apps/api/app/api/router.py

@@ -9,6 +9,7 @@ from app.api.routes.feature_flags import router as feature_flags_router
 from app.api.routes.generation_tasks import router as generation_tasks_router
 from app.api.routes.health import router as health_check_router
 from app.api.routes.ingest_jobs import router as ingest_jobs_router
+from app.api.routes.ai import router as ai_router
 from app.api.routes.internal_render import router as internal_render_router
 from app.api.routes.projects import router as projects_router
 from app.api.routes.share import router as share_router
@@ -134,6 +135,11 @@ api_router.include_router(
     prefix="/tts",
     tags=["TTS"],
 )
+api_router.include_router(
+    ai_router,
+    prefix="/ai",
+    tags=["AI"],
+)
 api_router.include_router(
     feature_flags_router,
     tags=["Internal"],

apps/api/app/api/routes/ai.py

@@ -0,0 +1,72 @@
+"""AI 相关接口 — 智能标题、智能素材匹配等.
+
+基于豆包大模型的 AI 能力接口，未配置 API Key 时自动降级为本地模拟。
+"""
+
+from __future__ import annotations
+
+from typing import List, Literal, Optional
+
+from app.services.ai_service import TITLE_STYLES, generate_smart_titles
+from fastapi import APIRouter
+from pydantic import BaseModel, Field
+
+router = APIRouter()
+
+
+# ── 请求/响应模型 ────────────────────────────────────────────────────────────
+
+
+class GenerateTitlesRequest(BaseModel):
+    """智能标题生成请求."""
+
+    description: str = Field(..., min_length=1, max_length=500, description="视频内容描述")
+    style: Literal["viral", "emotional", "informative"] = Field(
+        default="viral",
+        description="标题风格：viral爆款 / emotional情感 / informative信息",
+    )
+    count: int = Field(default=5, ge=3, le=10, description="生成数量，3-10个")
+
+
+class GenerateTitlesResponse(BaseModel):
+    """智能标题生成响应."""
+
+    titles: List[str] = Field(..., description="生成的标题列表")
+    style: str = Field(..., description="实际使用的风格")
+    source: str = Field(..., description="来源：doubao 或 fallback")
+    description: str = Field(..., description="原始描述")
+
+
+class TitleStyleInfo(BaseModel):
+    """标题风格信息."""
+
+    key: str
+    name: str
+    description: str
+
+
+# ── 路由 ────────────────────────────────────────────────────────────────────
+
+
+@router.post("/titles/generate", response_model=GenerateTitlesResponse)
+def generate_titles(request: GenerateTitlesRequest):
+    """生成智能标题.
+
+    根据视频描述生成指定风格的标题，支持爆款、情感、信息三种风格。
+    未配置豆包 API Key 时自动降级为本地规则生成。
+    """
+    result = generate_smart_titles(
+        description=request.description,
+        style=request.style,
+        count=request.count,
+    )
+    return GenerateTitlesResponse(**result)
+
+
+@router.get("/titles/styles", response_model=List[TitleStyleInfo])
+def list_title_styles():
+    """获取支持的标题风格列表."""
+    return [
+        TitleStyleInfo(key=key, name=info["name"], description=info["description"])
+        for key, info in TITLE_STYLES.items()
+    ]

apps/api/app/config.py

@@ -109,6 +109,14 @@ class Settings(BaseSettings):
     # 渲染引擎选择：legacy=旧VideoComposeService，unified=新UnifiedRenderService
     RENDER_ENGINE: str = "legacy"
 
+    # 豆包大模型配置（火山引擎方舟平台）
+    # 未配置 API Key 时自动降级为本地模拟生成
+    DOUBAO_API_KEY: str = ""
+    DOUBAO_MODEL: str = "doubao-seed-1-6-250615"
+    DOUBAO_BASE_URL: str = "https://ark.cn-beijing.volces.com/api/v3"
+    DOUBAO_TIMEOUT: int = 30
+    DOUBAO_MAX_RETRIES: int = 2
+
     model_config = SettingsConfigDict(
         env_file=".env",
         env_file_encoding="utf-8",

