fix: StructuredComponents batch 1 audit — TrimComponent, ProfileComponent, WrittenBookContent, and NBT serialization

Audited all 8 high-complexity structured components against official 1.20.6
decompiled STREAM_CODEC definitions. Found and fixed bugs in 3 components
plus a systemic NBT serialization issue:

TrimComponent (ID 35):
- Serialize had TrimPatternType and ShowInTooltip incorrectly nested inside
  the TrimMaterialType==0 branch; moved them outside to match Parse logic
- Description fields (TrimMaterial.description, TrimPattern.description) were
  read/written as String but official codec uses ComponentSerialization
  (NBT Tag format); changed to ReadNextNbt/GetNbt

ProfileComponent (ID 46):
- Serialize was missing the HasUniqueId Bool prefix before UUID
- Serialize only wrote properties when count > 0 but omitted the VarInt count
  prefix entirely when empty; now always writes VarInt count

WrittenBookContentComponent (ID 34):
- Page content uses Filterable<Component> where Component is NBT-encoded via
  ComponentSerialization.STREAM_CODEC, not plain String; changed Parse to use
  ReadNextNbt and Serialize to use GetNbt
- Added RawContentNbt/FilteredContentNbt fields to BookPage record for
  round-trip NBT preservation
- Removed unnecessary ChatParser.ParseText on title (it's a plain string)

DataTypes.GetNbt:
- Added TAG_String root support for 1.20.4+ (chat components like "Page 1"
  are encoded as TAG_String, not TAG_Compound)
- Fixed root name handling: versions >= 1.20.2 omit the root compound name,
  but GetNbt was unconditionally writing it

Components confirmed correct (no changes needed):
- FoodComponentComponent (ID 20), ToolComponent (ID 22),
  InstrumentComponent (ID 40), PotionContentsComponent (ID 31),
  AttributeModifiersComponent (ID 12)

Made-with: Cursor

MinecraftClient/Inventory/BookPage.cs

@@ -1,3 +1,10 @@
+using System.Collections.Generic;
+
 namespace MinecraftClient.Inventory;
 
-public record BookPage(string RawContent, bool HasFilteredContent, string? FilteredContent);
+public record BookPage(
+    string RawContent,
+    bool HasFilteredContent,
+    string? FilteredContent,
+    Dictionary<string, object>? RawContentNbt = null,
+    Dictionary<string, object>? FilteredContentNbt = null);

MinecraftClient/Protocol/Handlers/DataTypes.cs

@@ -1231,18 +1231,31 @@ namespace MinecraftClient.Protocol.Handlers
 
             if (root)
             {
+                if (protocolversion >= Protocol18Handler.MC_1_20_4_Version
+                    && nbt.Count == 1
+                    && nbt.TryGetValue("", out var rootVal) && rootVal is string rootStr)
+                {
+                    bytes.Add(8); // TAG_String
+                    var strBytes = Encoding.UTF8.GetBytes(rootStr);
+                    bytes.AddRange(GetUShort((ushort)strBytes.Length));
+                    bytes.AddRange(strBytes);
+                    return bytes.ToArray();
+                }
+
                 bytes.Add(10); // TAG_Compound
 
-                // NBT root name
+                if (protocolversion < Protocol18Handler.MC_1_20_2_Version)
-                string? rootName = null;
+                {
+                    string? rootName = null;
 
-                if (nbt.ContainsKey(""))
+                    if (nbt.ContainsKey(""))
-                    rootName = nbt[""] as string;
+                        rootName = nbt[""] as string;
 
-                rootName ??= "";
+                    rootName ??= "";
 
-                bytes.AddRange(GetUShort((ushort)rootName.Length));
+                    bytes.AddRange(GetUShort((ushort)rootName.Length));
-                bytes.AddRange(Encoding.ASCII.GetBytes(rootName));
+                    bytes.AddRange(Encoding.ASCII.GetBytes(rootName));
+                }
             }
 
             foreach (var item in nbt)

MinecraftClient/Protocol/Handlers/StructuredComponents/Components/1_20_6/ProfileComponent.cs

@@ -51,26 +51,22 @@ public class ProfileComponent(DataTypes dataTypes, ItemPalette itemPalette, SubC
             data.AddRange(DataTypes.GetString(Name));
         }
         
+        data.AddRange(DataTypes.GetBool(HasUniqueId));
         if (HasUniqueId)
             data.AddRange(DataTypes.GetUUID(Uuid));
 
