(":modules:rule"))
@@ -124,3 +124,18 @@ tasks.jar {
     duplicatesStrategy = DuplicatesStrategy.EXCLUDE
 }
 
+tasks.withType(org.gradle.api.tasks.scala.ScalaCompile::class).configureEach {
+    if (name == "compileScoverageScala") {
+        source = source.asFileTree.matching {
+            exclude("**/grpc/*.scala")
+            exclude("**/resource/GameDtoMapper.scala")
+            exclude("**/resource/GameResource.scala")
+            exclude("**/redis/GameRedis*.scala")
+        }
+    }
+}
+
+tasks.named("compileScoverageJava").configure {
+    dependsOn(tasks.named("quarkusGenerateCode"))
+}
+

modules/core/src/main/resources/application.yml

@@ -14,6 +14,12 @@ quarkus:
     server:
       use-separate-server: false
 
+nowchess:
+  redis:
+    host: localhost
+    port: 6379
+    prefix: nowchess
+
 "%dev":
   mp:
     jwt:
@@ -41,6 +47,8 @@ quarkus:
         url: http://localhost:8081
       rule-service:
         url: http://localhost:8082
+      store-service:
+        url: http://localhost:8085
 
 "%deployed":
   mp:
@@ -69,3 +77,10 @@ quarkus:
         url: ${IO_SERVICE_URL}
       rule-service:
         url: ${RULE_SERVICE_URL}
+      store-service:
+        url: ${STORE_SERVICE_URL}
+  nowchess:
+    redis:
+      host: ${REDIS_HOST}
+      port: ${REDIS_PORT:6379}
+      prefix: ${REDIS_PREFIX:nowchess}

modules/core/src/main/scala/de/nowchess/chess/client/GameRecordDto.scala

@@ -0,0 +1,24 @@
+package de.nowchess.chess.client
+
+case class GameRecordDto(
+  gameId: String,
+  fen: String,
+  pgn: String,
+  moveCount: Int,
+  whiteId: String,
+  whiteName: String,
+  blackId: String,
+  blackName: String,
+  mode: String,
+  resigned: Boolean,
+  limitSeconds: java.lang.Integer,
+  incrementSeconds: java.lang.Integer,
+  daysPerMove: java.lang.Integer,
+  whiteRemainingMs: java.lang.Long,
+  blackRemainingMs: java.lang.Long,
+  incrementMs: java.lang.Long,
+  clockLastTickAt: java.lang.Long,
+  clockMoveDeadline: java.lang.Long,
+  clockActiveColor: String,
+  pendingDrawOffer: String,
+)

modules/core/src/main/scala/de/nowchess/chess/client/StoreServiceClient.scala

@@ -0,0 +1,13 @@
+package de.nowchess.chess.client
+
+import jakarta.ws.rs.*
+import jakarta.ws.rs.core.MediaType
+import org.eclipse.microprofile.rest.client.inject.RegisterRestClient
+
+@RegisterRestClient(configKey = "store-service")
+@Path("/game")
+trait StoreServiceClient:
+  @GET
+  @Path("/{gameId}")
+  @Produces(Array(MediaType.APPLICATION_JSON))
+  def getGame(@PathParam("gameId") gameId: String): GameRecordDto

modules/core/src/main/scala/de/nowchess/chess/command/Command.scala

@@ -1,60 +0,0 @@
-package de.nowchess.chess.command
-
-import de.nowchess.api.board.{Piece, Square}
-import de.nowchess.api.game.GameContext
-
-/** Marker trait for all commands that can be executed and undone. Commands encapsulate user actions and game state
-  * transitions.
-  */
-trait Command:
-  /** Execute the command and return true if successful, false otherwise. */
-  def execute(): Boolean
-
-  /** Undo the command and return true if successful, false otherwise. */
-  def undo(): Boolean
-
-  /** A human-readable description of this command. */
-  def description: String
-
-/** Command to move a piece from one square to another. Stores the move result so undo can restore previous state.
-  */
-case class MoveCommand(
-    from: Square,
-    to: Square,
-    moveResult: Option[MoveResult] = None,
-    previousContext: Option[GameContext] = None,
-    notation: String = "",
-) extends Command:
-
-  override def execute(): Boolean =
-    moveResult.isDefined
-
-  override def undo(): Boolean =
-    previousContext.isDefined
-
-  override def description: String = s"Move from $from to $to"
-
-// Sealed hierarchy of move outcomes (for tracking state changes)
-sealed trait MoveResult
-object MoveResult:
-  case class Successful(newContext: GameContext, captured: Option[Piece]) extends MoveResult
-  case object InvalidFormat                                               extends MoveResult
-  case object InvalidMove                                                 extends MoveResult
-
-/** Command to quit the game. */
-case class QuitCommand() extends Command:
-  override def execute(): Boolean  = true
-  override def undo(): Boolean     = false
-  override def description: String = "Quit game"
-
-/** Command to reset the board to initial position. */
-case class ResetCommand(
-    previousContext: Option[GameContext] = None,
-) extends Command:
-
-  override def execute(): Boolean = true
-
-  override def undo(): Boolean =
-    previousContext.isDefined
-
-  override def description: String = "Reset board"

modules/core/src/main/scala/de/nowchess/chess/command/CommandInvoker.scala

@@ -1,67 +0,0 @@
-package de.nowchess.chess.command
-
-/** Manages command execution and history for undo/redo support. */
-class CommandInvoker:
-  private val executedCommands = scala.collection.mutable.ListBuffer[Command]()
-  @SuppressWarnings(Array("DisableSyntax.var"))
-  private var currentIndex = -1
-
-  /** Execute a command and add it to history. Discards any redo history if not at the end of the stack.
-    */
-  def execute(command: Command): Boolean = synchronized {
-    if command.execute() then
-      // Remove any commands after current index (redo stack is discarded)
-      while currentIndex < executedCommands.size - 1 do executedCommands.remove(executedCommands.size - 1)
-      executedCommands += command
-      currentIndex += 1
-      true
-    else false
-  }
-
-  /** Undo the last executed command if possible. */
-  def undo(): Boolean = synchronized {
-    if currentIndex >= 0 && currentIndex < executedCommands.size then
-      val command = executedCommands(currentIndex)
-      if command.undo() then
-        currentIndex -= 1
-        true
-      else false
-    else false
-  }
-
-  /** Redo the next command in history if available. */
-  def redo(): Boolean = synchronized {
-    if currentIndex + 1 < executedCommands.size then
-      val command = executedCommands(currentIndex + 1)
-      if command.execute() then
-        currentIndex += 1
-        true
-      else false
-    else false
-  }
-
-  /** Get the history of all executed commands. */
-  def history: List[Command] = synchronized {
-    executedCommands.toList
-  }
-
-  /** Get the current position in command history. */
-  def getCurrentIndex: Int = synchronized {
-    currentIndex
-  }
-
-  /** Clear all command history. */
-  def clear(): Unit = synchronized {
-    executedCommands.clear()
-    currentIndex = -1
-  }
-
-  /** Check if undo is available. */
-  def canUndo: Boolean = synchronized {
-    currentIndex >= 0
-  }
-
-  /** Check if redo is available. */
-  def canRedo: Boolean = synchronized {
-    currentIndex + 1 < executedCommands.size
-  }

modules/core/src/main/scala/de/nowchess/chess/config/RedisConfig.scala

@@ -0,0 +1,18 @@
+package de.nowchess.chess.config
+
+import jakarta.enterprise.context.ApplicationScoped
+import org.eclipse.microprofile.config.inject.ConfigProperty
+import scala.compiletime.uninitialized
+
+@ApplicationScoped
+class RedisConfig:
+  // scalafix:off DisableSyntax.var
+  @ConfigProperty(name = "nowchess.redis.host", defaultValue = "localhost")
+  var host: String = uninitialized
+
+  @ConfigProperty(name = "nowchess.redis.port", defaultValue = "6379")
+  var port: Int = uninitialized
+
+  @ConfigProperty(name = "nowchess.redis.prefix", defaultValue = "nowchess")
+  var prefix: String = uninitialized
+  // scalafix:on DisableSyntax.var

modules/core/src/main/scala/de/nowchess/chess/config/RedissonProducer.scala

@@ -0,0 +1,35 @@
+package de.nowchess.chess.config
+
+import jakarta.annotation.PreDestroy
+import jakarta.enterprise.context.ApplicationScoped
+import jakarta.enterprise.inject.Produces
+import jakarta.inject.Inject
+import org.redisson.Redisson
+import org.redisson.api.RedissonClient
+import org.redisson.config.Config
+import scala.compiletime.uninitialized
+
+@ApplicationScoped
+class RedissonProducer:
+
+  // scalafix:off DisableSyntax.var
+  @Inject
+  var redisConfig: RedisConfig = uninitialized
+
+  private var clientOpt: Option[RedissonClient] = None
+  // scalafix:on DisableSyntax.var
+
+  @Produces
+  @ApplicationScoped
+  def produceRedissonClient(): RedissonClient =
+    val config = new Config()
+    config.useSingleServer().setAddress(s"redis://${redisConfig.host}:${redisConfig.port}")
+    config.useSingleServer().setConnectionMinimumIdleSize(1)
+    config.useSingleServer().setConnectTimeout(500)
+    val client = Redisson.create(config)
+    clientOpt = Some(client)
+    client
+
+  @PreDestroy
+  def shutdown(): Unit =
+    clientOpt.foreach(_.shutdown())

modules/core/src/main/scala/de/nowchess/chess/engine/GameEngine.scala

@@ -18,7 +18,6 @@ import de.nowchess.api.game.{
 import de.nowchess.api.player.{PlayerId, PlayerInfo}
 import de.nowchess.chess.controller.Parser
 import de.nowchess.chess.observer.*
-import de.nowchess.chess.command.{CommandInvoker, MoveCommand, MoveResult}
 import de.nowchess.api.error.GameError
 import de.nowchess.api.game.WinReason.{Checkmate, Resignation}
 import de.nowchess.api.io.{GameContextExport, GameContextImport}
@@ -39,6 +38,10 @@ class GameEngine(
       Color.Black -> Human(PlayerInfo(PlayerId("p2"), "Player 2")),
     ),
     val timeControl: TimeControl = TimeControl.Unlimited,
+    initialClockState: Option[ClockState] = None,
+    initialDrawOffer: Option[Color] = None,
+    initialRedoStack: List[Move] = Nil,
+    initialTakebackRequest: Option[Color] = None,
 ) extends Observable:
   // Ensure that initialBoard is set correctly for threefold repetition detection
   private val contextWithInitialBoard =
@@ -48,15 +51,20 @@ class GameEngine(
   @SuppressWarnings(Array("DisableSyntax.var"))
   private var currentContext: GameContext = contextWithInitialBoard
   @SuppressWarnings(Array("DisableSyntax.var"))
-  private var pendingDrawOffer: Option[Color] = None
+  private var pendingDrawOffer: Option[Color] = initialDrawOffer
   @SuppressWarnings(Array("DisableSyntax.var"))
   private var clockState: Option[ClockState] =
-    ClockState.fromTimeControl(timeControl, contextWithInitialBoard.turn, Instant.now())
+    initialClockState.orElse(ClockState.fromTimeControl(timeControl, contextWithInitialBoard.turn, Instant.now()))
   @SuppressWarnings(Array("DisableSyntax.var"))
   private var scheduledCheck: Option[ScheduledFuture[?]] = None
   // One shared scheduler per engine; shut down with the game.
   private val scheduler: ScheduledExecutorService = Executors.newSingleThreadScheduledExecutor()
-  private val invoker                             = new CommandInvoker()
+  @SuppressWarnings(Array("DisableSyntax.var"))
+  private var redoStack: List[Move] = initialRedoStack
+  @SuppressWarnings(Array("DisableSyntax.var"))
+  private var isRedoing: Boolean = false
+  @SuppressWarnings(Array("DisableSyntax.var"))
+  private var pendingTakebackRequest: Option[Color] = initialTakebackRequest
 
