refactor(battle-node): extract LoadedHandler

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SVSim.BattleNode/Sessions/BattleSession.cs

@@ -38,6 +38,7 @@ public sealed class BattleSession
         {
             [NetworkBattleUri.InitNetwork] = new InitNetworkHandler(),
             [NetworkBattleUri.InitBattle] = new InitBattleHandler(),
+            [NetworkBattleUri.Loaded] = new LoadedHandler(),
         };
 
     private FrameDispatchContext BuildContext(IBattleParticipant from, MsgEnvelope env) =>

SVSim.BattleNode/Sessions/Dispatch/Handlers/LoadedHandler.cs

@@ -0,0 +1,34 @@
+using SVSim.BattleNode.Lifecycle;
+using SVSim.BattleNode.Protocol;
+
+namespace SVSim.BattleNode.Sessions.Dispatch.Handlers;
+
+internal sealed class LoadedHandler : IFrameHandler
+{
+    public IReadOnlyList<DispatchRoute> Handle(FrameDispatchContext ctx)
+    {
+        // case 3: Bot — silent (client populates opponent state from AIBattleStart HTTP data).
+        if (ctx.Type == BattleType.Bot && ctx.SenderPhase == BattleSessionPhase.AwaitingLoaded)
+        {
+            ctx.SenderPhase = BattleSessionPhase.AwaitingSwap;
+            return Array.Empty<DispatchRoute>();
+        }
+
+        // case 6: general — BattleStart (per-perspective) + Deal to the sender.
+        if (ctx.SenderPhase == BattleSessionPhase.AwaitingLoaded)
+        {
+            // A goes first deterministically (turnState 0); B goes second (turnState 1).
+            var turnState = ReferenceEquals(ctx.From, ctx.A) ? 0 : 1;
+            var r = new List<DispatchRoute>
+            {
+                new(ctx.From, ScriptedLifecycle.BuildBattleStart(
+                    ctx.From.Context, ctx.Other.Context, ctx.From.ViewerId, turnState), false),
+                new(ctx.From, ScriptedLifecycle.BuildDeal(), false),
+            };
+            ctx.SenderPhase = BattleSessionPhase.AwaitingSwap;
+            return r;
+        }
+
+        return Array.Empty<DispatchRoute>();
+    }
+}