Two bugs fixed:
1. EnchantmentsComponent was reading a trailing ShowTooltip boolean that
was removed from the wire format in MC 1.21.5. Created
EnchantmentsComponent1215 and StoredEnchantmentsComponent1215 that
omit the boolean. Used by StructuredComponentsRegistry1215 and 12111.
2. MC 1.21.5+ changed ServerboundContainerClickPacket to use HashedStack
(item holder id + count + hashed component patch map) instead of full
ItemStack for changed slots and carried item. Added GetHashedItemSlot()
in DataTypes.cs and gated SendWindowAction in Protocol18.cs to use it
for 1.21.5+. Since MCC doesn't track component hashes, an empty
HashedPatchMap is sent; the server detects stateId mismatch and resyncs.
Tested: AutoFishing bot successfully catches fish on MC 1.21.11 with
enchanted fishing rods (Lure III + Luck of the Sea III).
Made-with: Cursor
- SpawnEntity packet handler now registers non-player entities via OnSpawnEntity
for protocol >= 1.20.2 (previously only players were tracked, causing 'entity near'
to find nothing)
- PlaceBlock gains lookAtBlock option that sends a position/rotation update before the
block placement packet, fixing containers not opening via useblock
- Enchantment registry IDs are now dynamically parsed from server RegistryData
(minecraft:enchantment), fixing incorrect enchantment name display in 1.21
- AttributeModifiersComponent uses base SubComponent type to avoid InvalidCastException
when parsing 1.21-specific attribute subcomponents
Made-with: Cursor
- Add AttributeSubComponent121 that uses ResourceLocation(string) instead
of UUID+Name, matching the 1.21 attribute modifier wire format change.
Register it in SubComponentRegistry121 via new ReplaceSubComponent method.
- Add ProjectilePower packet handler: reads 1 double (accelerationPower)
for 1.21+, or 3 doubles (xPower/yPower/zPower) for 1.20.6.
- Add CustomReportDetails and ServerLinks packet handlers in both Play
and Configuration phases, consuming all fields to prevent byte offset
errors on 1.21 servers.
Made-with: Cursor
Audited batch 5 components (ChargedProjectiles, BundleContents, Container,
WritableBookContent, BlockState, PotDecorations) against official 1.20.6
decompiled STREAM_CODEC definitions. All network encodings were correct.
Removed redundant NumberOfItems/NumberOfPages/NumberOfProperties fields from
ContainerComponent, WritableBlookContentComponent, BlockStateComponent, and
PotDecorationsComponent. Serialize now uses the actual collection .Count
instead of a potentially stale cached value, matching the pattern already
used by ContainerComponent's Serialize and other components.
Also modernized loop style (foreach with deconstruction where applicable)
and fixed a typo in an exception message ("setialize" -> "serialize").
Made-with: Cursor
In 1.20.6+, ComponentSerialization.STREAM_CODEC uses
ByteBufCodecs.fromCodecWithRegistries (NBT tag format), not plain string.
The previous implementation incorrectly used ReadNextString/GetString
for custom_name (5), item_name (6), and lore (7) components.
Fixed all three to use ReadNextNbt/GetNbt, preserving raw NBT data for
round-trip serialization while still extracting readable text via
ChatParser.ParseText(Dictionary).
Other batch 4 components (custom_data, entity_data, bucket_entity_data,
block_entity_data, debug_stick_state, map_decorations, recipes, lock,
container_loot, intangible_projectile — all NBT; hide_additional_tooltip,
hide_tooltip, fire_resistant, creative_slot_lock — all Unit/Empty;
note_block_sound — ResourceLocation string) were verified correct.
Made-with: Cursor
Audited all 14 simple binary components (batch 3): max_stack_size,
max_damage, damage, unbreakable, rarity, custom_model_data, repair_cost,
enchantment_glint_override, ominous_bottle_amplifier, dyed_color,
map_color, map_id, map_post_processing, base_color.
Found and fixed 1 bug:
- EnchantmentGlintOverrideComponent: was reading/writing VarInt but the
official STREAM_CODEC uses ByteBufCodecs.BOOL (single byte boolean).
Changed property type from int to bool, Parse from ReadNextVarInt to
ReadNextBool, and Serialize from GetVarInt to GetBool.
All other 13 components matched the official 1.20.6 STREAM_CODEC
definitions exactly.
Verified in-game: connected to 1.20.6 vanilla server, received items
with enchantment_glint_override=true/false, dyed_color, map_color,
map_id, base_color, unbreakable, rarity, custom_model_data, repair_cost,
damage, max_damage. All parsed and serialized correctly with no errors.
