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

@@ -32,143 +32,6 @@ router = APIRouter(tags=["Generation"])
 
 
 
-# ── Helper: 封面标题叠加 ────────────────────────────────────────────────────
-
-
-def _escape_drawtext_text(text: str) -> str:
-    """转义 ffmpeg drawtext 的特殊字符."""
-    # ffmpeg drawtext 需要转义: ' → \'  , : → \:  , % → %%
-    escaped = text.replace("'", "'\\''")
-    escaped = escaped.replace(":", "\\:")
-    escaped = escaped.replace("%", "%%")
-    return escaped
-
-
-def _overlay_title_on_cover_image(
-    cover_image_url: str,
-    title_text: str,
-    title_config: dict | None = None,
-    plan_id: str = "",
-) -> str | None:
-    """用 ffmpeg drawtext 在封面图片上叠加标题文字.
-
-    轻量方案：下载现有封面图片 → ffmpeg drawtext 叠加标题 → 上传 OSS → 返回新 URL。
-    失败时返回 None，调用方应降级使用原 cover_url。
-
-    Args:
-        cover_image_url: 原始封面图片 URL
-        title_text: 标题文本
-        title_config: 标题样式配置（font_size, font_color, position 等）
-        plan_id: 计划 ID（用于日志）
-
-    Returns:
-        叠加标题后的新封面 URL，失败返回 None
-    """
-    import hashlib
-    import shutil
-    import subprocess
-    import tempfile
-    from pathlib import Path
-
-    from packages.shared.ffmpeg_utils import FFMPEG_BIN
-    from packages.shared.storage import get_shared_storage_service
-
-    logger.info(
-        "[封面标题叠加] 开始: plan_id=%s title=%s",
-        plan_id,
-        title_text[:30] if title_text else "",
-    )
-
-    title_config = title_config or {}
-
-    # 下载原始封面图片
-    tmp_dir = tempfile.mkdtemp(prefix="cover_title_")
-    input_path = Path(tmp_dir) / "input.jpg"
-    output_path = Path(tmp_dir) / "output.jpg"
-
-    try:
-        # 下载封面图片
-        import requests
-        resp = requests.get(cover_image_url, stream=True, timeout=30)
-        resp.raise_for_status()
-        with open(input_path, "wb") as f:
-            for chunk in resp.iter_content(chunk_size=8 * 1024):
-                if chunk:
-                    f.write(chunk)
-
-        if not input_path.exists() or input_path.stat().st_size == 0:
-            logger.warning("[封面标题叠加] 下载封面图片失败: %s", cover_image_url[:60])
-            return None
-
-        # 构建 ffmpeg drawtext filter
-        escaped_title = _escape_drawtext_text(title_text)
-
-        # 样式配置
-        font_size = int(title_config.get("font_size", 48))
-        font_color = title_config.get("font_color", "#ffffff") or "#ffffff"
-        # 去掉 # 前缀，ffmpeg 用 0xRRGGBB 格式
-        ffmpeg_color = font_color.replace("#", "0x")
-
-        # drawtext filter: 文字 + 黑色描边 + 阴影，居中偏下
-        drawtext_filter = (
-            f"drawtext=text='{escaped_title}'"
-            f":fontsize={font_size}"
-            f":fontcolor={ffmpeg_color}"
-            f":shadowcolor=0x000000:shadowx=2:shadowy=2"
-            f":borderw=2:bordercolor=black"
-            f":x=(w-text_w)/2:y=h*0.85-text_h"
-        )
-
-        # 执行 ffmpeg
-        cmd = [
-            FFMPEG_BIN,
-            "-y",
-            "-i", str(input_path),
-            "-vf", drawtext_filter,
-            "-q:v", "2",
-            str(output_path),
-        ]
-
-        result = subprocess.run(
-            cmd,
-            capture_output=True,
-            timeout=30,
-        )
-
-        if result.returncode != 0:
-            stderr_text = result.stderr.decode(errors="replace")[:200] if result.stderr else ""
-            logger.error(
-                "[封面标题叠加] ffmpeg 失败: rc=%d stderr=%s",
-                result.returncode,
-                stderr_text,
-            )
-            return None
-
-        if not output_path.exists() or output_path.stat().st_size == 0:
-            logger.warning("[封面标题叠加] ffmpeg 输出文件为空")
-            return None
-
-        # 上传到 OSS
-        url_hash = hashlib.sha256(cover_image_url.encode()).hexdigest()[:12]
-        storage_key = f"covers/{url_hash}_titled.jpg"
-
-        storage_svc = get_shared_storage_service()
-        new_url = storage_svc.upload_file(str(output_path), storage_key, content_type="image/jpeg")
-
-        logger.info(
-            "[封面标题叠加] ✅ 成功: plan_id=%s url=%s",
-            plan_id,
-            new_url[:60] if new_url else "",
-        )
-        return new_url
-
-    except Exception:
-        logger.exception("[封面标题叠加] 异常，降级使用原封面")
-        return None
-    finally:
-        # 清理临时文件
-        shutil.rmtree(tmp_dir, ignore_errors=True)
-
 
