use MinecraftEntityId type instead of u32 in az-protocol

azalea-client/src/attack.rs

@@ -86,7 +86,7 @@ pub fn handle_attack_event(
         send_packet_events.send(SendPacketEvent::new(
             event.entity,
             ServerboundInteract {
-                entity_id: *event.target,
+                entity_id: event.target,
                 action: s_interact::ActionType::Attack,
                 using_secondary_action: **sneaking,
             },

azalea-client/src/movement.rs

@@ -303,7 +303,7 @@ fn send_sprinting_if_needed(
             send_packet_events.send(SendPacketEvent::new(
                 entity,
                 ServerboundPlayerCommand {
-                    id: **minecraft_entity_id,
+                    id: *minecraft_entity_id,
                     action: sprinting_action,
                     data: 0,
                 },

azalea-client/src/packet_handling/game.rs

@@ -301,7 +301,7 @@ pub fn process_packet_events(ecs: &mut World) {
                         azalea_registry::EntityKind::Player,
                         new_instance_name,
                     );
-                    let entity_id = MinecraftEntityId(p.player_id);
+                    let entity_id = p.player_id;
                     // insert our components into the ecs :)
                     commands.entity(player_entity).insert((
                         entity_id,
@@ -643,7 +643,7 @@ pub fn process_packet_events(ecs: &mut World) {
                 let (mut entity_id_index, instance_name, tab_list) =
                     query.get_mut(player_entity).unwrap();
 
-                let entity_id = MinecraftEntityId(p.id);
+                let entity_id = p.id;
 
                 let Some(instance_name) = instance_name else {
                     warn!("got add player packet but we haven't gotten a login packet yet");
@@ -721,7 +721,7 @@ pub fn process_packet_events(ecs: &mut World) {
                 let (mut commands, mut query, entity_kind_query) = system_state.get_mut(ecs);
                 let (entity_id_index, instance_holder) = query.get_mut(player_entity).unwrap();
 
-                let entity = entity_id_index.get(MinecraftEntityId(p.id));
+                let entity = entity_id_index.get(p.id);
 
                 let Some(entity) = entity else {
                     // some servers like hypixel trigger this a lot :(
@@ -768,7 +768,7 @@ pub fn process_packet_events(ecs: &mut World) {
                 let (mut commands, mut query) = system_state.get_mut(ecs);
                 let (entity_id_index, instance_holder) = query.get_mut(player_entity).unwrap();
 
-                let Some(entity) = entity_id_index.get(MinecraftEntityId(p.id)) else {
+                let Some(entity) = entity_id_index.get(p.id) else {
                     // note that this log (and some other ones like the one in RemoveEntities)
                     // sometimes happens when killing mobs. it seems to be a vanilla bug, which is
                     // why it's a debug log instead of a warning
@@ -837,7 +837,7 @@ pub fn process_packet_events(ecs: &mut World) {
                 let (mut commands, mut query) = system_state.get_mut(ecs);
                 let (entity_id_index, instance_holder) = query.get_mut(player_entity).unwrap();
 
-                let Some(entity) = entity_id_index.get(MinecraftEntityId(p.id)) else {
+                let Some(entity) = entity_id_index.get(p.id) else {
                     warn!("Got teleport entity packet for unknown entity id {}", p.id);
                     continue;
                 };
@@ -883,7 +883,7 @@ pub fn process_packet_events(ecs: &mut World) {
 
                 debug!("Got move entity pos packet {p:?}");
 
-                let Some(entity) = entity_id_index.get(MinecraftEntityId(p.entity_id)) else {
+                let Some(entity) = entity_id_index.get(p.entity_id) else {
                     debug!(
                         "Got move entity pos packet for unknown entity id {}",
                         p.entity_id
@@ -924,7 +924,7 @@ pub fn process_packet_events(ecs: &mut World) {
 
                 debug!("Got move entity pos rot packet {p:?}");
 
-                let entity = entity_id_index.get(MinecraftEntityId(p.entity_id));
+                let entity = entity_id_index.get(p.entity_id);
 
                 if let Some(entity) = entity {
                     let new_delta = p.delta.clone();
@@ -977,7 +977,7 @@ pub fn process_packet_events(ecs: &mut World) {
                 let (mut commands, mut query) = system_state.get_mut(ecs);
                 let (entity_id_index, instance_holder) = query.get_mut(player_entity).unwrap();
 
-                let entity = entity_id_index.get(MinecraftEntityId(p.entity_id));
+                let entity = entity_id_index.get(p.entity_id);
 
                 if let Some(entity) = entity {
                     let new_look_direction = LookDirection {
@@ -1040,7 +1040,7 @@ pub fn process_packet_events(ecs: &mut World) {
                 };
 
                 for &id in &p.entity_ids {
-                    let Some(entity) = entity_id_index.remove(MinecraftEntityId(id)) else {
+                    let Some(entity) = entity_id_index.remove(id) else {
                         debug!("Tried to remove entity with id {id} but it wasn't in the EntityIdIndex");
                         continue;
                     };
@@ -1334,7 +1334,7 @@ pub fn process_packet_events(ecs: &mut World) {
                 let (mut commands, mut query, mut death_events) = system_state.get_mut(ecs);
                 let (entity_id, dead) = query.get_mut(player_entity).unwrap();
 
-                if **entity_id == p.player_id && dead.is_none() {
+                if *entity_id == p.player_id && dead.is_none() {
                     commands.entity(player_entity).insert(Dead);
                     death_events.send(DeathEvent {
                         entity: player_entity,
@@ -1475,7 +1475,7 @@ pub fn process_packet_events(ecs: &mut World) {
                 let (mut commands, mut query) = system_state.get_mut(ecs);
                 let (entity_id_index, instance_holder) = query.get_mut(player_entity).unwrap();
 
-                let Some(entity) = entity_id_index.get(MinecraftEntityId(p.id)) else {
+                let Some(entity) = entity_id_index.get(p.id) else {
                     debug!("Got teleport entity packet for unknown entity id {}", p.id);
                     continue;
                 };

azalea-client/tests/simulation.rs

@@ -22,7 +22,7 @@ use azalea_protocol::packets::{
     ConnectionProtocol, Packet, ProtocolPacket,
 };
 use azalea_registry::DimensionType;
-use azalea_world::Instance;
+use azalea_world::{Instance, MinecraftEntityId};
 use bevy_app::App;
 use bevy_app::PluginGroup;
 use bevy_ecs::{prelude::*, schedule::ExecutorKind};
@@ -67,7 +67,7 @@ fn test_set_health_before_login() {
     assert_eq!(*simulation.component::<Health>(), 15.);
 
     simulation.receive_packet(ClientboundLogin {
-        player_id: 0,
+        player_id: MinecraftEntityId(0),
         hardcore: false,
         levels: vec![],
         max_players: 20,

azalea-protocol/src/packets/game/c_add_entity.rs

@@ -2,13 +2,14 @@ use azalea_buf::AzBuf;
 use azalea_core::{position::Vec3, resource_location::ResourceLocation};
 use azalea_entity::{metadata::apply_default_metadata, EntityBundle};
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 use uuid::Uuid;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundAddEntity {
-    /// The id of the entity.
+    /// The numeric ID of the entity being added to the world.
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub uuid: Uuid,
     pub entity_type: azalea_registry::EntityKind,
     pub position: Vec3,

azalea-protocol/src/packets/game/c_add_experience_orb.rs

@@ -1,11 +1,12 @@
 use azalea_buf::AzBuf;
 use azalea_core::position::Vec3;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundAddExperienceOrb {
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub pos: Vec3,
     pub value: u16,
 }

azalea-protocol/src/packets/game/c_animate.rs

@@ -1,10 +1,11 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundAnimate {
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub action: AnimationAction,
 }
 

azalea-protocol/src/packets/game/c_block_destruction.rs

@@ -1,12 +1,13 @@
 use azalea_buf::AzBuf;
 use azalea_core::position::BlockPos;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundBlockDestruction {
     /// The ID of the entity breaking the block.
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub pos: BlockPos,
     /// 0–9 to set it, any other value to remove it.
     pub progress: u8,

azalea-protocol/src/packets/game/c_damage_event.rs

@@ -1,13 +1,14 @@
 use std::io::{Cursor, Write};
 
