Capture chunk-loaded sign data

src/client/java/com/example/signleakshield/mixin/ClientPlayNetworkHandlerChunkDataMixin.java

@@ -0,0 +1,32 @@
+package com.example.signleakshield.mixin;
+
+import com.example.signleakshield.ExploitState;
+import com.example.signleakshield.SignTextExtractor;
+import net.minecraft.block.entity.BlockEntityType;
+import net.minecraft.client.network.ClientPlayNetworkHandler;
+import net.minecraft.network.packet.s2c.play.ChunkDataS2CPacket;
+import net.minecraft.nbt.NbtCompound;
+import net.minecraft.util.math.BlockPos;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(ClientPlayNetworkHandler.class)
+public abstract class ClientPlayNetworkHandlerChunkDataMixin {
+    @Inject(method = "onChunkData", at = @At("HEAD"))
+    private void signleakshield$captureChunkData(ChunkDataS2CPacket packet, CallbackInfo ci) {
+        packet.getChunkData().getBlockEntities(packet.getChunkX(), packet.getChunkZ()).accept((localPos, type, nbt) -> {
+            if (nbt == null) {
+                return;
+            }
+
+            if (type != BlockEntityType.SIGN && type != BlockEntityType.HANGING_SIGN) {
+                return;
+            }
+
+            BlockPos pos = localPos.toImmutable();
+            ExploitState.SIGNS.put(pos, SignTextExtractor.fromNbt((NbtCompound) nbt));
+        });
+    }
+}

src/main/resources/signleakshield.mixins.json

@@ -4,6 +4,7 @@
   "compatibilityLevel": "JAVA_21",
   "client": [
     "ClientConnectionMixin",
+    "ClientPlayNetworkHandlerChunkDataMixin",
     "ClientPlayNetworkHandlerBlockEntityUpdateMixin",
     "ClientPlayNetworkHandlerSignEditorOpenMixin"
   ],