improve packet_order test, add BlockUpdatePlugin, fix packet order for sprinting

9 files changed, 157 insertions, 39 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b0547f05..8e1c0931 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,17 +10,20 @@ is breaking anyways, semantic versioning is not followed.
 
 ### Added
 
-- Update to Minecraft 1.21.6.
 - `HitResult` now contains the entity that's being looked at.
+- A `QueuedServerBlockUpdates` component that keeps track of block updates per `Update`.
 
 ### Changed
 
+- Update to Minecraft 1.21.6.
 - Renamed `azalea_entity::EntityKind` to `EntityKindComponent` to disambiguate with `azalea_registry::EntityKind`.
 - Moved functions and types related to hit results from `azalea::interact` to `azalea::interact::pick`.
 - `Client::attack` now takes `Entity` instead of `MinecraftEntityId`.
 
 ### Fixed
 
+- Fix packet order for loading (`PlayerLoaded`/`MovePlayerPos`) and sprinting (`PlayerInput`/`PlayerCommand`).
+
 ## [0.13.0+mc1.21.5] - 2025-06-15
 
 ### Added
diff --git a/azalea-client/src/client.rs b/azalea-client/src/client.rs
index c9cc5259..9481ba2d 100644
--- a/azalea-client/src/client.rs
+++ b/azalea-client/src/client.rs
@@ -47,6 +47,7 @@ use uuid::Uuid;
 use crate::{
     Account, DefaultPlugins,
     attack::{self},
+    block_update::QueuedServerBlockUpdates,
     chunks::ChunkBatchInfo,
     connection::RawConnection,
     disconnect::DisconnectEvent,
@@ -586,7 +587,8 @@ pub struct JoinedClientBundle {
     pub physics_state: PhysicsState,
     pub inventory: Inventory,
     pub tab_list: TabList,
-    pub current_sequence_number: BlockStatePredictionHandler,
+    pub block_state_prediction_handler: BlockStatePredictionHandler,
+    pub queued_server_block_updates: QueuedServerBlockUpdates,
     pub last_sent_direction: LastSentLookDirection,
     pub abilities: PlayerAbilities,
     pub permission_level: PermissionLevel,
diff --git a/azalea-client/src/plugins/block_update.rs b/azalea-client/src/plugins/block_update.rs
new file mode 100644
index 00000000..15e885b6
--- /dev/null
+++ b/azalea-client/src/plugins/block_update.rs
@@ -0,0 +1,49 @@
+use azalea_block::BlockState;
+use azalea_core::position::BlockPos;
+use bevy_app::{App, Plugin, Update};
+use bevy_ecs::prelude::*;
+
+use crate::{
+    chunks::handle_receive_chunk_event, interact::BlockStatePredictionHandler,
+    local_player::InstanceHolder,
+};
+
+pub struct BlockUpdatePlugin;
+impl Plugin for BlockUpdatePlugin {
+    fn build(&self, app: &mut App) {
+        app.add_systems(
+            Update,
+            // has to be after ReceiveChunkEvent is handled so if we get chunk+blockupdate in one
+            // Update then the block update actually gets applied
+            handle_block_update_event.after(handle_receive_chunk_event),
+        );
+    }
+}
+
+/// A component that holds the list of block updates that need to be handled.
+///
+/// This is updated by `read_packets` (in `PreUpdate`) and handled/cleared by
+/// [`handle_block_update_event`] (`Update`).
+///
+/// This is a component instead of an ECS event for performance reasons.
+#[derive(Component, Debug, Clone, Default)]
+pub struct QueuedServerBlockUpdates {
+    pub list: Vec<(BlockPos, BlockState)>,
+}
+
+pub fn handle_block_update_event(
+    mut query: Query<(
+        &mut QueuedServerBlockUpdates,
+        &InstanceHolder,
+        &mut BlockStatePredictionHandler,
+    )>,
+) {
+    for (mut queued, instance_holder, mut prediction_handler) in query.iter_mut() {
+        let world = instance_holder.instance.read();
+        for (pos, block_state) in queued.list.drain(..) {
+            if !prediction_handler.update_known_server_state(pos, block_state) {
+                world.chunks.set_block_state(pos, block_state);
+            }
+        }
+    }
+}
diff --git a/azalea-client/src/plugins/chunks.rs b/azalea-client/src/plugins/chunks.rs
index 7a99c16c..a4e19f7f 100644
--- a/azalea-client/src/plugins/chunks.rs
+++ b/azalea-client/src/plugins/chunks.rs
@@ -28,7 +28,7 @@ impl Plugin for ChunksPlugin {
             Update,
             (
                 handle_chunk_batch_start_event,
-                handle_receive_chunk_events,
+                handle_receive_chunk_event,
                 handle_chunk_batch_finished_event,
             )
                 .chain()
@@ -65,7 +65,7 @@ pub struct ChunkBatchFinishedEvent {
     pub batch_size: u32,
 }
 
