diff --git a/src/model/components.py b/src/model/components.py
index 1bb6173..b5b67bf 100644
--- a/src/model/components.py
+++ b/src/model/components.py
@@ -341,15 +341,37 @@ class CrossAttentionFusion(nn.Module):
 # 4. 专家混合层 (MoE Layer)
 # 对应 README: 20个专家 [1], 使用 components.py 中的 Expert 类
 # ------------------------------------------------------------------
+
+
+@torch.compiler.allow_in_graph
+def _sparse_moe_dispatch(x_flat, experts, topk_indices, topk_weights, num_experts):
+    output = torch.zeros_like(x_flat)
+    for e in range(num_experts):
+        mask = topk_indices == e
+        idx, k_idx = mask.nonzero(as_tuple=True)
+        if idx.numel() > 0:
+            w = topk_weights[idx, k_idx].unsqueeze(-1)
+            output.index_add_(0, idx, w * experts[e](x_flat[idx]))
+    return output
+
+
 class MoELayer(nn.Module):
-    def __init__(self, dim=512, num_experts=10, top_k=3, num_resblocks=8):
+    """
+    moe_mode 支持三种策略:
+      - "all": 计算全部专家，torch.compile 不断裂 (当前默认)
+      - "sparse": 只计算被路由到的专家 (产生 graph break)
+      - "sparse_allow_graph": 稀疏 MoE，通过 allow_in_graph 避免 graph break
+    """
+
+    def __init__(
+        self, dim=512, num_experts=10, top_k=3, num_resblocks=8, moe_mode="all"
+    ):
         super().__init__()
         self.num_experts = num_experts
         self.top_k = top_k
         self.dim = dim
+        self.moe_mode = moe_mode
 
-        # Import Expert from your existing components
-        # Assuming Expert class is defined as in components.py [2]
         self.experts = nn.ModuleList(
             [
                 Expert(
@@ -362,48 +384,41 @@ class MoELayer(nn.Module):
             ]
         )
 
-        # Gating Network [2]
         self.gate = nn.Linear(dim, num_experts)
 
     def forward(self, x):
-        """
-        并行化 MoE 前向传播，完全兼容 torch.compile 和 AMP。
-
-        Args:
-            x: [batch, seq_len, dim]
-        Returns:
-            out: [batch, seq_len, dim]
-        """
         B, L, D = x.shape
         num_tokens = B * L
+        x_flat = x.view(num_tokens, D)
 
-        # 展平输入以便处理
-        x_flat = x.view(num_tokens, D)  # [B*L, D]
+        gates = self.gate(x_flat)
+        topk_weights, topk_indices = torch.topk(gates, self.top_k, dim=-1)
+        topk_weights = F.softmax(topk_weights, dim=-1)
 
-        # 1. 计算门控分数
-        gates = self.gate(x_flat)  # [B*L, num_experts]
+        if self.moe_mode == "all":
+            expert_outputs = torch.stack(
+                [expert(x_flat) for expert in self.experts], dim=1
+            )
+            indices_expanded = topk_indices.unsqueeze(-1).expand(-1, -1, D)
+            selected_outputs = torch.gather(expert_outputs, 1, indices_expanded)
+            weighted_outputs = selected_outputs * topk_weights.unsqueeze(-1)
+            out_flat = weighted_outputs.sum(dim=1)
 
-        # 2. 选择 Top-K 专家
-        topk_weights, topk_indices = torch.topk(gates, self.top_k, dim=-1)  # [B*L, K]
+        elif self.moe_mode == "sparse":
+            out_flat = torch.zeros_like(x_flat)
+            for e in range(self.num_experts):
+                mask = topk_indices == e
+                idx, k_idx = mask.nonzero(as_tuple=True)
+                if idx.numel() > 0:
+                    w = topk_weights[idx, k_idx].unsqueeze(-1)
+                    out_flat.index_add_(0, idx, w * self.experts[e](x_flat[idx]))
 
-        # 归一化权重
-        topk_weights = F.softmax(topk_weights, dim=-1)  # [B*L, K]
+        elif self.moe_mode == "sparse_allow_graph":
+            out_flat = _sparse_moe_dispatch(
+                x_flat, self.experts, topk_indices, topk_weights, self.num_experts
+            )
 
