feat(CS): castle flag owner logo (C1 B9 02) + catapults for war atmosphere

#1 Castle flags now show the owner guild's logo: resolve owner name -> guild logo
(cached), broadcast C1 B9 02 (32-byte mark) to players on the castle map every 15s.
#3 War atmosphere: spawn catapult NPCs 221/222 at siege start (client renders them
as siege weapons); the 0xB2/0x17 start flag already flips the map to warzone mode.
All raw S6 packets, no client changes.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/GameLogic/PlugIns/PeriodicTasks/CastleSiegeEventPlugIn.cs

@@ -43,6 +43,19 @@ public sealed class CastleSiegeEventPlugIn : IPeriodicTaskPlugIn, ISupportCustom
         (CastleGateNumber, 93, 204),
     };
 
+    // Siege weapons spawned at siege start purely for war atmosphere. The client renders monster 221/222 as
+    // catapults (attacker/defender). They are NOT counted as defenses (destroying them doesn't open the throne).
+    private const short CatapultAttackNumber = 221;   // client MONSTER_SLINGSHOT_ATTACK
+    private const short CatapultDefenseNumber = 222;   // client MONSTER_SLINGSHOT_DEFENSE
+    private static readonly (short Number, byte X, byte Y)[] CatapultSpawns =
+    {
+        (CatapultDefenseNumber, 80, 140),
+        (CatapultDefenseNumber, 110, 140),
+        (CatapultDefenseNumber, 93, 178),
+        (CatapultAttackNumber, 74, 100),
+        (CatapultAttackNumber, 112, 100),
+    };
+
     // Crown Switch positions on Valley of Loren (from the map init) — held by standing on them: (number, x, y).
     private static readonly (short SwitchNumber, byte X, byte Y)[] SwitchPositions =
     {
@@ -52,6 +65,9 @@ public sealed class CastleSiegeEventPlugIn : IPeriodicTaskPlugIn, ISupportCustom
 
     private static readonly ConcurrentDictionary<IGameContext, CastleSiegeContext> Contexts = new();
 
+    private string? _cachedFlagOwner;
+    private byte[]? _cachedFlagLogo;
+
     /// <inheritdoc />
     public CastleSiegeConfiguration? Configuration { get; set; }
 
@@ -97,6 +113,12 @@ public sealed class CastleSiegeEventPlugIn : IPeriodicTaskPlugIn, ISupportCustom
         {
             await this.PersistStateAsync(gameContext, context).ConfigureAwait(false);
         }
+
+        // Keep the owner guild's logo painted on the castle flags for anyone on the castle map (any phase).
+        if (DateTime.UtcNow.Second % 15 == 0)
+        {
+            await this.BroadcastCastleFlagAsync(gameContext, context).ConfigureAwait(false);
+        }
     }
 
     /// <inheritdoc />
@@ -262,6 +284,31 @@ public sealed class CastleSiegeEventPlugIn : IPeriodicTaskPlugIn, ISupportCustom
             }
 
             context.SetDefenseCount(spawned);
+
+            // Spawn the catapults (siege weapons) for war atmosphere — not counted as defenses.
+            for (var i = 0; i < CatapultSpawns.Length; i++)
+            {
+                var spawn = CatapultSpawns[i];
+                var definition = gameContext.Configuration.Monsters.FirstOrDefault(m => m.Number == spawn.Number);
+                if (definition is null)
+                {
+                    continue;
+                }
+
+                var spawnArea = new MonsterSpawnArea
+                {
+                    MonsterDefinition = definition,
+                    Quantity = 1,
+                    X1 = spawn.X,
+                    X2 = spawn.X,
+                    Y1 = spawn.Y,
+                    Y2 = spawn.Y,
+                    Direction = Direction.South,
+                    SpawnTrigger = SpawnTrigger.OnceAtEventStart,
+                };
+
+                await concrete.MapInitializer.InitializeSpawnAsync(2000 + i, map, spawnArea).ConfigureAwait(false);
+            }
         }
         catch (Exception ex)
         {
@@ -335,6 +382,65 @@ public sealed class CastleSiegeEventPlugIn : IPeriodicTaskPlugIn, ISupportCustom
             }
         });
 
