Validate training completion handoff

backend/tests/test_yolo_training_supervisor.py

@@ -33,5 +33,17 @@ def test_container_running_fails_closed_on_inspect_error(monkeypatch) -> None:
 def test_completion_command_requires_non_empty_string_list(tmp_path: Path) -> None:
     invalid = tmp_path / "command.json"
     invalid.write_text('{"shell": "unsafe"}', encoding="utf-8")
-    value = MODULE.json.loads(invalid.read_text(encoding="utf-8"))
-    assert not isinstance(value, list)
+    try:
+        MODULE.load_completion_command(invalid)
+    except ValueError as exc:
+        assert "non-empty JSON list" in str(exc)
+    else:
+        raise AssertionError("mapping-shaped completion command was accepted")
+
+
+def test_completion_command_preserves_exact_argv_without_shell_parsing(tmp_path: Path) -> None:
+    command = tmp_path / "command.json"
+    command.write_text('["docker", "exec", "-d", "geointel", "python", "loop.py"]', encoding="utf-8")
+    assert MODULE.load_completion_command(command) == [
+        "docker", "exec", "-d", "geointel", "python", "loop.py"
+    ]