-pub fn handle_receive_chunk_events(
+pub fn handle_receive_chunk_event(
     mut events: EventReader<ReceiveChunkEvent>,
     mut query: Query<&InstanceHolder>,
 ) {
diff --git a/azalea-client/src/plugins/disconnect.rs b/azalea-client/src/plugins/disconnect.rs
index 8dddff09..80993476 100644
--- a/azalea-client/src/plugins/disconnect.rs
+++ b/azalea-client/src/plugins/disconnect.rs
@@ -56,6 +56,7 @@ pub struct DisconnectEvent {
 #[derive(Bundle)]
 pub struct RemoveOnDisconnectBundle {
     pub joined_client: JoinedClientBundle,
+
     pub entity: EntityBundle,
     pub minecraft_entity_id: MinecraftEntityId,
     pub instance_holder: InstanceHolder,
@@ -69,7 +70,7 @@ pub struct RemoveOnDisconnectBundle {
     pub chat_signing_session: chat_signing::ChatSigningSession,
     /// They're not authenticated anymore if they disconnected.
     pub is_authenticated: IsAuthenticated,
-    // send ServerboundPlayerLoaded next time we join
+    // send ServerboundPlayerLoaded next time we join.
     pub has_client_loaded: HasClientLoaded,
 }
 
diff --git a/azalea-client/src/plugins/mod.rs b/azalea-client/src/plugins/mod.rs
index 6f003b01..7c5cd3a3 100644
--- a/azalea-client/src/plugins/mod.rs
+++ b/azalea-client/src/plugins/mod.rs
@@ -2,6 +2,7 @@ use bevy_app::{PluginGroup, PluginGroupBuilder};
 
 pub mod attack;
 pub mod auto_reconnect;
+pub mod block_update;
 pub mod brand;
 pub mod chat;
 pub mod chat_signing;
@@ -48,6 +49,7 @@ impl PluginGroup for DefaultPlugins {
             .add(mining::MiningPlugin)
             .add(attack::AttackPlugin)
             .add(chunks::ChunksPlugin)
+            .add(block_update::BlockUpdatePlugin)
             .add(tick_end::TickEndPlugin)
             .add(loading::PlayerLoadedPlugin)
             .add(brand::BrandPlugin)
diff --git a/azalea-client/src/plugins/movement.rs b/azalea-client/src/plugins/movement.rs
index 5d43261f..e97d9ec1 100644
--- a/azalea-client/src/plugins/movement.rs
+++ b/azalea-client/src/plugins/movement.rs
@@ -65,8 +65,8 @@ impl Plugin for MovementPlugin {
                         .in_set(PhysicsSet)
                         .before(ai_step)
                         .before(azalea_physics::fluids::update_in_water_state_and_do_fluid_pushing),
-                    send_sprinting_if_needed.after(azalea_entity::update_in_loaded_chunk),
                     send_player_input_packet,
+                    send_sprinting_if_needed.after(azalea_entity::update_in_loaded_chunk),
                     send_position.after(PhysicsSet),
                 )
                     .chain(),
diff --git a/azalea-client/src/plugins/packet/game/mod.rs b/azalea-client/src/plugins/packet/game/mod.rs
index d9940937..fd6b712c 100644
--- a/azalea-client/src/plugins/packet/game/mod.rs
+++ b/azalea-client/src/plugins/packet/game/mod.rs
@@ -23,6 +23,7 @@ use tracing::{debug, error, trace, warn};
 
 use crate::{
     ClientInformation,
+    block_update::QueuedServerBlockUpdates,
     chat::{ChatPacket, ChatReceivedEvent},
     chunks,
     connection::RawConnection,
@@ -1058,17 +1059,10 @@ impl GamePacketHandler<'_> {
     pub fn block_update(&mut self, p: &ClientboundBlockUpdate) {
         debug!("Got block update packet {p:?}");
 
