From af3affb467c01ee2880fbbc366ea0420c0580ab8 Mon Sep 17 00:00:00 2001
From: mat <git@matdoes.dev>
Date: Tue, 6 May 2025 09:28:28 -1030
Subject: fix chunk errors when joining a world with a same name but different
 height

---
 azalea-client/src/local_player.rs            | 14 ++++++++++++++
 azalea-client/src/plugins/packet/game/mod.rs |  7 +++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

(limited to 'azalea-client/src')

diff --git a/azalea-client/src/local_player.rs b/azalea-client/src/local_player.rs
index 455cc470..bf1609ab 100644
--- a/azalea-client/src/local_player.rs
+++ b/azalea-client/src/local_player.rs
@@ -144,6 +144,20 @@ impl InstanceHolder {
             ))),
         }
     }
+
+    /// Reset the `Instance` to a new reference to an empty instance, but with
+    /// the same registries as the current one.
+    ///
+    /// This is used by Azalea when entering the config state.
+    pub fn reset(&mut self) {
+        let registries = self.instance.read().registries.clone();
+
+        let mut new_instance = Instance::default();
+        new_instance.registries = registries;
+        self.instance = Arc::new(RwLock::new(new_instance));
+
+        self.partial_instance.write().reset();
+    }
 }
 
 #[derive(Error, Debug)]
diff --git a/azalea-client/src/plugins/packet/game/mod.rs b/azalea-client/src/plugins/packet/game/mod.rs
index 71766f8b..b301973f 100644
--- a/azalea-client/src/plugins/packet/game/mod.rs
+++ b/azalea-client/src/plugins/packet/game/mod.rs
@@ -1496,10 +1496,11 @@ impl GamePacketHandler<'_> {
     pub fn start_configuration(&mut self, _p: &ClientboundStartConfiguration) {
         debug!("Got start configuration packet");
 
-        as_system::<(Commands, Query<&mut RawConnection>)>(
+        as_system::<(Commands, Query<(&mut RawConnection, &mut InstanceHolder)>)>(
             self.ecs,
             |(mut commands, mut query)| {
-                let Some(mut raw_conn) = query.get_mut(self.player).ok() else {
+                let Some((mut raw_conn, mut instance_holder)) = query.get_mut(self.player).ok()
+                else {
                     warn!("Got start configuration packet but player doesn't have a RawConnection");
                     return;
                 };
@@ -1515,6 +1516,8 @@ impl GamePacketHandler<'_> {
                     .insert(crate::client::InConfigState)
                     .remove::<crate::JoinedClientBundle>()
                     .remove::<EntityBundle>();
+
+                instance_holder.reset();
             },
         );
     }
-- 
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