fix: SRT 按 cue 解析并按 ID 回填译文，OCR 空帧分段与失败重试

tests/test_nodes.py

@@ -485,7 +485,7 @@ def test_llm_translate_lines_via_fake_api(monkeypatch) -> None:
                     "choices": [
                         {
                             "message": {
-                                "content": "译文一\n译文二\n译文三\n译文四\n译文五"
+                                "content": json.dumps([{"id": i, "text": text} for i, text in enumerate(["译文一", "译文二", "译文三", "译文四", "译文五"], 1)])
                             }
                         }
                     ]
@@ -548,7 +548,7 @@ def test_llm_translate_lines_default_timeout(monkeypatch) -> None:
 
     def fake_open(request, timeout):
         captured["timeout"] = timeout
-        return FakeUrlOpenResponse("译文一")
+        return FakeUrlOpenResponse('[{"id": 1, "text": "译文一"}]')
 
     monkeypatch.setattr("nodes.llm.urllib.request.urlopen", fake_open)
     monkeypatch.setenv("LLM_API_BASE", "http://fake/v1/chat/completions")
@@ -565,7 +565,7 @@ def test_llm_translate_lines_env_timeout(monkeypatch) -> None:
 
     def fake_open(request, timeout):
         captured["timeout"] = timeout
-        return FakeUrlOpenResponse("译文一")
+        return FakeUrlOpenResponse('[{"id": 1, "text": "译文一"}]')
 
     monkeypatch.setattr("nodes.llm.urllib.request.urlopen", fake_open)
     monkeypatch.setenv("LLM_API_BASE", "http://fake/v1/chat/completions")
@@ -598,8 +598,8 @@ def test_llm_invoke_success(tmp_path, monkeypatch) -> None:
     assert "译文1" in content
 
 
-def test_llm_invoke_pads_short_translation(tmp_path, monkeypatch) -> None:
-    """验证译文行数不足时用空行补齐，保持 SRT 结构完整。"""
+def test_llm_invoke_rejects_short_translation(tmp_path, monkeypatch) -> None:
+    """防御性校验：译文条数不足时失败，不用空行掩盖不完整结果。"""
     source = _make_srt(tmp_path, count=3)
     monkeypatch.setattr(
         "nodes.llm.translate_lines",
@@ -613,7 +613,7 @@ def test_llm_invoke_pads_short_translation(tmp_path, monkeypatch) -> None:
             output_dir=str(tmp_path / "out2"),
         )
     )
-    assert response.status == "completed"
+    assert response.status == "failed"
 
 
 def test_llm_invoke_missing_input(tmp_path) -> None: