diff --git a/nets/__init__.py b/nets/__init__.py
new file mode 100644
index 0000000..926ff2a
--- /dev/null
+++ b/nets/__init__.py
@@ -0,0 +1,3 @@
+from .nn import YOLO, yolo_v11_l, yolo_v11_m, yolo_v11_s, yolo_v11_t, yolo_v11_x, yolo_v11_n
+
+__all__ = ["YOLO", "yolo_v11_l", "yolo_v11_m", "yolo_v11_s", "yolo_v11_t", "yolo_v11_x", "yolo_v11_n"]
diff --git a/utils/__init__.py b/utils/__init__.py
new file mode 100644
index 0000000..07a7db3
--- /dev/null
+++ b/utils/__init__.py
@@ -0,0 +1,3 @@
+from .dataset import *
+from .fed_util import *
+from .util import *
\ No newline at end of file
diff --git a/utils/fed_util.py b/utils/fed_util.py
index fea2bc5..d0715b2 100644
--- a/utils/fed_util.py
+++ b/utils/fed_util.py
@@ -1,10 +1,15 @@
 import os
 import re
 import random
+import matplotlib.pyplot as plt
+from utils.dataset import Dataset
+import numpy as np
+import torch
 from collections import defaultdict
 from typing import Dict, List, Optional, Set, Any
 
 from nets import nn
+from nets import YOLO
 
 
 def _image_to_label_path(img_path: str) -> str:
@@ -59,6 +64,14 @@ def _parse_yolo_label_file(label_path: str) -> Set[int]:
     return class_ids
 
 
+def _read_list_file(txt_path: str):
+    """Read one path per line; keep as-is (absolute or relative)."""
+    if not txt_path or not os.path.exists(txt_path):
+        return []
+    with open(txt_path, "r", encoding="utf-8") as f:
+        return [ln.strip() for ln in f if ln.strip()]
+
+
 def divide_trainset(
     trainset_path: str,
     num_local_class: int,
@@ -230,7 +243,7 @@ def divide_trainset(
     return result
 
 
-def init_model(model_name, num_classes):
+def init_model(model_name, num_classes) -> YOLO:
     """
     Initialize the model for a specific learning task
     Args:
@@ -252,3 +265,74 @@ def init_model(model_name, num_classes):
         raise ValueError("Model {} is not supported.".format(model_name))
 
     return model
+
+
+def build_valset_if_available(cfg, params, args=None) -> Optional[Dataset]:
+    """
+    Try to build a validation Dataset.
+    - If cfg['val_txt'] exists, use it.
+    - Else if <dataset_path>/val.txt exists, use it.
+    - Else return None (testing will be skipped).
+    Args:
+        cfg: config dict
+        params: params dict for Dataset
+    Returns:
+        Dataset or None
+    """
+    input_size = args.input_size if args and hasattr(args, "input_size") else 640
+    val_txt = cfg.get("val_txt", "")
+    if not val_txt:
+        ds_root = cfg.get("dataset_path", "")
+        guess = os.path.join(ds_root, "val.txt") if ds_root else ""
+        val_txt = guess if os.path.exists(guess) else ""
+
+    val_files = _read_list_file(val_txt)
+    if not val_files:
+        import warnings
+
+        warnings.warn("No validation dataset found.")
+        return None
+
+    return Dataset(
+        filenames=val_files,
+        input_size=input_size,
+        params=params,
+        augment=True,
+    )
+
+
+def seed_everything(seed: int):
+    np.random.seed(seed)
+    torch.manual_seed(seed)
+    random.seed(seed)
+
+
+def plot_curves(save_dir, hist, savename="fed_yolo_curves.png"):
+    """
+    Plot mAP50-95, mAP50, precision, recall, and (optional) summed train loss per round.
+    Args:
+        save_dir: directory to save the plot
+        hist: history dict with keys "mAP", "mAP50", "precision", "recall", "train_loss"
+        savename: output filename
+    """
+    os.makedirs(save_dir, exist_ok=True)
+    rounds = np.arange(1, len(hist["mAP"]) + 1)
+
+    plt.figure()
+    if hist["mAP"]:
+        plt.plot(rounds, hist["mAP"], label="mAP50-95")
+    if hist["mAP50"]:
+        plt.plot(rounds, hist["mAP50"], label="mAP50")
+    if hist["precision"]:
+        plt.plot(rounds, hist["precision"], label="precision")
+    if hist["recall"]:
+        plt.plot(rounds, hist["recall"], label="recall")
+    if hist["train_loss"]:
+        plt.plot(rounds, hist["train_loss"], label="train_loss (sum of components)")
+    plt.xlabel("Global Round")
+    plt.ylabel("Metric")
+    plt.title("Federated YOLO - Server Metrics")
+    plt.legend()
+    out_png = os.path.join(save_dir, savename)
+    plt.savefig(out_png, dpi=150, bbox_inches="tight")
+    print(f"[plot] saved: {out_png}")