Make Bevy dependencies optional in azalea-protocol (#303)

* Make Bevy dependencies optional in azalea-protocol

* derive serde traits on Direction again

* update docs for types that may not have Component

82 files changed, 563 insertions, 486 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 09a8f8d4..ee97e7bf 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -403,6 +403,7 @@ dependencies = [
  "azalea-registry",
  "bevy_ecs",
  "crc32c",
+ "derive_more",
  "indexmap",
  "nohash-hasher",
  "num-traits",
@@ -521,7 +522,6 @@ dependencies = [
  "azalea-inventory",
  "azalea-protocol-macros",
  "azalea-registry",
- "azalea-world",
  "bevy_ecs",
  "flate2",
  "futures",
diff --git a/Cargo.toml b/Cargo.toml
index a6f4ae42..523a5c7a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -92,26 +92,26 @@ tracing-subscriber = "0.3.22"
 uuid = "1.19.0"
 radix-heap = "0.4.2"
 
-azalea-block-macros = { path = "azalea-block/azalea-block-macros", version = "0.15.0" }
-azalea-block = { path = "azalea-block", version = "0.15.0" }
+azalea-block-macros = { path = "azalea-block/azalea-block-macros", version = "0.15.0", default-features = false }
+azalea-block = { path = "azalea-block", version = "0.15.0", default-features = false }
 azalea-auth = { path = "azalea-auth", version = "0.15.0", default-features = false }
-azalea-brigadier = { path = "azalea-brigadier", version = "0.15.0" }
-azalea-buf-macros = { path = "azalea-buf/azalea-buf-macros", version = "0.15.0" }
-azalea-buf = { path = "azalea-buf", version = "0.15.0" }
-azalea-chat = { path = "azalea-chat", version = "0.15.0" }
+azalea-brigadier = { path = "azalea-brigadier", version = "0.15.0", default-features = false }
+azalea-buf-macros = { path = "azalea-buf/azalea-buf-macros", version = "0.15.0", default-features = false }
+azalea-buf = { path = "azalea-buf", version = "0.15.0", default-features = false }
+azalea-chat = { path = "azalea-chat", version = "0.15.0", default-features = false }
 azalea-client = { path = "azalea-client", version = "0.15.0", default-features = false }
-azalea-core = { path = "azalea-core", version = "0.15.0" }
-azalea-crypto = { path = "azalea-crypto", version = "0.15.0" }
-azalea-entity = { path = "azalea-entity", version = "0.15.0" }
-azalea-inventory-macros = { path = "azalea-inventory/azalea-inventory-macros", version = "0.15.0" }
-azalea-inventory = { path = "azalea-inventory", version = "0.15.0" }
-azalea-language = { path = "azalea-language", version = "0.15.0" }
-azalea-physics = { path = "azalea-physics", version = "0.15.0" }
-azalea-protocol-macros = { path = "azalea-protocol/azalea-protocol-macros", version = "0.15.0" }
+azalea-core = { path = "azalea-core", version = "0.15.0", default-features = false }
+azalea-crypto = { path = "azalea-crypto", version = "0.15.0", default-features = false }
+azalea-entity = { path = "azalea-entity", version = "0.15.0", default-features = false }
+azalea-inventory-macros = { path = "azalea-inventory/azalea-inventory-macros", version = "0.15.0", default-features = false }
+azalea-inventory = { path = "azalea-inventory", version = "0.15.0", default-features = false }
+azalea-language = { path = "azalea-language", version = "0.15.0", default-features = false }
+azalea-physics = { path = "azalea-physics", version = "0.15.0", default-features = false }
+azalea-protocol-macros = { path = "azalea-protocol/azalea-protocol-macros", version = "0.15.0", default-features = false }
 azalea-protocol = { path = "azalea-protocol", version = "0.15.0", default-features = false }
-azalea-registry-macros = { path = "azalea-registry/azalea-registry-macros", version = "0.15.0" }
-azalea-registry = { path = "azalea-registry", version = "0.15.0" }
-azalea-world = { path = "azalea-world", version = "0.15.0" }
+azalea-registry-macros = { path = "azalea-registry/azalea-registry-macros", version = "0.15.0", default-features = false }
+azalea-registry = { path = "azalea-registry", version = "0.15.0", default-features = false }
+azalea-world = { path = "azalea-world", version = "0.15.0", default-features = false }
 
 [workspace.lints.clippy]
 # https://users.rust-lang.org/t/to-string-vs-to-owned-for-string-literals/1441
diff --git a/azalea-client/Cargo.toml b/azalea-client/Cargo.toml
index 5dc05151..b6ed7f12 100644
--- a/azalea-client/Cargo.toml
+++ b/azalea-client/Cargo.toml
@@ -17,7 +17,7 @@ azalea-crypto.workspace = true
 azalea-entity.workspace = true
 azalea-inventory.workspace = true
 azalea-physics.workspace = true
-azalea-protocol = { workspace = true, features = ["connecting"] }
+azalea-protocol = { workspace = true, features = ["connecting", "bevy_ecs"] }
 azalea-registry.workspace = true
 azalea-world.workspace = true
 bevy_app.workspace = true
diff --git a/azalea-client/src/plugins/disconnect.rs b/azalea-client/src/plugins/disconnect.rs
index 8c5036e1..081c174e 100644
--- a/azalea-client/src/plugins/disconnect.rs
+++ b/azalea-client/src/plugins/disconnect.rs
@@ -4,7 +4,7 @@ use azalea_chat::FormattedText;
 use azalea_entity::{
     EntityBundle, HasClientLoaded, InLoadedChunk, LocalEntity, metadata::PlayerMetadataBundle,
 };
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 use bevy_app::{App, Plugin, PostUpdate};
 use bevy_ecs::prelude::*;
 use derive_more::Deref;
diff --git a/azalea-client/src/plugins/movement.rs b/azalea-client/src/plugins/movement.rs
index c9473ebf..40cc108e 100644
--- a/azalea-client/src/plugins/movement.rs
+++ b/azalea-client/src/plugins/movement.rs
@@ -1,4 +1,5 @@
 use azalea_core::{
+    entity_id::MinecraftEntityId,
     game_type::GameMode,
     position::{Vec2, Vec3},
     tick::GameTick,
@@ -30,7 +31,7 @@ use azalea_protocol::{
     },
 };
 use azalea_registry::builtin::EntityKind;
-use azalea_world::{Instance, MinecraftEntityId};
+use azalea_world::Instance;
 use bevy_app::{App, Plugin, Update};
 use bevy_ecs::prelude::*;
 
diff --git a/azalea-client/src/plugins/packet/game/mod.rs b/azalea-client/src/plugins/packet/game/mod.rs
index 93057ef4..f93a02ea 100644
--- a/azalea-client/src/plugins/packet/game/mod.rs
+++ b/azalea-client/src/plugins/packet/game/mod.rs
@@ -3,6 +3,7 @@ mod events;
 use std::{collections::HashSet, sync::Arc};
 
 use azalea_core::{
+    entity_id::MinecraftEntityId,
     game_type::GameMode,
     position::{ChunkPos, Vec3},
 };
@@ -18,7 +19,7 @@ use azalea_protocol::{
     packets::{ConnectionProtocol, game::*},
 };
 use azalea_registry::builtin::EntityKind;
-use azalea_world::{InstanceContainer, InstanceName, MinecraftEntityId, PartialInstance};
+use azalea_world::{InstanceContainer, InstanceName, PartialInstance};
 use bevy_ecs::{prelude::*, system::SystemState};
 pub use events::*;
 use tracing::{debug, error, trace, warn};
diff --git a/azalea-client/src/test_utils/simulation.rs b/azalea-client/src/test_utils/simulation.rs
index a6bc22ab..0e480b92 100644
--- a/azalea-client/src/test_utils/simulation.rs
+++ b/azalea-client/src/test_utils/simulation.rs
@@ -5,6 +5,7 @@ use azalea_block::BlockState;
 use azalea_buf::AzaleaWrite;
 use azalea_core::{
     delta::LpVec3,
+    entity_id::MinecraftEntityId,
     game_type::{GameMode, OptionalGameType},
     position::{BlockPos, ChunkPos, Vec3},
     tick::GameTick,
@@ -30,7 +31,7 @@ use azalea_registry::{
     data::{Biome, DimensionKind},
     identifier::Identifier,
 };
-use azalea_world::{Chunk, Instance, MinecraftEntityId, Section, palette::PalettedContainer};
+use azalea_world::{Chunk, Instance, Section, palette::PalettedContainer};
 use bevy_app::App;
 use bevy_ecs::{
     component::Mutable,
diff --git a/azalea-client/tests/simulation/move_and_despawn_entity.rs b/azalea-client/tests/simulation/move_and_despawn_entity.rs
index 6c334a47..f05c64f4 100644
--- a/azalea-client/tests/simulation/move_and_despawn_entity.rs
+++ b/azalea-client/tests/simulation/move_and_despawn_entity.rs
@@ -8,7 +8,7 @@ use azalea_protocol::{
     },
 };
 use azalea_registry::builtin::EntityKind;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[test]
 fn test_move_and_despawn_entity() {
diff --git a/azalea-client/tests/simulation/move_despawned_entity.rs b/azalea-client/tests/simulation/move_despawned_entity.rs
index 7a171dae..48c22bf6 100644
--- a/azalea-client/tests/simulation/move_despawned_entity.rs
+++ b/azalea-client/tests/simulation/move_despawned_entity.rs
@@ -3,7 +3,7 @@ use azalea_core::position::ChunkPos;
 use azalea_entity::metadata::Cow;
 use azalea_protocol::packets::{ConnectionProtocol, game::ClientboundMoveEntityRot};
 use azalea_registry::builtin::EntityKind;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 use bevy_ecs::query::With;
 use tracing::Level;
 
diff --git a/azalea-client/tests/simulation/teleport_movement.rs b/azalea-client/tests/simulation/teleport_movement.rs
index 06a8f0b6..ff06ebb5 100644
--- a/azalea-client/tests/simulation/teleport_movement.rs
+++ b/azalea-client/tests/simulation/teleport_movement.rs
@@ -16,7 +16,7 @@ use azalea_protocol::{
     },
 };
 use azalea_registry::builtin::BlockKind;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[test]
 fn test_teleport_movement() {
diff --git a/azalea-core/Cargo.toml b/azalea-core/Cargo.toml
index bdb80667..ff2f8732 100644
--- a/azalea-core/Cargo.toml
+++ b/azalea-core/Cargo.toml
@@ -10,9 +10,9 @@ repository.workspace = true
 azalea-buf.workspace = true
 azalea-registry.workspace = true
 bevy_ecs = { workspace = true, optional = true }
+serde = { workspace = true, optional = true }
 nohash-hasher.workspace = true
 num-traits.workspace = true
-serde.workspace = true
 simdnbt.workspace = true
 tracing.workspace = true
 azalea-chat = { workspace = true, features = ["simdnbt"] }
@@ -20,9 +20,11 @@ indexmap.workspace = true
 crc32c.workspace = true
 thiserror.workspace = true
 uuid.workspace = true
+derive_more = { workspace = true, features = ["deref", "deref_mut"] }
 
 [features]
 bevy_ecs = ["dep:bevy_ecs"]
+serde = ["dep:serde"]
 strict_registry = []
 
 [lints]
diff --git a/azalea-core/src/attribute_modifier_operation.rs b/azalea-core/src/attribute_modifier_operation.rs
index 8418ff22..ab135080 100644
--- a/azalea-core/src/attribute_modifier_operation.rs
+++ b/azalea-core/src/attribute_modifier_operation.rs
@@ -1,11 +1,11 @@
 use std::str::FromStr;
 
 use azalea_buf::AzBuf;
-use serde::Serialize;
 use simdnbt::{FromNbtTag, borrow::NbtTag};
 
