diff --git a/.claude/skills/mechanical-refactor-verify/mechanical_refactor_verify_utils.py b/.claude/skills/mechanical-refactor-verify/mechanical_refactor_verify_utils.py
index 5896bcb870..af83a77a59 100644
--- a/.claude/skills/mechanical-refactor-verify/mechanical_refactor_verify_utils.py
+++ b/.claude/skills/mechanical-refactor-verify/mechanical_refactor_verify_utils.py
@@ -11,11 +11,11 @@
 from pathlib import Path
 
 
-def exec_command(cmd: str, cwd: str | None = None, check: bool = True) -> str:
-    print(f"  $ {cmd}", flush=True)
+def exec_command(cmd: list[str], cwd: str | None = None, check: bool = True) -> str:
+    print(f"  $ {' '.join(shlex.quote(c) for c in cmd)}", flush=True)
     result = subprocess.run(
         cmd,
-        shell=True,
+        shell=False,
         cwd=cwd,
         capture_output=True,
         text=True,
@@ -27,7 +27,8 @@ def exec_command(cmd: str, cwd: str | None = None, check: bool = True) -> str:
 
 
 def git_add_and_commit(message: str, cwd: str) -> None:
-    exec_command(f"git add -A && git commit -m {shlex.quote(message)}", cwd=cwd)
+    exec_command(["git", "add", "-A"], cwd=cwd)
+    exec_command(["git", "commit", "-m", message], cwd=cwd)
 
 
 def dedent(text: str, n: int) -> str:
@@ -41,14 +42,14 @@ def verify_mechanical_refactor(
     target_commit: str,
     transform: "Callable[[Path], None]",
 ) -> None:
-    repo_root = exec_command("git rev-parse --show-toplevel")
+    repo_root = exec_command(["git", "rev-parse", "--show-toplevel"])
     worktree_dir = tempfile.mkdtemp(prefix="verify-mechanical-")
     branch_name = f"verify-mechanical-{base_commit[:8]}"
 
     try:
         print(f"[1/4] Creating worktree at {base_commit[:8]}...")
         exec_command(
-            f"git worktree add -b {branch_name} {worktree_dir} {base_commit}",
+            ["git", "worktree", "add", "-b", branch_name, worktree_dir, base_commit],
             cwd=repo_root,
         )
 
@@ -56,13 +57,13 @@ def verify_mechanical_refactor(
         transform(Path(worktree_dir))
 
         print("[3/4] Running pre-commit...")
-        exec_command("pre-commit run --all-files", cwd=worktree_dir, check=False)
-        if exec_command("git status --porcelain", cwd=worktree_dir):
+        exec_command(["pre-commit", "run", "--all-files"], cwd=worktree_dir, check=False)
+        if exec_command(["git", "status", "--porcelain"], cwd=worktree_dir):
             git_add_and_commit("pre-commit fixes", cwd=worktree_dir)
 
         print(f"[4/4] Diffing against {target_commit[:8]}...")
         diff = exec_command(
-            f"git diff {target_commit} -- .",
+            ["git", "diff", target_commit, "--", "."],
             cwd=worktree_dir,
             check=False,
         )
diff --git a/miles/backends/training_utils/ci_utils.py b/miles/backends/training_utils/ci_utils.py
index 42626c28a0..a9a3a0f65f 100644
--- a/miles/backends/training_utils/ci_utils.py
+++ b/miles/backends/training_utils/ci_utils.py
@@ -50,7 +50,7 @@ def check_grad_norm(
             rollout_id=rollout_id,
             step_id=step_id,
         )
-        expected_grad_norm = torch.load(ci_load_grad_norm_path, weights_only=False)
+        expected_grad_norm = torch.load(ci_load_grad_norm_path, weights_only=True)
         assert math.isclose(
             grad_norm,
             expected_grad_norm,