-use azalea_buf::{AzBuf, AzaleaRead, AzaleaReadVar, AzaleaWriteVar, AzaleaWrite};
+use azalea_buf::{AzBuf, AzaleaRead, AzaleaReadVar, AzaleaWrite, AzaleaWriteVar};
 use azalea_core::position::Vec3;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundDamageEvent {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     #[var]
     pub source_type_id: u32,
     pub source_cause_id: OptionalEntityId,

azalea-protocol/src/packets/game/c_entity_event.rs

@@ -1,8 +1,9 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundEntityEvent {
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub event_id: u8,
 }

azalea-protocol/src/packets/game/c_entity_position_sync.rs

@@ -1,12 +1,13 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 use crate::common::movements::PositionMoveRotation;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundEntityPositionSync {
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub values: PositionMoveRotation,
     pub on_ground: bool,
 }

azalea-protocol/src/packets/game/c_horse_screen_open.rs

@@ -1,5 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundHorseScreenOpen {
@@ -7,5 +8,5 @@ pub struct ClientboundHorseScreenOpen {
     pub container_id: i32,
     #[var]
     pub inventory_columns: u32,
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
 }

azalea-protocol/src/packets/game/c_hurt_animation.rs

@@ -1,9 +1,10 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundHurtAnimation {
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub yaw: f32,
 }

azalea-protocol/src/packets/game/c_login.rs

@@ -1,6 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_core::resource_location::ResourceLocation;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 use crate::packets::common::CommonPlayerSpawnInfo;
 
@@ -10,7 +11,7 @@ use crate::packets::common::CommonPlayerSpawnInfo;
 /// world, and the registry.
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundLogin {
-    pub player_id: u32,
+    pub player_id: MinecraftEntityId,
     pub hardcore: bool,
     pub levels: Vec<ResourceLocation>,
     #[var]

azalea-protocol/src/packets/game/c_move_entity_pos.rs

@@ -1,11 +1,12 @@
 use azalea_buf::AzBuf;
 use azalea_core::delta::PositionDelta8;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundMoveEntityPos {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub delta: PositionDelta8,
     pub on_ground: bool,
 }

azalea-protocol/src/packets/game/c_move_entity_pos_rot.rs

@@ -1,12 +1,13 @@
 use azalea_buf::AzBuf;
 use azalea_core::delta::PositionDelta8;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 /// This packet is sent by the server when an entity moves less then 8 blocks.
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundMoveEntityPosRot {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub delta: PositionDelta8,
     pub y_rot: i8,
     pub x_rot: i8,

azalea-protocol/src/packets/game/c_move_entity_rot.rs

@@ -1,10 +1,11 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundMoveEntityRot {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub y_rot: i8,
     pub x_rot: i8,
     pub on_ground: bool,

azalea-protocol/src/packets/game/c_move_minecart_along_track.rs

@@ -1,11 +1,12 @@
 use azalea_buf::AzBuf;
 use azalea_core::position::Vec3;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundMoveMinecartAlongTrack {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub lerp_steps: Vec<MinecartStep>,
 }
 

azalea-protocol/src/packets/game/c_player_combat_kill.rs

@@ -1,11 +1,12 @@
 use azalea_buf::AzBuf;
 use azalea_chat::FormattedText;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 /// Used to send a respawn screen.
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundPlayerCombatKill {
     #[var]
-    pub player_id: u32,
+    pub player_id: MinecraftEntityId,
     pub message: FormattedText,
 }

azalea-protocol/src/packets/game/c_player_position.rs

@@ -5,6 +5,7 @@ use crate::common::movements::{PositionMoveRotation, RelativeMovements};
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundPlayerPosition {
+    /// The teleport ID.
     #[var]
     pub id: u32,
     pub change: PositionMoveRotation,

azalea-protocol/src/packets/game/c_projectile_power.rs

@@ -1,8 +1,10 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundProjectilePower {
-    pub id: u32,
+    #[var]
+    pub id: MinecraftEntityId,
     pub acceleration_power: f64,
 }

azalea-protocol/src/packets/game/c_remove_entities.rs

@@ -1,8 +1,9 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundRemoveEntities {
     #[var]
-    pub entity_ids: Vec<u32>,
+    pub entity_ids: Vec<MinecraftEntityId>,
 }

azalea-protocol/src/packets/game/c_remove_mob_effect.rs

@@ -1,9 +1,10 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundRemoveMobEffect {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub effect: azalea_registry::MobEffect,
 }