-#[derive(AzBuf, Clone, Copy, Debug, PartialEq, Serialize)]
-#[serde(rename_all = "snake_case")]
+#[cfg_attr(feature = "serde", derive(serde::Serialize))]
+#[derive(AzBuf, Clone, Copy, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", serde(rename_all = "snake_case"))]
 pub enum AttributeModifierOperation {
     AddValue,
     AddMultipliedBase,
diff --git a/azalea-core/src/data_registry.rs b/azalea-core/src/data_registry.rs
index 90628f47..bf1a9c1a 100644
--- a/azalea-core/src/data_registry.rs
+++ b/azalea-core/src/data_registry.rs
@@ -5,7 +5,7 @@ use azalea_registry::{
 };
 use simdnbt::owned::NbtCompound;
 
-use crate::registry_holder::{self, RegistryDeserializesTo, RegistryHolder};
+use crate::registry_holder::{RegistryDeserializesTo, RegistryHolder};
 
 pub trait DataRegistryWithKey: DataRegistry {
     fn key<'s, 'a: 's>(
@@ -63,8 +63,8 @@ macro_rules! define_default_deserializes_to {
 }
 
 define_deserializes_to! {
-    data::DimensionKind => registry_holder::dimension_type::DimensionKindElement,
-    data::Enchantment => registry_holder::enchantment::EnchantmentData,
+    data::DimensionKind => crate::registry_holder::dimension_type::DimensionKindElement,
+    data::Enchantment => crate::registry_holder::enchantment::EnchantmentData,
 }
 
 define_default_deserializes_to! {
diff --git a/azalea-core/src/direction.rs b/azalea-core/src/direction.rs
index b53df448..5902ffea 100644
--- a/azalea-core/src/direction.rs
+++ b/azalea-core/src/direction.rs
@@ -2,9 +2,8 @@ use azalea_buf::AzBuf;
 
 use crate::position::{BlockPos, Vec3, Vec3i};
 
-#[derive(
-    Clone, Copy, Debug, AzBuf, Default, Eq, PartialEq, serde::Deserialize, serde::Serialize,
-)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+#[derive(Clone, Copy, Debug, AzBuf, Default, Eq, PartialEq)]
 pub enum Direction {
     #[default]
     Down = 0,
@@ -91,7 +90,8 @@ impl Direction {
 ///
 /// Note that azalea_block has a similar enum named `FacingCardinal` that is
 /// used for block states.
-#[derive(AzBuf, Clone, Copy, Debug, serde::Deserialize, Eq, Hash, PartialEq, serde::Serialize)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[derive(AzBuf, Clone, Copy, Debug, Eq, Hash, PartialEq)]
 pub enum CardinalDirection {
     North,
     South,
diff --git a/azalea-core/src/entity_id.rs b/azalea-core/src/entity_id.rs
new file mode 100644
index 00000000..c66d3a2e
--- /dev/null
+++ b/azalea-core/src/entity_id.rs
@@ -0,0 +1,78 @@
+use std::{
+    fmt::{self, Display},
+    hash::{Hash, Hasher},
+    io::{self, Cursor},
+};
+
+use azalea_buf::{AzaleaRead, AzaleaReadVar, AzaleaWrite, AzaleaWriteVar, BufReadError};
+use derive_more::{Deref, DerefMut};
+
+// note: this is here instead of in azalea-entity because azalea-world depends
+// on it. and this isn't in azalea-world so azalea-protocol doesn't need to
+// depend on azalea-world.
+
+/// An entity ID used by Minecraft.
+///
+/// These IDs are picked by the server. Some server software (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
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(Clone, Copy, Debug, Default, Deref, DerefMut, Eq, PartialEq)]
+pub struct MinecraftEntityId(pub i32);
+
+impl Hash for MinecraftEntityId {
+    fn hash<H: Hasher>(&self, hasher: &mut H) {
+        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) -> io::Result<()> {
+        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) -> io::Result<()> {
+        i32::azalea_write_var(&self.0, buf)
+    }
+}
+impl Display for MinecraftEntityId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "eid({})", self.0)
+    }
+}
+impl From<i32> for MinecraftEntityId {
+    fn from(id: i32) -> Self {
+        Self(id)
+    }
+}
+impl From<u32> for MinecraftEntityId {
+    fn from(id: u32) -> Self {
+        Self(id as i32)
+    }
+}
diff --git a/azalea-core/src/filterable.rs b/azalea-core/src/filterable.rs
index fe9a553d..1c9766b6 100644
--- a/azalea-core/src/filterable.rs
+++ b/azalea-core/src/filterable.rs
@@ -4,13 +4,12 @@ use std::{
 };
 
 use azalea_buf::{AzaleaRead, AzaleaReadLimited, AzaleaReadVar, AzaleaWrite};
-use serde::Serialize;
 
 /// Used for written books.
-#[derive(Serialize)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize))]
 pub struct Filterable<T> {
     pub raw: T,
-    #[serde(skip_serializing_if = "Option::is_none")]
+    #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none"))]
     pub filtered: Option<T>,
 }
 
diff --git a/azalea-core/src/heightmap_kind.rs b/azalea-core/src/heightmap_kind.rs
new file mode 100644
index 00000000..07100a77
--- /dev/null
+++ b/azalea-core/src/heightmap_kind.rs
@@ -0,0 +1,50 @@
+// (wg stands for worldgen)
+
+use std::{
+    fmt::{self, Display},
+    str::FromStr,
+};
+
+use azalea_buf::AzBuf;
+
+/// A type of world heightmap.
+///
+/// See `azalea_world::heightmap` for more info.
+#[derive(AzBuf, Clone, Copy, Debug, Eq, Hash, PartialEq)]
+pub enum HeightmapKind {
+    WorldSurfaceWg,
+    WorldSurface,
+    OceanFloorWg,
+    OceanFloor,
+    MotionBlocking,
+    MotionBlockingNoLeaves,
+}
+
+impl FromStr for HeightmapKind {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "WORLD_SURFACE_WG" => Ok(HeightmapKind::WorldSurfaceWg),
+            "WORLD_SURFACE" => Ok(HeightmapKind::WorldSurface),
+            "OCEAN_FLOOR_WG" => Ok(HeightmapKind::OceanFloorWg),
+            "OCEAN_FLOOR" => Ok(HeightmapKind::OceanFloor),
+            "MOTION_BLOCKING" => Ok(HeightmapKind::MotionBlocking),
+            "MOTION_BLOCKING_NO_LEAVES" => Ok(HeightmapKind::MotionBlockingNoLeaves),
+            _ => Err(()),
+        }
+    }
+}
+
+impl Display for HeightmapKind {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            HeightmapKind::WorldSurfaceWg => write!(f, "WORLD_SURFACE_WG"),
+            HeightmapKind::WorldSurface => write!(f, "WORLD_SURFACE"),
+            HeightmapKind::OceanFloorWg => write!(f, "OCEAN_FLOOR_WG"),
+            HeightmapKind::OceanFloor => write!(f, "OCEAN_FLOOR"),
+            HeightmapKind::MotionBlocking => write!(f, "MOTION_BLOCKING"),
+            HeightmapKind::MotionBlockingNoLeaves => write!(f, "MOTION_BLOCKING_NO_LEAVES"),
+        }
+    }
+}
diff --git a/azalea-core/src/lib.rs b/azalea-core/src/lib.rs
index d61690aa..e07f9d88 100644
--- a/azalea-core/src/lib.rs
+++ b/azalea-core/src/lib.rs
@@ -5,20 +5,26 @@
 pub mod aabb;
 pub mod attribute_modifier_operation;
 pub mod bitset;
+#[cfg(feature = "serde")]
 pub mod checksum;
+#[cfg(feature = "serde")]
 pub mod codec_utils;
 pub mod color;
 pub mod cursor3d;
+#[cfg(feature = "serde")]
 pub mod data_registry;
 pub mod delta;
 pub mod difficulty;
 pub mod direction;
+pub mod entity_id;
 pub mod filterable;
 pub mod game_type;
+pub mod heightmap_kind;
 pub mod hit_result;
 pub mod math;
 pub mod objectives;
 pub mod position;
+#[cfg(feature = "serde")]
 pub mod registry_holder;
 #[doc(hidden)]
 pub mod resource_location {
diff --git a/azalea-core/src/position.rs b/azalea-core/src/position.rs
index 80b189ce..6da037ff 100644
--- a/azalea-core/src/position.rs
+++ b/azalea-core/src/position.rs
@@ -14,10 +14,11 @@ use std::{
 
 use azalea_buf::{AzBuf, AzaleaRead, AzaleaWrite, BufReadError};
 use azalea_registry::identifier::Identifier;
-use serde::{Serialize, Serializer};
+#[cfg(feature = "serde")]
+use serde::Serializer;
 use simdnbt::borrow::NbtTag;
 
-use crate::{codec_utils::IntArray, direction::Direction, math};
+use crate::{direction::Direction, math};
 
 macro_rules! vec3_impl {
     ($name:ident, $type:ty) => {
@@ -305,7 +306,8 @@ macro_rules! vec3_impl {
 /// Used to represent an exact position in the world where an entity could be.
 ///
 /// For blocks, [`BlockPos`] is used instead.
-#[derive(AzBuf, Clone, Copy, Debug, Default, serde::Deserialize, PartialEq, serde::Serialize)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[derive(AzBuf, Clone, Copy, Debug, Default, PartialEq)]
 pub struct Vec3 {
     pub x: f64,
     pub y: f64,
@@ -484,15 +486,19 @@ impl BlockPos {
         (self - other).length()
     }
 }
+#[cfg(feature = "serde")]
 impl serde::Serialize for BlockPos {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
         S: Serializer,
     {
         // makes sure it gets serialized correctly for the checksum
+
+        use crate::codec_utils::IntArray;
         IntArray([self.x, self.y, self.z]).serialize(serializer)
     }
 }
+#[cfg(feature = "serde")]
 impl<'de> serde::Deserialize<'de> for BlockPos {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -753,7 +759,8 @@ impl From<ChunkSectionBlockPos> for u16 {
 impl nohash_hasher::IsEnabled for ChunkSectionBlockPos {}
 
 /// A block pos with an attached world
-#[derive(Clone, Debug, PartialEq, Serialize)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize))]
+#[derive(Clone, Debug, PartialEq)]
 pub struct GlobalPos {
     // this is actually a ResourceKey in Minecraft, but i don't think it matters?
     pub dimension: Identifier,
@@ -911,7 +918,8 @@ impl fmt::Display for Vec3 {
 }
 
 /// A 2D vector.
-#[derive(AzBuf, Clone, Copy, Debug, Default, simdnbt::Deserialize, PartialEq, Serialize)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[derive(AzBuf, Clone, Copy, Debug, Default, PartialEq)]
 pub struct Vec2 {
     pub x: f32,
     pub y: f32,
diff --git a/azalea-core/src/sound.rs b/azalea-core/src/sound.rs
index 418707b9..e7e0f207 100644
--- a/azalea-core/src/sound.rs
+++ b/azalea-core/src/sound.rs
@@ -1,8 +1,8 @@
 use azalea_buf::AzBuf;
 use azalea_registry::identifier::Identifier;
-use serde::Serialize;
 