-        # 3. 并行计算所有专家（消除 Python 循环中的动态控制流）
-        # torch.compile 会展开此列表推导式，因为 num_experts 是编译时常量
-        expert_outputs = torch.stack(
-            [expert(x_flat) for expert in self.experts], dim=1
-        )  # [B*L, num_experts, D]
+        else:
+            raise ValueError(f"Unknown moe_mode: {self.moe_mode}")
 
-        # 4. 使用 gather 选择对应专家的输出
-        # 扩展索引以匹配 expert_outputs 的维度 [B*L, num_experts, D]
-        indices_expanded = topk_indices.unsqueeze(-1).expand(-1, -1, D)  # [B*L, K, D]
-        selected_outputs = torch.gather(
-            expert_outputs, 1, indices_expanded
-        )  # [B*L, K, D]
-        # 5. 加权求和
-        weighted_outputs = selected_outputs * topk_weights.unsqueeze(-1)  # [B*L, K, D]
-        out_flat = weighted_outputs.sum(dim=1)  # [B*L, D]
-
-        # 恢复原始形状
         return out_flat.view(B, L, D)
diff --git a/src/model/inspect_preprocessed.py b/src/model/inspect_preprocessed.py
index 312cfe7..8c0cb5f 100644
--- a/src/model/inspect_preprocessed.py
+++ b/src/model/inspect_preprocessed.py
@@ -4,7 +4,8 @@
 
 功能：
 1. 统计 labels 的分布（出现次数、比例，最大/最小，未出现标签数）
-2. 随机抽样还原为人类可读文本，导出为 CSV 文件
+2. 统计 history_slot_ids 的有效长度分布
+3. 抽样还原为人类可读文本，导出为 CSV 文件
 
 用法：
     python -m model.inspect_preprocessed --data-dir /path/to/preprocessed/train
@@ -14,7 +15,6 @@
 import argparse
 import csv
 import json
-import random
 from collections import Counter
 from pathlib import Path
 
@@ -86,6 +86,36 @@ def analyze_labels(dataset: PreProcessedDataset, max_shards: int = 0):
     return counter, total
 
 
+def analyze_history_slots(dataset: PreProcessedDataset, max_shards: int = 0):
+    """统计 history_slot_ids 的有效长度分布（非零元素个数）"""
+    logger.info("正在统计 history_slot_ids 长度分布...")
+    counter = Counter()
+    total = 0
+
+    num_shards = dataset._num_shards if dataset._is_sharded else 1
+    effective_shards = min(num_shards, max_shards) if max_shards > 0 else num_shards
+
+    pbar = tqdm(range(effective_shards), desc="统计 history slots", unit="shard")
+
+    for shard_idx in pbar:
+        if dataset._is_sharded:
+            shard_data = dict(np.load(dataset.data_dir / f"shard_{shard_idx:06d}.npz"))
+            history_slots = shard_data["history_slot_ids"].astype(np.int64)
+        else:
+            history_slots = dataset.history_slot_ids[:].astype(np.int64)
+
+        lengths = np.count_nonzero(history_slots, axis=1)
+        unique, counts = np.unique(lengths, return_counts=True)
+        for uid, cnt in zip(unique, counts):
+            counter[int(uid)] += cnt
+        total += len(history_slots)
+
+        if dataset._is_sharded:
+            del shard_data
+
+    return counter, total
+
+
 def decode_sample(sample: dict, tokenizer, query_engine: QueryEngine) -> dict:
     """将一个样本还原为人类可读格式"""
     input_ids = (
@@ -139,6 +169,7 @@ def decode_sample(sample: dict, tokenizer, query_engine: QueryEngine) -> dict:
     pinyin_str = decode_pinyin_ids(pinyin_ids)
     label_info = query_engine.query_by_id(labels)
     history_str = decode_history(history_ids, query_engine)
+    history_slot_length = sum(1 for h in history_ids if h != 0)
 
     return {
         "context": context_text,
@@ -150,6 +181,7 @@ def decode_sample(sample: dict, tokenizer, query_engine: QueryEngine) -> dict:
         else f"<ID:{labels}>",
         "label_count": label_info.count if label_info else 0,
         "history": history_str,
+        "history_slot_length": history_slot_length,
         "full_tokens": token_text,
     }
 