   // Start scheduler immediately for live clocks so passive expiry fires without waiting for a move.
   clockState.foreach(scheduleExpiryCheck)
@@ -71,13 +79,16 @@ class GameEngine(
   def currentClockState: Option[ClockState] = synchronized(clockState)
 
   /** Check if undo is available. */
-  def canUndo: Boolean = synchronized(invoker.canUndo)
+  def canUndo: Boolean = synchronized(currentContext.moves.nonEmpty)
 
   /** Check if redo is available. */
-  def canRedo: Boolean = synchronized(invoker.canRedo)
+  def canRedo: Boolean = synchronized(redoStack.nonEmpty)
 
-  /** Get the command history for inspection (testing/debugging). */
+  /** Get redo stack moves for inspection. */
-  def commandHistory: List[de.nowchess.chess.command.Command] = synchronized(invoker.history)
+  def redoStackMoves: List[Move] = synchronized(redoStack)
+
+  /** Get pending takeback request (if any). */
+  def pendingTakebackRequestBy: Option[Color] = synchronized(pendingTakebackRequest)
 
   /** Process a raw move input string and update game state if valid. Notifies all observers of the outcome via
     * GameEvent.
@@ -162,8 +173,9 @@ class GameEngine(
     else
       currentContext = currentContext.withResult(Some(GameResult.Win(color.opposite, Resignation)))
       pendingDrawOffer = None
+      pendingTakebackRequest = None
       stopClock()
-      invoker.clear()
+      redoStack = Nil
       notifyObservers(ResignEvent(currentContext, color))
   }
 
@@ -193,8 +205,9 @@ class GameEngine(
         case Some(_) =>
           currentContext = currentContext.withResult(Some(GameResult.Draw(DrawReason.Agreement)))
           pendingDrawOffer = None
+          pendingTakebackRequest = None
           stopClock()
-          invoker.clear()
+          redoStack = Nil
           notifyObservers(DrawEvent(currentContext, DrawReason.Agreement))
   }
 
@@ -220,12 +233,12 @@ class GameEngine(
     else if currentContext.halfMoveClock >= 100 then
       currentContext = currentContext.withResult(Some(GameResult.Draw(DrawReason.FiftyMoveRule)))
       stopClock()
-      invoker.clear()
+      redoStack = Nil
       notifyObservers(DrawEvent(currentContext, DrawReason.FiftyMoveRule))
     else if ruleSet.isThreefoldRepetition(currentContext) then
       currentContext = currentContext.withResult(Some(GameResult.Draw(DrawReason.ThreefoldRepetition)))
       stopClock()
-      invoker.clear()
+      redoStack = Nil
       notifyObservers(DrawEvent(currentContext, DrawReason.ThreefoldRepetition))
     else notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.DrawCannotBeClaimed))
   }
@@ -239,6 +252,8 @@ class GameEngine(
       case Right(ctx) =>
         replayGame(ctx).map { _ =>
           pendingDrawOffer = None
+          pendingTakebackRequest = None
+          redoStack = Nil
           stopClock()
           clockState = ClockState.fromTimeControl(timeControl, currentContext.turn, Instant.now())
           notifyObservers(PgnLoadedEvent(currentContext))
@@ -248,7 +263,7 @@ class GameEngine(
   private def replayGame(ctx: GameContext): Either[GameError, Unit] =
     val savedContext = currentContext
     currentContext = GameContext.initial
-    invoker.clear()
+    redoStack = Nil
 
     if ctx.moves.isEmpty then
       currentContext = ctx.copy(initialBoard = ctx.board)
@@ -283,9 +298,10 @@ class GameEngine(
       else newContext
     currentContext = contextWithInitialBoard
     pendingDrawOffer = None
+    pendingTakebackRequest = None
+    redoStack = Nil
     stopClock()
     clockState = ClockState.fromTimeControl(timeControl, currentContext.turn, Instant.now())
-    invoker.clear()
     notifyObservers(BoardResetEvent(currentContext))
   }
 
@@ -293,9 +309,10 @@ class GameEngine(
   def reset(): Unit = synchronized {
     currentContext = GameContext.initial
     pendingDrawOffer = None
+    pendingTakebackRequest = None
+    redoStack = Nil
     stopClock()
     clockState = ClockState.fromTimeControl(timeControl, currentContext.turn, Instant.now())
-    invoker.clear()
     notifyObservers(BoardResetEvent(currentContext))
   }
 
@@ -304,7 +321,7 @@ class GameEngine(
     if currentContext.result.isEmpty then
       currentContext = currentContext.withResult(Some(GameResult.Draw(reason)))
       stopClock()
-      invoker.clear()
+      redoStack = Nil
       notifyObservers(DrawEvent(currentContext, reason))
   }
 
@@ -329,7 +346,8 @@ class GameEngine(
       else GameResult.Win(flagged.opposite, WinReason.TimeControl)
     currentContext = currentContext.withResult(Some(result))
     pendingDrawOffer = None
-    invoker.clear()
+    pendingTakebackRequest = None
+    redoStack = Nil
     notifyObservers(TimeFlagEvent(currentContext, flagged))
 
   private def scheduleExpiryCheck(cs: ClockState): Unit =
@@ -365,19 +383,15 @@ class GameEngine(
   // ──── Private helpers ────
 
   private def executeMove(move: Move): Unit =
+    if !isRedoing then
+      redoStack = Nil
+      pendingTakebackRequest = None
+
     val contextBefore = currentContext
     val nextContext   = ruleSet.applyMove(currentContext)(move)
     val captured      = computeCaptured(currentContext, move)
-
+    val notation      = translateMoveToNotation(move, contextBefore.board)
-    val cmd = MoveCommand(
+    currentContext    = nextContext
-      from = move.from,
-      to = move.to,
-      moveResult = Some(MoveResult.Successful(nextContext, captured)),
-      previousContext = Some(contextBefore),
-      notation = translateMoveToNotation(move, contextBefore.board),
-    )
-    invoker.execute(cmd)
-    currentContext = nextContext
 
     advanceClock(contextBefore.turn)
 
@@ -397,17 +411,17 @@ class GameEngine(
         currentContext = currentContext.withResult(Some(GameResult.Win(winner, Checkmate)))
         cancelScheduled()
         notifyObservers(CheckmateEvent(currentContext, winner))
-        invoker.clear()
+        redoStack = Nil
       else if status.isStalemate then
         currentContext = currentContext.withResult(Some(GameResult.Draw(DrawReason.Stalemate)))
         cancelScheduled()
         notifyObservers(DrawEvent(currentContext, DrawReason.Stalemate))
-        invoker.clear()
+        redoStack = Nil
       else if status.isInsufficientMaterial then
         currentContext = currentContext.withResult(Some(GameResult.Draw(DrawReason.InsufficientMaterial)))
         cancelScheduled()
         notifyObservers(DrawEvent(currentContext, DrawReason.InsufficientMaterial))
-        invoker.clear()
+        redoStack = Nil
       else if status.isCheck then notifyObservers(CheckDetectedEvent(currentContext))
 
     if currentContext.halfMoveClock >= 100 then notifyObservers(FiftyMoveRuleAvailableEvent(currentContext))
@@ -504,32 +518,68 @@ class GameEngine(
       else if ruleSet.isStalemate(currentContext) then notifyObservers(DrawEvent(currentContext, DrawReason.Stalemate))
     }
 
+  private def replayContextFromMoves(moves: List[Move]): GameContext =
+    moves.foldLeft(contextWithInitialBoard)((ctx, move) => ruleSet.applyMove(ctx)(move))
+
   private def performUndo(): Unit =
-    if invoker.canUndo then
+    if currentContext.moves.isEmpty then
-      val cmd = invoker.history(invoker.getCurrentIndex)
+      notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.NothingToUndo))
-      (cmd: @unchecked) match
+    else
-        case moveCmd: MoveCommand =>
+      val lastMove = currentContext.moves.last
-          moveCmd.previousContext.foreach(currentContext = _)
+      val prevCtx  = replayContextFromMoves(currentContext.moves.dropRight(1))
-          invoker.undo()
+      val notation = translateMoveToNotation(lastMove, prevCtx.board)
-          notifyObservers(MoveUndoneEvent(currentContext, moveCmd.notation))
+      redoStack = lastMove :: redoStack
-    else notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.NothingToUndo))
+      currentContext = prevCtx
+      notifyObservers(MoveUndoneEvent(currentContext, notation))
 
   private def performRedo(): Unit =
-    if invoker.canRedo then
+    if redoStack.isEmpty then
-      val cmd = invoker.history(invoker.getCurrentIndex + 1)
+      notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.NothingToRedo))
-      (cmd: @unchecked) match
+    else
-        case moveCmd: MoveCommand =>
+      val move = redoStack.head
-          for case MoveResult.Successful(nextCtx, cap) <- moveCmd.moveResult do
+      redoStack = redoStack.tail
-            currentContext = nextCtx
+      isRedoing = true
-            invoker.redo()
+      executeMove(move)
-            val capturedDesc = cap.map(c => s"${c.color.label} ${c.pieceType.label}")
+      isRedoing = false
-            notifyObservers(
+
-              MoveRedoneEvent(
+  def requestTakeback(color: Color): Unit = synchronized {
-                currentContext,
+    if currentContext.result.isDefined then
-                moveCmd.notation,
+      notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.GameAlreadyOver))
-                moveCmd.from.toString,
+    else if currentContext.moves.isEmpty then
-                moveCmd.to.toString,
+      notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.NothingToUndo))
-                capturedDesc,
+    else
-              ),
+      pendingTakebackRequest match
-            )
+        case Some(_) =>
-    else notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.NothingToRedo))
+          notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.TakebackRequestPending))
+        case None =>
+          pendingTakebackRequest = Some(color)
+          notifyObservers(TakebackRequestedEvent(currentContext, color))
+  }
+
+  def acceptTakeback(color: Color): Unit = synchronized {
+    if currentContext.result.isDefined then
+      notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.GameAlreadyOver))
+    else
+      pendingTakebackRequest match
+        case None =>
+          notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.NoTakebackRequestToAccept))
+        case Some(requester) if requester == color =>
+          notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.CannotAcceptOwnTakebackRequest))
+        case Some(_) =>
+          pendingTakebackRequest = None
+          performUndo()
+  }
+
+  def declineTakeback(color: Color): Unit = synchronized {
+    if currentContext.result.isDefined then
+      notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.GameAlreadyOver))
+    else
+      pendingTakebackRequest match
+        case None =>
+          notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.NoTakebackRequestToDecline))
+        case Some(requester) if requester == color =>
+          notifyObservers(InvalidMoveEvent(currentContext, InvalidMoveReason.CannotDeclineOwnTakebackRequest))
+        case Some(_) =>
+          pendingTakebackRequest = None
+          notifyObservers(TakebackDeclinedEvent(currentContext, color))
+  }

modules/core/src/main/scala/de/nowchess/chess/observer/InvalidMoveReason.scala

@@ -19,3 +19,8 @@ enum InvalidMoveReason:
   case CannotAcceptOwnDrawOffer
   case NoDrawOfferToDecline
   case CannotDeclineOwnDrawOffer
+  case TakebackRequestPending
+  case NoTakebackRequestToAccept
+  case CannotAcceptOwnTakebackRequest
+  case NoTakebackRequestToDecline
+  case CannotDeclineOwnTakebackRequest

modules/core/src/main/scala/de/nowchess/chess/observer/Observer.scala

@@ -60,15 +60,6 @@ case class MoveUndoneEvent(
     pgnNotation: String,
 ) extends GameEvent
 
