diff --git a/loop.py b/loop.py
index 659bc3e..db783d8 100644
--- a/loop.py
+++ b/loop.py
@@ -84,6 +84,10 @@ def run_train() -> "tuple[float | None, float, str]":
     t0 = time.time()
     env = dict(os.environ)
     env["METRICS_OUT"] = str(METRICS_JSON.resolve())
+    # train.py is copied into the run dir, so sys.path[0] is that run dir — which
+    # has no scripts/. Put the project root (where loop.py + scripts/ live) on
+    # PYTHONPATH so train.py's `from scripts.var_breach import ...` resolves.
+    env["PYTHONPATH"] = str(Path(__file__).resolve().parent) + os.pathsep + env.get("PYTHONPATH", "")
     try:
         r = subprocess.run(
             [sys.executable, str(TRAIN_PY.resolve())],