fix(backend): #1901 统一title字段名修复标题渲染不一致

问题：plan.config中标题配置字段名双轨不一致——Worker sync_configs_to_plan 写 plan.config['title']（归一化 size/font/color），API writeback_edit_plan_config 写 plan.config['title_config']（不归一化），三个渲染引擎读取不一致：
- video_compose_service（FFmpeg drawtext）：已读 title+fallback title_config ✅
- unified_render_service（ASS字幕）：只 title 无 fallback ❌
- subtitle_render_engine（字幕渲染）：只读 title_config ❌

修复：
- packages/application/generation_common.py writeback_edit_plan_config：统一写 plan.config['title']（而非 title_config），并做字段名归一化 font_size→size/font_preset→font/font_color→color，与 Worker sync_configs_to_plan 行为一致
- apps/worker/video_processing/subtitle_render_engine.py：_resolve_title_config 先读 plan.config['title']，fallback plan.config['title_config']（兼容存量老数据）
- apps/worker/video_processing/unified_render_service.py：同样先读 'title'，text 为空时 fallback 'title_config'
- apps/api/app/api/routes/generation_cover.py：封面E2标题配置读取加 title_config fallback
- 单测适配：test_generation_common.py/test_writeback_edit_plan_config.py 断言改 'title' 并验证归一化
- 所有渲染路径（智能剪辑/AI数字人/封面E2）统一读 'title'，老数据通过 fallback 继续渲染

apps/api/app/api/routes/generation_cover.py

@@ -766,7 +766,12 @@ def generate_cover(
             storage_svc = get_shared_storage_service()
             mk_client = get_mediakit_client()
             # 从 plan.config 读取完整标题样式，E2 从源素材抽帧时叠加（源素材本身无标题）
+            # #1901 统一读 "title"，兼容老数据 "title_config"
             _e2_title_cfg = (plan.config or {}).get("title", {}) or {}
+            if not isinstance(_e2_title_cfg, dict) or not (_e2_title_cfg.get("text") or "").strip():
+                _alt = (plan.config or {}).get("title_config", {}) or {}
+                if isinstance(_alt, dict):
+                    _e2_title_cfg = _alt
             if not isinstance(_e2_title_cfg, dict):
                 _e2_title_cfg = {}
             _e2_title_text = (_e2_title_cfg.get("text", "") or "").strip() if _e2_title_cfg.get("enabled", True) else ""

apps/api/app/services/generation_common.py

@@ -82,8 +82,12 @@ def writeback_edit_plan_config(
         merged["generation_task_id"] = task_id
 
         if title_config:
-            old_title_config = merged.get("title_config", {}) or {}
-            old_title_text = (old_title_config.get("text") or "").strip()
+            # #1901 统一字段名为 "title"（worker sync_configs_to_plan 写的是 "title"）
+            # 先读取新旧两个 key，判断标题文字是否变化
+            old_title_cfg = merged.get("title", {}) or {}
+            if not isinstance(old_title_cfg, dict) or not (old_title_cfg.get("text") or "").strip():
+                old_title_cfg = merged.get("title_config", {}) or {}
+            old_title_text = (old_title_cfg.get("text") or "").strip() if isinstance(old_title_cfg, dict) else ""
             new_title_text = (title_config.get("text") or "").strip()
             if old_title_text != new_title_text:
                 if "cover" in merged:
@@ -94,7 +98,17 @@ def writeback_edit_plan_config(
                         old_title_text,
                         new_title_text,
                     )
-            merged["title_config"] = title_config
+            # 字段名归一化（font_size→size, font_preset→font, font_color→color），与 worker sync_configs_to_plan 保持一致
+            normalized = dict(title_config)
+            if "font_size" in normalized and "size" not in normalized:
+                normalized["size"] = normalized["font_size"]
+            if "font_preset" in normalized and "font" not in normalized:
+                normalized["font"] = normalized["font_preset"]
+            if "font_color" in normalized and "color" not in normalized:
+                normalized["color"] = normalized["font_color"]
+            merged["title"] = normalized
+            # 清掉旧 key，避免双字段并存
+            merged.pop("title_config", None)
 
         plan_model.config = merged
         db.commit()