@@ -168,7 +200,7 @@ def main():
         "--num-samples",
         type=int,
         default=50,
-        help="随机抽样的样本数量（默认50）",
+        help="抽样的样本数量（默认50，取前 N 个样本）",
     )
     parser.add_argument(
         "--output",
@@ -182,24 +214,14 @@ def main():
         default=0,
         help="统计 labels 时最多读取的分片数（0=全部）",
     )
-    parser.add_argument(
-        "--seed",
-        type=int,
-        default=42,
-        help="随机种子",
-    )
     parser.add_argument(
         "--top-k",
         type=int,
         default=30,
         help="显示出现次数最多和最少的标签数量",
     )
-
     args = parser.parse_args()
 
-    random.seed(args.seed)
-    np.random.seed(args.seed)
-
     if args.output is None:
         args.output = str(Path(args.data_dir) / "samples.csv")
 
@@ -332,13 +354,56 @@ def main():
         )
     console.print(table_dist)
 
-    # ====== 2. 随机抽样还原 → CSV ======
-    num_samples = min(args.num_samples, len(dataset))
-    console.print(
-        f"\n[bold yellow]====== 随机抽样还原 ({num_samples} 个样本) → {args.output} ======[/bold yellow]"
+    # ====== 2. 历史槽位长度分析 ======
+    console.print("\n[bold yellow]====== 历史槽位长度分析 ======[/bold yellow]")
+    history_counter, history_total = analyze_history_slots(
+        dataset, max_shards=args.max_shards
     )
 
-    indices = random.sample(range(len(dataset)), num_samples)
+    if not history_counter:
+        console.print("[yellow]  无历史槽位数据[/yellow]")
+    else:
+        sorted_items = sorted(history_counter.items())
+        lengths_arr = [l for l, _ in sorted_items]
+        counts_arr = [c for _, c in sorted_items]
+        weighted_sum = sum(l * c for l, c in zip(lengths_arr, counts_arr))
+        avg_length = weighted_sum / history_total if history_total > 0 else 0
+
+        cumsum = 0
+        median_length = 0
+        for length, count in sorted_items:
+            cumsum += count
+            if cumsum >= history_total / 2:
+                median_length = length
+                break
+
+        console.print(f"\n总样本数: {history_total:,}")
+        console.print(f"最大历史槽位数: {max(lengths_arr)}")
+        console.print(f"最小历史槽位数: {min(lengths_arr)}")
+        console.print(f"平均历史槽位数: {avg_length:.2f}")
+        console.print(f"中位数历史槽位数: {median_length}")
+
+        hist_table = Table(
+            title="历史槽位有效长度分布",
+            show_header=True,
+            header_style="bold magenta",
+        )
+        hist_table.add_column("槽位数", style="cyan", width=10)
+        hist_table.add_column("样本数", style="green", width=12)
+        hist_table.add_column("占比", style="yellow", width=10)
+
+        for length, count in sorted_items:
+            pct = count / history_total * 100
+            hist_table.add_row(str(length), f"{count:,}", f"{pct:.2f}%")
+        console.print(hist_table)
+
+    # ====== 3. 抽样还原 → CSV ======
+    num_samples = min(args.num_samples, len(dataset))
+    console.print(
+        f"\n[bold yellow]====== 抽样还原 ({num_samples} 个样本) → {args.output} ======[/bold yellow]"
+    )
+
+    indices = list(range(num_samples))
 
     csv_path = Path(args.output)
     csv_path.parent.mkdir(parents=True, exist_ok=True)
@@ -352,6 +417,7 @@ def main():
         "context",
         "suffix",
         "history",
+        "history_slot_length",
         "full_tokens",
     ]
 