azalea-protocol/src/packets/game/c_rotate_head.rs

@@ -1,9 +1,10 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundRotateHead {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub y_head_rot: i8,
 }

azalea-protocol/src/packets/game/c_set_camera.rs

@@ -1,8 +1,9 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundSetCamera {
     #[var]
-    pub camera_id: u32,
+    pub camera_id: MinecraftEntityId,
 }

azalea-protocol/src/packets/game/c_set_entity_data.rs

@@ -1,11 +1,12 @@
 use azalea_buf::AzBuf;
 use azalea_entity::EntityMetadataItems;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundSetEntityData {
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub packed_items: EntityMetadataItems,
 }
 

azalea-protocol/src/packets/game/c_set_entity_link.rs

@@ -1,8 +1,9 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundSetEntityLink {
-    pub source_id: u32,
+    pub source_id: MinecraftEntityId,
-    pub dest_id: u32,
+    pub dest_id: MinecraftEntityId,
 }

azalea-protocol/src/packets/game/c_set_entity_motion.rs

@@ -1,10 +1,11 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundSetEntityMotion {
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub xa: i16,
     pub ya: i16,
     pub za: i16,

azalea-protocol/src/packets/game/c_set_equipment.rs

@@ -4,11 +4,12 @@ use azalea_buf::{AzBuf, BufReadError};
 use azalea_buf::{AzaleaRead, AzaleaWrite};
 use azalea_inventory::ItemStack;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundSetEquipment {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub slots: EquipmentSlots,
 }
 

azalea-protocol/src/packets/game/c_sound_entity.rs

@@ -1,6 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
 use azalea_registry::SoundEvent;
+use azalea_world::MinecraftEntityId;
 
 use super::c_sound::{CustomSound, SoundSource};
 
@@ -9,7 +10,7 @@ pub struct ClientboundSoundEntity {
     pub sound: azalea_registry::Holder<SoundEvent, CustomSound>,
     pub source: SoundSource,
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub volume: f32,
     pub pitch: f32,
     pub seed: u64,

azalea-protocol/src/packets/game/c_take_item_entity.rs

@@ -1,12 +1,13 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundTakeItemEntity {
     #[var]
     pub item_id: u32,
     #[var]
-    pub player_id: u32,
+    pub player_id: MinecraftEntityId,
     #[var]
     pub amount: u32,
 }

azalea-protocol/src/packets/game/c_teleport_entity.rs

@@ -1,13 +1,13 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 use crate::common::movements::{PositionMoveRotation, RelativeMovements};
 
-
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundTeleportEntity {
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub change: PositionMoveRotation,
     pub relatives: RelativeMovements,
     pub on_ground: bool,

azalea-protocol/src/packets/game/c_update_attributes.rs

@@ -2,11 +2,12 @@ use azalea_buf::AzBuf;
 use azalea_entity::attributes::AttributeModifier;
 use azalea_protocol_macros::ClientboundGamePacket;
 use azalea_registry::Attribute;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundUpdateAttributes {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub values: Vec<AttributeSnapshot>,
 }
 

azalea-protocol/src/packets/game/c_update_mob_effect.rs

@@ -1,11 +1,12 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
 use azalea_registry::MobEffect;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ClientboundGamePacket)]
 pub struct ClientboundUpdateMobEffect {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub mob_effect: MobEffect,
     #[var]
     pub effect_amplifier: u32,

azalea-protocol/src/packets/game/s_entity_tag_query.rs

@@ -1,10 +1,11 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ServerboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ServerboundGamePacket)]
 pub struct ServerboundEntityTagQuery {
     #[var]
     pub transaction_id: u32,
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
 }

azalea-protocol/src/packets/game/s_interact.rs

@@ -3,13 +3,14 @@ use std::io::{Cursor, Write};
 use azalea_buf::{AzBuf, AzaleaRead, AzaleaReadVar, AzaleaWrite, AzaleaWriteVar};
 use azalea_core::position::Vec3;
 use azalea_protocol_macros::ServerboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 use crate::packets::BufReadError;
 