apps/api/app/services/ai_service.py

@@ -0,0 +1,347 @@
+"""统一 AI 服务层 — 豆包大模型接入.
+
+提供基于字节跳动豆包大模型的 AI 能力：
+- 智能标题生成（爆款/情感/信息三种风格）
+- 后续扩展：智能素材匹配、AI 推荐片段编排等
+
+设计原则：
+1. 无 API Key 或调用失败时自动降级为本地模拟，不阻塞主流程
+2. 统一的客户端封装，新增能力只需加方法
+3. 所有模型相关配置集中在 Settings
+"""
+
+from __future__ import annotations
+
+import json
+import logging
+import random
+import time
+from typing import Any, Dict, List, Optional
+
+import httpx
+from app.config import get_settings
+
+logger = logging.getLogger(__name__)
+
+
+# ── 智能标题风格定义 ─────────────────────────────────────────────────────────
+
+TITLE_STYLES = {
+    "viral": {
+        "name": "爆款",
+        "description": "吸引点击、引发好奇的爆款标题，带有数字、疑问或反差感",
+        "examples": [
+            "3个方法让你效率翻倍，第2个最绝",
+            "为什么越努力越穷？真相扎心了",
+            "看完这个，我删掉了手机里一半的APP",
+        ],
+    },
+    "emotional": {
+        "name": "情感",
+        "description": "触动人心、引发共鸣的情感向标题",
+        "examples": [
+            "那些年我们一起追过的梦想",
+            "生活不易，但请相信光",
+            "致每一个在城市里打拼的你",
+        ],
+    },
+    "informative": {
+        "name": "信息",
+        "description": "清晰直白、传递核心信息的干货标题",
+        "examples": [
+            "2026年最新个税政策解读，一文讲透",
+            "新手剪辑入门：从0到1完整指南",
+            "产品对比：10款热门手机深度评测",
+        ],
+    },
+}
+
+
+# ── 豆包 AI 客户端 ──────────────────────────────────────────────────────────
+
+
+class DoubaoAIClient:
+    """豆包大模型 API 客户端.
+
+    使用火山引擎方舟平台的 OpenAI 兼容接口。
+    未配置 API Key 时，is_available 返回 False，调用方应降级处理。
+    """
+
+    def __init__(self) -> None:
+        settings = get_settings()
+        self.api_key: str = settings.DOUBAO_API_KEY
+        self.model: str = settings.DOUBAO_MODEL
+        self.base_url: str = settings.DOUBAO_BASE_URL.rstrip("/")
+        self.timeout: int = settings.DOUBAO_TIMEOUT
+        self.max_retries: int = settings.DOUBAO_MAX_RETRIES
+
+    @property
+    def is_available(self) -> bool:
+        """是否可用（配置了 API Key）."""
+        return bool(self.api_key)
+
+    def _chat_completion(
+        self,
+        messages: List[Dict[str, str]],
+        temperature: float = 0.7,
+        max_tokens: int = 1024,
+    ) -> Optional[str]:
+        """调用豆包 Chat Completion 接口.
+
+        Returns:
+            模型返回的文本内容，失败返回 None
+        """
+        if not self.is_available:
+            return None
+
+        url = f"{self.base_url}/chat/completions"
+        headers = {
+            "Authorization": f"Bearer {self.api_key}",
+            "Content-Type": "application/json",
+        }
+        payload = {
+            "model": self.model,
+            "messages": messages,
+            "temperature": temperature,
+            "max_tokens": max_tokens,
+        }
+
+        last_error: Optional[Exception] = None
+        for attempt in range(self.max_retries + 1):
+            try:
+                response = httpx.post(
+                    url,
+                    headers=headers,
+                    json=payload,
+                    timeout=self.timeout,
+                )
+                response.raise_for_status()
+                data = response.json()
+                content = data["choices"][0]["message"]["content"]
+                return content.strip()
+            except Exception as e:
+                last_error = e
+                if attempt < self.max_retries:
+                    wait = 0.5 * (2**attempt)
+                    logger.warning(
+                        "豆包API调用失败，%s秒后重试 (第%d/%d次): %s",
+                        wait,
+                        attempt + 1,
+                        self.max_retries + 1,
+                        e,
+                    )
+                    time.sleep(wait)
+
+        logger.error("豆包API调用最终失败: %s", last_error)
+        return None
+
+
+# ── 智能标题生成 ─────────────────────────────────────────────────────────────
+
+
+def _generate_titles_fallback(