 # ── Schemas ──────────────────────────────────────────────────────────────
 
@@ -421,33 +284,10 @@ def generate_cover(
                 )
 
         if cover_url_from_task:
-            # 检查是否有标题需要叠加（用户在选封面前已选标题）
-            final_cover_url = cover_url_from_task
-            title_text = ((plan.config or {}).get("title", {}) or {}).get("text", "") or ""
-            if title_text and title_text.strip():
-                title_config = (plan.config or {}).get("title", {}) or {}
-                titled_url = _overlay_title_on_cover_image(
-                    cover_image_url=cover_url_from_task,
-                    title_text=title_text,
-                    title_config=title_config,
-                    plan_id=plan_id,
-                )
-                if titled_url:
-                    final_cover_url = titled_url
-                    logger.info(
-                        "[封面生成] 标题叠加成功: plan_id=%s title=%s",
-                        plan_id,
-                        title_text[:30],
-                    )
-                else:
-                    logger.warning(
-                        "[封面生成] 标题叠加失败，降级使用原封面: plan_id=%s",
-                        plan_id,
-                    )
-
+            # 标题已在预览视频渲染时烧录（ASS字幕），封面帧自然包含标题
             cover_data = {
                 "type": "ai_frame",
-                "image_url": final_cover_url,
+                "image_url": cover_url_from_task,
                 "frame_time": 0.0,
                 "confidence": 0.95,
             }

apps/api/app/api/routes/generation_preview.py

@@ -5,6 +5,7 @@
 
 from __future__ import annotations
 
+import json
 import logging
 
 from app.auth import AuthenticatedUser, get_current_user
@@ -267,6 +268,20 @@ def create_preview_generation_task(
     # 从模板读取 editing_mode / mode 作为 strategy_id（渲染 pipeline 的 mode 参数）
     strategy_id = _resolve_strategy_id_from_template(request.template_id, db, user_id)
 
+    # 处理标题配置：如果有标题文本，序列化到 custom_title 字段传递给 worker
+    title_config = request.title_config or {}
+    title_text = (title_config.get("text") or "").strip()
+    custom_title_value = ""
+    if title_text:
+        # 将标题文本和样式配置序列化为 JSON 存入 custom_title
+        # Worker 端会解析 JSON 获取完整标题配置
+        custom_title_value = json.dumps(title_config, ensure_ascii=False)
+        logger.info(
+            "[预览生成] 标题配置: text=%s, config_keys=%s",
+            title_text[:30],
+            list(title_config.keys()),
+        )
+
     use_case = CreateGenerationTaskUseCase(generation_task_repository)
 
     try:
@@ -290,6 +305,7 @@ def create_preview_generation_task(
                 auto_retry_enabled=False,
                 auto_retry_max=0,
                 is_preview=True,
+                custom_title=custom_title_value,
             )
         )
     except ValueError as e:

apps/api/app/schemas/generation_task.py

@@ -181,6 +181,10 @@ class CreatePreviewGenerationTaskRequest(BaseModel):
         default="",
         description="关联的编辑计划ID（可选），用于确认生成时复用预览产物",
     )
+    title_config: dict = Field(
+        default_factory=dict,
+        description="标题配置（可选），渲染时烧录到预览视频中。支持字段: text/font/font_size/font_color/position/bold/stroke/shadow",
+    )
 
     @model_validator(mode="after")
     def _check_template_id(self) -> "CreatePreviewGenerationTaskRequest":

apps/worker/worker_app/tasks/generation.py

@@ -13,6 +13,7 @@
 
 from __future__ import annotations
 
+import json
 import logging
 import os
 import tempfile
@@ -1171,18 +1172,58 @@ def _render_video(
         )
 
     # 用户自定义标题覆盖模板标题（用户指定优先级最高）
+    # 支持两种格式：
+    # 1. JSON 格式（新）：{"text": "xxx", "font_size": 32, ...} — 包含标题文本和样式
+    # 2. 纯文本格式（旧）：直接作为标题文本使用
     if custom_title and custom_title.strip():
         plan_cfg = dict(virtual_plan.config or {})
         title_cfg = dict(plan_cfg.get("title", {}) or {})
-        title_cfg["text"] = custom_title.strip()
-        title_cfg["enabled"] = True
+        ct_stripped = custom_title.strip()
+        parsed_config = None
+        if ct_stripped.startswith("{"):
+            try:
+                parsed_config = json.loads(ct_stripped)
+            except (json.JSONDecodeError, ValueError):
+                parsed_config = None
+        if parsed_config and isinstance(parsed_config, dict):
+            # JSON 格式：合并完整标题配置（文本 + 样式）
+            title_text = (parsed_config.get("text") or "").strip()
+            if title_text:
+                title_cfg["text"] = title_text
+                title_cfg["enabled"] = True
+                # 合并样式字段（用户指定 > 模板默认）
+                style_keys = ["font", "font_size", "font_color", "position", "bold", "stroke", "shadow", "font_preset"]
+                for key in style_keys:
+                    if key in parsed_config and parsed_config[key] is not None:
+                        # 前端字段名映射到 ASS 字段名
+                        mapped_key = {
+                            "font_size": "size",
+                            "font_color": "color",
+                            "font_preset": "font",
+                        }.get(key, key)
+                        title_cfg[mapped_key] = parsed_config[key]
+                logger.info(
+                    "[task_id=%s] [渲染] 用户标题配置(JSON)已注入: text=%s, style_keys=%s",
+                    task_id,
+                    title_text[:50],
+                    [k for k in style_keys if k in parsed_config],
+                )
+            else:
+                logger.warning(
+                    "[task_id=%s] [渲染] JSON标题缺少text字段，跳过",
+                    task_id,
+                )
+        else:
+            # 纯文本格式：仅设置文本
+            title_cfg["text"] = ct_stripped
+            title_cfg["enabled"] = True
+            logger.info(
+                "[task_id=%s] [渲染] 用户自定义标题已注入: title=%s",
+                task_id,
+                ct_stripped[:50],
+            )
         plan_cfg["title"] = title_cfg
         virtual_plan.config = plan_cfg
-        logger.info(
-            "[task_id=%s] [渲染] 用户自定义标题已注入: title=%s",
-            task_id,
-            custom_title[:50],
-        )
 
     # 确保输出分辨率配置存在
     # 优先级：用户指定 > 模板配置 > 默认 1280x720

packages/application/generation_tasks.py

@@ -32,6 +32,7 @@ class CreateGenerationTaskCommand:
     output_height: int = 720
     cover_url: str = ""
     custom_title: str = ""
+    title_config: dict = field(default_factory=dict)
 
 
 class CreateGenerationTaskUseCase:

tests/unit/test_cover_title_overlay.py

@@ -1,219 +0,0 @@
-"""Tests for cover title overlay functionality in generation_cover.py."""
-
-from __future__ import annotations
-
-from unittest.mock import MagicMock, patch
-
-import pytest
-
-from apps.api.app.api.routes.generation_cover import _escape_drawtext_text
-
-
-class TestEscapeDrawtextText:
-    """Tests for _escape_drawtext_text helper."""
-
-    def test_single_quote_escaped(self):
-        """单引号应被转义."""
-        result = _escape_drawtext_text("it's a test")
-        assert "'\\''" in result
-
-    def test_colon_escaped(self):
-        """冒号应被转义."""
-        result = _escape_drawtext_text("test: value")
-        assert "\\:" in result
-
-    def test_percent_escaped(self):
-        """百分号应被转义."""
-        result = _escape_drawtext_text("100% done")
-        assert "%%" in result
-
-    def test_normal_text_unchanged(self):
-        """普通文本不应被修改."""
-        result = _escape_drawtext_text("普通标题")
-        assert result == "普通标题"
-
-    def test_multiple_special_chars(self):
-        """多个特殊字符都应被转义."""
-        result = _escape_drawtext_text("it's 50%: done")
-        assert "\\:" in result
-        assert "%%" in result
-
-
-class TestOverlayTitleOnCoverImage:
-    """Tests for _overlay_title_on_cover_image function."""
-
-    @patch("packages.shared.storage.get_shared_storage_service")
-    @patch("packages.shared.ffmpeg_utils.FFMPEG_BIN", "ffmpeg")
-    @patch("subprocess.run")
-    @patch("requests.get")
-    def test_successful_overlay(
-        self,
-        mock_requests_get: MagicMock,
-        mock_subprocess_run: MagicMock,
-        mock_storage_svc: MagicMock,
-        tmp_path,
-    ):
-        """成功叠加标题."""
-        from apps.api.app.api.routes.generation_cover import _overlay_title_on_cover_image
-
-        # Mock HTTP download
-        mock_response = MagicMock()
-        mock_response.iter_content.return_value = [b"fake image data"]
-        mock_response.raise_for_status = MagicMock()
-        mock_requests_get.return_value = mock_response
-
-        # Mock ffmpeg success
-        mock_result = MagicMock()
-        mock_result.returncode = 0
-        mock_subprocess_run.return_value = mock_result
-
-        # Mock storage upload
-        mock_storage = MagicMock()
-        mock_storage.upload_file.return_value = "https://example.com/covers/test_titled.jpg"
-        mock_storage_svc.return_value = mock_storage
-
-        # Need to mock Path operations
-        with (
-            patch("pathlib.Path.exists", return_value=True),
-            patch("pathlib.Path.stat") as mock_stat,
-            patch("pathlib.Path.mkdir"),
-            patch("pathlib.Path.unlink"),
-        ):
-            mock_stat.return_value.st_size = 1000
-
-            result = _overlay_title_on_cover_image(
-                cover_image_url="https://example.com/cover.jpg",
-                title_text="测试标题",
-                title_config={"font_size": 48},
-                plan_id="test-plan-123",
-            )
-
-            assert result == "https://example.com/covers/test_titled.jpg"
-
-    @patch("requests.get")
-    def test_download_failure_returns_none(self, mock_requests_get: MagicMock):
-        """下载失败时返回 None."""
-        from apps.api.app.api.routes.generation_cover import _overlay_title_on_cover_image
-
-        mock_requests_get.side_effect = Exception("Network error")
-
-        result = _overlay_title_on_cover_image(
-            cover_image_url="https://example.com/cover.jpg",
-            title_text="测试标题",
-            plan_id="test-plan-123",
-        )
-
-        assert result is None
-
-    @patch("subprocess.run")
-    @patch("requests.get")
-    def test_ffmpeg_failure_returns_none(
-        self,
-        mock_requests_get: MagicMock,
-        mock_subprocess_run: MagicMock,
-    ):
-        """ffmpeg 失败时返回 None."""
-        from apps.api.app.api.routes.generation_cover import _overlay_title_on_cover_image
-
-        # Mock successful download
-        mock_response = MagicMock()
-        mock_response.iter_content.return_value = [b"fake image data"]
-        mock_response.raise_for_status = MagicMock()
-        mock_requests_get.return_value = mock_response
-
-        # Mock ffmpeg failure
-        mock_result = MagicMock()
-        mock_result.returncode = 1
-        mock_result.stderr = b"ffmpeg error"
-        mock_subprocess_run.return_value = mock_result
-
-        with (
-            patch("pathlib.Path.exists", return_value=True),
-            patch("pathlib.Path.stat") as mock_stat,
-            patch("pathlib.Path.mkdir"),
-            patch("pathlib.Path.unlink"),
-        ):
-            mock_stat.return_value.st_size = 1000
-
-            result = _overlay_title_on_cover_image(
-                cover_image_url="https://example.com/cover.jpg",
-                title_text="测试标题",
-                plan_id="test-plan-123",
-            )
-
-            assert result is None
-
-
-class TestCoverRouteWithTitle:
-    """Integration tests for cover route with title overlay."""
-
-    @patch("apps.api.app.api.routes.generation_cover._overlay_title_on_cover_image")
-    def test_cover_url_with_title_overlay(self, mock_overlay: MagicMock):
-        """有标题时应调用叠加函数."""
-        mock_overlay.return_value = "https://example.com/covers/titled.jpg"
-
-        # Simulate plan.config with title
-        plan_config = {
-            "title": {"text": "测试标题", "font_size": 48},
-            "generation_task_id": "task-123",
-        }
-
-        title_text = (plan_config.get("title", {}) or {}).get("text", "") or ""
-        assert title_text == "测试标题"
-
-        # Should call overlay
-        if title_text and title_text.strip():
-            result = mock_overlay(
-                cover_image_url="https://example.com/cover.jpg",
-                title_text=title_text,
-                title_config=plan_config.get("title", {}),
-                plan_id="test-plan",
-            )
-            assert result == "https://example.com/covers/titled.jpg"
-
-    def test_cover_url_without_title_no_overlay(self):
-        """无标题时不应调用叠加函数."""
-        plan_config = {
-            "title": {"text": "", "font_size": 48},
-            "generation_task_id": "task-123",
-        }
-
-        title_text = (plan_config.get("title", {}) or {}).get("text", "") or ""
-        assert title_text == ""
-
-        # Should NOT call overlay - title is empty
-        assert not (title_text and title_text.strip())
-
-    def test_cover_url_with_title_config_none(self):
-        """title_config 为 None 时应正常处理."""
-        plan_config = {
-            "generation_task_id": "task-123",
-        }
-
-        title_text = (plan_config.get("title", {}) or {}).get("text", "") or ""
-        assert title_text == ""
-
-    @patch("apps.api.app.api.routes.generation_cover._overlay_title_on_cover_image")
-    def test_overlay_failure_fallback_to_original(self, mock_overlay: MagicMock):
-        """叠加失败时应降级使用原封面."""
-        mock_overlay.return_value = None  # 叠加失败
-
-        # Simulate the fallback logic
-        cover_url_from_task = "https://example.com/original.jpg"
-        title_text = "测试标题"
-        title_config = {"font_size": 48}
-
-        titled_url = mock_overlay(
-            cover_image_url=cover_url_from_task,
-            title_text=title_text,
-            title_config=title_config,
-            plan_id="test-plan",
-        )
-
-        # 叠加失败时应该降级使用原封面
-        if titled_url:
-            final_cover_url = titled_url
-        else:
-            final_cover_url = cover_url_from_task
-
-        assert final_cover_url == "https://example.com/original.jpg"

