fix(core): 脚本 agent 用通用字段解析,根治模型 schema 漂移致旁白/画面空

模型每次生成都换字段名(scene/screenDescription/画面…;dialogue 字符串 /
lines:[{role,content}] / caption…),逐一追变体是治标。改为通用解析:
- _pick_field:优先键命中 → 否则按关键词模糊匹配,跳过 bgMusic/note/shotNo 等非内容键
- 画面来源:visual/scene/screenDescription/画面… 任意命中
- 旁白来源:结构化 dialogue/lines 优先,其次整句 dialogue,再退 narration/voiceover/caption/字幕
实测覆盖 4 种真实/契约变体,全部正确填充;新增通用解析回归用例,23 测试通过。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/backend/apps/ai/tests.py

@@ -51,6 +51,25 @@ class NormalizeDraftTests(SimpleTestCase):
         self.assertIn("防晒泛白太尴尬", draft["segments"][0]["narration"])
         self.assertEqual(len(draft["segments"][0]["dialogue"]), 2)  # lines→结构化对白
 
+    def test_generic_resolver_covers_unseen_field_names(self):
+        """模型每次换字段名(scene/screenDescription/画面…、dialogue/lines/caption…)。
+        通用解析应「优先键 + 关键词模糊匹配」都能填,且跳过 bgMusic/note 等非内容键。"""
+        variants = {
+            "canonical": {"total_duration": 15, "segments": [{"role": "钩子", "narration": "口播A", "visual": "画面A"}]},
+            "scene+dialogue_str+subtitle": {"total_duration": 15, "shots": [{"scene": "画面B", "dialogue": "口播B", "subtitle": "字幕B"}]},
+            "scene+lines+caption": {"total_duration": 15, "shots": [{"scene": "画面C", "lines": [{"role": "女主", "content": "口播C"}], "caption": "字幕C"}]},
+            "screenDescription+dialogue+bgMusic+note": {"total_duration": 15, "shots": [{"screenDescription": "画面D", "dialogue": "口播D", "bgMusic": "音乐D", "note": "备注D"}]},
+        }
+        for name, raw in variants.items():
+            draft = normalize_draft(json.dumps(raw, ensure_ascii=False), aspect_ratio="9:16", total_duration=15)
+            seg = draft["segments"][0]
+            self.assertTrue(seg["narration"], f"{name}: 旁白为空")
+            self.assertTrue(seg["visual"], f"{name}: 画面为空")
+        # bgMusic/note 不得被误当画面/旁白
+        d = normalize_draft(json.dumps(variants["screenDescription+dialogue+bgMusic+note"], ensure_ascii=False), aspect_ratio="9:16", total_duration=15)
+        self.assertEqual(d["segments"][0]["visual"], "画面D")
+        self.assertEqual(d["segments"][0]["narration"], "口播D")
+
     def test_string_dialogue_not_iterated_as_chars(self):
         """dialogue 为整句字符串时,要当作旁白而不是逐字符遍历。"""
         raw = json.dumps({