-/** Fired when a previously undone move is redone, carrying PGN notation of the replayed move. */
-case class MoveRedoneEvent(
-    context: GameContext,
-    pgnNotation: String,
-    fromSquare: String,
-    toSquare: String,
-    capturedPiece: Option[String],
-) extends GameEvent
-
 /** Fired after a PGN string is successfully loaded and all moves are replayed into history. */
 case class PgnLoadedEvent(
     context: GameContext,
@@ -98,6 +89,18 @@ case class TimeFlagEvent(
     flaggedColor: Color,
 ) extends GameEvent
 
+/** Fired when a player requests a takeback of the last move. */
+case class TakebackRequestedEvent(
+    context: GameContext,
+    requestedBy: Color,
+) extends GameEvent
+
+/** Fired when a player declines a takeback request. */
+case class TakebackDeclinedEvent(
+    context: GameContext,
+    declinedBy: Color,
+) extends GameEvent
+
 /** Observer trait: implement to receive game state updates. */
 trait Observer:
   def onGameEvent(event: GameEvent): Unit

modules/core/src/main/scala/de/nowchess/chess/redis/C2sMessage.scala

@@ -0,0 +1,8 @@
+package de.nowchess.chess.redis
+
+sealed trait C2sMessage
+
+object C2sMessage:
+  case object Connected extends C2sMessage
+  case class Move(uci: String) extends C2sMessage
+  case object Ping extends C2sMessage

modules/core/src/main/scala/de/nowchess/chess/redis/GameRedisPublisher.scala

@@ -0,0 +1,56 @@
+package de.nowchess.chess.redis
+
+import com.fasterxml.jackson.databind.ObjectMapper
+import de.nowchess.api.dto.GameStateEventDto
+import de.nowchess.api.game.{CorrespondenceClockState, LiveClockState}
+import de.nowchess.chess.grpc.IoGrpcClientWrapper
+import de.nowchess.chess.observer.{GameEvent, Observer}
+import de.nowchess.chess.registry.GameRegistry
+import de.nowchess.chess.resource.GameDtoMapper
+import org.redisson.api.RTopic
+
+class GameRedisPublisher(
+    gameId: String,
+    registry: GameRegistry,
+    redisson: org.redisson.api.RedissonClient,
+    objectMapper: ObjectMapper,
+    s2cTopicName: String,
+    writebackEmit: String => Unit,
+    ioClient: IoGrpcClientWrapper,
+    onGameOver: String => Unit,
+) extends Observer:
+
+  def onGameEvent(event: GameEvent): Unit =
+    registry.get(gameId).foreach { entry =>
+      val dto = GameDtoMapper.toGameStateDto(entry, ioClient)
+      val json = objectMapper.writeValueAsString(GameStateEventDto(dto))
+      redisson.getTopic(s2cTopicName).publish(json)
+
+      val clock = entry.engine.currentClockState
+      val wb = GameWritebackEventDto(
+        gameId = gameId,
+        fen = dto.fen,
+        pgn = dto.pgn,
+        moveCount = entry.engine.context.moves.size,
+        whiteId = entry.white.id.value,
+        whiteName = entry.white.displayName,
+        blackId = entry.black.id.value,
+        blackName = entry.black.displayName,
+        mode = entry.mode.toString,
+        resigned = entry.resigned,
+        limitSeconds = entry.engine.timeControl match { case de.nowchess.api.game.TimeControl.Clock(l, _) => Some(l); case _ => None },
+        incrementSeconds = entry.engine.timeControl match { case de.nowchess.api.game.TimeControl.Clock(_, i) => Some(i); case _ => None },
+        daysPerMove = entry.engine.timeControl match { case de.nowchess.api.game.TimeControl.Correspondence(d) => Some(d); case _ => None },
+        whiteRemainingMs = clock.collect { case c: LiveClockState => c.whiteRemainingMs },
+        blackRemainingMs = clock.collect { case c: LiveClockState => c.blackRemainingMs },
+        incrementMs = clock.collect { case c: LiveClockState => c.incrementMs },
+        clockLastTickAt = clock.collect { case c: LiveClockState => c.lastTickAt.toEpochMilli },
+        clockMoveDeadline = clock.collect { case c: CorrespondenceClockState => c.moveDeadline.toEpochMilli },
+        clockActiveColor = clock.map(_.activeColor.label.toLowerCase),
+        pendingDrawOffer = entry.engine.pendingDrawOfferBy.map(_.label.toLowerCase),
+        redoStack = entry.engine.redoStackMoves.map(GameDtoMapper.moveToUci),
+        pendingTakebackRequest = entry.engine.pendingTakebackRequestBy.map(_.label.toLowerCase),
+      )
+      writebackEmit(objectMapper.writeValueAsString(wb))
+      if entry.engine.context.result.isDefined then onGameOver(gameId)
+    }

modules/core/src/main/scala/de/nowchess/chess/redis/GameRedisSubscriberManager.scala

@@ -0,0 +1,102 @@
+package de.nowchess.chess.redis
+
+import com.fasterxml.jackson.databind.ObjectMapper
+import de.nowchess.api.dto.GameFullEventDto
+import de.nowchess.chess.config.RedisConfig
+import de.nowchess.chess.grpc.IoGrpcClientWrapper
+import de.nowchess.chess.observer.Observer
+import de.nowchess.chess.registry.GameRegistry
+import de.nowchess.chess.resource.GameDtoMapper
+import jakarta.annotation.PreDestroy
+import jakarta.enterprise.context.ApplicationScoped
+import jakarta.inject.Inject
+import org.redisson.api.listener.MessageListener
+import org.redisson.api.RedissonClient
+import scala.compiletime.uninitialized
+import scala.util.Try
+import java.util.concurrent.ConcurrentHashMap
+
+@ApplicationScoped
+class GameRedisSubscriberManager:
+
+  // scalafix:off DisableSyntax.var
+  @Inject var redisson: RedissonClient = uninitialized
+  @Inject var registry: GameRegistry = uninitialized
+  @Inject var objectMapper: ObjectMapper = uninitialized
+  @Inject var redisConfig: RedisConfig = uninitialized
+  @Inject var ioClient: IoGrpcClientWrapper = uninitialized
+  // scalafix:on DisableSyntax.var
+
+  private val c2sListeners = new ConcurrentHashMap[String, Int]()
+  private val s2cObservers = new ConcurrentHashMap[String, Observer]()
+
+  private def c2sTopic(gameId: String): String =
+    s"${redisConfig.prefix}:game:$gameId:c2s"
+
+  private def s2cTopicName(gameId: String): String =
+    s"${redisConfig.prefix}:game:$gameId:s2c"
+
+  def subscribeGame(gameId: String): Unit =
+    try
+      val topic = redisson.getTopic(c2sTopic(gameId))
+      val listenerId = topic.addListener(classOf[String], new MessageListener[String]:
+        def onMessage(channel: CharSequence, msg: String): Unit =
+          handleC2sMessage(gameId, msg)
+      )
+      c2sListeners.put(gameId, listenerId)
+
+      val writebackTopic = redisson.getTopic("game-writeback")
+      val writebackFn: String => Unit = json => writebackTopic.publish(json)
+      val obs = new GameRedisPublisher(gameId, registry, redisson, objectMapper, s2cTopicName(gameId), writebackFn, ioClient, unsubscribeGame)
+      s2cObservers.put(gameId, obs)
+      registry.get(gameId).foreach(_.engine.subscribe(obs))
+    catch
+      case e: Exception =>
+        System.err.println(s"Warning: Redis subscription failed for game $gameId: ${e.getMessage}")
+        ()
+
+  def unsubscribeGame(gameId: String): Unit =
+    Option(c2sListeners.remove(gameId)).foreach { listenerId =>
+      redisson.getTopic(c2sTopic(gameId)).removeListener(listenerId)
+    }
+    Option(s2cObservers.remove(gameId)).foreach { obs =>
+      registry.get(gameId).foreach(_.engine.unsubscribe(obs))
+    }
+
+  private def handleC2sMessage(gameId: String, msg: String): Unit =
+    parseC2sMessage(msg) match
+      case Some(C2sMessage.Connected)   => handleConnected(gameId)
+      case Some(C2sMessage.Move(uci))   => handleMove(gameId, uci)
+      case Some(C2sMessage.Ping)        => ()
+      case None                         => ()
+
+  private def handleConnected(gameId: String): Unit =
+    registry.get(gameId).foreach { entry =>
+      val dto = GameDtoMapper.toGameFullDto(entry, ioClient)
+      val json = objectMapper.writeValueAsString(GameFullEventDto(dto))
+      redisson.getTopic(s2cTopicName(gameId)).publish(json)
+    }
+
+  private def handleMove(gameId: String, uci: String): Unit =
+    registry.get(gameId).foreach { entry =>
+      entry.engine.processUserInput(uci)
+    }
+
+  private def parseC2sMessage(msg: String): Option[C2sMessage] =
+    Try(objectMapper.readTree(msg)).toOption.flatMap { node =>
+      Option(node.get("type")).map(_.asText()).flatMap {
+        case "CONNECTED" => Some(C2sMessage.Connected)
+        case "MOVE"      => Option(node.get("uci")).map(u => C2sMessage.Move(u.asText()))
+        case "PING"      => Some(C2sMessage.Ping)
+        case _           => None
+      }
+    }
+
+  @PreDestroy
+  def cleanup(): Unit =
+    c2sListeners.forEach((gameId, listenerId) =>
+      redisson.getTopic(c2sTopic(gameId)).removeListener(listenerId)
+    )
+    s2cObservers.forEach((gameId, obs) =>
+      registry.get(gameId).foreach(_.engine.unsubscribe(obs))
+    )

modules/core/src/main/scala/de/nowchess/chess/redis/GameWritebackEventDto.scala

@@ -0,0 +1,26 @@
+package de.nowchess.chess.redis
+
+case class GameWritebackEventDto(
+  gameId: String,
+  fen: String,
+  pgn: String,
+  moveCount: Int,
+  whiteId: String,
+  whiteName: String,
+  blackId: String,
+  blackName: String,
+  mode: String,
+  resigned: Boolean,
+  limitSeconds: Option[Int],
+  incrementSeconds: Option[Int],
+  daysPerMove: Option[Int],
+  whiteRemainingMs: Option[Long],
+  blackRemainingMs: Option[Long],
+  incrementMs: Option[Long],
+  clockLastTickAt: Option[Long],
+  clockMoveDeadline: Option[Long],
+  clockActiveColor: Option[String],
+  pendingDrawOffer: Option[String],
+  redoStack: List[String] = Nil,
+  pendingTakebackRequest: Option[String] = None,
+)

modules/core/src/main/scala/de/nowchess/chess/registry/GameCacheDto.scala

@@ -0,0 +1,25 @@
+package de.nowchess.chess.registry
+
+case class GameCacheDto(
+  gameId: String,
+  whiteId: String,
+  whiteName: String,
+  blackId: String,
+  blackName: String,
+  mode: String,
+  pgn: String,
+  fen: String,
+  resigned: Boolean,
+  limitSeconds: Option[Int],
+  incrementSeconds: Option[Int],
+  daysPerMove: Option[Int],
+  whiteRemainingMs: Option[Long],
+  blackRemainingMs: Option[Long],
+  incrementMs: Option[Long],
+  clockLastTickAt: Option[Long],
+  clockMoveDeadline: Option[Long],
+  clockActiveColor: Option[String],
+  pendingDrawOffer: Option[String],
+  redoStack: List[String] = Nil,
+  pendingTakebackRequest: Option[String] = None,
+)