tests/unit/test_preview_title_config.py

@@ -0,0 +1,190 @@
+"""Tests for preview title_config feature.
+
+验证预览 API 的 title_config 字段和 Worker 的标题配置解析逻辑。
+"""
+
+from __future__ import annotations
+
+import json
+
+import pytest
+
+
+class TestPreviewTitleConfigSchema:
+    """测试 CreatePreviewGenerationTaskRequest 的 title_config 字段."""
+
+    def test_title_config_default_empty(self):
+        """title_config 默认为空 dict."""
+        from app.schemas.generation_task import CreatePreviewGenerationTaskRequest
+
+        req = CreatePreviewGenerationTaskRequest(
+            template_id="test_template",
+            asset_ids=["asset1"],
+        )
+        assert req.title_config == {}
+
+    def test_title_config_with_text(self):
+        """传入标题文本."""
+        from app.schemas.generation_task import CreatePreviewGenerationTaskRequest
+
+        req = CreatePreviewGenerationTaskRequest(
+            template_id="test_template",
+            asset_ids=["asset1"],
+            title_config={"text": "测试标题"},
+        )
+        assert req.title_config["text"] == "测试标题"
+
+    def test_title_config_with_full_style(self):
+        """传入完整标题样式配置."""
+        from app.schemas.generation_task import CreatePreviewGenerationTaskRequest
+
+        config = {
+            "text": "我的视频标题",
+            "font": "思源黑体",
+            "font_size": 48,
+            "font_color": "#ffffff",
+            "position": "top",
+            "bold": True,
+            "stroke": 2,
+            "shadow": True,
+        }
+        req = CreatePreviewGenerationTaskRequest(
+            template_id="test_template",
+            asset_ids=["asset1"],
+            title_config=config,
+        )
+        assert req.title_config["text"] == "我的视频标题"
+        assert req.title_config["font_size"] == 48
+        assert req.title_config["position"] == "top"
+
+
+class TestCommandTitleConfig:
+    """测试 CreateGenerationTaskCommand 的 title_config 字段."""
+
+    def test_command_has_title_config(self):
+        """Command 包含 title_config 字段."""
+        from packages.application.generation_tasks import CreateGenerationTaskCommand
+
+        cmd = CreateGenerationTaskCommand(
+            title_config={"text": "hello", "font_size": 32},
+        )
+        assert cmd.title_config["text"] == "hello"
+        assert cmd.title_config["font_size"] == 32
+
+    def test_command_title_config_default_empty(self):
+        """Command 的 title_config 默认为空 dict."""
+        from packages.application.generation_tasks import CreateGenerationTaskCommand
+
+        cmd = CreateGenerationTaskCommand()
+        assert cmd.title_config == {}
+
+
+class TestWorkerTitleConfigParsing:
+    """测试 Worker 渲染时的标题配置解析逻辑."""
+
+    def test_json_format_parsing(self):
+        """JSON 格式的 custom_title 能正确解析."""
+        config = {"text": "测试标题", "font_size": 48, "font_color": "#ff0000"}
+        custom_title = json.dumps(config, ensure_ascii=False)
+
+        ct_stripped = custom_title.strip()
+        parsed = None
+        if ct_stripped.startswith("{"):
+            try:
+                parsed = json.loads(ct_stripped)
+            except (json.JSONDecodeError, ValueError):
+                parsed = None
+
+        assert parsed is not None
+        assert parsed["text"] == "测试标题"
+        assert parsed["font_size"] == 48
+
+    def test_plain_text_fallback(self):
+        """纯文本的 custom_title 不触发 JSON 解析."""
+        custom_title = "简单的标题文字"
+
+        ct_stripped = custom_title.strip()
+        parsed = None
+        if ct_stripped.startswith("{"):
+            try:
+                parsed = json.loads(ct_stripped)
+            except (json.JSONDecodeError, ValueError):
+                parsed = None
+
+        assert parsed is None
+
+    def test_invalid_json_fallback(self):
+        """无效 JSON 的 custom_title 降级为纯文本."""
+        custom_title = "{invalid json"
+
+        ct_stripped = custom_title.strip()
+        parsed = None
+        if ct_stripped.startswith("{"):
+            try:
+                parsed = json.loads(ct_stripped)
+            except (json.JSONDecodeError, ValueError):
+                parsed = None
+
+        assert parsed is None
+
+    def test_json_without_text_skipped(self):
+        """JSON 格式但缺少 text 字段时，跳过标题注入."""
+        config = {"font_size": 48}
+        custom_title = json.dumps(config, ensure_ascii=False)
+
+        ct_stripped = custom_title.strip()
+        parsed = json.loads(ct_stripped)
+        title_text = (parsed.get("text") or "").strip()
+
+        assert title_text == ""
+
+    def test_style_key_mapping(self):
+        """前端字段名正确映射到 ASS 字段名."""
+        config = {
+            "text": "标题",
+            "font_size": 48,
+            "font_color": "#ffffff",
+            "font_preset": "思源黑体",
+        }
+
+        style_keys = ["font", "font_size", "font_color", "position", "bold", "stroke", "shadow", "font_preset"]
+        title_cfg = {}
+        for key in style_keys:
+            if key in config and config[key] is not None:
+                mapped_key = {
+                    "font_size": "size",
+                    "font_color": "color",
+                    "font_preset": "font",
+                }.get(key, key)
+                title_cfg[mapped_key] = config[key]
+
+        assert title_cfg["size"] == 48
+        assert title_cfg["color"] == "#ffffff"
+        assert title_cfg["font"] == "思源黑体"
+
+
+class TestPreviewRouteTitleConfigPassing:
+    """测试预览路由正确序列化 title_config 到 custom_title."""
+
+    def test_title_config_serialization(self):
+        """title_config 序列化为 JSON 字符串."""
+        title_config = {
+            "text": "我的标题",
+            "font_size": 32,
+            "font_color": "#d4a843",
+        }
+        serialized = json.dumps(title_config, ensure_ascii=False)
+
+        parsed = json.loads(serialized)
+        assert parsed["text"] == "我的标题"
+        assert parsed["font_size"] == 32
+
+    def test_empty_title_config_produces_empty_string(self):
+        """空 title_config 时 custom_title 为空字符串."""
+        title_config = {}
+        title_text = (title_config.get("text") or "").strip()
+        custom_title_value = ""
+        if title_text:
+            custom_title_value = json.dumps(title_config, ensure_ascii=False)
+
+        assert custom_title_value == ""