@@ -372,6 +438,7 @@ def main():
                     decoded["context"],
                     decoded["suffix"],
                     decoded["history"],
+                    decoded["history_slot_length"],
                     decoded["full_tokens"],
                 ]
             )
diff --git a/src/model/merge_shards.py b/src/model/merge_shards.py
new file mode 100644
index 0000000..e6ed5de
--- /dev/null
+++ b/src/model/merge_shards.py
@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+"""将分片 .npz 合并为单个 .npz 文件，合并后删除原分片"""
+
+import argparse
+import gc
+import json
+from pathlib import Path
+
+import numpy as np
+from tqdm import tqdm
+
+FIELDS = [
+    "input_ids",
+    "token_type_ids",
+    "attention_mask",
+    "labels",
+    "history_slot_ids",
+    "pinyin_ids",
+]
+
+
+def merge_split(data_dir: Path, output_name: str = "shard_000000.npz"):
+    with open(data_dir / "metadata.json") as f:
+        meta = json.load(f)
+    num_shards = meta["num_shards"]
+    if num_shards <= 1:
+        print(f"{data_dir}: already single shard, skip")
+        return
+
+    merged = {}
+    for field in FIELDS:
+        pieces = []
+        for i in tqdm(
+            range(num_shards), desc=f"Merging {data_dir.name}/{field}", unit="shard"
+        ):
+            data = np.load(data_dir / f"shard_{i:06d}.npz")
+            pieces.append(data[field])
+            data.close()
+        merged[field] = np.concatenate(pieces, axis=0)
+        del pieces
+        gc.collect()
+
+    total = len(merged["labels"])
+    # 先删原分片（避免与新文件名冲突）
+    for i in range(num_shards):
+        (data_dir / f"shard_{i:06d}.npz").unlink()
+    # 再写合并文件
+    np.savez_compressed(data_dir / output_name, **merged)
+    del merged
+    gc.collect()
+
+    # 更新 metadata
+    meta["num_shards"] = 1
+    meta["shard_size"] = total
+    with open(data_dir / "metadata.json", "w", encoding="utf-8") as f:
+        json.dump(meta, f, indent=2, ensure_ascii=False)
+
+    print(f"{data_dir.name}: {num_shards} shards → 1 shard, {total:,} samples")
+
+
+def main():
+    parser = argparse.ArgumentParser(description="合并分片 .npz 为单个文件")
+    parser.add_argument(
+        "--input-dir", type=str, required=True, help="数据集目录（含 train/ 和 eval/）"
+    )
+    parser.add_argument(
+        "--output-name", type=str, default="shard_000000.npz", help="合并后文件名"
+    )
+    parser.add_argument(
+        "--train-only", action="store_true", help="仅合并 train，跳过 eval"
+    )
+
+    args = parser.parse_args()
+    root = Path(args.input_dir)
+
+    for split in ["train", "eval"]:
+        split_dir = root / split
+        if not split_dir.exists():
+            print(f"{split_dir}: not found, skip")
+            continue
+        if args.train_only and split == "eval":
+            continue
+        merge_split(split_dir, args.output_name)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/src/model/model.py b/src/model/model.py
index 6591170..a5ac2c4 100644
--- a/src/model/model.py
+++ b/src/model/model.py
@@ -35,12 +35,13 @@ class InputMethodEngine(nn.Module):
         vocab_size: int = 10019,
         pinyin_vocab_size: int = 28,
         dim: int = 512,
-        num_slots: int = 8,  # 历史槽位数量 (对应 README 中的 8 个槽位)
-        n_layers: int = 4,  # Transformer 层数
-        n_heads: int = 4,  # 注意力头数
-        num_experts: int = 10,  # MoE 专家数量
-        max_seq_len: int = 128,  # 最大上下文长度
-        compile: bool = False,  # 是否开启 torch.compile 优化
+        num_slots: int = 8,
+        n_layers: int = 4,
+        n_heads: int = 4,
+        num_experts: int = 10,
+        max_seq_len: int = 128,
+        compile: bool = False,
+        moe_mode: str = "all",  # "all" / "sparse" / "sparse_allow_graph"
     ):
         super().__init__()
         self.dim = dim
@@ -72,7 +73,13 @@ class InputMethodEngine(nn.Module):
         self.cross_attn = CrossAttentionFusion(dim=dim, n_heads=n_heads)
 
         # 4. 混合专家层 (MoE)
-        self.moe = MoELayer(dim=dim, num_experts=num_experts, top_k=3, num_resblocks=12)
+        self.moe = MoELayer(
+            dim=dim,
+            num_experts=num_experts,
+            top_k=3,
+            num_resblocks=12,
+            moe_mode=moe_mode,
+        )
 