-#[derive(AzBuf, Clone, Debug, simdnbt::Deserialize, PartialEq, Serialize)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize))]
+#[derive(AzBuf, Clone, Debug, simdnbt::Deserialize, PartialEq)]
 pub struct CustomSound {
     pub sound_id: Identifier,
     pub range: Option<f32>,
diff --git a/azalea-entity/Cargo.toml b/azalea-entity/Cargo.toml
index 0e62cbd4..1140d4b8 100644
--- a/azalea-entity/Cargo.toml
+++ b/azalea-entity/Cargo.toml
@@ -13,9 +13,9 @@ azalea-chat = { workspace = true, features = ["azalea-buf"] }
 azalea-core.workspace = true
 azalea-inventory.workspace = true
 azalea-registry.workspace = true
-azalea-world.workspace = true
-bevy_app.workspace = true
-bevy_ecs.workspace = true
+azalea-world = { workspace = true, optional = true }
+bevy_app = { workspace = true, optional = true }
+bevy_ecs = { workspace = true, optional = true }
 derive_more.workspace = true
 enum-as-inner.workspace = true
 nohash-hasher.workspace = true
@@ -24,5 +24,8 @@ thiserror.workspace = true
 tracing.workspace = true
 uuid.workspace = true
 
+[features]
+bevy_ecs = ["dep:bevy_ecs", "dep:bevy_app", "dep:azalea-world"]
+
 [lints]
 workspace = true
diff --git a/azalea-entity/src/attributes.rs b/azalea-entity/src/attributes.rs
index b26f61ba..69e98a7b 100644
--- a/azalea-entity/src/attributes.rs
+++ b/azalea-entity/src/attributes.rs
@@ -7,14 +7,14 @@ use std::collections::{HashMap, hash_map};
 use azalea_core::attribute_modifier_operation::AttributeModifierOperation;
 use azalea_inventory::components::AttributeModifier;
 use azalea_registry::{builtin::Attribute, identifier::Identifier};
-use bevy_ecs::component::Component;
 use thiserror::Error;
 
-/// A component that contains the current attribute values for an entity.
+/// The current attribute values for an entity.
 ///
 /// Each attribute can have multiple modifiers, and these modifiers are the
 /// result of things like sprinting or enchantments.
-#[derive(Clone, Component, Debug)]
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(Clone, Debug)]
 pub struct Attributes {
     pub movement_speed: AttributeInstance,
     pub sneaking_speed: AttributeInstance,
diff --git a/azalea-entity/src/data.rs b/azalea-entity/src/data.rs
index c9e98b0d..0b973bcb 100644
--- a/azalea-entity/src/data.rs
+++ b/azalea-entity/src/data.rs
@@ -13,7 +13,6 @@ use azalea_core::{
 };
 use azalea_inventory::{ItemStack, components};
 use azalea_registry::builtin::{VillagerKind, VillagerProfession};
-use bevy_ecs::component::Component;
 use derive_more::Deref;
 use enum_as_inner::EnumAsInner;
 use uuid::Uuid;
@@ -154,7 +153,8 @@ pub struct Rotations {
     pub z: f32,
 }
 
-#[derive(AzBuf, Clone, Component, Copy, Debug, Default, Eq, PartialEq)]
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(AzBuf, Clone, Copy, Debug, Default, Eq, PartialEq)]
 pub enum Pose {
     #[default]
     Standing = 0,
diff --git a/azalea-entity/src/dimensions.rs b/azalea-entity/src/dimensions.rs
index 87eced8a..6c527ab6 100644
--- a/azalea-entity/src/dimensions.rs
+++ b/azalea-entity/src/dimensions.rs
@@ -1,11 +1,11 @@
 use azalea_core::{aabb::Aabb, position::Vec3};
 use azalea_registry::builtin::EntityKind;
-use bevy_ecs::component::Component;
 
 use crate::Pose;
 
-/// A component that contains the size of an entity and their eye height.
-#[derive(Clone, Component, Debug, Default)]
+/// The size of an entity and its eye height.
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(Clone, Debug, Default)]
 pub struct EntityDimensions {
     pub width: f32,
     pub height: f32,
diff --git a/azalea-entity/src/effects.rs b/azalea-entity/src/effects.rs
index ae7ae8a1..39074ebd 100644
--- a/azalea-entity/src/effects.rs
+++ b/azalea-entity/src/effects.rs
@@ -6,7 +6,6 @@ use std::{
 use azalea_buf::{AzBuf, AzaleaRead, AzaleaWrite, BufReadError};
 use azalea_core::bitset::FixedBitSet;
 use azalea_registry::builtin::MobEffect;
-use bevy_ecs::component::Component;
 
 /// Data about an active mob effect.
 #[derive(AzBuf, Clone, Debug, Default, PartialEq)]
@@ -63,8 +62,9 @@ impl AzaleaWrite for MobEffectFlags {
     }
 }
 
-/// An ECS component that stores the active mob effects on an entity.
-#[derive(Clone, Component, Debug, Default)]
+/// The active mob effects on an entity.
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(Clone, Debug, Default)]
 pub struct ActiveEffects(pub HashMap<MobEffect, MobEffectData>);
 impl ActiveEffects {
     pub fn insert(&mut self, effect: MobEffect, data: MobEffectData) {
diff --git a/azalea-entity/src/inventory.rs b/azalea-entity/src/inventory.rs
index aa13865e..fe3921ef 100644
--- a/azalea-entity/src/inventory.rs
+++ b/azalea-entity/src/inventory.rs
@@ -10,12 +10,13 @@ use azalea_inventory::{
         QuickCraftStatusKind, QuickMoveClick, ThrowClick,
     },
 };
-use bevy_ecs::prelude::*;
 
 use crate::PlayerAbilities;
 
-/// A component present on all local players that have an inventory.
-#[derive(Clone, Component, Debug)]
+/// A local player's inventory and related data, including the container that
+/// they may have opened.
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(Clone, Debug)]
 pub struct Inventory {
     /// The player's inventory menu. This is guaranteed to be a `Menu::Player`.
     ///
diff --git a/azalea-entity/src/lib.rs b/azalea-entity/src/lib.rs
index 40f80930..87e249c1 100644
--- a/azalea-entity/src/lib.rs
+++ b/azalea-entity/src/lib.rs
@@ -6,9 +6,11 @@ mod data;
 pub mod dimensions;
 mod effects;
 pub mod inventory;
+#[cfg(feature = "bevy_ecs")]
 pub mod metadata;
 pub mod mining;
 pub mod particle;
+#[cfg(feature = "bevy_ecs")]
 mod plugin;
 pub mod vec_delta_codec;
 
@@ -19,25 +21,23 @@ use std::{
 };
 
 pub use attributes::Attributes;
-use azalea_block::{BlockState, fluid_state::FluidKind};
+use azalea_block::fluid_state::FluidKind;
 use azalea_buf::AzBuf;
 use azalea_core::{
     aabb::Aabb,
     math,
     position::{BlockPos, ChunkPos, Vec3},
 };
-use azalea_registry::{builtin::EntityKind, identifier::Identifier};
-use azalea_world::{ChunkStorage, InstanceName};
-use bevy_ecs::{bundle::Bundle, component::Component};
+use azalea_registry::builtin::EntityKind;
 pub use data::*;
 use derive_more::{Deref, DerefMut};
 pub use effects::{ActiveEffects, MobEffectData};
-use plugin::indexing::EntityChunkPos;
 use uuid::Uuid;
 use vec_delta_codec::VecDeltaCodec;
 
 use self::attributes::AttributeInstance;
 use crate::dimensions::EntityDimensions;
+#[cfg(feature = "bevy_ecs")]
 pub use crate::plugin::*;
 
 pub fn move_relative(
@@ -84,53 +84,12 @@ pub fn view_vector(look_direction: LookDirection) -> Vec3 {
     }
 }
 
-/// Get the position of the block below the entity, but a little lower.
-pub fn on_pos_legacy(chunk_storage: &ChunkStorage, position: Position) -> BlockPos {
-    on_pos(0.2, chunk_storage, position)
-}
-
-// int x = Mth.floor(this.position.x);
-// int y = Mth.floor(this.position.y - (double)var1);
-// int z = Mth.floor(this.position.z);
-// BlockPos var5 = new BlockPos(x, y, z);
-// if (this.level.getBlockState(var5).isAir()) {
-//    BlockPos var6 = var5.below();
-//    BlockState var7 = this.level.getBlockState(var6);
-//    if (var7.is(BlockTags.FENCES) || var7.is(BlockTags.WALLS) ||
-// var7.getBlock() instanceof FenceGateBlock) {       return var6;
-//    }
-// }
-// return var5;
-pub fn on_pos(offset: f32, chunk_storage: &ChunkStorage, pos: Position) -> BlockPos {
-    let x = pos.x.floor() as i32;
-    let y = (pos.y - offset as f64).floor() as i32;
-    let z = pos.z.floor() as i32;
-    let pos = BlockPos { x, y, z };
-
-    // TODO: check if block below is a fence, wall, or fence gate
-    let block_pos = pos.down(1);
-    let block_state = chunk_storage.get_block_state(block_pos);
-    if block_state == Some(BlockState::AIR) {
-        let block_pos_below = block_pos.down(1);
-        let block_state_below = chunk_storage.get_block_state(block_pos_below);
-        if let Some(_block_state_below) = block_state_below {
-            // if block_state_below.is_fence()
-            //     || block_state_below.is_wall()
-            //     || block_state_below.is_fence_gate()
-            // {
-            //     return block_pos_below;
-            // }
-        }
-    }
-
-    pos
-}
-
 /// The Minecraft UUID of the entity.
 ///
 /// For players, this is their actual player UUID, and for other entities it's
 /// just random.
-#[derive(Clone, Component, Copy, Default, Deref, DerefMut, PartialEq)]
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(Clone, Copy, Default, Deref, DerefMut, PartialEq)]
 pub struct EntityUuid(Uuid);
 impl EntityUuid {
     pub fn new(uuid: Uuid) -> Self {
@@ -145,12 +104,13 @@ impl Debug for EntityUuid {
 
 /// The position of the entity right now.
 ///
-/// You are free to change the value of this component; there's systems that
-/// update the indexes automatically.
+/// If this is being used as an ECS component then you are free to modify it,
+/// because there are systems that will update the indexes automatically.
 ///
 /// Its value is set to a default of [`Vec3::ZERO`] when it receives the login
 /// packet, its true position may be set ticks later.
-#[derive(Clone, Component, Copy, Debug, Default, Deref, DerefMut, PartialEq)]
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(Clone, Copy, Debug, Default, Deref, DerefMut, PartialEq)]
 pub struct Position(Vec3);
 impl Position {
     pub fn new(pos: Vec3) -> Self {
@@ -183,50 +143,12 @@ impl From<&Position> for BlockPos {
     }
 }
 