modules/core/src/main/scala/de/nowchess/chess/registry/GameRegistryImpl.scala

@@ -1,23 +0,0 @@
-package de.nowchess.chess.registry
-
-import jakarta.enterprise.context.ApplicationScoped
-import java.security.SecureRandom
-import java.util.concurrent.ConcurrentHashMap
-
-@ApplicationScoped
-class GameRegistryImpl extends GameRegistry:
-  private val games = ConcurrentHashMap[String, GameEntry]()
-  private val rng   = new SecureRandom()
-
-  def store(entry: GameEntry): Unit =
-    games.put(entry.gameId, entry)
-
-  def get(gameId: String): Option[GameEntry] =
-    Option(games.get(gameId))
-
-  def update(entry: GameEntry): Unit =
-    games.put(entry.gameId, entry)
-
-  def generateId(): String =
-    val chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
-    Iterator.continually(rng.nextInt(chars.length)).map(chars).take(8).mkString // NOSONAR

modules/core/src/main/scala/de/nowchess/chess/registry/RedisGameRegistry.scala

@@ -0,0 +1,202 @@
+package de.nowchess.chess.registry
+
+import com.fasterxml.jackson.databind.ObjectMapper
+import de.nowchess.api.board.Color
+import de.nowchess.api.game.{ClockState, CorrespondenceClockState, GameContext, GameMode, LiveClockState, TimeControl}
+import de.nowchess.api.move.Move
+import de.nowchess.api.player.{PlayerId, PlayerInfo}
+import de.nowchess.chess.client.{GameRecordDto, StoreServiceClient}
+import de.nowchess.chess.controller.Parser
+import de.nowchess.chess.engine.GameEngine
+import de.nowchess.chess.grpc.RuleSetGrpcAdapter
+import de.nowchess.chess.config.RedisConfig
+import de.nowchess.chess.grpc.IoGrpcClientWrapper
+import de.nowchess.chess.resource.GameDtoMapper
+import jakarta.enterprise.context.ApplicationScoped
+import jakarta.inject.Inject
+import org.eclipse.microprofile.rest.client.inject.RestClient
+import org.redisson.api.RedissonClient
+import scala.compiletime.uninitialized
+import scala.util.Try
+import java.nio.charset.StandardCharsets
+import java.security.{MessageDigest, SecureRandom}
+import java.time.Instant
+import java.util.concurrent.{ConcurrentHashMap, TimeUnit}
+
+@ApplicationScoped
+class RedisGameRegistry extends GameRegistry:
+  @Inject
+  // scalafix:off DisableSyntax.var
+  var redisson: RedissonClient = uninitialized
+  @Inject var redisConfig: RedisConfig = uninitialized
+  @Inject var objectMapper: ObjectMapper = uninitialized
+  @Inject var ioClient: IoGrpcClientWrapper = uninitialized
+  @Inject var ruleSetAdapter: RuleSetGrpcAdapter = uninitialized
+  @Inject @RestClient var storeClient: StoreServiceClient = uninitialized
+  // scalafix:on
+
+  private val localEngines = ConcurrentHashMap[String, GameEntry]()
+  private val rng = new SecureRandom()
+
+  private def cacheKey(gameId: String) = s"${redisConfig.prefix}:game:entry:$gameId"
+  private def bucket(gameId: String) = redisson.getBucket[String](cacheKey(gameId))
+
+  def generateId(): String =
+    val chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
+    Iterator.continually(rng.nextInt(chars.length)).map(chars).take(8).mkString
+
+  def store(entry: GameEntry): Unit =
+    localEngines.put(entry.gameId, entry)
+    val combined = ioClient.exportCombined(entry.engine.context)
+    bucket(entry.gameId).set(toJson(entry, combined.fen, combined.pgn), 30, TimeUnit.MINUTES)
+
+  def get(gameId: String): Option[GameEntry] =
+    Option(localEngines.get(gameId)) match
+      case Some(localEntry) =>
+        readRedisDto(gameId).flatMap(dto => Try(reconstruct(dto)).toOption) match
+          case Some(redisEntry) if !sameSnapshot(localEntry, redisEntry) =>
+            localEngines.put(gameId, redisEntry)
+            Some(redisEntry)
+          case _ => Some(localEntry)
+      case None => fromRedis(gameId).orElse(fromDb(gameId))
+
+  def update(entry: GameEntry): Unit =
+    localEngines.put(entry.gameId, entry)
+    val combined = ioClient.exportCombined(entry.engine.context)
+    bucket(entry.gameId).set(toJson(entry, combined.fen, combined.pgn), 30, TimeUnit.MINUTES)
+
+  private def readRedisDto(gameId: String): Option[GameCacheDto] =
+    Try(Option(bucket(gameId).get())).toOption.flatten.flatMap { json =>
+      Try(objectMapper.readValue(json, classOf[GameCacheDto])).toOption
+    }
+
+  private def fromRedis(gameId: String): Option[GameEntry] =
+    readRedisDto(gameId)
+      .flatMap(dto => Try(reconstruct(dto)).toOption)
+      .map { entry =>
+        localEngines.put(gameId, entry)
+        entry
+      }
+
+  private def fromDb(gameId: String): Option[GameEntry] =
+    Try {
+      val record = storeClient.getGame(gameId)
+      val dto = GameCacheDto(
+        gameId = record.gameId,
+        fen = record.fen,
+        pgn = record.pgn,
+        whiteId = record.whiteId,
+        whiteName = record.whiteName,
+        blackId = record.blackId,
+        blackName = record.blackName,
+        mode = record.mode,
+        resigned = record.resigned,
+        limitSeconds = Option(record.limitSeconds).map(_.intValue),
+        incrementSeconds = Option(record.incrementSeconds).map(_.intValue),
+        daysPerMove = Option(record.daysPerMove).map(_.intValue),
+        whiteRemainingMs = Option(record.whiteRemainingMs).map(_.longValue),
+        blackRemainingMs = Option(record.blackRemainingMs).map(_.longValue),
+        incrementMs = Option(record.incrementMs).map(_.longValue),
+        clockLastTickAt = Option(record.clockLastTickAt).map(_.longValue),
+        clockMoveDeadline = Option(record.clockMoveDeadline).map(_.longValue),
+        clockActiveColor = Option(record.clockActiveColor),
+        pendingDrawOffer = Option(record.pendingDrawOffer),
+      )
+      (dto, reconstruct(dto))
+    }.toOption
+      .map { case (dto, entry) =>
+        localEngines.put(gameId, entry)
+        bucket(gameId).set(objectMapper.writeValueAsString(dto), 30, TimeUnit.MINUTES)
+        entry
+      }
+
+  private def reconstruct(dto: GameCacheDto): GameEntry =
+    val ctx = if dto.pgn.nonEmpty then ioClient.importPgn(dto.pgn) else GameContext.initial
+    val tc = (dto.limitSeconds, dto.daysPerMove) match
+      case (Some(l), _)    => TimeControl.Clock(l, dto.incrementSeconds.getOrElse(0))
+      case (None, Some(d)) => TimeControl.Correspondence(d)
+      case _               => TimeControl.Unlimited
+    val toColor: String => Color = s => if s == "white" then Color.White else Color.Black
+    val restoredClock: Option[ClockState] =
+      dto.clockLastTickAt.map { tick =>
+        LiveClockState(
+          whiteRemainingMs = dto.whiteRemainingMs.get,
+          blackRemainingMs = dto.blackRemainingMs.get,
+          incrementMs = dto.incrementMs.get,
+          lastTickAt = Instant.ofEpochMilli(tick),
+          activeColor = toColor(dto.clockActiveColor.get),
+        )
+      }.orElse {
+        dto.clockMoveDeadline.map { deadline =>
+          CorrespondenceClockState(
+            moveDeadline = Instant.ofEpochMilli(deadline),
+            daysPerMove = dto.daysPerMove.get,
+            activeColor = toColor(dto.clockActiveColor.get),
+          )
+        }
+      }
+    val restoredDrawOffer = dto.pendingDrawOffer.map(toColor)
+    val restoredTakebackRequest = dto.pendingTakebackRequest.map(toColor)
+    val redoMoves = dto.redoStack.flatMap { uci =>
+      Parser.parseMove(uci).flatMap { case (from, to, pp) =>
+        ruleSetAdapter.legalMoves(ctx)(from)
+          .find(m => m.to == to && (pp.isEmpty || m.moveType == de.nowchess.api.move.MoveType.Promotion(pp.get)))
+      }
+    }
+    val engine = GameEngine(
+      initialContext = ctx,
+      ruleSet = ruleSetAdapter,
+      timeControl = tc,
+      initialClockState = restoredClock,
+      initialDrawOffer = restoredDrawOffer,
+      initialRedoStack = redoMoves,
+      initialTakebackRequest = restoredTakebackRequest,
+    )
+    GameEntry(
+      gameId = dto.gameId,
+      engine = engine,
+      white = PlayerInfo(PlayerId(dto.whiteId), dto.whiteName),
+      black = PlayerInfo(PlayerId(dto.blackId), dto.blackName),
+      resigned = dto.resigned,
+      mode = if dto.mode == "Authenticated" then GameMode.Authenticated else GameMode.Open,
+    )
+
+  private def toJson(entry: GameEntry, fen: String, pgn: String): String =
+    objectMapper.writeValueAsString(toDto(entry, fen, pgn))
+
+  private def toDto(entry: GameEntry, fen: String, pgn: String): GameCacheDto =
+    val clock = entry.engine.currentClockState
+    GameCacheDto(
+      gameId = entry.gameId,
+      whiteId = entry.white.id.value,
+      whiteName = entry.white.displayName,
+      blackId = entry.black.id.value,
+      blackName = entry.black.displayName,
+      mode = entry.mode.toString,
+      pgn = pgn,
+      fen = fen,
+      resigned = entry.resigned,
+      limitSeconds = entry.engine.timeControl match { case TimeControl.Clock(l, _) => Some(l); case _ => None },
+      incrementSeconds = entry.engine.timeControl match { case TimeControl.Clock(_, i) => Some(i); case _ => None },
+      daysPerMove = entry.engine.timeControl match { case TimeControl.Correspondence(d) => Some(d); case _ => None },
+      whiteRemainingMs = clock.collect { case c: LiveClockState => c.whiteRemainingMs },
+      blackRemainingMs = clock.collect { case c: LiveClockState => c.blackRemainingMs },
+      incrementMs = clock.collect { case c: LiveClockState => c.incrementMs },
+      clockLastTickAt = clock.collect { case c: LiveClockState => c.lastTickAt.toEpochMilli },
+      clockMoveDeadline = clock.collect { case c: CorrespondenceClockState => c.moveDeadline.toEpochMilli },
+      clockActiveColor = clock.map(_.activeColor.label.toLowerCase),
+      pendingDrawOffer = entry.engine.pendingDrawOfferBy.map(_.label.toLowerCase),
+      redoStack = entry.engine.redoStackMoves.map(GameDtoMapper.moveToUci),
+      pendingTakebackRequest = entry.engine.pendingTakebackRequestBy.map(_.label.toLowerCase),
+    )
+
+  private def sameSnapshot(localEntry: GameEntry, redisEntry: GameEntry): Boolean =
+    entryHash(localEntry).exists(localHash => entryHash(redisEntry).contains(localHash))
+
+  private def entryHash(entry: GameEntry): Option[String] =
+    Try {
+      val combined = ioClient.exportCombined(entry.engine.context)
+      val canonicalJson = objectMapper.writeValueAsString(toDto(entry, combined.fen, combined.pgn))
+      val digest = MessageDigest.getInstance("SHA-256").digest(canonicalJson.getBytes(StandardCharsets.UTF_8))
+      digest.map("%02x".format(_)).mkString
+    }.toOption

