From af6f37ff7ef15d8bbfffd9c38a2f9a7c795133f5 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sat, 21 Feb 2026 23:03:59 +0000
Subject: [PATCH 1/2] Initial plan


From 812fa19c7a076a17ea18a5bb5b5c622343b01c69 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sat, 21 Feb 2026 23:07:25 +0000
Subject: [PATCH 2/2] Add src/scripts/run_policy.py

Co-authored-by: Arcilios <190793348+Arcilios@users.noreply.github.com>
---
 src/scripts/run_policy.py | 65 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 src/scripts/run_policy.py

diff --git a/src/scripts/run_policy.py b/src/scripts/run_policy.py
new file mode 100644
index 00000000..03ec19ff
--- /dev/null
+++ b/src/scripts/run_policy.py
@@ -0,0 +1,65 @@
+"""Script to run a trained policy in simulation."""
+
+import argparse
+
+parser = argparse.ArgumentParser(description="Run a trained policy in MuJoCo or MJX simulation.")
+parser.add_argument("--run_dir", type=str, required=True, help="Run directory containing the trained policy.")
+parser.add_argument("--checkpoint", type=int, required=True, help="Checkpoint step to load.")
+parser.add_argument("--num_steps", type=int, default=1000, help="Number of steps to run the policy.")
+parser.add_argument("--save_video", action="store_true", default=False, help="Save a video of the rollout.")
+parser.add_argument("--output", type=str, default=None, help="Output path for the saved video (without extension).")
+
+args = parser.parse_args()
+
+import functools
+from brax.training.agents.ppo import networks as ppo_networks
+from etils import epath
+from omegaconf import OmegaConf
+from src.locomotion import get_env_class
+from src.robots.robot import Robot
+from src.tools.rollouts import get_rollout, save_rollout
+
+
+def main():
+    run_dir = epath.Path(args.run_dir).resolve()
+    policy_path = run_dir / "logs" / "checkpoints" / f"{args.checkpoint}" / "policy"
+    config_dir = str(run_dir / ".hydra" / "config.yaml")
+
+    try:
+        config = OmegaConf.load(config_dir)
+    except FileNotFoundError as e:
+        print(f"Error: Could not find required file: {e}")
+        print(f"Please check that the run_dir '{args.run_dir}' and checkpoint files exist.")
+        return
+
+    env_cfg = config.sim
+    agent_cfg = config.agent
+
+    EnvClass = get_env_class(config.env.name)
+    robot = Robot(config.robot.name)
+    env = EnvClass(
+        config.robot.name,
+        robot,
+        config.env.terrain,
+        env_cfg,
+    )
+
+    make_networks_factory = functools.partial(
+        ppo_networks.make_ppo_networks,
+        policy_hidden_layer_sizes=agent_cfg.policy_hidden_layer_sizes,
+        value_hidden_layer_sizes=agent_cfg.value_hidden_layer_sizes,
+    )
+
+    if args.save_video:
+        output_path = args.output if args.output else str(run_dir / f"rollout_{args.checkpoint}")
+        print(f"Running policy for {args.num_steps} steps and saving video to '{output_path}'...")
+        save_rollout(output_path, str(policy_path), env, make_networks_factory, args.num_steps)
+        print("Done.")
+    else:
+        print(f"Running policy for {args.num_steps} steps...")
+        rollout = get_rollout(str(policy_path), env, make_networks_factory, args.num_steps)
+        print(f"Rollout complete. Total frames: {len(rollout)}")
+
+
+if __name__ == "__main__":
+    main()