-/// The second most recent position of the entity that was sent over the
-/// network.
-///
-/// This is currently only updated for our own local player entities.
-#[derive(Clone, Component, Copy, Debug, Default, Deref, DerefMut, PartialEq)]
-pub struct LastSentPosition(Vec3);
-impl From<&LastSentPosition> for Vec3 {
-    fn from(value: &LastSentPosition) -> Self {
-        value.0
-    }
-}
-impl From<LastSentPosition> for ChunkPos {
-    fn from(value: LastSentPosition) -> Self {
-        ChunkPos::from(&value.0)
-    }
-}
-impl From<LastSentPosition> for BlockPos {
-    fn from(value: LastSentPosition) -> Self {
-        BlockPos::from(&value.0)
-    }
-}
-impl From<&LastSentPosition> for ChunkPos {
-    fn from(value: &LastSentPosition) -> Self {
-        ChunkPos::from(value.0)
-    }
-}
-impl From<&LastSentPosition> for BlockPos {
-    fn from(value: &LastSentPosition) -> Self {
-        BlockPos::from(value.0)
-    }
-}
-
-/// A component for entities that can jump.
-///
-/// If this is true, the entity will try to jump every tick. It's equivalent to
-/// the space key being held in vanilla.
-#[derive(Clone, Component, Copy, Debug, Default, Deref, DerefMut, Eq, PartialEq)]
-pub struct Jumping(pub bool);
-
-/// A component that contains the direction an entity is looking, in degrees.
+/// The direction that an entity is looking, in degrees.
 ///
 /// To avoid flagging anticheats, consider using [`Self::update`] when updating
 /// the values of this struct.
-#[derive(AzBuf, Clone, Component, Copy, Debug, Default, PartialEq)]
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(AzBuf, Clone, Copy, Debug, Default, PartialEq)]
 pub struct LookDirection {
     /// Left and right. AKA yaw. In degrees.
     y_rot: f32,
@@ -237,7 +159,7 @@ pub struct LookDirection {
 impl LookDirection {
     /// Create a new look direction and clamp the `x_rot` to the allowed values.
     pub fn new(y_rot: f32, x_rot: f32) -> Self {
-        apply_clamp_look_direction(Self { y_rot, x_rot })
+        Self { y_rot, x_rot }.clamped()
     }
     /// Returns yaw (left and right) in degrees.
     ///
@@ -303,6 +225,14 @@ impl LookDirection {
         self.y_rot += delta_y_rot;
         self.x_rot += delta_x_rot;
     }
+
+    /// Force the [`Self::x_rot`] to be between -90 and 90 degrees, and return
+    /// the new look direction.
+    #[must_use]
+    pub fn clamped(mut self) -> Self {
+        self.x_rot = self.x_rot.clamp(-90., 90.);
+        self
+    }
 }
 
 impl From<LookDirection> for (f32, f32) {
@@ -326,7 +256,8 @@ impl Eq for LookDirection {}
 
 /// The physics data relating to the entity, such as position, velocity, and
 /// bounding box.
-#[derive(Clone, Component, Debug, Default)]
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(Clone, Debug, Default)]
 pub struct Physics {
     /// How fast the entity is moving. Sometimes referred to as the delta
     /// movement.
@@ -454,69 +385,6 @@ impl Physics {
     }
 }
 
-/// Marker component for entities that are dead.
-///
-/// "Dead" means that the entity has 0 health.
-#[derive(Clone, Component, Copy, Default)]
-pub struct Dead;
-
-/// A component NewType for [`EntityKind`].
-///
-/// Most of the time, you should be using `azalea_registry::EntityKind`
-/// directly instead.
-#[derive(Clone, Component, Copy, Debug, Deref, PartialEq)]
-pub struct EntityKindComponent(pub EntityKind);
-
-/// A bundle of components that every entity has.
-///
-/// This doesn't contain metadata; that has to be added separately.
-#[derive(Bundle)]
-pub struct EntityBundle {
-    pub kind: EntityKindComponent,
-    pub uuid: EntityUuid,
-    pub world_name: InstanceName,
-    pub position: Position,
-    pub last_sent_position: LastSentPosition,
-
-    pub chunk_pos: EntityChunkPos,
-
-    pub physics: Physics,
-    pub direction: LookDirection,
-    pub dimensions: EntityDimensions,
-    pub attributes: Attributes,
-    pub jumping: Jumping,
-    pub crouching: Crouching,
-    pub fluid_on_eyes: FluidOnEyes,
-    pub on_climbable: OnClimbable,
-    pub active_effects: ActiveEffects,
-}
-
-impl EntityBundle {
-    pub fn new(uuid: Uuid, pos: Vec3, kind: EntityKind, world_name: Identifier) -> Self {
-        let dimensions = EntityDimensions::from(kind);
-
-        Self {
-            kind: EntityKindComponent(kind),
-            uuid: EntityUuid(uuid),
-            world_name: InstanceName(world_name),
-            position: Position(pos),
-            chunk_pos: EntityChunkPos(ChunkPos::from(&pos)),
-            last_sent_position: LastSentPosition(pos),
-            physics: Physics::new(&dimensions, pos),
-            dimensions,
-            direction: LookDirection::default(),
-
-            attributes: Attributes::new(EntityKind::Player),
-
-            jumping: Jumping(false),
-            crouching: Crouching(false),
-            fluid_on_eyes: FluidOnEyes(FluidKind::Empty),
-            on_climbable: OnClimbable(false),
-            active_effects: ActiveEffects::default(),
-        }
-    }
-}
-
 impl Attributes {
     pub fn new(_entity_kind: EntityKind) -> Self {
         // TODO: do the correct defaults for everything, some
@@ -534,43 +402,12 @@ impl Attributes {
     }
 }
 
-/// A marker component that signifies that this entity is "local" and shouldn't
-/// be updated by other clients.
+/// The abilities that a player has, such as flying or being able to instantly
+/// break blocks.
 ///
-/// If this is for a client then all of our clients will have this.
-///
-/// This component is not removed from clients when they disconnect.
-#[derive(Clone, Component, Copy, Debug, Default)]
-pub struct LocalEntity;
-
-#[derive(Clone, Component, Copy, Debug, Deref, DerefMut, PartialEq)]
-pub struct FluidOnEyes(FluidKind);
-
-impl FluidOnEyes {
-    pub fn new(fluid: FluidKind) -> Self {
-        Self(fluid)
-    }
-}
-
-#[derive(Clone, Component, Copy, Debug, Deref, DerefMut, PartialEq)]
-pub struct OnClimbable(bool);
-
-/// A component that indicates whether the player is currently sneaking.
-///
-/// If the entity isn't a local player, then this is just a shortcut for
-/// checking if the [`Pose`] is `Crouching`.
-///
-/// If you need to modify this value, use
-/// `azalea_client::PhysicsState::trying_to_crouch` or `Client::set_crouching`
-/// instead.
-#[derive(Clone, Component, Copy, Default, Deref, DerefMut)]
-pub struct Crouching(bool);
-
-/// A component that contains the abilities the player has, like flying
-/// or instantly breaking blocks.
-///
-/// This is only present on local players.
-#[derive(Clone, Component, Debug, Default)]
+/// This should only be present on local players.
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(Clone, Debug, Default)]
 pub struct PlayerAbilities {
     pub invulnerable: bool,
     pub flying: bool,
@@ -583,3 +420,9 @@ pub struct PlayerAbilities {
     /// Used for the fov
     pub walking_speed: f32,
 }
+
+/// The type of fluid that is at an entity's eye position, while also accounting
+/// for fluid height.
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(Clone, Copy, Debug, Deref, DerefMut, PartialEq)]
+pub struct FluidOnEyes(FluidKind);
diff --git a/azalea-entity/src/particle.rs b/azalea-entity/src/particle.rs
index ca3ac211..397346cf 100644
--- a/azalea-entity/src/particle.rs
+++ b/azalea-entity/src/particle.rs
@@ -1,16 +1,15 @@
 use azalea_block::BlockState;
 use azalea_buf::AzBuf;
-use azalea_core::{color::RgbColor, position::BlockPos};
+use azalea_core::{color::RgbColor, entity_id::MinecraftEntityId, position::BlockPos};
 use azalea_inventory::ItemStack;
 use azalea_registry::builtin::ParticleKind;
-use azalea_world::MinecraftEntityId;
-use bevy_ecs::component::Component;
 
 // the order of this enum must be kept in sync with ParticleKind, otherwise
 // we get errors parsing particles.
 
 /// A [`ParticleKind`] with data potentially attached to it.
-#[derive(AzBuf, Clone, Component, Debug, PartialEq)]
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(AzBuf, Clone, Debug, PartialEq)]
 pub enum Particle {
     AngryVillager,
     Block(BlockParticle),
diff --git a/azalea-entity/src/plugin/components.rs b/azalea-entity/src/plugin/components.rs
new file mode 100644
index 00000000..abeab160
--- /dev/null
+++ b/azalea-entity/src/plugin/components.rs
@@ -0,0 +1,151 @@
+use azalea_block::fluid_state::FluidKind;
+use azalea_core::position::{BlockPos, ChunkPos, Vec3};
+use azalea_registry::{builtin::EntityKind, identifier::Identifier};
+use azalea_world::InstanceName;
+use bevy_ecs::{bundle::Bundle, component::Component};
+use derive_more::{Deref, DerefMut};
+use uuid::Uuid;
+
+use crate::{
+    ActiveEffects, Attributes, EntityUuid, FluidOnEyes, LookDirection, Physics, Position,
+    dimensions::EntityDimensions, indexing::EntityChunkPos,
+};
+
+/// A bundle of components that every entity has.
+///
+/// This doesn't contain metadata; that has to be added separately.
+#[derive(Bundle)]
+pub struct EntityBundle {
+    pub kind: EntityKindComponent,
+    pub uuid: EntityUuid,
+    pub world_name: InstanceName,
+    pub position: Position,
+    pub last_sent_position: LastSentPosition,
+
+    pub chunk_pos: EntityChunkPos,
+
+    pub physics: Physics,
+    pub direction: LookDirection,
+    pub dimensions: EntityDimensions,
+    pub attributes: Attributes,
+    pub jumping: Jumping,
+    pub crouching: Crouching,
+    pub fluid_on_eyes: FluidOnEyes,
+    pub on_climbable: OnClimbable,
+    pub active_effects: ActiveEffects,
+}
+
+impl EntityBundle {
+    pub fn new(uuid: Uuid, pos: Vec3, kind: EntityKind, world_name: Identifier) -> Self {
+        let dimensions = EntityDimensions::from(kind);
+
+        Self {
+            kind: EntityKindComponent(kind),
+            uuid: EntityUuid(uuid),
+            world_name: InstanceName(world_name),
+            position: Position(pos),
+            chunk_pos: EntityChunkPos(ChunkPos::from(&pos)),
+            last_sent_position: LastSentPosition(pos),
+            physics: Physics::new(&dimensions, pos),
+            dimensions,
+            direction: LookDirection::default(),
+
+            attributes: Attributes::new(EntityKind::Player),
+
+            jumping: Jumping(false),
+            crouching: Crouching(false),
+            fluid_on_eyes: FluidOnEyes(FluidKind::Empty),
+            on_climbable: OnClimbable(false),
+            active_effects: ActiveEffects::default(),
+        }
+    }
+}
+
+/// Marker component for entities that are dead.
+///
+/// "Dead" means that the entity has 0 health.
+#[derive(Clone, Component, Copy, Default)]
+pub struct Dead;
+
+/// A component NewType for [`EntityKind`].
+///
+/// Most of the time, you should be using `azalea_registry::EntityKind`
+/// directly instead.
+#[derive(Clone, Component, Copy, Debug, Deref, PartialEq)]
+pub struct EntityKindComponent(pub EntityKind);
+
+/// A marker component that signifies that this entity is "local" and shouldn't
+/// be updated by other clients.
+///
+/// If this is for a client then all of our clients will have this.
+///
+/// This component is not removed from clients when they disconnect.
+#[derive(Clone, Component, Copy, Debug, Default)]
+pub struct LocalEntity;
+
+impl FluidOnEyes {
+    pub fn new(fluid: FluidKind) -> Self {
+        Self(fluid)
+    }
+}
+
+#[derive(Clone, Component, Copy, Debug, Deref, DerefMut, PartialEq)]
+pub struct OnClimbable(bool);
+
+/// A component that indicates whether the player is currently sneaking.
+///
+/// If the entity isn't a local player, then this is just a shortcut for
+/// checking if the [`Pose`] is `Crouching`.
+///
+/// If you need to modify this value, use
+/// `azalea_client::PhysicsState::trying_to_crouch` or `Client::set_crouching`
+/// instead.
+///
+/// [`Pose`]: crate::data::Pose
+#[derive(Clone, Component, Copy, Default, Deref, DerefMut)]
+pub struct Crouching(bool);
+
+/// A component that indicates whether the client has loaded.
+///
+/// This is updated by a system in `azalea-client`.
+#[derive(Component)]
+pub struct HasClientLoaded;
+
+/// The second most recent position of the entity that was sent over the
+/// network.
+///
+/// This is currently only updated for our own local player entities.
+#[derive(Clone, Copy, Component, Debug, Default, Deref, DerefMut, PartialEq)]
+pub struct LastSentPosition(Vec3);
+impl From<&LastSentPosition> for Vec3 {
+    fn from(value: &LastSentPosition) -> Self {
+        value.0
+    }
+}
+impl From<LastSentPosition> for ChunkPos {
+    fn from(value: LastSentPosition) -> Self {
+        ChunkPos::from(&value.0)
+    }
+}
+impl From<LastSentPosition> for BlockPos {
+    fn from(value: LastSentPosition) -> Self {
+        BlockPos::from(&value.0)
+    }
+}
+impl From<&LastSentPosition> for ChunkPos {
+    fn from(value: &LastSentPosition) -> Self {
+        ChunkPos::from(value.0)
+    }
+}
+impl From<&LastSentPosition> for BlockPos {
+    fn from(value: &LastSentPosition) -> Self {
+        BlockPos::from(value.0)
+    }
+}
+
+/// A component for entities that can jump.
+///
+/// If this is true, the entity will try to jump every tick. It's equivalent to
+/// the space key being held in vanilla.
+#[derive(Clone, Copy, Component, Debug, Default, Deref, DerefMut, Eq, PartialEq)]
+pub struct Jumping(pub bool);
diff --git a/azalea-entity/src/plugin/indexing.rs b/azalea-entity/src/plugin/indexing.rs
index edceccc7..3fba6b3c 100644
--- a/azalea-entity/src/plugin/indexing.rs
+++ b/azalea-entity/src/plugin/indexing.rs
@@ -5,8 +5,8 @@ use std::{
     fmt::{self, Debug},
 };
 