         # 5. 槽位注意力池化
         self.slot_attention = nn.Linear(dim, 1)
diff --git a/src/model/subsample.py b/src/model/subsample.py
new file mode 100644
index 0000000..16e5829
--- /dev/null
+++ b/src/model/subsample.py
@@ -0,0 +1,429 @@
+#!/usr/bin/env python3
+"""
+子采样脚本：从预处理的 .npz 分片中抽取子集。
+
+策略：
+  1. 第1遍扫描：只读 labels 字段，统计每个 label ID 的样本数，记录分片大小
+  2. 中间计算：按每 ID 最多 N 个样本封顶（硬封顶），不足目标总量则从超额池补足
+  3. 第2遍扫描：读取全部字段，按精确保留配额抽取训练样本，同时抽取评估集
+
+用法：
+    python -m model.subsample \
+        --input-dir ./preprocessed \
+        --output-dir ./subsampled \
+        --cap-per-label 300000 \
+        --target-total 100000000 \
+        --num-eval 2560
+"""
+
+import argparse
+import gc
+import json
+from pathlib import Path
+from typing import Dict, List, Tuple
+
+import numpy as np
+from loguru import logger
+from rich.console import Console
+from tqdm import tqdm
+
+FIELDS = [
+    "input_ids",
+    "token_type_ids",
+    "attention_mask",
+    "labels",
+    "history_slot_ids",
+    "pinyin_ids",
+]
+
+
+def _global_to_shard(
+    positions: np.ndarray, shard_sizes: List[int]
+) -> Dict[int, List[int]]:
+    """将全局位置映射为 {shard_idx: [local_indices]}"""
+    cumsum = np.cumsum([0] + shard_sizes)
+    mapping: Dict[int, List[int]] = {}
+    for pos in positions:
+        shard_idx = int(np.searchsorted(cumsum, pos, side="right") - 1)
+        local_idx = pos - cumsum[shard_idx]
+        mapping.setdefault(shard_idx, []).append(local_idx)
+    return mapping
+
+
+def pass1_count(input_dir: Path, split: str) -> Tuple[Dict[int, int], List[int]]:
+    """
+    第1遍扫描：只读 labels，统计每个 label ID 的总样本数，记录各分片大小。
+    返回 (label_counts, shard_sizes)。
+    """
+    metadata_path = input_dir / split / "metadata.json"
+    with open(metadata_path) as f:
+        metadata = json.load(f)
+
+    num_shards = metadata["num_shards"]
+    label_counts: Dict[int, int] = {}
+    shard_sizes: List[int] = []
+
+    pbar = tqdm(total=num_shards, desc="Pass 1: counting labels", unit="shard")
+
+    for shard_idx in range(num_shards):
+        shard_path = input_dir / split / f"shard_{shard_idx:06d}.npz"
+        data = np.load(shard_path)
+        labels = data["labels"]
+        n = len(labels)
+        shard_sizes.append(n)
+
+        unique, counts = np.unique(labels, return_counts=True)
+        for uid, cnt in zip(unique, counts):
+            uid = int(uid)
+            label_counts[uid] = label_counts.get(uid, 0) + int(cnt)
+
+        data.close()
+        pbar.update(1)
+
+    pbar.close()
+    return label_counts, shard_sizes
+
+
+def compute_quotas(
+    label_counts: Dict[int, int],
+    cap: int = 300_000,
+    target_total: int = 100_000_000,
+) -> Dict[int, int]:
+    """
+    计算每个 label 的精确保留配额（硬封顶）。
+
+    策略：
+    - 每 ID 保留 min(count, cap)
+    - 若封顶后总量 >= target_total，直接用封顶策略
+    - 若封顶后总量 < target_total，从超额池（count > cap 的部分）等比抽取补足
+    """
+    capped_total = sum(min(cnt, cap) for cnt in label_counts.values())
+
+    if capped_total >= target_total:
+        return {label: min(cnt, cap) for label, cnt in label_counts.items()}
+
+    # 封顶不足，从超额池补足
+    deficit = target_total - capped_total
+    excess_per_label = {lbl: max(0, cnt - cap) for lbl, cnt in label_counts.items()}
+    excess_total = sum(excess_per_label.values())
+
+    quotas: Dict[int, int] = {}
+    if excess_total > 0:
+        ratio = min(1.0, deficit / excess_total)
+        for label, cnt in label_counts.items():
+            base = min(cnt, cap)
+            extra = int(excess_per_label[label] * ratio)
+            quotas[label] = base + extra
+    else:
+        quotas = {label: min(cnt, cap) for label, cnt in label_counts.items()}
+
+    return quotas
+
+
+def pass2_subsample(
+    input_dir: Path,
+    output_dir: Path,
+    split: str,
+    quotas: Dict[int, int],
+    eval_map: Dict[int, List[int]],
+    shard_sizes: List[int],