modules/core/src/main/scala/de/nowchess/chess/resource/GameDtoMapper.scala

@@ -0,0 +1,73 @@
+package de.nowchess.chess.resource
+
+import de.nowchess.api.board.Color
+import de.nowchess.api.dto.*
+import de.nowchess.api.game.{CorrespondenceClockState, DrawReason, GameResult, LiveClockState, WinReason}
+import de.nowchess.api.move.{Move, MoveType, PromotionPiece}
+import de.nowchess.api.player.PlayerInfo
+import de.nowchess.chess.grpc.IoGrpcClientWrapper
+import de.nowchess.chess.registry.GameEntry
+import java.time.Instant
+
+object GameDtoMapper:
+
+  def statusOf(entry: GameEntry): String =
+    if entry.engine.pendingTakebackRequestBy.isDefined then "takebackRequested"
+    else if entry.engine.pendingDrawOfferBy.isDefined then "drawOffered"
+    else
+      val ctx = entry.engine.context
+      ctx.result match
+        case Some(GameResult.Win(_, WinReason.Checkmate))   => "checkmate"
+        case Some(GameResult.Win(_, WinReason.Resignation)) => "resign"
+        case Some(GameResult.Win(_, WinReason.TimeControl)) => "timeout"
+        case Some(GameResult.Draw(DrawReason.Stalemate))            => "stalemate"
+        case Some(GameResult.Draw(DrawReason.InsufficientMaterial)) => "insufficientMaterial"
+        case Some(GameResult.Draw(_))                               => "draw"
+        case None =>
+          if ctx.halfMoveClock >= 100 then "fiftyMoveAvailable"
+          else if entry.engine.ruleSet.isCheck(ctx) then "check"
+          else "started"
+
+  def moveToUci(move: Move): String =
+    val base = s"${move.from}${move.to}"
+    move.moveType match
+      case MoveType.Promotion(PromotionPiece.Queen)  => s"${base}q"
+      case MoveType.Promotion(PromotionPiece.Rook)   => s"${base}r"
+      case MoveType.Promotion(PromotionPiece.Bishop) => s"${base}b"
+      case MoveType.Promotion(PromotionPiece.Knight) => s"${base}n"
+      case _                                         => base
+
+  def toPlayerDto(info: PlayerInfo): PlayerInfoDto =
+    PlayerInfoDto(info.id.value, info.displayName)
+
+  def toClockDto(entry: GameEntry): Option[ClockDto] =
+    val now = Instant.now()
+    entry.engine.currentClockState.map {
+      case cs: LiveClockState =>
+        ClockDto(cs.remainingMs(Color.White, now), cs.remainingMs(Color.Black, now))
+      case cs: CorrespondenceClockState =>
+        val remaining = cs.remainingMs(cs.activeColor, now)
+        ClockDto(
+          whiteRemainingMs = if cs.activeColor == Color.White then remaining else -1L,
+          blackRemainingMs = if cs.activeColor == Color.Black then remaining else -1L,
+        )
+    }
+
+  def toGameStateDto(entry: GameEntry, ioClient: IoGrpcClientWrapper): GameStateDto =
+    val ctx = entry.engine.context
+    val exported = ioClient.exportCombined(ctx)
+    GameStateDto(
+      fen = exported.fen,
+      pgn = exported.pgn,
+      turn = ctx.turn.label.toLowerCase,
+      status = statusOf(entry),
+      winner = ctx.result.collect { case GameResult.Win(c, _) => c.label.toLowerCase },
+      moves = ctx.moves.map(moveToUci),
+      undoAvailable = entry.engine.canUndo,
+      redoAvailable = entry.engine.canRedo,
+      clock = toClockDto(entry),
+      takebackRequestedBy = entry.engine.pendingTakebackRequestBy.map(_.label.toLowerCase),
+    )
+
+  def toGameFullDto(entry: GameEntry, ioClient: IoGrpcClientWrapper): GameFullDto =
+    GameFullDto(entry.gameId, toPlayerDto(entry.white), toPlayerDto(entry.black), toGameStateDto(entry, ioClient))

modules/core/src/main/scala/de/nowchess/chess/resource/GameResource.scala

@@ -22,6 +22,7 @@ import de.nowchess.chess.engine.GameEngine
 import de.nowchess.chess.exception.{BadRequestException, GameNotFoundException}
 import de.nowchess.chess.grpc.{IoGrpcClientWrapper, RuleSetGrpcAdapter}
 import de.nowchess.chess.observer.*
+import de.nowchess.chess.redis.GameRedisSubscriberManager
 import de.nowchess.chess.registry.{GameEntry, GameRegistry}
 import jakarta.enterprise.context.ApplicationScoped
 import jakarta.inject.Inject
@@ -51,6 +52,9 @@ class GameResource:
 
   @Inject
   var jwt: JsonWebToken = uninitialized
+
+  @Inject
+  var subscriberManager: GameRedisSubscriberManager = uninitialized
   // scalafix:on DisableSyntax.var
 
   private val DefaultWhite = PlayerInfo(PlayerId("p1"), "Player 1")
@@ -79,31 +83,6 @@ class GameResource:
 
   // ── mapping ──────────────────────────────────────────────────────────────
 
-  private def statusOf(entry: GameEntry): String =
-    if entry.engine.pendingDrawOfferBy.isDefined then "drawOffered"
-    else
-      val ctx = entry.engine.context
-      ctx.result match
-        case Some(GameResult.Win(_, WinReason.Checkmate))           => "checkmate"
-        case Some(GameResult.Win(_, WinReason.Resignation))         => "resign"
-        case Some(GameResult.Win(_, WinReason.TimeControl))         => "timeout"
-        case Some(GameResult.Draw(DrawReason.Stalemate))            => "stalemate"
-        case Some(GameResult.Draw(DrawReason.InsufficientMaterial)) => "insufficientMaterial"
-        case Some(GameResult.Draw(_))                               => "draw"
-        case None =>
-          if ctx.halfMoveClock >= 100 then "fiftyMoveAvailable"
-          else if entry.engine.ruleSet.isCheck(ctx) then "check"
-          else "started"
-
-  private def moveToUci(move: Move): String =
-    val base = s"${move.from}${move.to}"
-    move.moveType match
-      case MoveType.Promotion(PromotionPiece.Queen)  => s"${base}q"
-      case MoveType.Promotion(PromotionPiece.Rook)   => s"${base}r"
-      case MoveType.Promotion(PromotionPiece.Bishop) => s"${base}b"
-      case MoveType.Promotion(PromotionPiece.Knight) => s"${base}n"
-      case _                                         => base
-
   private def toLegalMoveDto(move: Move): LegalMoveDto =
     val (moveTypeStr, promotionStr) = move.moveType match
       case MoveType.Normal(false)                    => ("normal", None)
@@ -115,41 +94,7 @@ class GameResource:
       case MoveType.Promotion(PromotionPiece.Rook)   => ("promotion", Some("rook"))
       case MoveType.Promotion(PromotionPiece.Bishop) => ("promotion", Some("bishop"))
       case MoveType.Promotion(PromotionPiece.Knight) => ("promotion", Some("knight"))
-    LegalMoveDto(move.from.toString, move.to.toString, moveToUci(move), moveTypeStr, promotionStr)
+    LegalMoveDto(move.from.toString, move.to.toString, GameDtoMapper.moveToUci(move), moveTypeStr, promotionStr)
-
-  private def toPlayerDto(info: PlayerInfo): PlayerInfoDto =
-    PlayerInfoDto(info.id.value, info.displayName)
-
-  private def toClockDto(entry: GameEntry): Option[ClockDto] =
-    val now = Instant.now()
-    entry.engine.currentClockState.map {
-      case cs: LiveClockState =>
-        ClockDto(cs.remainingMs(Color.White, now), cs.remainingMs(Color.Black, now))
-      case cs: CorrespondenceClockState =>
-        val remaining = cs.remainingMs(cs.activeColor, now)
-        ClockDto(
-          whiteRemainingMs = if cs.activeColor == Color.White then remaining else -1L,
-          blackRemainingMs = if cs.activeColor == Color.Black then remaining else -1L,
-        )
-    }
-
-  private def toGameStateDto(entry: GameEntry): GameStateDto =
-    val ctx      = entry.engine.context
-    val exported = ioClient.exportCombined(ctx)
-    GameStateDto(
-      fen = exported.fen,
-      pgn = exported.pgn,
-      turn = ctx.turn.label.toLowerCase,
-      status = statusOf(entry),
-      winner = ctx.result.collect { case GameResult.Win(c, _) => c.label.toLowerCase },
-      moves = ctx.moves.map(moveToUci),
-      undoAvailable = entry.engine.canUndo,
-      redoAvailable = entry.engine.canRedo,
-      clock = toClockDto(entry),
-    )
-
-  private def toGameFullDto(entry: GameEntry): GameFullDto =
-    GameFullDto(entry.gameId, toPlayerDto(entry.white), toPlayerDto(entry.black), toGameStateDto(entry))
 
   private def playerInfoFrom(dto: Option[PlayerInfoDto], default: PlayerInfo): PlayerInfo =
     dto.fold(default)(d => PlayerInfo(PlayerId(d.id), d.displayName))
@@ -213,15 +158,16 @@ class GameResource:
     val mode  = req.mode.getOrElse(GameMode.Open)
     val entry = newEntry(GameContext.initial, white, black, tc, mode)
     registry.store(entry)
+    subscriberManager.subscribeGame(entry.gameId)
     println(s"Created game ${entry.gameId}")
-    created(toGameFullDto(entry))
+    created(GameDtoMapper.toGameFullDto(entry, ioClient))
 
   @GET
   @Path("/{gameId}")
   @Produces(Array(MediaType.APPLICATION_JSON))
   def getGame(@PathParam("gameId") gameId: String): Response =
     val entry = registry.get(gameId).getOrElse(throw GameNotFoundException(gameId))
-    ok(toGameFullDto(entry))
+    ok(GameDtoMapper.toGameFullDto(entry, ioClient))
 
   @POST
   @Path("/{gameId}/resign")
@@ -244,7 +190,8 @@ class GameResource:
     if Parser.parseMove(uci).isEmpty then
       throw BadRequestException("INVALID_UCI", s"Invalid UCI notation: $uci", Some("uci"))
     applyMoveInput(entry.engine, uci).foreach(err => throw BadRequestException("INVALID_MOVE", err, Some("uci")))
-    ok(toGameStateDto(entry))
+    registry.update(entry)
+    ok(GameDtoMapper.toGameStateDto(entry, ioClient))
 
   @GET
   @Path("/{gameId}/moves")
@@ -271,7 +218,8 @@ class GameResource:
     val entry = registry.get(gameId).getOrElse(throw GameNotFoundException(gameId))
     if !entry.engine.canUndo then throw BadRequestException("NO_UNDO", "No moves to undo")
     entry.engine.undo()
-    ok(toGameStateDto(entry))
+    registry.update(entry)
+    ok(GameDtoMapper.toGameStateDto(entry, ioClient))
 
   @POST
   @Path("/{gameId}/redo")
@@ -280,7 +228,8 @@ class GameResource:
     val entry = registry.get(gameId).getOrElse(throw GameNotFoundException(gameId))
     if !entry.engine.canRedo then throw BadRequestException("NO_REDO", "No moves to redo")
     entry.engine.redo()
-    ok(toGameStateDto(entry))
+    registry.update(entry)
+    ok(GameDtoMapper.toGameStateDto(entry, ioClient))
 
