refactor(battlenode): type MatchContext.ClassId as CardClass enum (§C)

Behavior-preserving; full solution builds, 1013 tests green.

ClassId is the one genuinely-closed set of the three flagged stringly fields, so it
becomes a CardClass enum (1..8). Wire stays "1".."8": producer casts
(CardClass)run.ClassId, ServerBattleFrames renders via CardClassWire.ToWireValue().
RankBattleController's AI-start path drops a fragile int.TryParse(...)?:-1 for (int)cast.

CharaId (free-form leader/skin id, e.g. "5000123") and CountryCode (open-ended account
data) stay string with proper XML docs; CountryCodes.Korea/Japan name the captured values.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

SVSim.BattleNode/Bridge/CardClass.cs

@@ -0,0 +1,29 @@
+namespace SVSim.BattleNode.Bridge;
+
+/// <summary>
+/// A Shadowverse class (craft). The wire carries it as the stringified ordinal (<c>"1".."8"</c> on
+/// the <c>classId</c> field); this enum replaces that stringly-typed value on
+/// <see cref="MatchContext.ClassId"/> so the legal set lives in the type, not a trailing comment.
+/// <see cref="None"/> covers an unset / placeholder context. Use <see cref="CardClassWire.ToWireValue"/>
+/// to render the wire string.
+/// </summary>
+public enum CardClass
+{
+    None = 0,
+    Forestcraft = 1,
+    Swordcraft = 2,
+    Runecraft = 3,
+    Dragoncraft = 4,
+    Shadowcraft = 5,
+    Bloodcraft = 6,
+    Havencraft = 7,
+    Portalcraft = 8,
+}
+
+/// <summary>Wire rendering for <see cref="CardClass"/>.</summary>
+public static class CardClassWire
+{
+    /// <summary>The <c>classId</c> wire value — the class ordinal as a string (<c>"1".."8"</c>,
+    /// <c>"0"</c> for <see cref="CardClass.None"/>), matching what the client sends/expects.</summary>
+    public static string ToWireValue(this CardClass cardClass) => ((int)cardClass).ToString();
+}

SVSim.BattleNode/Bridge/CountryCodes.cs

@@ -0,0 +1,13 @@
+namespace SVSim.BattleNode.Bridge;
+
+/// <summary>
+/// Known values for <see cref="MatchContext.CountryCode"/>. NOT a closed set — the field is the
+/// account's region code copied verbatim from viewer data (any value, possibly empty), and the node
+/// never branches on it. These constants just name the values seen in the prod captures so test
+/// fixtures and docs aren't sprinkled with bare <c>"KOR"</c>/<c>"JPN"</c> literals.
+/// </summary>
+public static class CountryCodes
+{
+    public const string Korea = "KOR";
+    public const string Japan = "JPN";
+}

SVSim.BattleNode/Bridge/MatchContext.cs

@@ -12,12 +12,25 @@ public sealed record MatchContext(
     IReadOnlyList<long> SelfDeckCardIds,
 
     // Player class + leader (BattleStartSelfInfo)
-    string ClassId,         // "1".."8"
-    string CharaId,         // "1".."8" — equals ClassId when no leader skin chosen
+
+    /// <summary>The player's class. Rendered onto the wire <c>classId</c> as <c>"1".."8"</c> via
+    /// <see cref="CardClassWire.ToWireValue"/>; a closed set, so it's typed, not stringly.</summary>
+    CardClass ClassId,
+
+    /// <summary>Leader/skin id on the wire <c>charaId</c>. FREE-FORM, not a class enum: it's the
+    /// equipped leader-skin id (e.g. <c>"5000123"</c>) when one is chosen, else the class ordinal
+    /// (<c>"1".."8"</c>). Passed through verbatim — the node never interprets it.</summary>
+    string CharaId,
+
     string CardMasterName,  // current card-master, e.g. "card_master_node_10015"
 
     // Player cosmetics (MatchedSelfInfo)
-    string CountryCode,     // "KOR", "JPN", ...
+
+    /// <summary>Account region code, wire <c>country_code</c>. OPEN-ENDED account data (any value,
+    /// possibly empty); the node never branches on it. <see cref="CountryCodes"/> names the values
+    /// seen in captures.</summary>
+    string CountryCode,
+
     string UserName,
     string SleeveId,
     string EmblemId,

SVSim.BattleNode/Lifecycle/ServerBattleFrames.cs

@@ -59,7 +59,7 @@ public static class ServerBattleFrames
                 SelfInfo: new BattleStartSelfInfo(
                     Rank: BattleFrameDefaults.PlayerRank,
                     BattlePoint: BattleFrameDefaults.PlayerBattlePoint,
-                    ClassId: selfCtx.ClassId,
+                    ClassId: selfCtx.ClassId.ToWireValue(),
                     CharaId: selfCtx.CharaId,
                     CardMasterName: selfCtx.CardMasterName),
                 OppoInfo: new BattleStartOppoInfo(
@@ -69,7 +69,7 @@ public static class ServerBattleFrames
                     IsMasterRank: "0",
                     BattlePoint: 0,
                     MasterPoint: "0",
-                    ClassId: oppoCtx.ClassId,
+                    ClassId: oppoCtx.ClassId.ToWireValue(),
                     CharaId: oppoCtx.CharaId,
                     CardMasterName: oppoCtx.CardMasterName)));
 

SVSim.BattleNode/Sessions/Participants/NoOpBotParticipant.cs

@@ -20,7 +20,7 @@ public sealed class NoOpBotParticipant : IBattleParticipant
     public long ViewerId => ServerBattleFrames.FakeOpponentViewerId;
     public MatchContext Context { get; } = new(
         SelfDeckCardIds: Array.Empty<long>(),
-        ClassId: "0", CharaId: "0", CardMasterName: BotCardMasterName,
+        ClassId: CardClass.None, CharaId: "0", CardMasterName: BotCardMasterName,
         CountryCode: "", UserName: "Bot", SleeveId: "0",
         EmblemId: "0", DegreeId: "0", FieldId: 0, IsOfficial: 0,
         BattleModeId: 0);