+    shard_size: int = 5_000_000,
+) -> Tuple[int, int]:
+    """
+    第2遍扫描：读取全部字段，抽取评估样本 + 按精确保留配额子采样训练样本。
+
+    quotas: {label_id: exact_number_to_keep}
+    返回 (train_kept, eval_kept)。
+    """
+    metadata_path = input_dir / split / "metadata.json"
+    with open(metadata_path) as f:
+        metadata = json.load(f)
+
+    num_shards = metadata["num_shards"]
+    max_seq_length = metadata["max_seq_length"]
+
+    output_train_dir = output_dir / "train"
+    output_eval_dir = output_dir / "eval"
+    output_train_dir.mkdir(parents=True, exist_ok=True)
+    output_eval_dir.mkdir(parents=True, exist_ok=True)
+
+    rng = np.random.RandomState()
+    remaining = dict(quotas)  # {label_id: remaining_to_keep}
+
+    train_buffers: Dict[str, List[np.ndarray]] = {f: [] for f in FIELDS}
+    train_buf_count = 0
+    train_shard_idx = 0
+    total_train_kept = 0
+
+    eval_buffers: Dict[str, List[np.ndarray]] = {f: [] for f in FIELDS}
+    total_eval_kept = 0
+
+    pbar = tqdm(total=num_shards, desc="Pass 2: subsampling", unit="shard")
+
+    for src_shard_idx in range(num_shards):
+        shard_path = input_dir / split / f"shard_{src_shard_idx:06d}.npz"
+        data = np.load(shard_path)
+        n = shard_sizes[src_shard_idx]
+
+        eval_local = np.array(eval_map.get(src_shard_idx, []), dtype=np.int64)
+
+        is_eval = np.zeros(n, dtype=bool)
+        if len(eval_local) > 0:
+            is_eval[eval_local] = True
+
+        # ── 第一步：只加载 labels，计算掩码 ──
+        labels = data["labels"]
+
+        # 抽取评估样本的 labels
+        if len(eval_local) > 0:
+            eval_buffers["labels"].append(labels[eval_local].copy())
+
+        # 计算训练保留位置
+        train_candidates = labels[~is_eval]
+        train_n = len(train_candidates)
+        n_kept = 0
+        keep_original_indices = np.array([], dtype=np.int64)
+
+        if train_n > 0:
+            sort_idx = np.argsort(train_candidates, kind="stable")
+            sorted_labels = train_candidates[sort_idx]
+            unique_vals, starts = np.unique(sorted_labels, return_index=True)
+            ends = np.append(starts[1:], train_n)
+
+            train_keep_mask = np.zeros(train_n, dtype=bool)
+            for i in range(len(unique_vals)):
+                label_val = int(unique_vals[i])
+                start, end = starts[i], ends[i]
+                cnt_in_shard = end - start
+                need = remaining.get(label_val, 0)
+                select = min(cnt_in_shard, need)
+                if select >= cnt_in_shard:
+                    train_keep_mask[sort_idx[start:end]] = True
+                elif select > 0:
+                    chosen = rng.choice(cnt_in_shard, size=select, replace=False)
+                    train_keep_mask[sort_idx[start + chosen]] = True
+                remaining[label_val] = max(0, remaining.get(label_val, 0) - select)
+
+            original_train_indices = np.where(~is_eval)[0]
+            keep_original_indices = original_train_indices[train_keep_mask]
+            n_kept = len(keep_original_indices)
+
+            # 释放标签相关的临时数组
+            del train_candidates, sort_idx, sorted_labels
+            del unique_vals, starts, ends, train_keep_mask
+            del original_train_indices
+            gc.collect()
+
+        del labels, is_eval
+        gc.collect()
+
+        # ── 第二步：逐字段加载，抽取评估 + 训练 ──
+        # 评估：跳过 labels（已在第一步抽取）
+        if len(eval_local) > 0:
+            for f in FIELDS:
+                if f == "labels":
+                    continue
+                arr = data[f]
+                eval_buffers[f].append(arr[eval_local].copy())
+                del arr
+                gc.collect()
+            total_eval_kept += len(eval_local)
+
+        # 训练：逐字段加载，立即删除
+        if n_kept > 0:
+            for f in FIELDS:
+                arr = data[f]
+                train_buffers[f].append(arr[keep_original_indices].copy())