   @POST
   @Path("/{gameId}/draw/{action}")
@@ -293,12 +242,28 @@ class GameResource:
     assertGameNotOver(entry)
     val color = colorOf(entry)
     action match
-      case "offer"   => entry.engine.offerDraw(color); ok(OkResponseDto())
+      case "offer"   => entry.engine.offerDraw(color); registry.update(entry); ok(OkResponseDto())
-      case "accept"  => entry.engine.acceptDraw(color); ok(OkResponseDto())
+      case "accept"  => entry.engine.acceptDraw(color); registry.update(entry); ok(OkResponseDto())
-      case "decline" => entry.engine.declineDraw(color); ok(OkResponseDto())
+      case "decline" => entry.engine.declineDraw(color); registry.update(entry); ok(OkResponseDto())
-      case "claim"   => entry.engine.claimDraw(); ok(OkResponseDto())
+      case "claim"   => entry.engine.claimDraw(); registry.update(entry); ok(OkResponseDto())
       case _         => throw BadRequestException("INVALID_ACTION", s"Unknown draw action: $action", Some("action"))
 
+  @POST
+  @Path("/{gameId}/takeback/{action}")
+  @Produces(Array(MediaType.APPLICATION_JSON))
+  def takebackAction(
+      @PathParam("gameId") gameId: String,
+      @PathParam("action") action: String,
+  ): Response =
+    val entry = registry.get(gameId).getOrElse(throw GameNotFoundException(gameId))
+    assertGameNotOver(entry)
+    val color = colorOf(entry)
+    action match
+      case "request" => entry.engine.requestTakeback(color); registry.update(entry); ok(OkResponseDto())
+      case "accept"  => entry.engine.acceptTakeback(color); registry.update(entry); ok(GameDtoMapper.toGameStateDto(entry, ioClient))
+      case "decline" => entry.engine.declineTakeback(color); registry.update(entry); ok(OkResponseDto())
+      case _         => throw BadRequestException("INVALID_ACTION", s"Unknown takeback action: $action", Some("action"))
+
   @POST
   @Path("/import/fen")
   @Consumes(Array(MediaType.APPLICATION_JSON))
@@ -310,7 +275,8 @@ class GameResource:
     val tc    = toTimeControl(body.timeControl)
     val entry = newEntry(ctx, white, black, tc)
     registry.store(entry)
-    created(toGameFullDto(entry))
+    subscriberManager.subscribeGame(entry.gameId)
+    created(GameDtoMapper.toGameFullDto(entry, ioClient))
 
   @POST
   @Path("/import/pgn")
@@ -320,7 +286,8 @@ class GameResource:
     val ctx   = ioClient.importPgn(body.pgn)
     val entry = newEntry(ctx, DefaultWhite, DefaultBlack)
     registry.store(entry)
-    created(toGameFullDto(entry))
+    subscriberManager.subscribeGame(entry.gameId)
+    created(GameDtoMapper.toGameFullDto(entry, ioClient))
 
   @GET
   @Path("/{gameId}/export/fen")

modules/core/src/main/scala/de/nowchess/chess/resource/GameWebSocketResource.scala

@@ -1,132 +0,0 @@
-package de.nowchess.chess.resource
-
-import com.fasterxml.jackson.databind.ObjectMapper
-import de.nowchess.api.board.Color
-import de.nowchess.api.dto.*
-import de.nowchess.api.game.{CorrespondenceClockState, DrawReason, GameResult, LiveClockState}
-import de.nowchess.api.move.{Move, MoveType, PromotionPiece}
-import de.nowchess.api.player.PlayerInfo
-import de.nowchess.chess.client.IoServiceClient
-import de.nowchess.chess.observer.*
-import de.nowchess.chess.registry.{GameEntry, GameRegistry}
-import io.quarkus.websockets.next.*
-import jakarta.inject.Inject
-import org.eclipse.microprofile.rest.client.inject.RestClient
-
-import java.time.Instant
-import java.util.concurrent.ConcurrentHashMap
-import scala.compiletime.uninitialized
-
-@WebSocket(path = "/api/board/game/{gameId}/ws")
-class GameWebSocketResource:
-
-  // scalafix:off DisableSyntax.var
-  @Inject
-  var registry: GameRegistry = uninitialized
-
-  @Inject
-  var objectMapper: ObjectMapper = uninitialized
-
-  @Inject
-  @RestClient
-  var ioClient: IoServiceClient = uninitialized
-  // scalafix:on DisableSyntax.var
-
-  private val connectionObservers = new ConcurrentHashMap[String, (String, Observer)]()
-
-  @OnOpen
-  def onOpen(connection: WebSocketConnection): Unit =
-    val gameId = connection.pathParam("gameId")
-    registry.get(gameId) match
-      case None =>
-        val err = ErrorEventDto(ApiErrorDto("GAME_NOT_FOUND", s"Game $gameId not found", None))
-        connection
-          .sendText(objectMapper.writeValueAsString(err))
-          .flatMap(_ => connection.close())
-          .subscribe()
-          .`with`(_ => (), _ => ())
-      case Some(entry) =>
-        val initial = objectMapper.writeValueAsString(GameFullEventDto(toGameFullDto(entry)))
-        val obs = new Observer:
-          def onGameEvent(event: GameEvent): Unit =
-            registry.get(gameId).foreach { updated =>
-              connection
-                .sendText(objectMapper.writeValueAsString(GameStateEventDto(toGameStateDto(updated))))
-                .subscribe()
-                .`with`(_ => (), _ => ())
-            }
-        connection
-          .sendText(initial)
-          .subscribe()
-          .`with`(
-            _ => {
-              connectionObservers.put(connection.id(), (gameId, obs))
-              entry.engine.subscribe(obs)
-            },
-            _ => (),
-          )
-
-  @OnClose
-  def onClose(connection: WebSocketConnection): Unit =
-    Option(connectionObservers.remove(connection.id())).foreach { case (gameId, obs) =>
-      registry.get(gameId).foreach(_.engine.unsubscribe(obs))
-    }
-
-  private def statusOf(entry: GameEntry): String =
-    if entry.engine.pendingDrawOfferBy.isDefined then "drawOffered"
-    else
-      val ctx = entry.engine.context
-      ctx.result match
-        case Some(GameResult.Win(_, _)) =>
-          if entry.resigned then "resign"
-          else if entry.engine.ruleSet.isCheckmate(ctx) then "checkmate"
-          else "timeout"
-        case Some(GameResult.Draw(DrawReason.Stalemate))            => "stalemate"
-        case Some(GameResult.Draw(DrawReason.InsufficientMaterial)) => "insufficientMaterial"
-        case Some(GameResult.Draw(_))                               => "draw"
-        case None =>
-          if ctx.halfMoveClock >= 100 then "fiftyMoveAvailable"
-          else if entry.engine.ruleSet.isCheck(ctx) then "check"
-          else "started"
-
-  private def moveToUci(move: Move): String =
-    val base = s"${move.from}${move.to}"
-    move.moveType match
-      case MoveType.Promotion(PromotionPiece.Queen)  => s"${base}q"
-      case MoveType.Promotion(PromotionPiece.Rook)   => s"${base}r"
-      case MoveType.Promotion(PromotionPiece.Bishop) => s"${base}b"
-      case MoveType.Promotion(PromotionPiece.Knight) => s"${base}n"
-      case _                                         => base
-
-  private def toPlayerDto(info: PlayerInfo): PlayerInfoDto =
-    PlayerInfoDto(info.id.value, info.displayName)
-
-  private def toClockDto(entry: GameEntry): Option[ClockDto] =
-    val now = Instant.now()
-    entry.engine.currentClockState.map {
-      case cs: LiveClockState =>
-        ClockDto(cs.remainingMs(Color.White, now), cs.remainingMs(Color.Black, now))
-      case cs: CorrespondenceClockState =>
-        val remaining = cs.remainingMs(cs.activeColor, now)
-        ClockDto(
-          whiteRemainingMs = if cs.activeColor == Color.White then remaining else -1L,
-          blackRemainingMs = if cs.activeColor == Color.Black then remaining else -1L,
-        )
-    }
-
-  private def toGameStateDto(entry: GameEntry): GameStateDto =
-    val ctx = entry.engine.context
-    GameStateDto(
-      fen = ioClient.exportFen(ctx),
-      pgn = ioClient.exportPgn(ctx),
-      turn = ctx.turn.label.toLowerCase,
-      status = statusOf(entry),
-      winner = ctx.result.collect { case GameResult.Win(c, _) => c.label.toLowerCase },
-      moves = ctx.moves.map(moveToUci),
-      undoAvailable = entry.engine.canUndo,
-      redoAvailable = entry.engine.canRedo,
-      clock = toClockDto(entry),
-    )
-
-  private def toGameFullDto(entry: GameEntry): GameFullDto =
-    GameFullDto(entry.gameId, toPlayerDto(entry.white), toPlayerDto(entry.black), toGameStateDto(entry))

modules/core/src/test/resources/application.yml

@@ -7,3 +7,9 @@ quarkus:
       io-grpc:
         host: localhost
         port: 9081
+
+nowchess:
+  redis:
+    host: localhost
+    port: 6379
+    prefix: test-core

modules/io/build.gradle.kts

@@ -115,3 +115,15 @@ tasks.reportScoverage {
 tasks.jar {
     duplicatesStrategy = DuplicatesStrategy.EXCLUDE
 }
+
+tasks.withType(org.gradle.api.tasks.scala.ScalaCompile::class).configureEach {
+    if (name == "compileScoverageScala") {
+        source = source.asFileTree.matching {
+            exclude("**/grpc/*.scala")
+        }
+    }
+}
+
+tasks.named("compileScoverageJava").configure {
+    dependsOn(tasks.named("quarkusGenerateCode"))
+}

modules/rule/build.gradle.kts

@@ -115,3 +115,15 @@ tasks.reportScoverage {
 tasks.jar {
     duplicatesStrategy = DuplicatesStrategy.EXCLUDE
 }
+
+tasks.withType(org.gradle.api.tasks.scala.ScalaCompile::class).configureEach {
+    if (name == "compileScoverageScala") {
+        source = source.asFileTree.matching {
+            exclude("**/grpc/*.scala")
+        }
+    }
+}
+
+tasks.named("compileScoverageJava").configure {
+    dependsOn(tasks.named("quarkusGenerateCode"))
+}