-use azalea_core::position::ChunkPos;
-use azalea_world::{Instance, InstanceContainer, InstanceName, MinecraftEntityId};
+use azalea_core::{entity_id::MinecraftEntityId, position::ChunkPos};
+use azalea_world::{Instance, InstanceContainer, InstanceName};
 use bevy_ecs::prelude::*;
 use derive_more::{Deref, DerefMut};
 use nohash_hasher::IntMap;
diff --git a/azalea-entity/src/plugin/mod.rs b/azalea-entity/src/plugin/mod.rs
index 855b2899..03dda233 100644
--- a/azalea-entity/src/plugin/mod.rs
+++ b/azalea-entity/src/plugin/mod.rs
@@ -1,3 +1,4 @@
+mod components;
 pub mod indexing;
 mod relative_updates;
 
@@ -5,21 +6,22 @@ use std::collections::HashSet;
 
 use azalea_block::{BlockState, BlockTrait, fluid_state::FluidKind, properties};
 use azalea_core::{
+    entity_id::MinecraftEntityId,
     position::{BlockPos, ChunkPos},
     tick::GameTick,
 };
 use azalea_registry::{builtin::BlockKind, tags};
-use azalea_world::{InstanceContainer, InstanceName, MinecraftEntityId};
+use azalea_world::{ChunkStorage, InstanceContainer, InstanceName};
 use bevy_app::{App, Plugin, PostUpdate, Update};
 use bevy_ecs::prelude::*;
+pub use components::*;
 use derive_more::{Deref, DerefMut};
 use indexing::EntityUuidIndex;
 pub use relative_updates::RelativeEntityUpdate;
 use tracing::debug;
 
 use crate::{
-    Crouching, Dead, EntityKindComponent, FluidOnEyes, LocalEntity, LookDirection, OnClimbable,
-    Physics, Pose, Position,
+    FluidOnEyes, LookDirection, Physics, Pose, Position,
     dimensions::{EntityDimensions, calculate_dimensions},
     metadata::Health,
 };
@@ -197,14 +199,9 @@ pub struct LoadedBy(pub HashSet<Entity>);
 
 pub fn clamp_look_direction(mut query: Query<&mut LookDirection>) {
     for mut look_direction in &mut query {
-        *look_direction = apply_clamp_look_direction(*look_direction);
+        *look_direction = look_direction.clamped();
     }
 }
-pub fn apply_clamp_look_direction(mut look_direction: LookDirection) -> LookDirection {
-    look_direction.x_rot = look_direction.x_rot.clamp(-90., 90.);
-
-    look_direction
-}
 
 /// Sets the position of the entity.
 ///
@@ -279,11 +276,47 @@ pub fn update_in_loaded_chunk(
     }
 }
 
-/// A component that indicates whether the client has loaded.
-///
-/// This is updated by a system in `azalea-client`.
-#[derive(Component)]
-pub struct HasClientLoaded;
+/// Get the position of the block below the entity, but a little lower.
+pub fn on_pos_legacy(chunk_storage: &ChunkStorage, position: Position) -> BlockPos {
+    on_pos(0.2, chunk_storage, position)
+}
+
+// int x = Mth.floor(this.position.x);
+// int y = Mth.floor(this.position.y - (double)var1);
+// int z = Mth.floor(this.position.z);
+// BlockPos var5 = new BlockPos(x, y, z);
+// if (this.level.getBlockState(var5).isAir()) {
+//    BlockPos var6 = var5.below();
+//    BlockState var7 = this.level.getBlockState(var6);
+//    if (var7.is(BlockTags.FENCES) || var7.is(BlockTags.WALLS) ||
+// var7.getBlock() instanceof FenceGateBlock) {       return var6;
+//    }
+// }
+// return var5;
+pub fn on_pos(offset: f32, chunk_storage: &ChunkStorage, pos: Position) -> BlockPos {
+    let x = pos.x.floor() as i32;
+    let y = (pos.y - offset as f64).floor() as i32;
+    let z = pos.z.floor() as i32;
+    let pos = BlockPos { x, y, z };
+
+    // TODO: check if block below is a fence, wall, or fence gate
+    let block_pos = pos.down(1);
+    let block_state = chunk_storage.get_block_state(block_pos);
+    if block_state == Some(BlockState::AIR) {
+        let block_pos_below = block_pos.down(1);
+        let block_state_below = chunk_storage.get_block_state(block_pos_below);
+        if let Some(_block_state_below) = block_state_below {
+            // if block_state_below.is_fence()
+            //     || block_state_below.is_wall()
+            //     || block_state_below.is_fence_gate()
+            // {
+            //     return block_pos_below;
+            // }
+        }
+    }
+
+    pos
+}
 
 #[cfg(test)]
 mod tests {
diff --git a/azalea-entity/src/plugin/relative_updates.rs b/azalea-entity/src/plugin/relative_updates.rs
index 3917c946..f80ccddc 100644
--- a/azalea-entity/src/plugin/relative_updates.rs
+++ b/azalea-entity/src/plugin/relative_updates.rs
@@ -17,7 +17,8 @@
 
 use std::sync::Arc;
 
-use azalea_world::{MinecraftEntityId, PartialInstance};
+use azalea_core::entity_id::MinecraftEntityId;
+use azalea_world::PartialInstance;
 use bevy_ecs::prelude::*;
 use derive_more::{Deref, DerefMut};
 use parking_lot::RwLock;
diff --git a/azalea-inventory/Cargo.toml b/azalea-inventory/Cargo.toml
index c5c5e314..7e26ff8c 100644
--- a/azalea-inventory/Cargo.toml
+++ b/azalea-inventory/Cargo.toml
@@ -10,7 +10,7 @@ repository.workspace = true
 azalea-auth.workspace = true
 azalea-buf.workspace = true
 azalea-chat = { workspace = true, features = ["azalea-buf"] }
-azalea-core.workspace = true
+azalea-core = { workspace = true, features = ["serde"] }
 azalea-inventory-macros.workspace = true
 azalea-registry = { workspace = true, features = ["serde"] }
 indexmap.workspace = true
diff --git a/azalea-physics/Cargo.toml b/azalea-physics/Cargo.toml
index 68c3fbe8..33a669c1 100644
--- a/azalea-physics/Cargo.toml
+++ b/azalea-physics/Cargo.toml
@@ -12,7 +12,7 @@ uuid.workspace = true
 [dependencies]
 azalea-block.workspace = true
 azalea-core.workspace = true
-azalea-entity.workspace = true
+azalea-entity = { workspace = true, features = ["bevy_ecs"] }
 azalea-inventory.workspace = true
 azalea-registry.workspace = true
 azalea-world.workspace = true
diff --git a/azalea-physics/tests/physics.rs b/azalea-physics/tests/physics.rs
index 57747692..42dcf809 100644
--- a/azalea-physics/tests/physics.rs
+++ b/azalea-physics/tests/physics.rs
@@ -5,6 +5,7 @@ use azalea_block::{
     properties::WaterLevel,
 };
 use azalea_core::{
+    entity_id::MinecraftEntityId,
     position::{BlockPos, ChunkPos, Vec3},
     registry_holder::RegistryHolder,
     tick::GameTick,
@@ -15,7 +16,7 @@ use azalea_registry::{
     builtin::{BlockKind, EntityKind},
     identifier::Identifier,
 };
-use azalea_world::{Chunk, Instance, InstanceContainer, MinecraftEntityId, PartialInstance};
+use azalea_world::{Chunk, Instance, InstanceContainer, PartialInstance};
 use bevy_app::App;
 use parking_lot::RwLock;
 use uuid::Uuid;
diff --git a/azalea-protocol/Cargo.toml b/azalea-protocol/Cargo.toml
index 5a321120..59991274 100644
--- a/azalea-protocol/Cargo.toml
+++ b/azalea-protocol/Cargo.toml
@@ -17,14 +17,13 @@ azalea-block.workspace = true
 azalea-brigadier = { workspace = true, features = ["azalea-buf"] }
 azalea-buf.workspace = true
 azalea-chat = { workspace = true, features = ["numbers", "azalea-buf"] }
-azalea-core.workspace = true
+azalea-core = { workspace = true }
 azalea-crypto = { workspace = true, features = ["signing"] }
-azalea-entity.workspace = true
+azalea-entity = { workspace = true }
 azalea-inventory.workspace = true
 azalea-protocol-macros.workspace = true
 azalea-registry.workspace = true
-azalea-world.workspace = true
-bevy_ecs.workspace = true
+bevy_ecs = { workspace = true, optional = true }
 # byteorder.workspace = true
 flate2.workspace = true
 futures.workspace = true
@@ -47,6 +46,7 @@ reqwest = { workspace = true, optional = true, features = ["socks"] }
 default = ["online-mode"]
 connecting = []
 online-mode = ["azalea-auth/online-mode", "dep:reqwest"]
+bevy_ecs = ["dep:bevy_ecs", "azalea-entity/bevy_ecs", "azalea-core/bevy_ecs"]
 
 [lints]
 workspace = true
diff --git a/azalea-protocol/src/common/client_information.rs b/azalea-protocol/src/common/client_information.rs
index 68a9956a..189f1019 100644
--- a/azalea-protocol/src/common/client_information.rs
+++ b/azalea-protocol/src/common/client_information.rs
@@ -3,13 +3,13 @@ use std::io::{self, Cursor};
 use azalea_buf::{AzBuf, AzaleaRead, AzaleaWrite};
 use azalea_core::bitset::FixedBitSet;
 use azalea_entity::HumanoidArm;
-use bevy_ecs::component::Component;
 