+                del arr
+                gc.collect()
+            train_buf_count += n_kept
+            total_train_kept += n_kept
+
+        del keep_original_indices
+        data.close()
+        gc.collect()
+
+        if train_buf_count >= shard_size:
+            merged = {}
+            for f in FIELDS:
+                merged[f] = np.concatenate(train_buffers[f], axis=0)
+            np.savez_compressed(
+                output_train_dir / f"shard_{train_shard_idx:06d}.npz", **merged
+            )
+            logger.debug(
+                f"Saved train shard {train_shard_idx}: {train_buf_count} samples"
+            )
+            train_shard_idx += 1
+            train_buffers = {f: [] for f in FIELDS}
+            train_buf_count = 0
+            del merged
+            gc.collect()
+
+        pbar.update(1)
+
+    pbar.close()
+
+    # 剩余缓冲
+    if train_buf_count > 0:
+        merged = {}
+        for f in FIELDS:
+            merged[f] = np.concatenate(train_buffers[f], axis=0)
+        np.savez_compressed(
+            output_train_dir / f"shard_{train_shard_idx:06d}.npz", **merged
+        )
+        logger.debug(f"Saved train shard {train_shard_idx}: {train_buf_count} samples")
+        train_shard_idx += 1
+
+    # 评估数据
+    if total_eval_kept > 0:
+        eval_merged = {}
+        for f in FIELDS:
+            eval_merged[f] = np.concatenate(eval_buffers[f], axis=0)
+        np.savez_compressed(output_eval_dir / "shard_000000.npz", **eval_merged)
+    else:
+        logger.warning("No eval samples extracted!")
+
+    # 写 metadata
+    train_metadata = {
+        "num_samples": total_train_kept,
+        "max_seq_length": max_seq_length,
+        "dtype": "int16",
+        "fields": FIELDS,
+        "shard_size": shard_size,
+        "num_shards": train_shard_idx,
+    }
+    with open(output_train_dir / "metadata.json", "w", encoding="utf-8") as f:
+        json.dump(train_metadata, f, indent=2, ensure_ascii=False)
+
+    eval_metadata = {
+        "num_samples": total_eval_kept,
+        "max_seq_length": max_seq_length,
+        "dtype": "int16",
+        "fields": FIELDS,
+        "shard_size": total_eval_kept,
+        "num_shards": 1,
+    }
+    with open(output_eval_dir / "metadata.json", "w", encoding="utf-8") as f:
+        json.dump(eval_metadata, f, indent=2, ensure_ascii=False)
+
+    return total_train_kept, total_eval_kept
+
+
+def main():
+    console = Console()
+
+    parser = argparse.ArgumentParser(description="从预处理 .npz 分片中抽取子集")
+    parser.add_argument("--input-dir", type=str, required=True, help="输入预处理目录")
+    parser.add_argument("--output-dir", type=str, required=True, help="输出子采样目录")
+    parser.add_argument(
+        "--cap-per-label",
+        type=int,
+        default=300_000,
+        help="每个 label ID 最大保留样本数",
+    )
+    parser.add_argument(
+        "--target-total",
+        type=int,
+        default=100_000_000,
+        help="目标训练集样本总数",
+    )
+    parser.add_argument(
+        "--shard-size",
+        type=int,
+        default=5_000_000,
+        help="输出分片大小（样本数）",
+    )
+    parser.add_argument("--num-eval", type=int, default=2560, help="评估集样本数")
+
+    args = parser.parse_args()
+    input_dir = Path(args.input_dir)
+    output_dir = Path(args.output_dir)
+    output_dir.mkdir(parents=True, exist_ok=True)
+
+    console.print("[bold cyan]=== 子采样预处理数据 ===[/bold cyan]")
+    console.print(f"输入目录: {input_dir}")
+    console.print(f"输出目录: {output_dir}")
+    console.print(f"每 ID 封顶: {args.cap_per_label:,}")
+    console.print(f"目标训练集: {args.target_total:,}")
+    console.print(f"评估集: {args.num_eval}")
+    console.print()
+
+    # ── 第 1 遍：统计 ──
+    console.print("[bold]第 1 遍扫描：统计标签分布...[/bold]")
+    label_counts, shard_sizes = pass1_count(input_dir, "train")
+
+    total_samples = sum(shard_sizes)