apps/worker/video_processing/subtitle_render_engine.py

@@ -321,8 +321,14 @@ def build_subtitles_from_plan(
 
     has_any = False
 
-    # 1. 标题
-    title_cfg = plan_config.get("title_config") or {}
+    # 1. 标题（#1901 统一读 "title"，兼容老数据 "title_config"）
+    title_cfg = plan_config.get("title") or {}
+    if not isinstance(title_cfg, dict) or not (title_cfg.get("text") or "").strip():
+        _alt = plan_config.get("title_config") or {}
+        if isinstance(_alt, dict):
+            title_cfg = _alt
+    if not isinstance(title_cfg, dict):
+        title_cfg = {}
     if isinstance(title_cfg, dict):
         title_text = str(title_cfg.get("text", ""))
         title_enabled = title_cfg.get("enabled", True)

apps/worker/video_processing/unified_render_service.py

@@ -572,7 +572,12 @@ class UnifiedRenderService:
             ASS 文件路径，没有字幕时返回 None
         """
         config = self.plan.config or {}
+        # #1901 统一读 "title"，兼容老数据 "title_config"
         title_cfg = config.get("title", {}) or {}
+        if not isinstance(title_cfg, dict) or not (title_cfg.get("text") or "").strip():
+            _alt = config.get("title_config") or {}
+            if isinstance(_alt, dict):
+                title_cfg = _alt
         if not isinstance(title_cfg, dict):
             title_cfg = {}
         subtitle_cfg = config.get("subtitle", {}) or {}

tests/unit/test_generation_common.py

@@ -107,29 +107,67 @@ class TestWritebackEditPlanConfig:
         writeback_edit_plan_config("p1", "task-xyz", None, db)
         assert plan.config["generation_task_id"] == "task-xyz"
         assert plan.config["other"] == "keep-me"
-        assert "title_config" not in plan.config
+        assert "title" not in plan.config or not plan.config.get("title")
         db.commit.assert_called_once()
 
-    def test_merges_title_config_without_title_change(self):
+    def test_merges_title_without_title_change(self):
+        """#1901: 写 'title' 字段，未变标题保留 cover。"""
+        from app.services.generation_common import writeback_edit_plan_config
+
+        plan = _make_plan_model({"title": {"text": "old"}, "cover": "x"})
+        db = MagicMock()
+        db.query.return_value.filter.return_value.first.return_value = plan
+        writeback_edit_plan_config("p1", "t1", {"text": "old"}, db)
+        assert plan.config["title"] == {"text": "old"}
+        # 旧 key 不应残留
+        assert "title_config" not in plan.config
+        # 标题未变 → cover 保留
+        assert plan.config.get("cover") == "x"
+
+    def test_merges_title_fallback_to_old_title_config_key(self):
+        """#1901: 老数据存在 title_config（无 title）时，也能正确识别旧标题文字。"""
         from app.services.generation_common import writeback_edit_plan_config
 
         plan = _make_plan_model({"title_config": {"text": "old"}, "cover": "x"})
         db = MagicMock()
         db.query.return_value.filter.return_value.first.return_value = plan
         writeback_edit_plan_config("p1", "t1", {"text": "old"}, db)
-        assert plan.config["title_config"] == {"text": "old"}
-        # 标题未变 → cover 保留
+        # 写入新 key "title"，旧 key 被清除
+        assert plan.config["title"] == {"text": "old"}
+        assert "title_config" not in plan.config
         assert plan.config.get("cover") == "x"
 
     def test_title_change_clears_cover(self):
+        """#1901: 标题变化时清 cover，新配置写到 'title'。"""
         from app.services.generation_common import writeback_edit_plan_config
 
