Remove undefined traits from CK3 character history

ImperatorToCK3/CK3/Characters/CharacterCollection.cs

@@ -824,4 +824,23 @@ internal void ConvertImperatorCharacterDNA(DNAFactory dnaFactory) {
 			}
 		}
 	}
+
+	public void RemoveUndefinedTraits(TraitMapper traitMapper) {
+		Logger.Info("Removing undefined traits from CK3 character history...");
+
+		var definedTraits = traitMapper.ValidCK3TraitIDs.ToHashSet();
+
+		foreach (var character in this) {
+			if (character.FromImperator) {
+				continue;
+			}
+
+			var traitsField = character.History.Fields["traits"];
+			int removedCount = traitsField.InitialEntries.RemoveAll(
+				kvp => !definedTraits.Contains(kvp.Value.ToString() ?? string.Empty));
+			if (removedCount > 0) {
+				Logger.Debug($"Removed {removedCount} undefined traits from character {character.Id}.");
+			}
+		}
+	}
 }

ImperatorToCK3/CK3/World.cs

@@ -243,6 +243,9 @@ public World(Imperator.World impWorld, Configuration config, Thread? irCoaExtrac
                 		Logger.Warn($"No base mapping found for I:R culture {cultureStr}!");
                 	}
                 }
+			},
+			() => { // depends on TraitMapper and CK3 characters being loaded
+				Characters.RemoveUndefinedTraits(traitMapper);
 			}
 		);
 

ImperatorToCK3/Mappers/Trait/TraitMapper.cs

@@ -10,6 +10,8 @@ internal class TraitMapper {
 	protected IDictionary<string, string> ImperatorToCK3TraitMap = new Dictionary<string, string>();
 	protected IdObjectCollection<string, CK3.Characters.Trait> CK3Traits = [];
 
+	public IEnumerable<string> ValidCK3TraitIDs => CK3Traits.Select(t => t.Id);
+
 	// TODO: add a method for logging all unmapped I:R traits
 
 	public TraitMapper() { }