-        if (NumberOfProperties > 0)
+        data.AddRange(DataTypes.GetVarInt(ProfileProperties.Count));
+        foreach (var profileProperty in ProfileProperties)
         {
-            if(NumberOfProperties != ProfileProperties.Count)
+            data.AddRange(DataTypes.GetString(profileProperty.Name));
-                throw new Exception("Can't serialize the ProfileComponent because the NumberOfProperties and ProfileProperties.Count differ!");
+            data.AddRange(DataTypes.GetString(profileProperty.Value));
-
+            data.AddRange(DataTypes.GetBool(profileProperty.HasSignature));
-            foreach (var profileProperty in ProfileProperties)
+            if (profileProperty.HasSignature)
             {
-                data.AddRange(DataTypes.GetString(profileProperty.Name));
+                if(string.IsNullOrEmpty(profileProperty.Signature))
-                data.AddRange(DataTypes.GetString(profileProperty.Value));
+                    throw new NullReferenceException("Can't serialize the ProfileComponent because HasSignature is true, but the Signature is null/empty!");
-                data.AddRange(DataTypes.GetBool(profileProperty.HasSignature));
+                
-                if (profileProperty.HasSignature)
+                data.AddRange(DataTypes.GetString(profileProperty.Signature));
-                {
-                    if(string.IsNullOrEmpty(profileProperty.Signature))
-                        throw new NullReferenceException("Can't serialize the ProfileComponent because HasSignature is true, but the Signature is null/empty!");
-                    
-                    data.AddRange(DataTypes.GetString(profileProperty.Signature));
-                }
             }
         }
         

MinecraftClient/Protocol/Handlers/StructuredComponents/Components/1_20_6/TrimComponent.cs

@@ -15,10 +15,12 @@ public class TrimComponent(DataTypes dataTypes, ItemPalette itemPalette, SubComp
     public float ItemModelIndex { get; set; }
     public int NumberOfOverrides { get; set; }
     public List<TrimAssetOverride>? Overrides { get; set; }
+    public Dictionary<string, object>? DescriptionNbt { get; set; }
     public string Description { get; set; } = null!;
     public int TrimPatternType { get; set; }
     public string TrimPatternTypeAssetName { get; set; } = null!;
     public int TemplateItem { get; set; }
+    public Dictionary<string, object>? TrimPatternTypeDescriptionNbt { get; set; }
     public string TrimPatternTypeDescription { get; set; } = null!;
     public bool Decal { get; set; }
     public bool ShowInTooltip { get; set; }
@@ -43,7 +45,8 @@ public class TrimComponent(DataTypes dataTypes, ItemPalette itemPalette, SubComp
                         dataTypes.ReadNextString(data)));
             }
 
-            Description = ChatParser.ParseText(dataTypes.ReadNextString(data));
+            DescriptionNbt = dataTypes.ReadNextNbt(data);
+            Description = ChatParser.ParseText(DescriptionNbt);
         }
 
         TrimPatternType = dataTypes.ReadNextVarInt(data);
@@ -52,7 +55,8 @@ public class TrimComponent(DataTypes dataTypes, ItemPalette itemPalette, SubComp
         {
             TrimPatternTypeAssetName = dataTypes.ReadNextString(data);
             TemplateItem = dataTypes.ReadNextVarInt(data);
-            TrimPatternTypeDescription = dataTypes.ReadNextString(data);
+            TrimPatternTypeDescriptionNbt = dataTypes.ReadNextNbt(data);
+            TrimPatternTypeDescription = ChatParser.ParseText(TrimPatternTypeDescriptionNbt);
             Decal = dataTypes.ReadNextBool(data);
         }
 
@@ -67,8 +71,8 @@ public class TrimComponent(DataTypes dataTypes, ItemPalette itemPalette, SubComp
 
         if (TrimMaterialType == 0)
         {
-            if (string.IsNullOrEmpty(AssetName) || string.IsNullOrEmpty(Description))
+            if (string.IsNullOrEmpty(AssetName))
-                throw new NullReferenceException("Can't serialize the TrimComponent because the Asset Name or Description are null!");
+                throw new NullReferenceException("Can't serialize the TrimComponent because the Asset Name is null!");
             