+    private async ValueTask BroadcastCastleFlagAsync(IGameContext gameContext, CastleSiegeContext context)
+    {
+        try
+        {
+            if (context.OwnerGuildName is not { Length: > 0 } owner)
+            {
+                return;
+            }
+
+            var logo = await this.GetOwnerLogoAsync(gameContext, owner).ConfigureAwait(false);
+            if (logo is null)
+            {
+                return;
+            }
+
+            await gameContext.ForEachPlayerAsync(async player =>
+            {
+                if (player.CurrentMap?.Definition.Number == ValleyOfLorenMapNumber)
+                {
+                    await player.InvokeViewPlugInAsync<ICastleSiegeStatusViewPlugIn>(p => p.SetCastleFlagAsync(logo)).ConfigureAwait(false);
+                }
+            }).ConfigureAwait(false);
+        }
+        catch (Exception ex)
+        {
+            gameContext.LoggerFactory.CreateLogger<CastleSiegeEventPlugIn>()
+                .LogError(ex, "Castle Siege: error while broadcasting the castle flag.");
+        }
+    }
+
+    private async ValueTask<byte[]?> GetOwnerLogoAsync(IGameContext gameContext, string ownerName)
+    {
+        if (this._cachedFlagOwner == ownerName && this._cachedFlagLogo is not null)
+        {
+            return this._cachedFlagLogo;
+        }
+
+        if (gameContext is not IGameServerContext serverContext)
+        {
+            return null;
+        }
+
+        var guildId = await serverContext.GuildServer.GetGuildIdByNameAsync(ownerName).ConfigureAwait(false);
+        if (guildId == 0)
+        {
+            return null;
+        }
+
+        var guild = await serverContext.GuildServer.GetGuildAsync(guildId).ConfigureAwait(false);
+        if (guild?.Logo is not { Length: > 0 } logo)
+        {
+            return null;
+        }
+
+        this._cachedFlagOwner = ownerName;
+        this._cachedFlagLogo = logo;
+        return logo;
+    }
+
     private static async Task WarpRegisteredMembersToSiegeAsync(IGameContext gameContext, CastleSiegeContext context)
     {
         try

src/GameLogic/Views/CastleSiege/ICastleSiegeStatusViewPlugIn.cs

@@ -22,4 +22,10 @@ public interface ICastleSiegeStatusViewPlugIn : IViewPlugIn
     /// <param name="hour">The remaining hours.</param>
     /// <param name="minute">The remaining minutes.</param>
     ValueTask SetTimerAsync(byte hour, byte minute);
+
+    /// <summary>
+    /// Sends the castle owner guild's 32-byte logo (C1 B9 02) so the client paints it onto the castle flags.
+    /// </summary>
+    /// <param name="guildLogo">The owner guild's 32-byte logo/emblem.</param>
+    ValueTask SetCastleFlagAsync(ReadOnlyMemory<byte> guildLogo);
 }

src/GameServer/RemoteView/CastleSiege/CastleSiegeStatusViewPlugIn.cs

@@ -75,4 +75,30 @@ public class CastleSiegeStatusViewPlugIn : ICastleSiegeStatusViewPlugIn
 
         await connection.SendAsync(WritePacket).ConfigureAwait(false);
     }
+
+    /// <inheritdoc />
+    public async ValueTask SetCastleFlagAsync(ReadOnlyMemory<byte> guildLogo)
+    {
+        var connection = this._player.Connection;
+        if (connection is null)
+        {
+            return;
+        }
+
+        int WritePacket()
+        {
+            // C1 24 B9 02 <32-byte guild logo>
+            var span = connection.Output.GetSpan(36)[..36];
+            span.Clear();
+            span[0] = 0xC1;
+            span[1] = 0x24;
+            span[2] = 0xB9;
+            span[3] = 0x02;
+            var logo = guildLogo.Span;
+            logo[..Math.Min(32, logo.Length)].CopyTo(span.Slice(4, 32));
+            return span.Length;
+        }
+
+        await connection.SendAsync(WritePacket).ConfigureAwait(false);
+    }
 }