modules/store/build.gradle.kts

@@ -0,0 +1,108 @@
+plugins {
+    id("scala")
+    id("org.scoverage") version "8.1"
+    id("io.quarkus")
+}
+
+group = "de.nowchess"
+version = "1.0-SNAPSHOT"
+
+@Suppress("UNCHECKED_CAST")
+val versions = rootProject.extra["VERSIONS"] as Map<String, String>
+
+repositories {
+    mavenCentral()
+}
+
+scala {
+    scalaVersion = versions["SCALA3"]!!
+}
+
+scoverage {
+    scoverageVersion.set(versions["SCOVERAGE"]!!)
+}
+
+tasks.withType<ScalaCompile> {
+    scalaCompileOptions.additionalParameters = listOf("-encoding", "UTF-8")
+}
+
+val quarkusPlatformGroupId: String by project
+val quarkusPlatformArtifactId: String by project
+val quarkusPlatformVersion: String by project
+
+dependencies {
+
+    runtimeOnly("io.quarkus:quarkus-jdbc-h2")
+
+    compileOnly("org.scala-lang:scala3-compiler_3") {
+        version {
+            strictly(versions["SCALA3"]!!)
+        }
+    }
+    implementation("org.scala-lang:scala3-library_3") {
+        version {
+            strictly(versions["SCALA3"]!!)
+        }
+    }
+
+    implementation(platform("${quarkusPlatformGroupId}:${quarkusPlatformArtifactId}:${quarkusPlatformVersion}"))
+    implementation("io.quarkus:quarkus-rest")
+    implementation("io.quarkus:quarkus-rest-jackson")
+    implementation("io.quarkus:quarkus-config-yaml")
+    implementation("io.quarkus:quarkus-arc")
+    implementation("io.quarkus:quarkus-hibernate-orm-panache")
+    implementation("io.quarkus:quarkus-jdbc-postgresql")
+    implementation("io.quarkus:quarkus-smallrye-health")
+    implementation("com.fasterxml.jackson.module:jackson-module-scala_3:${versions["JACKSON_SCALA"]!!}")
+    implementation("org.redisson:redisson:${versions["REDISSON"]!!}")
+
+    testImplementation(platform("org.junit:junit-bom:5.13.4"))
+    testImplementation("org.junit.jupiter:junit-jupiter")
+    testImplementation("org.scalatest:scalatest_3:${versions["SCALATEST"]!!}")
+    testImplementation("co.helmethair:scalatest-junit-runner:${versions["SCALATEST_JUNIT"]!!}")
+    testImplementation("io.quarkus:quarkus-junit5")
+    testImplementation("io.quarkus:quarkus-junit5-mockito")
+    testImplementation("io.rest-assured:rest-assured")
+    testImplementation("io.quarkus:quarkus-jdbc-h2")
+
+    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
+}
+
+configurations.matching { !it.name.startsWith("scoverage") }.configureEach {
+    resolutionStrategy.force("org.scala-lang:scala-library:${versions["SCALA_LIBRARY"]!!}")
+}
+configurations.scoverage {
+    resolutionStrategy.eachDependency {
+        if (requested.group == "org.scoverage" && requested.name.startsWith("scalac-scoverage-plugin_")) {
+            useTarget("${requested.group}:scalac-scoverage-plugin_2.13.16:2.3.0")
+        }
+    }
+}
+
+tasks.withType<JavaCompile> {
+    options.encoding = "UTF-8"
+    options.compilerArgs.add("-parameters")
+}
+
+tasks.withType<Jar>().configureEach {
+    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
+}
+
+tasks.test {
+    useJUnitPlatform {
+        includeEngines("scalatest", "junit-jupiter")
+        testLogging {
+            events("passed", "skipped", "failed")
+            showStandardStreams = true
+            exceptionFormat = org.gradle.api.tasks.testing.logging.TestExceptionFormat.FULL
+        }
+    }
+    finalizedBy(tasks.reportScoverage)
+}
+tasks.reportScoverage {
+    dependsOn(tasks.test)
+}
+
+tasks.jar {
+    duplicatesStrategy = DuplicatesStrategy.INCLUDE
+}

modules/store/src/main/scala/de/nowchess/store/config/RedisConfig.scala

@@ -0,0 +1,16 @@
+package de.nowchess.store.config
+
+import jakarta.enterprise.context.ApplicationScoped
+import org.eclipse.microprofile.config.inject.ConfigProperty
+import scala.compiletime.uninitialized
+
+@ApplicationScoped
+class RedisConfig:
+  @ConfigProperty(name = "nowchess.redis.host", defaultValue = "localhost")
+  var host: String = uninitialized
+
+  @ConfigProperty(name = "nowchess.redis.port", defaultValue = "6379")
+  var port: Int = uninitialized
+
+  @ConfigProperty(name = "nowchess.redis.prefix", defaultValue = "nowchess")
+  var prefix: String = uninitialized

modules/store/src/main/scala/de/nowchess/store/config/RedissonProducer.scala

@@ -0,0 +1,29 @@
+package de.nowchess.store.config
+
+import jakarta.annotation.PreDestroy
+import jakarta.enterprise.context.ApplicationScoped
+import jakarta.enterprise.inject.Produces
+import jakarta.inject.Inject
+import org.redisson.Redisson
+import org.redisson.api.RedissonClient
+import org.redisson.config.Config
+import scala.compiletime.uninitialized
+
+@ApplicationScoped
+class RedissonProducer:
+  @Inject
+  var redisConfig: RedisConfig = uninitialized
+
+  @Produces
+  @ApplicationScoped
+  def redissonClient(): RedissonClient =
+    val config = new Config()
+    config.useSingleServer()
+      .setAddress(s"redis://${redisConfig.host}:${redisConfig.port}")
+      .setConnectionMinimumIdleSize(1)
+      .setConnectTimeout(500)
+    Redisson.create(config)
+
+  @PreDestroy
+  def close(client: RedissonClient): Unit =
+    client.shutdown()

modules/store/src/main/scala/de/nowchess/store/domain/GameRecord.scala

@@ -0,0 +1,82 @@
+package de.nowchess.store.domain
+
+import io.quarkus.hibernate.orm.panache.PanacheEntityBase
+import jakarta.persistence.*
+import scala.compiletime.uninitialized
+import java.time.Instant
+
+@Entity
+@Table(name = "game_records")
+class GameRecord extends PanacheEntityBase:
+  // scalafix:off DisableSyntax.var
+  @Id
+  @Column(nullable = false)
+  var gameId: String = uninitialized
+
+  @Column(nullable = false, columnDefinition = "TEXT")
+  var fen: String = uninitialized
+
+  @Column(nullable = false, columnDefinition = "TEXT")
+  var pgn: String = uninitialized
+
+  @Column(nullable = false)
+  var moveCount: Int = 0
+
+  @Column(nullable = false)
+  var createdAt: Instant = uninitialized
+
+  @Column(nullable = false)
+  var updatedAt: Instant = uninitialized
+
+  // Player info
+  @Column(nullable = false)
+  var whiteId: String = uninitialized
+
+  @Column(nullable = false)
+  var whiteName: String = uninitialized
+
+  @Column(nullable = false)
+  var blackId: String = uninitialized
+
+  @Column(nullable = false)
+  var blackName: String = uninitialized
+
+  @Column(nullable = false)
+  var mode: String = uninitialized
+
+  // Time control
+  @Column
+  var limitSeconds: java.lang.Integer = uninitialized
+
+  @Column
+  var incrementSeconds: java.lang.Integer = uninitialized
+
+  @Column
+  var daysPerMove: java.lang.Integer = uninitialized
+
+  // Clock state
+  @Column
+  var whiteRemainingMs: java.lang.Long = uninitialized
+
+  @Column
+  var blackRemainingMs: java.lang.Long = uninitialized
+
+  @Column
+  var incrementMs: java.lang.Long = uninitialized
+
+  @Column
+  var clockLastTickAt: java.lang.Long = uninitialized
+
+  @Column
+  var clockMoveDeadline: java.lang.Long = uninitialized
+
+  @Column
+  var clockActiveColor: String = uninitialized
+
+  // Game meta
+  @Column(nullable = false)
+  var resigned: Boolean = false
+
+  @Column
+  var pendingDrawOffer: String = uninitialized
+  // scalafix:on

modules/store/src/main/scala/de/nowchess/store/redis/GameWritebackEventDto.scala

@@ -0,0 +1,24 @@
+package de.nowchess.store.redis
+
+case class GameWritebackEventDto(
+  gameId: String,
+  fen: String,
+  pgn: String,
+  moveCount: Int,
+  whiteId: String,
+  whiteName: String,
+  blackId: String,
+  blackName: String,
+  mode: String,
+  resigned: Boolean,
+  limitSeconds: Option[Int],
+  incrementSeconds: Option[Int],
+  daysPerMove: Option[Int],
+  whiteRemainingMs: Option[Long],
+  blackRemainingMs: Option[Long],
+  incrementMs: Option[Long],
+  clockLastTickAt: Option[Long],
+  clockMoveDeadline: Option[Long],
+  clockActiveColor: Option[String],
+  pendingDrawOffer: Option[String],
+)

modules/store/src/main/scala/de/nowchess/store/redis/GameWritebackStreamListener.scala

@@ -0,0 +1,30 @@
+package de.nowchess.store.redis
+
+import com.fasterxml.jackson.databind.ObjectMapper
+import de.nowchess.store.service.GameWritebackService
+import jakarta.annotation.PostConstruct
+import jakarta.enterprise.context.ApplicationScoped
+import jakarta.inject.Inject
+import org.redisson.api.listener.MessageListener
+import org.redisson.api.RedissonClient
+import scala.compiletime.uninitialized
+import scala.util.Try
+
+@ApplicationScoped
+class GameWritebackStreamListener:
+  @Inject
+  // scalafix:off DisableSyntax.var
+  var redisson: RedissonClient = uninitialized
+  @Inject var objectMapper: ObjectMapper = uninitialized
+  @Inject var writebackService: GameWritebackService = uninitialized
+  // scalafix:on
+
+  @PostConstruct
+  def startListening(): Unit =
+    val topic = redisson.getTopic("game-writeback")
+    topic.addListener(classOf[String], new MessageListener[String]:
+      def onMessage(channel: CharSequence, json: String): Unit =
+        Try(objectMapper.readValue(json, classOf[GameWritebackEventDto]))
+          .toOption
+          .foreach(writebackService.writeBack)
+    )

modules/store/src/main/scala/de/nowchess/store/repository/GameRecordRepository.scala

@@ -0,0 +1,23 @@
+package de.nowchess.store.repository
+
+import de.nowchess.store.domain.GameRecord
+import jakarta.enterprise.context.ApplicationScoped
+import jakarta.inject.Inject
+import jakarta.persistence.EntityManager
+import scala.compiletime.uninitialized
+
+@ApplicationScoped
+class GameRecordRepository:
+  @Inject
+  // scalafix:off DisableSyntax.var
+  var em: EntityManager = uninitialized
+  // scalafix:on
+
+  def findByGameId(gameId: String): Option[GameRecord] =
+    Option(em.find(classOf[GameRecord], gameId))
+
+  def persist(record: GameRecord): Unit =
+    em.persist(record)
+
+  def merge(record: GameRecord): Unit =
+    em.merge(record)

modules/store/src/main/scala/de/nowchess/store/resource/StoreGameResource.scala

@@ -0,0 +1,23 @@
+package de.nowchess.store.resource
+
+import de.nowchess.store.repository.GameRecordRepository
+import jakarta.enterprise.context.ApplicationScoped
+import jakarta.inject.Inject
+import jakarta.ws.rs.*
+import jakarta.ws.rs.core.{MediaType, Response}
+import scala.compiletime.uninitialized
+
+@Path("/game")
+@ApplicationScoped
+class StoreGameResource:
+  @Inject
+  // scalafix:off DisableSyntax.var
+  var repository: GameRecordRepository = uninitialized
+  // scalafix:on
+
+  @GET
+  @Path("/{gameId}")
+  @Produces(Array(MediaType.APPLICATION_JSON))
+  def getGame(@PathParam("gameId") gameId: String): Response =
+    repository.findByGameId(gameId)
+      .fold(Response.status(404).build())(r => Response.ok(r).build())

modules/store/src/main/scala/de/nowchess/store/service/GameWritebackService.scala