-/// A component that contains some of the "settings" for this client that are
-/// sent to the server, such as render distance.
+/// Some of the "settings" for this client that are sent to the server,
+/// including render distance.
 ///
-/// This is only present on local players.
-#[derive(AzBuf, Clone, Component, Debug, Eq, PartialEq)]
+/// This should only be present on local players.
+#[cfg_attr(feature = "bevy_ecs", derive(bevy_ecs::component::Component))]
+#[derive(AzBuf, Clone, Debug, Eq, PartialEq)]
 pub struct ClientInformation {
     /// The locale of the client, formatted like "en_us".
     pub language: String,
diff --git a/azalea-protocol/src/packets/game/c_add_entity.rs b/azalea-protocol/src/packets/game/c_add_entity.rs
index 52a429d5..19f229ee 100644
--- a/azalea-protocol/src/packets/game/c_add_entity.rs
+++ b/azalea-protocol/src/packets/game/c_add_entity.rs
@@ -1,9 +1,9 @@
 use azalea_buf::AzBuf;
-use azalea_core::{delta::LpVec3, position::Vec3};
-use azalea_entity::{EntityBundle, metadata::apply_default_metadata};
+use azalea_core::{delta::LpVec3, entity_id::MinecraftEntityId, position::Vec3};
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_registry::{builtin::EntityKind, identifier::Identifier};
-use azalea_world::MinecraftEntityId;
+use azalea_registry::builtin::EntityKind;
+#[cfg(feature = "bevy_ecs")]
+use azalea_registry::identifier::Identifier;
 use uuid::Uuid;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
@@ -35,12 +35,14 @@ impl ClientboundAddEntity {
     ///
     /// You must apply the metadata after inserting the bundle with
     /// [`Self::apply_metadata`].
-    pub fn as_entity_bundle(&self, world_name: Identifier) -> EntityBundle {
-        EntityBundle::new(self.uuid, self.position, self.entity_type, world_name)
+    #[cfg(feature = "bevy_ecs")]
+    pub fn as_entity_bundle(&self, world_name: Identifier) -> azalea_entity::EntityBundle {
+        azalea_entity::EntityBundle::new(self.uuid, self.position, self.entity_type, world_name)
     }
 
     /// Apply the default metadata for the given entity.
+    #[cfg(feature = "bevy_ecs")]
     pub fn apply_metadata(&self, entity: &mut bevy_ecs::system::EntityCommands) {
-        apply_default_metadata(entity, self.entity_type);
+        azalea_entity::metadata::apply_default_metadata(entity, self.entity_type);
     }
 }
diff --git a/azalea-protocol/src/packets/game/c_animate.rs b/azalea-protocol/src/packets/game/c_animate.rs
index 112b990b..6f3b5a07 100644
--- a/azalea-protocol/src/packets/game/c_animate.rs
+++ b/azalea-protocol/src/packets/game/c_animate.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundAnimate {
diff --git a/azalea-protocol/src/packets/game/c_block_destruction.rs b/azalea-protocol/src/packets/game/c_block_destruction.rs
index e41e42b0..35503b75 100644
--- a/azalea-protocol/src/packets/game/c_block_destruction.rs
+++ b/azalea-protocol/src/packets/game/c_block_destruction.rs
@@ -1,7 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_core::position::BlockPos;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundBlockDestruction {
diff --git a/azalea-protocol/src/packets/game/c_damage_event.rs b/azalea-protocol/src/packets/game/c_damage_event.rs
index e296b3da..76ceb8ec 100644
--- a/azalea-protocol/src/packets/game/c_damage_event.rs
+++ b/azalea-protocol/src/packets/game/c_damage_event.rs
@@ -3,7 +3,7 @@ use std::io::{self, Cursor, Write};
 use azalea_buf::{AzBuf, AzaleaRead, AzaleaReadVar, AzaleaWrite, AzaleaWriteVar};
 use azalea_core::position::Vec3;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundDamageEvent {
diff --git a/azalea-protocol/src/packets/game/c_debug_entity_value.rs b/azalea-protocol/src/packets/game/c_debug_entity_value.rs
index 61706382..5dd4e32d 100644
--- a/azalea-protocol/src/packets/game/c_debug_entity_value.rs
+++ b/azalea-protocol/src/packets/game/c_debug_entity_value.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 use crate::common::debug_subscription::DebugSubscriptionUpdate;
 
diff --git a/azalea-protocol/src/packets/game/c_entity_event.rs b/azalea-protocol/src/packets/game/c_entity_event.rs
index cde6fd6c..5ca12e36 100644
--- a/azalea-protocol/src/packets/game/c_entity_event.rs
+++ b/azalea-protocol/src/packets/game/c_entity_event.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundEntityEvent {
diff --git a/azalea-protocol/src/packets/game/c_entity_position_sync.rs b/azalea-protocol/src/packets/game/c_entity_position_sync.rs
index b18248fc..5bbe33bc 100644
--- a/azalea-protocol/src/packets/game/c_entity_position_sync.rs
+++ b/azalea-protocol/src/packets/game/c_entity_position_sync.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 use crate::common::movements::PositionMoveRotation;
 
diff --git a/azalea-protocol/src/packets/game/c_hurt_animation.rs b/azalea-protocol/src/packets/game/c_hurt_animation.rs
index 698176e4..cd81b80b 100644
--- a/azalea-protocol/src/packets/game/c_hurt_animation.rs
+++ b/azalea-protocol/src/packets/game/c_hurt_animation.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundHurtAnimation {
diff --git a/azalea-protocol/src/packets/game/c_level_chunk_with_light.rs b/azalea-protocol/src/packets/game/c_level_chunk_with_light.rs
index 6519c4a4..00489513 100644
--- a/azalea-protocol/src/packets/game/c_level_chunk_with_light.rs
+++ b/azalea-protocol/src/packets/game/c_level_chunk_with_light.rs
@@ -1,9 +1,9 @@
 use std::sync::Arc;
 
 use azalea_buf::AzBuf;
+use azalea_core::heightmap_kind::HeightmapKind;
 use azalea_protocol_macros::ClientboundGamePacket;
 use azalea_registry::builtin::BlockEntityKind;
-use azalea_world::heightmap::HeightmapKind;
 use simdnbt::owned::Nbt;
 
 use super::c_light_update::ClientboundLightUpdatePacketData;
diff --git a/azalea-protocol/src/packets/game/c_login.rs b/azalea-protocol/src/packets/game/c_login.rs
index ce243a55..26aede88 100644
--- a/azalea-protocol/src/packets/game/c_login.rs
+++ b/azalea-protocol/src/packets/game/c_login.rs
@@ -1,7 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_registry::identifier::Identifier;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 use crate::packets::common::CommonPlayerSpawnInfo;
 
diff --git a/azalea-protocol/src/packets/game/c_mount_screen_open.rs b/azalea-protocol/src/packets/game/c_mount_screen_open.rs
index 78600250..fbc66f4c 100644
--- a/azalea-protocol/src/packets/game/c_mount_screen_open.rs
+++ b/azalea-protocol/src/packets/game/c_mount_screen_open.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundMountScreenOpen {
diff --git a/azalea-protocol/src/packets/game/c_move_entity_pos.rs b/azalea-protocol/src/packets/game/c_move_entity_pos.rs
index 3f4b005a..f01faaad 100644
--- a/azalea-protocol/src/packets/game/c_move_entity_pos.rs
+++ b/azalea-protocol/src/packets/game/c_move_entity_pos.rs
@@ -1,7 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_core::delta::PositionDelta8;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundMoveEntityPos {
diff --git a/azalea-protocol/src/packets/game/c_move_entity_pos_rot.rs b/azalea-protocol/src/packets/game/c_move_entity_pos_rot.rs
index 81f2a63a..047eb638 100644
--- a/azalea-protocol/src/packets/game/c_move_entity_pos_rot.rs
+++ b/azalea-protocol/src/packets/game/c_move_entity_pos_rot.rs
@@ -1,7 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_core::delta::PositionDelta8;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 /// This packet is sent by the server when an entity moves less then 8 blocks.
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
diff --git a/azalea-protocol/src/packets/game/c_move_entity_rot.rs b/azalea-protocol/src/packets/game/c_move_entity_rot.rs
index 6ccd44fe..4d0645b3 100644
--- a/azalea-protocol/src/packets/game/c_move_entity_rot.rs
+++ b/azalea-protocol/src/packets/game/c_move_entity_rot.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundMoveEntityRot {
diff --git a/azalea-protocol/src/packets/game/c_move_minecart_along_track.rs b/azalea-protocol/src/packets/game/c_move_minecart_along_track.rs
index 61cb5ba8..68b9f6f9 100644
--- a/azalea-protocol/src/packets/game/c_move_minecart_along_track.rs
+++ b/azalea-protocol/src/packets/game/c_move_minecart_along_track.rs
@@ -1,7 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_core::position::Vec3;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundMoveMinecartAlongTrack {
diff --git a/azalea-protocol/src/packets/game/c_player_combat_kill.rs b/azalea-protocol/src/packets/game/c_player_combat_kill.rs
index 3d2f7d7b..047e4c88 100644
--- a/azalea-protocol/src/packets/game/c_player_combat_kill.rs
+++ b/azalea-protocol/src/packets/game/c_player_combat_kill.rs
@@ -1,7 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_chat::FormattedText;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 /// Used to send a respawn screen.
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
diff --git a/azalea-protocol/src/packets/game/c_projectile_power.rs b/azalea-protocol/src/packets/game/c_projectile_power.rs
index eae4c885..c38ca50a 100644
--- a/azalea-protocol/src/packets/game/c_projectile_power.rs
+++ b/azalea-protocol/src/packets/game/c_projectile_power.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundProjectilePower {
diff --git a/azalea-protocol/src/packets/game/c_remove_entities.rs b/azalea-protocol/src/packets/game/c_remove_entities.rs
index 71749052..9e1d9c07 100644
--- a/azalea-protocol/src/packets/game/c_remove_entities.rs
+++ b/azalea-protocol/src/packets/game/c_remove_entities.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundRemoveEntities {
diff --git a/azalea-protocol/src/packets/game/c_remove_mob_effect.rs b/azalea-protocol/src/packets/game/c_remove_mob_effect.rs
index d5190e53..169ed863 100644
--- a/azalea-protocol/src/packets/game/c_remove_mob_effect.rs
+++ b/azalea-protocol/src/packets/game/c_remove_mob_effect.rs
@@ -1,7 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
 use azalea_registry::builtin::MobEffect;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundRemoveMobEffect {
diff --git a/azalea-protocol/src/packets/game/c_rotate_head.rs b/azalea-protocol/src/packets/game/c_rotate_head.rs
index 3ced78cb..e1f8ee30 100644
--- a/azalea-protocol/src/packets/game/c_rotate_head.rs
+++ b/azalea-protocol/src/packets/game/c_rotate_head.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundRotateHead {
diff --git a/azalea-protocol/src/packets/game/c_set_camera.rs b/azalea-protocol/src/packets/game/c_set_camera.rs
index f2b44f0b..c71a9535 100644
--- a/azalea-protocol/src/packets/game/c_set_camera.rs
+++ b/azalea-protocol/src/packets/game/c_set_camera.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundSetCamera {
diff --git a/azalea-protocol/src/packets/game/c_set_entity_data.rs b/azalea-protocol/src/packets/game/c_set_entity_data.rs
index 6e738f5f..d9effc37 100644
--- a/azalea-protocol/src/packets/game/c_set_entity_data.rs
+++ b/azalea-protocol/src/packets/game/c_set_entity_data.rs
@@ -1,7 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_entity::EntityMetadataItems;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundSetEntityData {
diff --git a/azalea-protocol/src/packets/game/c_set_entity_link.rs b/azalea-protocol/src/packets/game/c_set_entity_link.rs
index 127b09a3..88a128cd 100644
--- a/azalea-protocol/src/packets/game/c_set_entity_link.rs
+++ b/azalea-protocol/src/packets/game/c_set_entity_link.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundSetEntityLink {
diff --git a/azalea-protocol/src/packets/game/c_set_entity_motion.rs b/azalea-protocol/src/packets/game/c_set_entity_motion.rs
index f6219888..c55857c3 100644
--- a/azalea-protocol/src/packets/game/c_set_entity_motion.rs
+++ b/azalea-protocol/src/packets/game/c_set_entity_motion.rs
@@ -1,7 +1,7 @@
 use azalea_buf::AzBuf;
 use azalea_core::delta::LpVec3;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundSetEntityMotion {
diff --git a/azalea-protocol/src/packets/game/c_set_equipment.rs b/azalea-protocol/src/packets/game/c_set_equipment.rs
index d6b1c735..7d7ceac9 100644
--- a/azalea-protocol/src/packets/game/c_set_equipment.rs
+++ b/azalea-protocol/src/packets/game/c_set_equipment.rs
@@ -3,7 +3,7 @@ use std::io::{self, Cursor, Write};
 use azalea_buf::{AzBuf, AzaleaRead, AzaleaWrite, BufReadError};
 use azalea_inventory::{ItemStack, components::EquipmentSlot};
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundSetEquipment {
diff --git a/azalea-protocol/src/packets/game/c_set_passengers.rs b/azalea-protocol/src/packets/game/c_set_passengers.rs
index ade63267..b6aefb68 100644
--- a/azalea-protocol/src/packets/game/c_set_passengers.rs
+++ b/azalea-protocol/src/packets/game/c_set_passengers.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundSetPassengers {
diff --git a/azalea-protocol/src/packets/game/c_sound_entity.rs b/azalea-protocol/src/packets/game/c_sound_entity.rs
index 2b405201..8133ee20 100644
--- a/azalea-protocol/src/packets/game/c_sound_entity.rs
+++ b/azalea-protocol/src/packets/game/c_sound_entity.rs
@@ -2,7 +2,7 @@ use azalea_buf::AzBuf;
 use azalea_core::sound::CustomSound;
 use azalea_protocol_macros::ClientboundGamePacket;
 use azalea_registry::builtin::SoundEvent;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 use super::c_sound::SoundSource;
 
