feat: 落沙替换改回固定目标版，移除记录器mixin

记录+回放方案会把沙子替换成自己（记录命中沙子自身变更），不可用。改为沙子下落直接变legacyFallingBlockTarget。移除LevelChunkMixin。

src/main/java/com/github/zly2006/carpetslsaddition/mixin/legacy/FallingBlockEntityMixin.java

@@ -2,18 +2,22 @@ package com.github.zly2006.carpetslsaddition.mixin.legacy;
 
 import com.github.zly2006.carpetslsaddition.SLSCarpetSettings;
 import com.github.zly2006.carpetslsaddition.ServerMain;
-import com.github.zly2006.carpetslsaddition.util.LegacyBlockChangeRecorder;
 import net.minecraft.core.BlockPos;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.Block;
 import net.minecraft.world.level.block.state.BlockState;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.ModifyVariable;
 
 /**
- * [旧版] 落沙替换的核心注入点——重建 1.12 的"替换窗口"（记录+回放版）。
+ * [旧版] 落沙替换——固定目标版。
  *
- * <p>当 {@code legacyFallingBlockReplace} 开启时，若该位置在最近 {@code WINDOW_TICKS} 内被改动过，
- * 就用记录的新方块作为下落实体的内容。这样玩家搭建的装置（改变世界方块）会决定下落实体的内容。
+ * <p>26.1.2 单线程下 1.12 的"替换窗口"物理不存在，本 mixin 采用直接方案：
+ * 当 {@code legacyFallingBlockReplace} 开启且配置了 {@code legacyFallingBlockTarget} 时，
+ * 把下落实体的方块状态替换为目标方块的默认状态——沙子下落即变目标方块。
  */
 @Mixin(net.minecraft.world.entity.item.FallingBlockEntity.class)
 public class FallingBlockEntityMixin {
@@ -24,17 +28,19 @@ public class FallingBlockEntityMixin {
             argsOnly = true,
             index = 2
     )
-    private static BlockState legacyReplaceFallingState(BlockState original, net.minecraft.world.level.Level level, BlockPos pos, BlockState state) {
+    private static BlockState legacyReplaceFallingState(BlockState original, Level level, BlockPos pos, BlockState state) {
         if (!SLSCarpetSettings.legacyExploitMode || !SLSCarpetSettings.legacyFallingBlockReplace) {
             return original;
         }
-        ServerMain.LOGGER.info("[SLSA-DEBUG] fall() pos={} original={}", pos, original.getBlock());
-        BlockState recent = LegacyBlockChangeRecorder.getRecentChange(pos);
-        if (recent != null && !recent.isAir()) {
-            ServerMain.LOGGER.info("[SLSA-DEBUG] >>> REPLACE at {}: {} -> {}", pos, original.getBlock(), recent.getBlock());
-            return recent;
+        String target = SLSCarpetSettings.legacyFallingBlockTarget;
+        if (target == null || target.isEmpty() || "#none".equals(target)) {
+            return original;
         }
-        ServerMain.LOGGER.info("[SLSA-DEBUG] no recent change at {}, recent={}", pos, recent);
-        return original;
+        Block block = BuiltInRegistries.BLOCK.getOptional(Identifier.withDefaultNamespace(target)).orElse(null);
+        if (block == null) {
+            return original;
+        }
+        ServerMain.LOGGER.info("[SLSA-DEBUG] >>> REPLACE at {}: {} -> {}", pos, original.getBlock(), block);
+        return block.defaultBlockState();
     }
 }

src/main/java/com/github/zly2006/carpetslsaddition/mixin/legacy/FallingBlockMixin.java

@@ -34,7 +34,6 @@ public abstract class FallingBlockMixin {
     @Inject(method = "getDelayAfterPlace", at = @At("HEAD"), cancellable = true)
     private void legacyDelayAfterPlace(CallbackInfoReturnable<Integer> cir) {
         if (SLSCarpetSettings.legacyExploitMode && SLSCarpetSettings.legacyInstantFall) {
-            com.github.zly2006.carpetslsaddition.ServerMain.LOGGER.info("[SLSA-DEBUG] getDelayAfterPlace called -> 0");
             cir.setReturnValue(0);
         }
     }
@@ -73,7 +72,6 @@ public abstract class FallingBlockMixin {
     @Inject(method = "tick", at = @At("HEAD"))
     private void legacyTick(BlockState state, ServerLevel level, BlockPos pos, RandomSource rand, CallbackInfo ci) {
         if (SLSCarpetSettings.legacyExploitMode && SLSCarpetSettings.legacyInstantFall) {
-            com.github.zly2006.carpetslsaddition.ServerMain.LOGGER.info("[SLSA-DEBUG] FallingBlock.tick pos={}", pos);
             LegacyExploitState.markInstantFall(pos);
         }
     }

src/main/java/com/github/zly2006/carpetslsaddition/mixin/legacy/LevelChunkMixin.java

@@ -1,35 +0,0 @@
-package com.github.zly2006.carpetslsaddition.mixin.legacy;
-
-import com.github.zly2006.carpetslsaddition.SLSCarpetSettings;
-import com.github.zly2006.carpetslsaddition.util.LegacyBlockChangeRecorder;
-import net.minecraft.core.BlockPos;
-import net.minecraft.world.level.block.state.BlockState;
-import net.minecraft.world.level.chunk.LevelChunk;
-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.CallbackInfoReturnable;
-
-/**
- * [旧版] 方块变更记录——为"替换窗口"提供数据源。
- *
- * <p>hook {@link LevelChunk#setBlockState}：当规则开启时，记录每次方块变更（位置 + 新状态 + 当前 tick）。
- * 重力方块下落时（{@code FallingBlockEntityMixin}）会查询此记录，
- * 若该位置"刚被改过"，就用记录的新方块作为下落实体内容——重建 1.12 的窗口替换效果。
- *
- * <p>仅在 {@code legacyExploitMode} + {@code legacyFallingBlockReplace} 同时开启时记录，避免性能损耗。
- */
-@Mixin(LevelChunk.class)
-public abstract class LevelChunkMixin {
-
-    @Inject(method = "setBlockState", at = @At("RETURN"))
-    private void legacyRecordBlockChange(BlockPos pos, BlockState newState, int flags, CallbackInfoReturnable<BlockState> cir) {
-        if (!SLSCarpetSettings.legacyExploitMode || !SLSCarpetSettings.legacyFallingBlockReplace) {
-            return;
-        }
-        if (newState == null) {
-            return;
-        }
-        LegacyBlockChangeRecorder.record(pos, newState);
-    }
-}

src/main/resources/slsaddition.mixins.json

@@ -20,7 +20,6 @@
     "legacy.FallingBlockEntityMixin",
     "legacy.ScheduledTickMixin",
     "legacy.ChunkMapMixin",
-    "legacy.LevelChunkMixin",
     "entity.MixinArmadilloEntity",
     "entity.MixinArmorStandEntity",
     "entity.MixinBoatEntity",