feat(actpred): 新增 ONNX Runtime 推理后端 OnnxPredictor

维度从 ONNX session 元数据自动推导，预处理复现训练流水线；Pi 5 实测
12ms/次含预处理（纯推理 5.9ms），与 torch 前向差异 <1e-5。新增 6 个
单测（真实导出 ONNX 对齐验证），全量 71 测试通过。

actpred/onnx_infer.py

@@ -0,0 +1,175 @@
+"""actpred ONNX Runtime 推理封装 —— CPU 后端（Pi 5 实测 5.9ms/次，PyTorch 的 ~5 倍）
+
+接口对齐 predict.ActionPredictorInference：predict(images, action_history)。
+
+模型维度从 ONNX session 输入元数据动态推导（images: [1,F,3,S,S]，
+action_history: [1,H,D]），无需 checkpoint。
+图像预处理复现训练时的 dataset.py 流水线：Resize → /255 → ImageNet 归一化。
+
+背景见 docs/reports/actpred_inference_speed_benchmark_20260813.md。
+"""
+
+import argparse
+import json
+import os
+
+import numpy as np
+from PIL import Image
+
+IMAGENET_MEAN = np.array([0.485, 0.456, 0.406], dtype=np.float32)
+IMAGENET_STD = np.array([0.229, 0.224, 0.225], dtype=np.float32)
+
+
+def parse_action_history(s: str, action_dim: int) -> np.ndarray:
+    steps = s.split(":")
+    history = []
+    for step in steps:
+        values = [float(v) for v in step.split(",")]
+        if len(values) != action_dim:
+            raise ValueError(
+                f"Expected {action_dim} values per step, got {len(values)}")
+        history.append(values)
+    return np.array(history, dtype=np.float32)
+
+
+class OnnxPredictor:
+    """ONNX Runtime 动作预测推理器（CPU 后端）
+
+    用法：
+        with OnnxPredictor("model.onnx") as predictor:
+            action = predictor.predict(images, action_history)
+    """
+
+    def __init__(self, onnx_path: str, stats_path: str = None,
+                 providers=None):
+        import onnxruntime as ort
+
+        if providers is None:
+            providers = ["CPUExecutionProvider"]
+        ort.set_default_logger_severity(3)    # 抑制 GPU 探测等无害警告
+        opts = ort.SessionOptions()
+        opts.log_severity_level = 3
+        self._session = ort.InferenceSession(
+            str(onnx_path), sess_options=opts, providers=providers)
+
+        inputs = {i.name: [d if isinstance(d, int) else -1
+                           for d in i.shape] for i in self._session.get_inputs()}
+        img_shape, hist_shape = self._locate_inputs(inputs)
+        _, self.frame_len, _, self.image_size, _ = img_shape
+        _, self.history_len, self.action_dim = hist_shape
+        self._image_name = next(n for n, s in inputs.items() if len(s) == 5)
+        self._history_name = next(n for n, s in inputs.items() if len(s) == 3)
+
+        self._action_mean = None
+        self._action_std = None
+        if stats_path is not None:
+            if not os.path.exists(stats_path):
+                raise FileNotFoundError(f"统计文件不存在: {stats_path}")
+            stats = np.load(stats_path)
+            if stats.shape != (2, self.action_dim):
+                raise ValueError(
+                    f"action_stats.npy 形状应为 (2, {self.action_dim})，"
+                    f"实际为 {stats.shape}: {stats_path}")
+            self._action_mean = stats[0].astype(np.float32)
+            self._action_std = stats[1].astype(np.float32)
+
+    @staticmethod
+    def _locate_inputs(inputs):
+        """按维度数识别图像(5维)/动作历史(3维)输入，返回各自形状"""
+        img = [s for s in inputs.values() if len(s) == 5]
+        hist = [s for s in inputs.values() if len(s) == 3]
+        if len(img) != 1 or len(hist) != 1:
+            raise ValueError(
+                "ONNX 输入应为 1 个 5 维图像 + 1 个 3 维动作历史，"
+                f"实际: {inputs}")
+        if img[0][2] != 3 or img[0][3] != img[0][4]:
+            raise ValueError(
+                f"图像输入形状应为 [1,F,3,S,S]，实际为 {img[0]}")
+        return img[0], hist[0]
+
+    # ---------------- 生命周期 ----------------
+
+    def close(self):
+        self._session = None
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc, tb):
+        self.close()
+        return False
+
+    # ---------------- 推理 ----------------
+
+    def predict(self, images, action_history: np.ndarray) -> np.ndarray:
+        """images: 长度为 frame_len 的 RGB 图像列表（旧→新，末帧为当前帧）
+
+        返回 (action_dim,) float32 动作向量。
+        """
+        if self._session is None:
+            raise RuntimeError("predictor 已关闭")
+        if not isinstance(images, (list, tuple)):
+            images = [images]
+        if len(images) != self.frame_len:
+            raise ValueError(
+                f"images 应为 {self.frame_len} 帧，实际为 {len(images)} 帧。"
+                "冷启动时可重复传入同一帧。")
+        action_history = np.asarray(action_history, dtype=np.float32)
+        expected = (self.history_len, self.action_dim)
+        if action_history.shape != expected:
+            raise ValueError(
+                f"action_history 形状应为 {expected}，实际为 {action_history.shape}")
+
+        if self._action_mean is not None:
+            action_history = (action_history - self._action_mean) / self._action_std
+
+        frames = np.stack([self._preprocess(img) for img in images])
+        feeds = {
+            self._image_name: frames[np.newaxis],                 # (1,F,3,S,S)
+            self._history_name: action_history[np.newaxis],       # (1,H,D)
+        }
+        result = self._session.run(None, feeds)[0].reshape(-1).astype(np.float32)
+        if self._action_mean is not None:
+            result = result * self._action_std + self._action_mean
+        return result
+
+    def _preprocess(self, image) -> np.ndarray:
+        """Resize → /255 → ImageNet 归一化 → (3, S, S) float32"""
+        img = Image.fromarray(image) if isinstance(image, np.ndarray) else image
+        img = img.convert("RGB").resize(
+            (self.image_size, self.image_size), Image.BILINEAR)
+        x = np.asarray(img, dtype=np.float32) / 255.0     # HWC
+        x = x.transpose(2, 0, 1)                          # CHW
+        return (x - IMAGENET_MEAN[:, None, None]) / IMAGENET_STD[:, None, None]
+
+
+def main():
+    parser = argparse.ArgumentParser(description="actpred ONNX Runtime inference")
+    parser.add_argument("--model", required=True, help="ONNX 模型路径")
+    parser.add_argument("--images", required=True, nargs="+",
+                        help="按时间顺序（旧→新）传入 frame_len 个图像路径")
+    parser.add_argument("--action-history", required=True,
+                        help="冒号分隔各步，每步 action_dim 个值")
+    parser.add_argument("--stats", default=None,
+                        help="action_stats.npy 路径（训练时启用归一化才需要）")
+    parser.add_argument("--output-format", choices=["json", "raw"],
+                        default="json")
+    args = parser.parse_args()
+
+    with OnnxPredictor(args.model, stats_path=args.stats) as predictor:
+        if len(args.images) != predictor.frame_len:
+            raise SystemExit(
+                f"--images 需传入 {predictor.frame_len} 个路径（旧→新），"
+                f"实际为 {len(args.images)} 个")
+        images = [np.array(Image.open(p).convert("RGB")) for p in args.images]
+        history = parse_action_history(args.action_history, predictor.action_dim)
+        predicted = predictor.predict(images, history)
+
+    if args.output_format == "json":
+        print(json.dumps({"predicted_action": predicted.tolist()}, indent=2))
+    else:
+        print(" ".join(f"{v:.4f}" for v in predicted))
+
+
+if __name__ == "__main__":
+    main()