             data.AddRange(DataTypes.GetString(AssetName));
             data.AddRange(DataTypes.GetVarInt(Ingredient));
@@ -85,22 +89,22 @@ public class TrimComponent(DataTypes dataTypes, ItemPalette itemPalette, SubComp
                     data.AddRange(DataTypes.GetString(assetName));
                 }
             }
-            data.AddRange(DataTypes.GetString(Description));
+            data.AddRange(DataTypes.GetNbt(DescriptionNbt));
-
-            data.AddRange(DataTypes.GetVarInt(TrimPatternType));
-            if (TrimPatternType == 0)
-            {
-                if (string.IsNullOrEmpty(TrimPatternTypeAssetName) || string.IsNullOrEmpty(TrimPatternTypeDescription))
-                    throw new NullReferenceException("Can't serialize the TrimComponent because the TrimPatternTypeAssetName or TrimPatternTypeDescription are null!");
-                
-                data.AddRange(DataTypes.GetString(TrimPatternTypeAssetName));
-                data.AddRange(DataTypes.GetVarInt(TemplateItem));
-                data.AddRange(DataTypes.GetString(TrimPatternTypeDescription));
-                data.AddRange(DataTypes.GetBool(Decal));
-            }
-            
-            data.AddRange(DataTypes.GetBool(ShowInTooltip));
         }
+
+        data.AddRange(DataTypes.GetVarInt(TrimPatternType));
+        if (TrimPatternType == 0)
+        {
+            if (string.IsNullOrEmpty(TrimPatternTypeAssetName))
+                throw new NullReferenceException("Can't serialize the TrimComponent because the TrimPatternTypeAssetName is null!");
+            
+            data.AddRange(DataTypes.GetString(TrimPatternTypeAssetName));
+            data.AddRange(DataTypes.GetVarInt(TemplateItem));
+            data.AddRange(DataTypes.GetNbt(TrimPatternTypeDescriptionNbt));
+            data.AddRange(DataTypes.GetBool(Decal));
+        }
+        
+        data.AddRange(DataTypes.GetBool(ShowInTooltip));
         
         return new Queue<byte>(data);
     }

MinecraftClient/Protocol/Handlers/StructuredComponents/Components/1_20_6/WrittenBlookContentComponent.cs

@@ -20,7 +20,7 @@ public class WrittenBlookContentComponent(DataTypes dataTypes, ItemPalette itemP
     
     public override void Parse(Queue<byte> data)
     {
-        RawTitle = ChatParser.ParseText(dataTypes.ReadNextString(data));
+        RawTitle = dataTypes.ReadNextString(data);
         HasFilteredTitle = dataTypes.ReadNextBool(data);
 
         if (HasFilteredTitle)
@@ -32,14 +32,19 @@ public class WrittenBlookContentComponent(DataTypes dataTypes, ItemPalette itemP
 
         for (var i = 0; i < NumberOfPages; i++)
         {
-            var rawContent = ChatParser.ParseText(dataTypes.ReadNextString(data));
+            var rawContentNbt = dataTypes.ReadNextNbt(data);
+            var rawContent = ChatParser.ParseText(rawContentNbt);
             var hasFilteredContent = dataTypes.ReadNextBool(data);
-            var filteredContent = null as string;
+            Dictionary<string, object>? filteredContentNbt = null;
+            string? filteredContent = null;
             
-            if(hasFilteredContent)
+            if (hasFilteredContent)
-                filteredContent = dataTypes.ReadNextString(data);
+            {
+                filteredContentNbt = dataTypes.ReadNextNbt(data);
+                filteredContent = ChatParser.ParseText(filteredContentNbt);
+            }
             
-            Pages.Add(new BookPage(rawContent, hasFilteredContent, filteredContent));
+            Pages.Add(new BookPage(rawContent, hasFilteredContent, filteredContent, rawContentNbt, filteredContentNbt));
         }
 
         Resolved = dataTypes.ReadNextBool(data);
@@ -55,30 +60,22 @@ public class WrittenBlookContentComponent(DataTypes dataTypes, ItemPalette itemP
         if (HasFilteredTitle)
         {
             if(FilteredTitle is null)
-                throw new InvalidOperationException("Can not setialize WrittenBlookContentComponent1206 because HasFilteredTitle is true but FilteredTitle is null!");
+                throw new InvalidOperationException("Can not serialize WrittenBookContentComponent because HasFilteredTitle is true but FilteredTitle is null!");
             
             data.AddRange(DataTypes.GetString(FilteredTitle));
         }
         
         data.AddRange(DataTypes.GetString(Author));
         data.AddRange(DataTypes.GetVarInt(Generation));
-        data.AddRange(DataTypes.GetVarInt(NumberOfPages));
+        data.AddRange(DataTypes.GetVarInt(Pages.Count));
-
-        if (NumberOfPages != Pages.Count)
-            throw new InvalidOperationException("Can not setialize WrittenBlookContentComponent1206 because NumberOfPages != Pages.Count!");
 
         foreach (var page in Pages)
         {
-            data.AddRange(DataTypes.GetString(page.RawContent));
+            data.AddRange(DataTypes.GetNbt(page.RawContentNbt));
             data.AddRange(DataTypes.GetBool(page.HasFilteredContent));
 
             if (page.HasFilteredContent)
-            {
+                data.AddRange(DataTypes.GetNbt(page.FilteredContentNbt));
-                if(page.FilteredContent is null)
-                    throw new InvalidOperationException("Can not setialize WrittenBlookContentComponent1206 because page.HasFilteredContent = true, but FilteredContent is null!");
-                
-                data.AddRange(DataTypes.GetString(page.FilteredContent));
-            }
         }
         data.AddRange(DataTypes.GetBool(Resolved));
         return new Queue<byte>(data);