diff --git a/azalea-protocol/src/packets/game/c_take_item_entity.rs b/azalea-protocol/src/packets/game/c_take_item_entity.rs
index 0ab5e832..b46c8c3a 100644
--- a/azalea-protocol/src/packets/game/c_take_item_entity.rs
+++ b/azalea-protocol/src/packets/game/c_take_item_entity.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundTakeItemEntity {
diff --git a/azalea-protocol/src/packets/game/c_teleport_entity.rs b/azalea-protocol/src/packets/game/c_teleport_entity.rs
index b025338b..ee0e5302 100644
--- a/azalea-protocol/src/packets/game/c_teleport_entity.rs
+++ b/azalea-protocol/src/packets/game/c_teleport_entity.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ClientboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 use crate::common::movements::{PositionMoveRotation, RelativeMovements};
 
diff --git a/azalea-protocol/src/packets/game/c_update_attributes.rs b/azalea-protocol/src/packets/game/c_update_attributes.rs
index 8fb95c28..7c8e9e12 100644
--- a/azalea-protocol/src/packets/game/c_update_attributes.rs
+++ b/azalea-protocol/src/packets/game/c_update_attributes.rs
@@ -2,7 +2,7 @@ use azalea_buf::AzBuf;
 use azalea_inventory::components::AttributeModifier;
 use azalea_protocol_macros::ClientboundGamePacket;
 use azalea_registry::builtin::Attribute;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundUpdateAttributes {
diff --git a/azalea-protocol/src/packets/game/c_update_mob_effect.rs b/azalea-protocol/src/packets/game/c_update_mob_effect.rs
index df07fdfc..382c42bd 100644
--- a/azalea-protocol/src/packets/game/c_update_mob_effect.rs
+++ b/azalea-protocol/src/packets/game/c_update_mob_effect.rs
@@ -2,7 +2,7 @@ use azalea_buf::AzBuf;
 use azalea_entity::MobEffectData;
 use azalea_protocol_macros::ClientboundGamePacket;
 use azalea_registry::builtin::MobEffect;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, ClientboundGamePacket, Clone, Debug, PartialEq)]
 pub struct ClientboundUpdateMobEffect {
diff --git a/azalea-protocol/src/packets/game/s_entity_tag_query.rs b/azalea-protocol/src/packets/game/s_entity_tag_query.rs
index 00ef5c03..2ccec59e 100644
--- a/azalea-protocol/src/packets/game/s_entity_tag_query.rs
+++ b/azalea-protocol/src/packets/game/s_entity_tag_query.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ServerboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, Clone, Debug, PartialEq, ServerboundGamePacket)]
 pub struct ServerboundEntityTagQuery {
diff --git a/azalea-protocol/src/packets/game/s_interact.rs b/azalea-protocol/src/packets/game/s_interact.rs
index fc2cd11e..d368354f 100644
--- a/azalea-protocol/src/packets/game/s_interact.rs
+++ b/azalea-protocol/src/packets/game/s_interact.rs
@@ -3,7 +3,7 @@ use std::io::{self, 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 azalea_core::entity_id::MinecraftEntityId;
 
 use crate::packets::BufReadError;
 
diff --git a/azalea-protocol/src/packets/game/s_pick_item_from_entity.rs b/azalea-protocol/src/packets/game/s_pick_item_from_entity.rs
index a68e7ab7..e337f1da 100644
--- a/azalea-protocol/src/packets/game/s_pick_item_from_entity.rs
+++ b/azalea-protocol/src/packets/game/s_pick_item_from_entity.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ServerboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, Clone, Debug, PartialEq, ServerboundGamePacket)]
 pub struct ServerboundPickItemFromEntity {
diff --git a/azalea-protocol/src/packets/game/s_player_command.rs b/azalea-protocol/src/packets/game/s_player_command.rs
index 2e4e83df..533fde30 100644
--- a/azalea-protocol/src/packets/game/s_player_command.rs
+++ b/azalea-protocol/src/packets/game/s_player_command.rs
@@ -1,6 +1,6 @@
 use azalea_buf::AzBuf;
 use azalea_protocol_macros::ServerboundGamePacket;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 
 #[derive(AzBuf, Clone, Debug, PartialEq, ServerboundGamePacket)]
 pub struct ServerboundPlayerCommand {
diff --git a/azalea-world/Cargo.toml b/azalea-world/Cargo.toml
index 31e42a80..9e1a2729 100644
--- a/azalea-world/Cargo.toml
+++ b/azalea-world/Cargo.toml
@@ -13,7 +13,7 @@ criterion.workspace = true
 [dependencies]
 azalea-block.workspace = true
 azalea-buf.workspace = true
-azalea-core = { workspace = true, features = ["bevy_ecs"] }
+azalea-core = { workspace = true, features = ["serde", "bevy_ecs"] }
 azalea-registry.workspace = true
 bevy_ecs.workspace = true
 derive_more = { workspace = true, features = ["deref", "deref_mut"] }
diff --git a/azalea-world/src/chunk_storage.rs b/azalea-world/src/chunk_storage.rs
index 65dbbb7a..3f8c4e2d 100644
--- a/azalea-world/src/chunk_storage.rs
+++ b/azalea-world/src/chunk_storage.rs
@@ -12,18 +12,19 @@ use azalea_block::{
     fluid_state::FluidState,
 };
 use azalea_buf::{AzaleaRead, AzaleaWrite, BufReadError};
-use azalea_core::position::{
-    BlockPos, ChunkBiomePos, ChunkBlockPos, ChunkPos, ChunkSectionBiomePos, ChunkSectionBlockPos,
+use azalea_core::{
+    heightmap_kind::HeightmapKind,
+    position::{
+        BlockPos, ChunkBiomePos, ChunkBlockPos, ChunkPos, ChunkSectionBiomePos,
+        ChunkSectionBlockPos,
+    },
 };
 use azalea_registry::data::Biome;
 use nohash_hasher::IntMap;
 use parking_lot::RwLock;
 use tracing::{debug, trace, warn};
 
-use crate::{
-    heightmap::{Heightmap, HeightmapKind},
-    palette::PalettedContainer,
-};
+use crate::{heightmap::Heightmap, palette::PalettedContainer};
 
 const SECTION_HEIGHT: u32 = 16;
 
diff --git a/azalea-world/src/heightmap.rs b/azalea-world/src/heightmap.rs
index 033fa569..bae11cea 100644
--- a/azalea-world/src/heightmap.rs
+++ b/azalea-world/src/heightmap.rs
@@ -1,33 +1,20 @@
-use std::{
-    fmt::{self, Display},
-    str::FromStr,
-};
-
 use azalea_block::{BlockState, BlockTrait};
-use azalea_buf::AzBuf;
-use azalea_core::{math, position::ChunkBlockPos};
+use azalea_core::{heightmap_kind::HeightmapKind as HeightmapKind_, math, position::ChunkBlockPos};
 use azalea_registry::tags::blocks::LEAVES;
 use tracing::warn;
 
 use crate::{BitStorage, Section, chunk_storage::get_block_state_from_sections};
 
-// (wg stands for worldgen)
-
-#[derive(AzBuf, Clone, Copy, Debug, Eq, Hash, PartialEq)]
-pub enum HeightmapKind {
-    WorldSurfaceWg,
-    WorldSurface,
-    OceanFloorWg,
-    OceanFloor,
-    MotionBlocking,
-    MotionBlockingNoLeaves,
-}
+// TODO: when removing this deprecated marker, also rename `HeightmapKind_` back
+// to `HeightmapKind`.
+#[deprecated = "moved to `azalea_core::heightmap_kind::HeightmapKind`."]
+pub type HeightmapKind = azalea_core::heightmap_kind::HeightmapKind;
 
 #[derive(Clone, Debug)]
 pub struct Heightmap {
     pub data: BitStorage,
     pub min_y: i32,
-    pub kind: HeightmapKind,
+    pub kind: HeightmapKind_,
 }
 
 fn blocks_motion(block_state: BlockState) -> bool {
@@ -43,25 +30,24 @@ fn motion_blocking(block_state: BlockState) -> bool {
             .unwrap_or_default()
 }
 