Made-with: Cursor
Audited all 8 batch-2 components (enchantments, stored_enchantments,
can_place_on, can_break, lodestone_tracker, firework_explosion, fireworks,
banner_patterns, suspicious_stew_effects, bees) against official 1.20.6
decompiled STREAM_CODEC definitions.
Found and fixed 3 bugs in BlockPredicate/PropertySubComponent:
1. BlockPredicateSubcomponent.Serialize(): missing HasNbt bool write.
Parse reads the bool but Serialize skipped writing it, causing all
subsequent fields to be offset by one byte.
2. BlockPredicateSubcomponent.Serialize(): missing Properties list count
VarInt write. Parse reads VarInt count before iterating, but Serialize
only wrote the elements without the preceding count.
3. PropertySubComponent: RangedMatcher min/max values must use Optional
encoding (Bool prefix + conditional String), matching the official
ByteBufCodecs.either(ExactMatcher, RangedMatcher) where RangedMatcher
uses ByteBufCodecs.optional(STRING_UTF8) for both min and max fields.
Previously read/wrote plain Strings unconditionally.
Remaining 6 components (enchantments, stored_enchantments, lodestone_tracker,
firework_explosion, fireworks, banner_patterns, suspicious_stew_effects, bees)
verified correct — no changes needed.
Made-with: Cursor
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
EnchantmentsComponent (used by both regular and stored enchantments)
was directly casting the registry VarInt ID to the Enchantments enum
via (Enchantments)id. However, the Enchantments enum is ordered
alphabetically (AquaAffinity=0, BaneOfArthropods=1, ..., Sharpness=32)
while the 1.20.6 registry uses a completely different order
(protection=0, fire_protection=1, ..., sharpness=13). This caused all
enchantment names to display incorrectly (e.g. Sharpness V shown as
"Unknown Enchantment with ID: 32").
Changes:
- Parse now uses EnchantmentMapping.GetEnchantmentByRegistryId1206()
to properly map registry IDs to enum values via the existing
1.20.6+ mapping table
- Serialize now uses EnchantmentMapping.GetRegistryId1206ByEnchantment()
to convert enum values back to registry IDs (reverse lookup)
- Fixed translation key prefix: "Enchantments.minecraft." (wrong) ->
"enchantment.minecraft." (matches en_us.json resource keys)
- Fixed 3 long-standing typos in the Enchantments enum that prevented
translation lookup from matching resource keys:
- DepthStrieder -> DepthStrider (depth_strieder vs depth_strider)
- Efficency -> Efficiency (efficency vs efficiency)
- Loyality -> Loyalty (loyality vs loyalty)
Verified on vanilla 1.20.6 server: items with sharpness, efficiency,
unbreaking, fortune, mending, and bane_of_arthropods all display
correct localized names (锋利, 效率, 耐久, 时运, 经验修补, 节肢杀手).
Made-with: Cursor
Both components had incorrect Parse/Serialize implementations that would
cause packet deserialization misalignment when encountered in-game.
PotionContentsComponent (3 bugs):
- Serialize unconditionally wrote VarInt(PotionId) and Int(CustomColor)
even when HasPotionId/HasCustomColor was false. The official format
(PotionContents.STREAM_CODEC) uses Optional encoding: Bool(hasValue)
followed by the value only when true. The extra bytes caused all
subsequent fields in the packet to be read at wrong offsets.
- Serialize omitted the VarInt(count) prefix for the custom effects list.
The official codec uses ByteBufCodecs.list() which always writes a
VarInt count header before the list elements.
- Also fixed typo: PotiononId -> PotionId.
InstrumentComponent (3 bugs):
- The official Instrument.STREAM_CODEC uses ByteBufCodecs.holder() which
encodes as VarInt(holderId): 0 = inline data, N>0 = registry ref (N-1).
The SoundEvent field inside uses the same holder pattern. The old code
unconditionally read SoundName (ResourceLocation) and HasFixedRange/
FixedRange even when SoundEventHolderId != 0 (registry reference case
has no inline data).
- UseDuration was read/written as Float, but the official codec uses
ByteBufCodecs.VAR_INT. This caused a 4-byte vs variable-length
mismatch that would shift all subsequent data.
- HasFixedRange was read unconditionally when SoundEventHolderId == 0,
but FixedRange was also read unconditionally. The official SoundEvent
DIRECT_STREAM_CODEC uses Optional<Float> encoding: Bool(hasValue)
followed by Float only when true.