@@ -0,0 +1,69 @@
+package de.nowchess.store.service
+
+import de.nowchess.store.domain.GameRecord
+import de.nowchess.store.redis.GameWritebackEventDto
+import de.nowchess.store.repository.GameRecordRepository
+import jakarta.enterprise.context.ApplicationScoped
+import jakarta.inject.Inject
+import jakarta.transaction.Transactional
+import scala.compiletime.uninitialized
+import java.time.Instant
+
+@ApplicationScoped
+class GameWritebackService:
+  @Inject
+  // scalafix:off DisableSyntax.var
+  var repository: GameRecordRepository = uninitialized
+  // scalafix:on
+
+  @Transactional
+  def writeBack(event: GameWritebackEventDto): Unit =
+    repository.findByGameId(event.gameId) match
+      case None =>
+        val record = new GameRecord
+        record.gameId = event.gameId
+        record.fen = event.fen
+        record.pgn = event.pgn
+        record.moveCount = event.moveCount
+        record.whiteId = event.whiteId
+        record.whiteName = event.whiteName
+        record.blackId = event.blackId
+        record.blackName = event.blackName
+        record.mode = event.mode
+        record.resigned = event.resigned
+        record.limitSeconds = event.limitSeconds.map(java.lang.Integer.valueOf).orNull
+        record.incrementSeconds = event.incrementSeconds.map(java.lang.Integer.valueOf).orNull
+        record.daysPerMove = event.daysPerMove.map(java.lang.Integer.valueOf).orNull
+        record.whiteRemainingMs = event.whiteRemainingMs.map(java.lang.Long.valueOf).orNull
+        record.blackRemainingMs = event.blackRemainingMs.map(java.lang.Long.valueOf).orNull
+        record.incrementMs = event.incrementMs.map(java.lang.Long.valueOf).orNull
+        record.clockLastTickAt = event.clockLastTickAt.map(java.lang.Long.valueOf).orNull
+        record.clockMoveDeadline = event.clockMoveDeadline.map(java.lang.Long.valueOf).orNull
+        record.clockActiveColor = event.clockActiveColor.orNull
+        record.pendingDrawOffer = event.pendingDrawOffer.orNull
+        record.createdAt = Instant.now()
+        record.updatedAt = Instant.now()
+        repository.persist(record)
+      case Some(r) if event.moveCount > r.moveCount || event.pgn != r.pgn =>
+        r.fen = event.fen
+        r.pgn = event.pgn
+        r.moveCount = event.moveCount
+        r.whiteId = event.whiteId
+        r.whiteName = event.whiteName
+        r.blackId = event.blackId
+        r.blackName = event.blackName
+        r.mode = event.mode
+        r.resigned = event.resigned
+        r.limitSeconds = event.limitSeconds.map(java.lang.Integer.valueOf).orNull
+        r.incrementSeconds = event.incrementSeconds.map(java.lang.Integer.valueOf).orNull
+        r.daysPerMove = event.daysPerMove.map(java.lang.Integer.valueOf).orNull
+        r.whiteRemainingMs = event.whiteRemainingMs.map(java.lang.Long.valueOf).orNull
+        r.blackRemainingMs = event.blackRemainingMs.map(java.lang.Long.valueOf).orNull
+        r.incrementMs = event.incrementMs.map(java.lang.Long.valueOf).orNull
+        r.clockLastTickAt = event.clockLastTickAt.map(java.lang.Long.valueOf).orNull
+        r.clockMoveDeadline = event.clockMoveDeadline.map(java.lang.Long.valueOf).orNull
+        r.clockActiveColor = event.clockActiveColor.orNull
+        r.pendingDrawOffer = event.pendingDrawOffer.orNull
+        r.updatedAt = Instant.now()
+        repository.merge(r)
+      case _ => ()

modules/ws/build.gradle.kts

@@ -0,0 +1,92 @@
+plugins {
+    id("scala")
+    id("org.scoverage") version "8.1"
+    id("io.quarkus")
+}
+
+group = "de.nowchess"
+version = "1.0-SNAPSHOT"
+
+@Suppress("UNCHECKED_CAST")
+val versions = rootProject.extra["VERSIONS"] as Map<String, String>
+@Suppress("UNCHECKED_CAST")
+val scoverageExcluded = rootProject.extra["SCOVERAGE_EXCLUDED"] as List<String>
+
+repositories {
+    mavenCentral()
+}
+
+scala {
+    scalaVersion = versions["SCALA3"]!!
+}
+
+scoverage {
+    scoverageVersion.set(versions["SCOVERAGE"]!!)
+    excludedFiles.set(scoverageExcluded)
+}
+
+tasks.withType<ScalaCompile> {
+    scalaCompileOptions.additionalParameters = listOf("-encoding", "UTF-8")
+}
+
+val quarkusPlatformGroupId: String by project
+val quarkusPlatformArtifactId: String by project
+val quarkusPlatformVersion: String by project
+
+dependencies {
+
+    compileOnly("org.scala-lang:scala3-compiler_3") {
+        version {
+            strictly(versions["SCALA3"]!!)
+        }
+    }
+    implementation("org.scala-lang:scala3-library_3") {
+        version {
+            strictly(versions["SCALA3"]!!)
+        }
+    }
+
+    implementation(enforcedPlatform("${quarkusPlatformGroupId}:${quarkusPlatformArtifactId}:${quarkusPlatformVersion}"))
+    implementation("io.quarkus:quarkus-websockets-next")
+    implementation("io.quarkus:quarkus-arc")
+    implementation("io.quarkus:quarkus-config-yaml")
+    implementation("io.quarkus:quarkus-smallrye-health")
+    implementation("org.redisson:redisson:${versions["REDISSON"]!!}")
+
+    testImplementation(platform("org.junit:junit-bom:${versions["JUNIT_BOM"]!!}"))
+    testImplementation("org.junit.jupiter:junit-jupiter")
+    testImplementation("org.scalatest:scalatest_3:${versions["SCALATEST"]!!}")
+    testImplementation("co.helmethair:scalatest-junit-runner:${versions["SCALATEST_JUNIT"]!!}")
+    testImplementation("io.quarkus:quarkus-junit5")
+    testImplementation("io.quarkus:quarkus-junit5-mockito")
+
+    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
+    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine")
+}
+
+configurations.matching { !it.name.startsWith("scoverage") }.configureEach {
+    resolutionStrategy.force("org.scala-lang:scala-library:${versions["SCALA_LIBRARY"]!!}")
+}
+configurations.scoverage {
+    resolutionStrategy.eachDependency {
+        if (requested.group == "org.scoverage" && requested.name.startsWith("scalac-scoverage-plugin_")) {
+            useTarget("${requested.group}:scalac-scoverage-plugin_2.13.16:2.3.0")
+        }
+    }
+}
+
+tasks.withType<JavaCompile> {
+    options.encoding = "UTF-8"
+    options.compilerArgs.add("-parameters")
+}
+tasks.withType<Jar>().configureEach { duplicatesStrategy = DuplicatesStrategy.EXCLUDE }
+
+tasks.test {
+    useJUnitPlatform {
+        includeEngines("scalatest", "junit-jupiter")
+        testLogging { events("passed", "skipped", "failed") }
+    }
+    finalizedBy(tasks.reportScoverage)
+}
+tasks.reportScoverage { dependsOn(tasks.test) }
+tasks.jar { duplicatesStrategy = DuplicatesStrategy.EXCLUDE }

modules/ws/src/main/resources/application.yml

@@ -0,0 +1,28 @@
+quarkus:
+  http:
+    port: 8084
+  application:
+    name: nowchess-ws
+  grpc:
+    server:
+      use-separate-server: false
+
+nowchess:
+  redis:
+    host: localhost
+    port: 6379
+    prefix: nowchess
+
+"%dev":
+  nowchess:
+    redis:
+      host: localhost
+      port: 6379
+      prefix: nowchess
+
+"%deployed":
+  nowchess:
+    redis:
+      host: ${REDIS_HOST}
+      port: ${REDIS_PORT:6379}
+      prefix: ${REDIS_PREFIX:nowchess}

modules/ws/src/main/scala/de/nowchess/ws/config/RedisConfig.scala

@@ -0,0 +1,18 @@
+package de.nowchess.ws.config
+
+import jakarta.enterprise.context.ApplicationScoped
+import org.eclipse.microprofile.config.inject.ConfigProperty
+import scala.compiletime.uninitialized
+
+@ApplicationScoped
+class RedisConfig:
+  // scalafix:off DisableSyntax.var
+  @ConfigProperty(name = "nowchess.redis.host", defaultValue = "localhost")
+  var host: String = uninitialized
+
+  @ConfigProperty(name = "nowchess.redis.port", defaultValue = "6379")
+  var port: Int = uninitialized
+
+  @ConfigProperty(name = "nowchess.redis.prefix", defaultValue = "nowchess")
+  var prefix: String = uninitialized
+  // scalafix:on DisableSyntax.var

modules/ws/src/main/scala/de/nowchess/ws/config/RedissonProducer.scala

@@ -0,0 +1,35 @@
+package de.nowchess.ws.config
+
+import jakarta.annotation.PreDestroy
+import jakarta.enterprise.context.ApplicationScoped
+import jakarta.enterprise.inject.Produces
+import jakarta.inject.Inject
+import org.redisson.Redisson
+import org.redisson.api.RedissonClient
+import org.redisson.config.Config
+import scala.compiletime.uninitialized
+
+@ApplicationScoped
+class RedissonProducer:
+
+  // scalafix:off DisableSyntax.var
+  @Inject
+  var redisConfig: RedisConfig = uninitialized
+
+  private var clientOpt: Option[RedissonClient] = None
+  // scalafix:on DisableSyntax.var
+
+  @Produces
+  @ApplicationScoped
+  def produceRedissonClient(): RedissonClient =
+    val config = new Config()
+    config.useSingleServer().setAddress(s"redis://${redisConfig.host}:${redisConfig.port}")
+    config.useSingleServer().setConnectionMinimumIdleSize(1)
+    config.useSingleServer().setConnectTimeout(500)
+    val client = Redisson.create(config)
+    clientOpt = Some(client)
+    client
+
+  @PreDestroy
+  def shutdown(): Unit =
+    clientOpt.foreach(_.shutdown())

modules/ws/src/main/scala/de/nowchess/ws/resource/GameWebSocketResource.scala

@@ -0,0 +1,52 @@
+package de.nowchess.ws.resource
+
+import de.nowchess.ws.config.RedisConfig
+import io.quarkus.websockets.next.*
+import jakarta.inject.Inject
+import org.redisson.api.listener.MessageListener
+import org.redisson.api.RedissonClient
+import scala.compiletime.uninitialized
+import java.util.concurrent.ConcurrentHashMap
+
+@WebSocket(path = "/api/board/game/{gameId}/ws")
+class GameWebSocketResource:
+
+  // scalafix:off DisableSyntax.var
+  @Inject
+  var redisson: RedissonClient = uninitialized
+
+  @Inject
+  var redisConfig: RedisConfig = uninitialized
+  // scalafix:on DisableSyntax.var
+
+  private val listenerIds = new ConcurrentHashMap[String, (String, Int)]()
+
+  private def s2cTopic(gameId: String): String =
+    s"${redisConfig.prefix}:game:$gameId:s2c"
+
+  private def c2sTopic(gameId: String): String =
+    s"${redisConfig.prefix}:game:$gameId:c2s"
+
+  @OnOpen
+  def onOpen(connection: WebSocketConnection): Unit =
+    val gameId = connection.pathParam("gameId")
+    val topic = redisson.getTopic(s2cTopic(gameId))
+    val listenerId = topic.addListener(classOf[String], new MessageListener[String]:
+      def onMessage(channel: CharSequence, msg: String): Unit =
+        connection.sendText(msg).subscribe().`with`(_ => (), _ => ())
+    )
+    listenerIds.put(connection.id(), (gameId, listenerId))
+    val connectedMsg = s"""{"type":"CONNECTED","gameId":"$gameId"}"""
+    redisson.getTopic(c2sTopic(gameId)).publish(connectedMsg)
+
+  @OnTextMessage
+  def onTextMessage(connection: WebSocketConnection, message: String): Unit =
+    Option(listenerIds.get(connection.id())).foreach { case (gameId, _) =>
+      redisson.getTopic(c2sTopic(gameId)).publish(message)
+    }
+
+  @OnClose
+  def onClose(connection: WebSocketConnection): Unit =
+    Option(listenerIds.remove(connection.id())).foreach { case (gameId, listenerId) =>
+      redisson.getTopic(s2cTopic(gameId)).removeListener(listenerId)
+    }

modules/ws/src/test/resources/application.yml

@@ -0,0 +1,11 @@
+quarkus:
+  http:
+    port: 8084
+  application:
+    name: nowchess-ws
+
+nowchess:
+  redis:
+    host: localhost
+    port: 6379
+    prefix: test

settings.gradle.kts

@@ -21,4 +21,6 @@ include(
     "modules:rule",
     "modules:bot",
     "modules:account",
+    "modules:ws",
+    "modules:store",
 )