 #[derive(Clone, Debug, AzBuf, ServerboundGamePacket)]
 pub struct ServerboundInteract {
     #[var]
-    pub entity_id: u32,
+    pub entity_id: MinecraftEntityId,
     pub action: ActionType,
     /// Whether the player is sneaking
     pub using_secondary_action: bool,

azalea-protocol/src/packets/game/s_pick_item_from_entity.rs

@@ -1,9 +1,10 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ServerboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ServerboundGamePacket)]
 pub struct ServerboundPickItemFromEntity {
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub include_data: bool,
 }

azalea-protocol/src/packets/game/s_player_command.rs

@@ -1,10 +1,11 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ServerboundGamePacket;
+use azalea_world::MinecraftEntityId;
 
 #[derive(Clone, Debug, AzBuf, ServerboundGamePacket)]
 pub struct ServerboundPlayerCommand {
     #[var]
-    pub id: u32,
+    pub id: MinecraftEntityId,
     pub action: Action,
     #[var]
     pub data: u32,

azalea-world/src/world.rs

@@ -1,5 +1,6 @@
-use std::fmt::Formatter;
+use std::fmt::{self, Display, Formatter};
 use std::hash::{Hash, Hasher};
+use std::io::{self, Cursor};
 use std::{
     collections::{HashMap, HashSet},
     fmt::Debug,
@@ -7,6 +8,7 @@ use std::{
 
 use azalea_block::fluid_state::FluidState;
 use azalea_block::BlockState;
+use azalea_buf::{AzaleaRead, AzaleaReadVar, AzaleaWrite, AzaleaWriteVar, BufReadError};
 use azalea_core::position::{BlockPos, ChunkPos};
 use azalea_core::registry_holder::RegistryHolder;
 use bevy_ecs::{component::Component, entity::Entity};
@@ -39,20 +41,60 @@ impl PartialInstance {
     }
 }
 
-/// An entity ID used by Minecraft. These are not guaranteed to be unique in
+/// An entity ID used by Minecraft.
-/// shared worlds, that's what [`Entity`] is for.
+///
+/// These IDs are picked by the server. Some server softwares (like Bungeecord)
+/// may pick entity IDs per-player, so you should avoid relying on them for
+/// identifying IDs (especially if you're using a shared world -- i.e. a swarm).
+///
+/// You might find [`Entity`] more useful, since that's an ID decided by us that
+/// is likely to be correct across shared worlds. You could also use the
+/// `EntityUuid` from `azalea_entity`, that one is unlikely to change even
+/// across server restarts.
+///
+/// This serializes as a i32. Usually it's a VarInt in the protocol, but not
+/// always. If you do need it to serialize as a VarInt, make sure to use use the
+/// `#[var]` attribute.
 ///
 /// [`Entity`]: bevy_ecs::entity::Entity
 #[derive(Component, Copy, Clone, Debug, PartialEq, Eq, Deref, DerefMut)]
-pub struct MinecraftEntityId(pub u32);
+pub struct MinecraftEntityId(pub i32);
 
 impl Hash for MinecraftEntityId {
     fn hash<H: Hasher>(&self, hasher: &mut H) {
-        hasher.write_u32(self.0);
+        hasher.write_i32(self.0);
     }
 }
 impl nohash_hasher::IsEnabled for MinecraftEntityId {}
 
+// we can't have the default be #[var] because mojang doesn't use varints for
+// entities sometimes :(
+impl AzaleaRead for MinecraftEntityId {
+    fn azalea_read(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
+        i32::azalea_read(buf).map(MinecraftEntityId)
+    }
+}
+impl AzaleaWrite for MinecraftEntityId {
+    fn azalea_write(&self, buf: &mut impl io::Write) -> Result<(), io::Error> {
+        i32::azalea_write(&self.0, buf)
+    }
+}
+impl AzaleaReadVar for MinecraftEntityId {
+    fn azalea_read_var(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
+        i32::azalea_read_var(buf).map(MinecraftEntityId)
+    }
+}
+impl AzaleaWriteVar for MinecraftEntityId {
+    fn azalea_write_var(&self, buf: &mut impl io::Write) -> Result<(), io::Error> {
+        i32::azalea_write_var(&self.0, buf)
+    }
+}
+impl Display for MinecraftEntityId {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        write!(f, "eid({})", self.0)
+    }
+}
+
 /// Keep track of certain metadatas that are only relevant for this partial
 /// world.
 #[derive(Debug, Default)]