-        as_system::<Query<(&InstanceHolder, &mut BlockStatePredictionHandler)>>(
-            self.ecs,
-            |mut query| {
-                let (local_player, mut prediction_handler) = query.get_mut(self.player).unwrap();
-
-                let world = local_player.instance.read();
-                if !prediction_handler.update_known_server_state(p.pos, p.block_state) {
-                    world.chunks.set_block_state(p.pos, p.block_state);
-                }
-            },
-        );
+        as_system::<Query<&mut QueuedServerBlockUpdates>>(self.ecs, |mut query| {
+            let mut queued = query.get_mut(self.player).unwrap();
+            queued.list.push((p.pos, p.block_state));
+        });
     }
 
     pub fn animate(&mut self, p: &ClientboundAnimate) {
@@ -1078,19 +1072,13 @@ impl GamePacketHandler<'_> {
     pub fn section_blocks_update(&mut self, p: &ClientboundSectionBlocksUpdate) {
         debug!("Got section blocks update packet {p:?}");
 
-        as_system::<Query<(&InstanceHolder, &mut BlockStatePredictionHandler)>>(
-            self.ecs,
-            |mut query| {
-                let (local_player, mut prediction_handler) = query.get_mut(self.player).unwrap();
-                let world = local_player.instance.read();
-                for new_state in &p.states {
-                    let pos = p.section_pos + new_state.pos;
-                    if !prediction_handler.update_known_server_state(pos, new_state.state) {
-                        world.chunks.set_block_state(pos, new_state.state);
-                    }
-                }
-            },
-        );
+        as_system::<Query<&mut QueuedServerBlockUpdates>>(self.ecs, |mut query| {
+            let mut queued = query.get_mut(self.player).unwrap();
+            for new_state in &p.states {
+                let pos = p.section_pos + new_state.pos;
+                queued.list.push((pos, new_state.state));
+            }
+        });
     }
 
     pub fn game_event(&mut self, p: &ClientboundGameEvent) {
diff --git a/azalea-client/tests/packet_order.rs b/azalea-client/tests/packet_order.rs
index 1d3b29a2..d4dd2558 100644
--- a/azalea-client/tests/packet_order.rs
+++ b/azalea-client/tests/packet_order.rs
@@ -1,26 +1,32 @@
 use std::{collections::VecDeque, sync::Arc};
 
-use azalea_client::{packet::game::SendPacketEvent, test_utils::prelude::*};
+use azalea_client::{
+    SprintDirection, StartSprintEvent, packet::game::SendPacketEvent, test_utils::prelude::*,
+};
 use azalea_core::{
-    position::{ChunkPos, Vec3},
+    position::{BlockPos, ChunkPos, Vec3},
     resource_location::ResourceLocation,
 };
 use azalea_entity::LookDirection;
 use azalea_protocol::{
-    common::movements::{PositionMoveRotation, RelativeMovements},
+    common::movements::{MoveFlags, PositionMoveRotation, RelativeMovements},
     packets::{
         ConnectionProtocol,
         config::{ClientboundFinishConfiguration, ClientboundRegistryData},
-        game::{ClientboundPlayerPosition, ServerboundAcceptTeleportation, ServerboundGamePacket},
+        game::{
+            ClientboundBlockUpdate, ClientboundPlayerPosition, ServerboundAcceptTeleportation,
+            ServerboundGamePacket, ServerboundMovePlayerPos, ServerboundMovePlayerPosRot,
+            ServerboundMovePlayerStatusOnly,
+        },
     },
 };
-use azalea_registry::{DataRegistry, DimensionType};
+use azalea_registry::{Block, DataRegistry, DimensionType};
 use bevy_ecs::observer::Trigger;
 use parking_lot::Mutex;
 use simdnbt::owned::{NbtCompound, NbtTag};
 
 #[test]
-fn test_set_health_before_login() {
+fn test_packet_order() {
     init_tracing();
 
     let mut simulation = Simulation::new(ConnectionProtocol::Configuration);
@@ -53,16 +59,26 @@ fn test_set_health_before_login() {
 
     // receive a chunk so the player is "loaded" now
     simulation.receive_packet(make_basic_empty_chunk(ChunkPos::new(0, 0), (384 + 64) / 16));
+    simulation.receive_packet(ClientboundBlockUpdate {
+        pos: BlockPos::new(1, 1, 3),
+        block_state: Block::Stone.into(),
+    });
     simulation.receive_packet(ClientboundPlayerPosition {
         id: 1,
         change: PositionMoveRotation {
-            pos: Vec3::new(1., 2., 3.),
+            pos: Vec3::new(1.5, 2., 3.5),
             delta: Vec3::ZERO,
             look_direction: LookDirection::default(),
         },
         relative: RelativeMovements::all_absolute(),
     });
     simulation.tick();
+
+    assert_eq!(
+        simulation.get_block_state(BlockPos::new(1, 1, 3)),
+        Some(Block::Stone.into())
+    );
+
     println!("sent_packets: {:?}", sent_packets.list.lock());
     sent_packets.expect("AcceptTeleportation", |p| {
         matches!(
@@ -71,7 +87,16 @@ fn test_set_health_before_login() {
         )
     });
     sent_packets.expect("MovePlayerPosRot", |p| {
-        matches!(p, ServerboundGamePacket::MovePlayerPosRot(_))
+        matches!(
+            p,
+            ServerboundGamePacket::MovePlayerPosRot(ServerboundMovePlayerPosRot {
+                flags: MoveFlags {
+                    on_ground: false,
+                    horizontal_collision: false
+                },
+                ..
+            })
+        )
     });
 
     // in vanilla these might be sent in a later tick (depending on how long it
@@ -81,11 +106,59 @@ fn test_set_health_before_login() {
         matches!(p, ServerboundGamePacket::PlayerLoaded(_))
     });
     sent_packets.expect("MovePlayerPos", |p| {
-        matches!(p, ServerboundGamePacket::MovePlayerPos(_))
+        matches!(
+            p,
+            ServerboundGamePacket::MovePlayerPos(ServerboundMovePlayerPos {
+                flags: MoveFlags {
+                    on_ground: false,
+                    horizontal_collision: false
+                },
+                ..
+            })
+        )
     });
 
     sent_packets.expect_tick_end();
     sent_packets.expect_empty();
+
+    // it takes a tick for on_ground to be true
+    simulation.tick();
+    sent_packets.expect("MovePlayerStatusOnly", |p| {
+        matches!(
+            p,
+            ServerboundGamePacket::MovePlayerStatusOnly(ServerboundMovePlayerStatusOnly {
+                flags: MoveFlags {
+                    on_ground: true,
+                    horizontal_collision: false
+                }
+            })
+        )
+    });
+    sent_packets.expect_tick_end();
+    sent_packets.expect_empty();
+
+    // make sure nothing happens now
+    simulation.tick();
+    sent_packets.expect_tick_end();
+    sent_packets.expect_empty();
+
+    // now sprint for a tick
+    simulation.send_event(StartSprintEvent {
+        entity: simulation.entity,
+        direction: SprintDirection::Forward,
+    });
+    simulation.tick();
+    sent_packets.expect("PlayerInput", |p| {
+        matches!(p, ServerboundGamePacket::PlayerInput(_))
+    });
+    sent_packets.expect("PlayerCommand", |p| {
+        matches!(p, ServerboundGamePacket::PlayerCommand(_))
+    });
+    sent_packets.expect("MovePlayerPos", |p| {
+        matches!(p, ServerboundGamePacket::MovePlayerPos(_))
+    });
+    sent_packets.expect_tick_end();
+    sent_packets.expect_empty();
 }
 
 #[derive(Clone)]