+    num_labels = len(label_counts)
+    capped_total = sum(min(cnt, args.cap_per_label) for cnt in label_counts.values())
+
+    console.print(f"分片数: {len(shard_sizes)}")
+    console.print(f"总样本数: {total_samples:,}")
+    console.print(f"标签种类: {num_labels}")
+    console.print(f"封顶后样本数 (每ID≤{args.cap_per_label:,}): {capped_total:,}")
+    console.print()
+
+    # ── 计算保留配额 ──
+    quotas = compute_quotas(
+        label_counts,
+        cap=args.cap_per_label,
+        target_total=args.target_total,
+    )
+    expected_train = sum(quotas.values())
+    console.print(f"期望训练集大小: {expected_train:,}")
+
+    # 标签分布统计
+    stats_n_capped = sum(1 for cnt in label_counts.values() if cnt > args.cap_per_label)
+    stats_n_below = num_labels - stats_n_capped
+    stats_n_quota_full = sum(1 for lbl, q in quotas.items() if q >= args.cap_per_label)
+    console.print(
+        f"超过封顶的标签数: {stats_n_capped}, 不足封顶的标签数: {stats_n_below}, "
+        f"配额打满(≥{args.cap_per_label // 10000}万): {stats_n_quota_full}"
+    )
+    console.print()
+
+    # ── 抽取评估集位置 ──
+    rng = np.random.RandomState()
+    eval_positions = rng.choice(total_samples, size=args.num_eval, replace=False)
+    eval_positions.sort()
+    eval_map = _global_to_shard(eval_positions, shard_sizes)
+    console.print(f"评估集: {args.num_eval} 个位置已分配到 {len(eval_map)} 个分片中")
+    console.print()
+
+    # ── 第 2 遍：子采样 ──
+    console.print("[bold]第 2 遍扫描：子采样 + 抽取评估集...[/bold]")
+    train_count, eval_count = pass2_subsample(
+        input_dir,
+        output_dir,
+        "train",
+        quotas,
+        eval_map,
+        shard_sizes,
+        args.shard_size,
+    )
+
+    # ── 输出总结 ──
+    console.print()
+    console.print("[bold green]=== 完成 ===[/bold green]")
+    console.print(f"训练集: {train_count:,} 样本")
+    console.print(f"评估集: {eval_count:,} 样本")
+
+    for split in ["train", "eval"]:
+        sdir = output_dir / split
+        if sdir.exists():
+            total_size = sum(
+                f.stat().st_size for f in sdir.iterdir() if f.suffix == ".npz"
+            )
+            meta_path = sdir / "metadata.json"
+            if meta_path.exists():
+                with open(meta_path) as mf:
+                    meta = json.load(mf)
+            else:
+                meta = {}
+            console.print(
+                f"  {split}/: {total_size / (1024**3):.2f} GB, "
+                f"{meta.get('num_shards', '?')} shards"
+            )
+
+
+if __name__ == "__main__":
+    main()
diff --git a/src/model/trainer.py b/src/model/trainer.py
index 165c996..6f7f8b9 100644
--- a/src/model/trainer.py
+++ b/src/model/trainer.py
@@ -1157,6 +1157,11 @@ def train(
         "--compile/--no-compile",
         help="是否开启 torch.compile 优化（需 PyTorch 2.0+）",
     ),
+    moe_mode: str = typer.Option(
+        "all",
+        "--moe-mode",
+        help="MoE 计算策略: all（全量计算）, sparse（稀疏计算）, sparse_allow_graph（稀疏+allow_in_graph）",
+    ),
 ):
     """
     训练输入法模型
@@ -1211,6 +1216,7 @@ def train(
     config_table.add_row("模型", "MoE专家数", str(num_experts))
     config_table.add_row("模型", "使用拼音", str(use_pinyin))
     config_table.add_row("模型", "编译优化", str(compile))
+    config_table.add_row("模型", "MoE策略", moe_mode)
 
     config_table.add_row("训练", "训练轮数", str(num_epochs))
     config_table.add_row("训练", "学习率", f"{learning_rate:.2e}")
@@ -1331,6 +1337,7 @@ def train(
         "auto_resume": auto_resume,
         "max_iter_length": max_iter_length,
         "compile": compile,
+        "moe_mode": moe_mode,
         "is_train_preprocessed": is_train_preprocessed,
         "is_eval_preprocessed": is_eval_preprocessed,
         "total_steps": total_steps,
@@ -1353,6 +1360,7 @@ def train(
         num_experts=num_experts,
         max_seq_len=max_seq_len,
         compile=compile,
+        moe_mode=moe_mode,
     )
 
     console.print(