-        plan = _make_plan_model({"title_config": {"text": "old"}, "cover": "x"})
+        plan = _make_plan_model({"title": {"text": "old"}, "cover": "x"})
         db = MagicMock()
         db.query.return_value.filter.return_value.first.return_value = plan
         writeback_edit_plan_config("p1", "t1", {"text": "new-title"}, db)
         assert "cover" not in plan.config
-        assert plan.config["title_config"] == {"text": "new-title"}
+        assert plan.config["title"] == {"text": "new-title"}
+        assert "title_config" not in plan.config
+
+    def test_title_config_normalizes_legacy_keys(self):
+        """#1901: 写入时归一化 font_size/font_preset/font_color → size/font/color，与 worker 对齐。"""
+        from app.services.generation_common import writeback_edit_plan_config
+
+        plan = _make_plan_model({})
+        db = MagicMock()
+        db.query.return_value.filter.return_value.first.return_value = plan
+        writeback_edit_plan_config(
+            "p1", "t1",
+            {"text": "hi", "font_size": 32, "font_preset": "楷体", "font_color": "#ff0000", "bold": True},
+            db,
+        )
+        title = plan.config["title"]
+        assert title["text"] == "hi"
+        assert title["size"] == 32
+        assert title["font"] == "楷体"
+        assert title["color"] == "#ff0000"
+        # 原始 key 保留（方便调用方排查，但归一化后的 key 必须存在）
+        assert title["font_size"] == 32
 
     def test_config_not_dict_treated_as_empty(self):
         from app.services.generation_common import writeback_edit_plan_config
@@ -139,7 +177,8 @@ class TestWritebackEditPlanConfig:
         db.query.return_value.filter.return_value.first.return_value = plan
         writeback_edit_plan_config("p1", "t1", {"text": "hi"}, db)
         assert plan.config["generation_task_id"] == "t1"
-        assert plan.config["title_config"] == {"text": "hi"}
+        assert plan.config["title"] == {"text": "hi"}
+        assert "title_config" not in plan.config
 
     def test_exception_triggers_rollback_and_logs(self, caplog):
         from app.services.generation_common import writeback_edit_plan_config

tests/unit/test_writeback_edit_plan_config.py

@@ -57,7 +57,7 @@ class TestWritebackEditPlanConfig:
         mock_db.query.assert_called_once()
         mock_db.commit.assert_not_called()
 
-    # ---- 行 170-182: 正常写入 + title_config ----
+    # ---- 行 170-182: 正常写入 + title（#1901 统一字段名） ----
     def test_success_with_title_config(self, mock_db, mock_plan):
         mock_db.first.return_value = mock_plan
 
@@ -69,7 +69,11 @@ class TestWritebackEditPlanConfig:
         )
 
         assert mock_plan.config["generation_task_id"] == "task_456"
-        assert mock_plan.config["title_config"] == {"text": "标题", "font_size": 36}
+        # #1901: 统一写到 "title" 字段，且 font_size 已归一化为 size
+        assert mock_plan.config["title"]["text"] == "标题"
+        assert mock_plan.config["title"]["size"] == 36
+        assert mock_plan.config["title"]["font_size"] == 36
+        assert "title_config" not in mock_plan.config
         assert mock_plan.config["existing_key"] == "existing_value"
         mock_db.commit.assert_called_once()
 
@@ -80,7 +84,7 @@ class TestWritebackEditPlanConfig:
         _writeback_edit_plan_config(plan_id="plan_123", task_id="task_789", title_config=None, db=mock_db)
 
         assert mock_plan.config["generation_task_id"] == "task_789"
-        assert "title_config" not in mock_plan.config
+        assert "title" not in mock_plan.config or not mock_plan.config.get("title")
         mock_db.commit.assert_called_once()
 
     # ---- 行 170: config 不是 dict → 兜底空 dict ----
@@ -115,12 +119,12 @@ class TestWritebackEditPlanConfig:
         _writeback_edit_plan_config(plan_id="plan_123", task_id="task_1", title_config=None, db=mock_db)
         mock_db.rollback.assert_called_once()
 
-    # ---- 行 173: title_config 为空 dict → 不写入 title_config ----
+    # ---- 行 173: title_config 为空 dict → 不写入 title ----
     def test_empty_title_config_not_written(self, mock_db, mock_plan):
         mock_db.first.return_value = mock_plan
 
         _writeback_edit_plan_config(plan_id="plan_123", task_id="task_1", title_config={}, db=mock_db)
 
         # 空 dict 为 falsy，不写入
-        assert "title_config" not in mock_plan.config
+        assert "title" not in mock_plan.config or not mock_plan.config.get("title")
         assert mock_plan.config["generation_task_id"] == "task_1"