These components are used for potion items and goat horns respectively.
Verified against official 1.20.6 decompiled source:
- net.minecraft.world.item.alchemy.PotionContents (STREAM_CODEC)
- net.minecraft.world.item.Instrument (STREAM_CODEC/DIRECT_STREAM_CODEC)
- net.minecraft.sounds.SoundEvent (STREAM_CODEC/DIRECT_STREAM_CODEC)
- net.minecraft.network.codec.ByteBufCodecs (holder/optional/list)
Made-with: Cursor
Audited all 58 StructuredComponent subclasses against the official Minecraft
1.20.6 decompiled source to verify Parse()/Serialize() symmetry. Found and
fixed four bugs across four components:
1. ContainerComponent: Parse() skipped null item slots (empty slots in a
container) but Serialize() looped NumberOfItems times using Items[i],
causing IndexOutOfRangeException when any slot was empty. The official
ItemContainerContents uses OPTIONAL_STREAM_CODEC which serializes empty
slots as VarInt(0). Fixed: Parse now stores all slots including nulls,
Serialize uses Items.Count and iterates all entries. GetItemSlot(null)
correctly writes VarInt(0) for empty slots.
2. ChargedProjectilesComponent: Used Items.OfType<Item>() in Serialize()
which silently dropped null entries, causing the serialized count to
differ from the written VarInt header. The official ChargedProjectiles
uses STREAM_CODEC (non-optional, no empty slots allowed). Fixed: Items
list is now List<Item> (non-nullable), Parse defensively skips nulls,
Serialize writes Items.Count matching the actual list.
3. BundleContentsComponent: Same issue as ChargedProjectilesComponent.
Applied the same fix pattern.
4. FoodComponentComponent: Two type mismatches vs the official
FoodProperties.DIRECT_STREAM_CODEC:
- Saturation was declared as bool and read with ReadNextBool (1 byte),
but the protocol sends it as float (4 bytes). This caused all
subsequent fields in the component to be read at wrong offsets,
corrupting CanAlwaysEat, SecondsToEat, and the effects list.
- NumberOfEffects was serialized with GetFloat() instead of GetVarInt(),
writing 4 bytes of IEEE 754 float instead of a variable-length integer.
Fixed both Parse and Serialize to use correct types.
Also removed redundant NumberOfItems/NumberOfEffects fields from components
where the count is derivable from the list length, and replaced
ArgumentNullException with cleaner patterns.
Tested end-to-end on vanilla 1.20.6 server: item receiving (diamond_sword,
golden_apple, diamond_pickaxe), inventory slot movement (click to pick up
and place), and inventory listing all work correctly with no server-side
protocol errors.
Made-with: Cursor
In 1.20.6+, items use structured components instead of NBT for metadata.
Previously, ReadNextItemSlot parsed the components but never stored them
on the Item instance, leaving DisplayName/Lores/Damage/Enchantments all
empty. GetItemSlot also still used the pre-1.20.6 format (bool + VarInt +
byte + NBT), causing the server to reject any item operation packets.
Changes:
Item.cs:
- Add List<StructuredComponent>? Components field to hold the raw
component list for round-trip serialization
- DisplayName property: read from CustomNameComponent (with
ItemNameComponent as fallback) when Components is present
- Lores property: read from LoreNameComponent1206 when Components is
present
- Damage property: read from DamageComponent when Components is present
- Add EnchantmentList property: read from EnchantmentsComponent (covers
both normal and StoredEnchantmentsComponent for enchanted books)
- ToFullString(): use EnchantmentList with EnchantmentMapping for display
when available, fall back to NBT path for older versions
- Add CloneWithCount() method that preserves both NBT and Components
DataTypes.cs - ReadNextItemSlot:
- Assign parsed strcturedComponentsToAdd to item.Components
DataTypes.cs - GetItemSlot:
- Add 1.20.6+ branch: write VarInt(count) + VarInt(itemId) + component
counts + serialized components (using each component's TypeId and
Serialize() method)
- Empty slot sends VarInt(0) per the 1.20.6 protocol spec
StructuredComponent.cs:
- Add int TypeId property (default -1) to store the registry type ID
assigned during parsing, enabling round-trip serialization
StructuredComponentRegistry.cs:
- Set component.TypeId = id after instantiation in ParseComponent()
McClient.cs:
- Replace manual Item constructor calls (new Item(type, count, nbt))
with Item.CloneWithCount() to preserve Components during inventory
operations like slot moves, stack splits, and right-click placement
Made-with: Cursor