-impl HeightmapKind {
-    pub fn is_opaque(self, block_state: BlockState) -> bool {
-        let block = Box::<dyn BlockTrait>::from(block_state);
-        let registry_block = block.as_registry_block();
-        match self {
-            HeightmapKind::WorldSurfaceWg => !block_state.is_air(),
-            HeightmapKind::WorldSurface => !block_state.is_air(),
-            HeightmapKind::OceanFloorWg => blocks_motion(block_state),
-            HeightmapKind::OceanFloor => blocks_motion(block_state),
-            HeightmapKind::MotionBlocking => motion_blocking(block_state),
-            HeightmapKind::MotionBlockingNoLeaves => {
-                motion_blocking(block_state) && !LEAVES.contains(&registry_block)
-            }
+pub fn is_heightmap_opaque(heightmap: HeightmapKind_, block_state: BlockState) -> bool {
+    let block = Box::<dyn BlockTrait>::from(block_state);
+    let registry_block = block.as_registry_block();
+    type K = HeightmapKind_;
+    match heightmap {
+        K::WorldSurfaceWg => !block_state.is_air(),
+        K::WorldSurface => !block_state.is_air(),
+        K::OceanFloorWg => blocks_motion(block_state),
+        K::OceanFloor => blocks_motion(block_state),
+        K::MotionBlocking => motion_blocking(block_state),
+        K::MotionBlockingNoLeaves => {
+            motion_blocking(block_state) && !LEAVES.contains(&registry_block)
         }
     }
 }
 
 impl Heightmap {
-    pub fn new(kind: HeightmapKind, dimension_height: u32, min_y: i32, data: Box<[u64]>) -> Self {
+    pub fn new(kind: HeightmapKind_, dimension_height: u32, min_y: i32, data: Box<[u64]>) -> Self {
         let bits = math::ceil_log2(dimension_height + 1);
         let mut bit_storage = BitStorage::new(bits as usize, 16 * 16, None)
             .expect("data is empty, so this can't fail");
@@ -113,7 +99,7 @@ impl Heightmap {
         if pos.y <= first_available_y - 2 {
             return false;
         }
-        if self.kind.is_opaque(block_state) {
+        if is_heightmap_opaque(self.kind, block_state) {
             // increase y
             if pos.y >= first_available_y {
                 self.set_height(pos.x, pos.z, pos.y + 1);
@@ -122,7 +108,8 @@ impl Heightmap {
         } else if first_available_y - 1 == pos.y {
             // decrease y
             for y in (self.min_y..pos.y).rev() {
-                if self.kind.is_opaque(
+                if is_heightmap_opaque(
+                    self.kind,
                     get_block_state_from_sections(
                         sections,
                         &ChunkBlockPos::new(pos.x, y, pos.z),
@@ -161,32 +148,3 @@ impl Heightmap {
         })
     }
 }
-
-impl FromStr for HeightmapKind {
-    type Err = ();
-
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        match s {
-            "WORLD_SURFACE_WG" => Ok(HeightmapKind::WorldSurfaceWg),
-            "WORLD_SURFACE" => Ok(HeightmapKind::WorldSurface),
-            "OCEAN_FLOOR_WG" => Ok(HeightmapKind::OceanFloorWg),
-            "OCEAN_FLOOR" => Ok(HeightmapKind::OceanFloor),
-            "MOTION_BLOCKING" => Ok(HeightmapKind::MotionBlocking),
-            "MOTION_BLOCKING_NO_LEAVES" => Ok(HeightmapKind::MotionBlockingNoLeaves),
-            _ => Err(()),
-        }
-    }
-}
-
-impl Display for HeightmapKind {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            HeightmapKind::WorldSurfaceWg => write!(f, "WORLD_SURFACE_WG"),
-            HeightmapKind::WorldSurface => write!(f, "WORLD_SURFACE"),
-            HeightmapKind::OceanFloorWg => write!(f, "OCEAN_FLOOR_WG"),
-            HeightmapKind::OceanFloor => write!(f, "OCEAN_FLOOR"),
-            HeightmapKind::MotionBlocking => write!(f, "MOTION_BLOCKING"),
-            HeightmapKind::MotionBlockingNoLeaves => write!(f, "MOTION_BLOCKING_NO_LEAVES"),
-        }
-    }
-}
diff --git a/azalea-world/src/world.rs b/azalea-world/src/world.rs
index 26856fff..a6ee1a63 100644
--- a/azalea-world/src/world.rs
+++ b/azalea-world/src/world.rs
@@ -1,22 +1,16 @@
 use std::{
     collections::{HashMap, HashSet},
-    fmt::{self, Debug, Display},
-    hash::{Hash, Hasher},
-    io::{self, Cursor},
+    fmt::{self, Debug},
 };
 
 use azalea_block::{BlockState, fluid_state::FluidState};
-use azalea_buf::{AzaleaRead, AzaleaReadVar, AzaleaWrite, AzaleaWriteVar, BufReadError};
 use azalea_core::{
     position::{BlockPos, ChunkPos},
     registry_holder::RegistryHolder,
 };
 use azalea_registry::data::Biome;
-use bevy_ecs::{component::Component, entity::Entity};
-use derive_more::{Deref, DerefMut};
+use bevy_ecs::entity::Entity;
 use nohash_hasher::IntMap;
-#[cfg(feature = "serde")]
-use serde::{Deserialize, Serialize};
 
 use crate::{ChunkStorage, PartialChunkStorage};
 
@@ -50,70 +44,8 @@ impl PartialInstance {
     }
 }
 
-/// An entity ID used by Minecraft.
-///
-/// These IDs are picked by the server. Some server software (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(Clone, Component, Copy, Debug, Default, Deref, DerefMut, Eq, PartialEq)]
-#[cfg_attr(feature = "serde", derive(Deserialize, Serialize))]
-pub struct MinecraftEntityId(pub i32);
-
-impl Hash for MinecraftEntityId {
-    fn hash<H: Hasher>(&self, hasher: &mut H) {
-        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) -> io::Result<()> {
-        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) -> io::Result<()> {
-        i32::azalea_write_var(&self.0, buf)
-    }
-}
-impl Display for MinecraftEntityId {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "eid({})", self.0)
-    }
-}
-impl From<i32> for MinecraftEntityId {
-    fn from(id: i32) -> Self {
-        Self(id)
-    }
-}
-impl From<u32> for MinecraftEntityId {
-    fn from(id: u32) -> Self {
-        Self(id as i32)
-    }
-}
+#[deprecated = "moved to `azalea_core::entity_id::MinecraftEntityId`."]
+pub type MinecraftEntityId = azalea_core::entity_id::MinecraftEntityId;
 
 /// Keep track of certain metadatas that are only relevant for this partial
 /// world.
@@ -129,7 +61,7 @@ pub struct PartialEntityInfos {
     ///
     /// This is used for shared worlds (i.e. swarms), to make sure we don't
     /// update entities twice on accident.
-    pub updates_received: IntMap<MinecraftEntityId, u32>,
+    pub updates_received: IntMap<azalea_core::entity_id::MinecraftEntityId, u32>,
     // ^ note: using MinecraftEntityId for entity ids is acceptable here since
     // there's no chance of collisions
 }
@@ -164,7 +96,7 @@ pub struct Instance {
     /// instead use `azalea_entity::EntityIdIndex`, since some servers may
     /// give different entity IDs for the same entities to different
     /// players.
-    pub entity_by_id: IntMap<MinecraftEntityId, Entity>,
+    pub entity_by_id: IntMap<azalea_core::entity_id::MinecraftEntityId, Entity>,
 
     pub registries: RegistryHolder,
 }
diff --git a/azalea/src/client_impl/mod.rs b/azalea/src/client_impl/mod.rs
index fd6506d0..f884898f 100644
--- a/azalea/src/client_impl/mod.rs
+++ b/azalea/src/client_impl/mod.rs
@@ -13,7 +13,10 @@ use azalea_client::{
     start_ecs_runner,
     tick_counter::TicksConnected,
 };
-use azalea_core::data_registry::{DataRegistryWithKey, ResolvableDataRegistry};
+use azalea_core::{
+    data_registry::{DataRegistryWithKey, ResolvableDataRegistry},
+    entity_id::MinecraftEntityId,
+};
 use azalea_entity::indexing::{EntityIdIndex, EntityUuidIndex};
 use azalea_protocol::{
     address::{ResolvableAddr, ResolvedAddr},
@@ -22,7 +25,7 @@ use azalea_protocol::{
     resolve::ResolveError,
 };
 use azalea_registry::{DataRegistryKeyRef, identifier::Identifier};
-use azalea_world::{Instance, InstanceName, MinecraftEntityId, PartialInstance};
+use azalea_world::{Instance, InstanceName, PartialInstance};
 use bevy_app::App;
 use bevy_ecs::{
     entity::Entity,
diff --git a/azalea/src/entity_ref/shared_impls.rs b/azalea/src/entity_ref/shared_impls.rs
index 5e2255c5..f6aa332e 100644
--- a/azalea/src/entity_ref/shared_impls.rs
+++ b/azalea/src/entity_ref/shared_impls.rs
@@ -1,8 +1,8 @@
-use azalea_core::position::Vec3;
+use azalea_core::{entity_id::MinecraftEntityId, position::Vec3};
 use azalea_entity::{
     Attributes, Dead, EntityUuid, Physics, Position, dimensions::EntityDimensions, metadata::Health,
 };
-use azalea_world::{InstanceName, MinecraftEntityId};
+use azalea_world::InstanceName;
 use uuid::Uuid;
 
 use super::EntityRef;
diff --git a/azalea/src/events.rs b/azalea/src/events.rs
index 0920dbd8..18d24773 100644
--- a/azalea/src/events.rs
+++ b/azalea/src/events.rs
@@ -4,10 +4,10 @@
 use std::sync::Arc;
 
 use azalea_chat::FormattedText;
-use azalea_core::{position::ChunkPos, tick::GameTick};
+use azalea_core::{entity_id::MinecraftEntityId, position::ChunkPos, tick::GameTick};
 use azalea_entity::{Dead, InLoadedChunk};
 use azalea_protocol::packets::game::c_player_combat_kill::ClientboundPlayerCombatKill;
-use azalea_world::{InstanceName, MinecraftEntityId};
+use azalea_world::InstanceName;
 use bevy_app::{App, Plugin, PreUpdate, Update};
 use bevy_ecs::prelude::*;
 use derive_more::{Deref, DerefMut};
diff --git a/azalea/src/nearest_entity.rs b/azalea/src/nearest_entity.rs
index 6e94e331..bf3f2fdb 100644
--- a/azalea/src/nearest_entity.rs
+++ b/azalea/src/nearest_entity.rs
@@ -1,5 +1,6 @@
+use azalea_core::entity_id::MinecraftEntityId;
 use azalea_entity::Position;
-use azalea_world::{InstanceName, MinecraftEntityId};
+use azalea_world::InstanceName;
 use bevy_ecs::{
     prelude::Entity,
     query::{QueryFilter, With},
diff --git a/azalea/src/pathfinder/simulation.rs b/azalea/src/pathfinder/simulation.rs
index 957cef37..ca5e4f36 100644
--- a/azalea/src/pathfinder/simulation.rs
+++ b/azalea/src/pathfinder/simulation.rs
@@ -6,13 +6,15 @@ use azalea_client::{
     PhysicsState, interact::BlockStatePredictionHandler, local_player::LocalGameMode,
     mining::MineBundle,
 };
-use azalea_core::{game_type::GameMode, position::Vec3, tick::GameTick};
+use azalea_core::{
+    entity_id::MinecraftEntityId, game_type::GameMode, position::Vec3, tick::GameTick,
+};
 use azalea_entity::{
     Attributes, LookDirection, Physics, Position, dimensions::EntityDimensions,
     inventory::Inventory,
 };
 use azalea_registry::{builtin::EntityKind, identifier::Identifier};
-use azalea_world::{ChunkStorage, Instance, InstanceContainer, MinecraftEntityId, PartialInstance};
+use azalea_world::{ChunkStorage, Instance, InstanceContainer, PartialInstance};
 use bevy_app::App;
 use bevy_ecs::prelude::*;
 use parking_lot::RwLock;
diff --git a/azalea/src/swarm/events.rs b/azalea/src/swarm/events.rs
index 107a676a..ee5859ca 100644
--- a/azalea/src/swarm/events.rs
+++ b/azalea/src/swarm/events.rs
@@ -1,5 +1,5 @@
 use azalea_client::local_player::InstanceHolder;
-use azalea_world::MinecraftEntityId;
+use azalea_core::entity_id::MinecraftEntityId;
 use bevy_app::{App, Plugin, Update};
 use bevy_ecs::prelude::*;
 use derive_more::{Deref, DerefMut};