fix(cli): reject null batch runtime fields

Reject explicit null video_aspect and video_concat_mode values during all-entry batch preflight so invalid later entries cannot fail after earlier tasks have started.

Author: lihuiyang1024

cli.py

@@ -933,6 +933,15 @@ def _validate_batch_task_params(
         raise ValueError(
             "video_source must be one of: pexels, pixabay, coverr, local"
         )
+    for field_name, value in (
+        ("video_aspect", params.video_aspect),
+        ("video_concat_mode", params.video_concat_mode),
+    ):
+        # These schema fields remain Optional for compatibility with historical
+        # API payloads, but the video pipeline always dereferences their enum
+        # values. A manifest's explicit null must fail before any batch task starts.
+        if value is None:
+            raise ValueError(f"{field_name} cannot be null")
     if params.video_source == "local" and stop_at == "terms":
         raise ValueError(
             "stop_at=terms has no effect with video_source=local"

test/services/test_cli.py

@@ -956,6 +956,36 @@ def test_batch_rejects_invalid_video_clip_speed_before_start(self):
         self.assertEqual(code, 2)
         start.assert_not_called()
 
+    def test_later_null_runtime_field_prevents_every_batch_task_from_starting(self):
+        for field_name in ("video_aspect", "video_concat_mode"):
+            with self.subTest(field_name=field_name), tempfile.TemporaryDirectory() as temp_dir:
+                manifest = Path(temp_dir) / "tasks.json"
+                manifest.write_text(
+                    json.dumps(
+                        [
+                            {"video_subject": "valid first task"},
+                            {
+                                "video_subject": "invalid later task",
+                                field_name: None,
+                            },
+                        ]
+                    ),
+                    encoding="utf-8",
+                )
+                with patch("app.services.task.start") as start:
+                    code = cli.run_cli(
+                        [
+                            "--batch-file",
+                            str(manifest),
+                            "--stop-at",
+                            "video",
+                            "--no-subtitle-enabled",
+                        ]
+                    )
+
+                self.assertEqual(code, 2)
+                start.assert_not_called()
+
     def test_batch_manifest_limits_size_and_task_count(self):
         with tempfile.TemporaryDirectory() as temp_dir:
             oversized = Path(temp_dir) / "oversized.jsonl"