+    description: str,
+    style: str = "viral",
+    count: int = 5,
+) -> List[str]:
+    """本地降级：基于模板规则生成标题.
+
+    当豆包 API 不可用或调用失败时使用，保证接口始终有返回。
+    """
+    style_info = TITLE_STYLES.get(style, TITLE_STYLES["viral"])
+    examples = style_info["examples"]
+
+    # 从描述中提取关键词（取前几个词）
+    keywords = [w for w in description.strip().split() if len(w) > 1][:3]
+    keyword = keywords[0] if keywords else "精彩内容"
+
+    # 基于模板生成
+    templates = [
+        f"「{keyword}」{examples[0][:10]}...",
+        f"{keyword}：{examples[1]}",
+        f"关于{keyword}，你不知道的3件事",
+        f"{keyword}入门指南，新手必看",
+        f"深度解析：{keyword}背后的秘密",
+        f"{keyword}怎么做？手把手教你",
+        f"干货分享 | {keyword}全攻略",
+        f"建议收藏：{keyword}实用技巧",
+        f"{keyword}避坑指南，别再踩雷了",
+        f"一分钟搞懂{keyword}",
+    ]
+
+    random.shuffle(templates)
+    return templates[: min(count, len(templates))]
+
+
+def _parse_titles_from_response(content: str) -> List[str]:
+    """从模型返回中解析标题列表.
+
+    支持多种返回格式：
+    - JSON 数组: ["标题1", "标题2"]
+    - 编号列表: 1. 标题1 / 2. 标题2
+    - 换行分隔: 标题1\n标题2
+    - 带破折号: - 标题1
+    """
+    if not content:
+        return []
+
+    # 尝试解析 JSON
+    try:
+        # 清理可能的 markdown 代码块标记
+        cleaned = content.strip()
+        if cleaned.startswith("```"):
+            cleaned = cleaned.strip("`")
+            if cleaned.lower().startswith("json"):
+                cleaned = cleaned[4:]
+            cleaned = cleaned.strip()
+
+        data = json.loads(cleaned)
+        if isinstance(data, list):
+            return [str(item).strip() for item in data if str(item).strip()]
+        if isinstance(data, dict) and "titles" in data:
+            titles = data["titles"]
+            if isinstance(titles, list):
+                return [str(t).strip() for t in titles if str(t).strip()]
+    except (json.JSONDecodeError, ValueError):
+        pass
+
+    # 尝试按行解析
+    titles: List[str] = []
+    for line in content.strip().split("\n"):
+        line = line.strip()
+        if not line:
+            continue
+        # 去掉编号前缀 "1. " "1、" "（1）"
+        import re
+
+        line = re.sub(r"^[\d]+[\.、\)）]\s*", "", line)
+        # 去掉破折号前缀 "- " "• "
+        line = re.sub(r"^[-•·]\s*", "", line)
+        # 去掉引号
+        line = line.strip('"').strip("'").strip("「」")
+        if line and len(line) < 100:  # 过滤过长的行
+            titles.append(line)
+
+    return titles
+
+
+def generate_smart_titles(
+    description: str,
+    style: str = "viral",
+    count: int = 5,
+) -> Dict[str, Any]:
+    """生成智能标题.
+
+    Args:
+        description: 视频内容描述
+        style: 标题风格 viral/emotional/informative
+        count: 生成数量（5-10）
+
+    Returns:
+        {
+            "titles": [...],
+            "style": "viral",
+            "source": "doubao" | "fallback",  # 实际来源
+            "description": "...",
+        }
+    """
+    # 参数校验与边界处理
+    if style not in TITLE_STYLES:
+        style = "viral"
+    count = max(3, min(10, count))  # 3-10 个
+    description = (description or "").strip()
+
+    client = DoubaoAIClient()
+    if not client.is_available:
+        logger.info("豆包API未配置，使用本地降级生成标题")
+        titles = _generate_titles_fallback(description, style, count)
+        return {
+            "titles": titles,
+            "style": style,
+            "source": "fallback",
+            "description": description,
+        }
+
+    style_info = TITLE_STYLES[style]
+    system_prompt = (
+        f"你是一个专业的短视频标题创作专家，擅长根据视频内容生成吸引人的标题。\n"
+        f"请根据以下视频描述，生成{count}个{style_info['name']}风格的标题。\n"
+        f"风格说明：{style_info['description']}\n"
+        f"要求：\n"
+        f"1. 每个标题控制在8-25字之间\n"
+        f"2. 直接返回JSON数组格式，不要其他文字\n"
+        f"3. 标题要贴合内容，有吸引力"
+    )
+
+    user_prompt = f"视频描述：{description}\n\n请生成标题："
+
+    messages = [
+        {"role": "system", "content": system_prompt},
+        {"role": "user", "content": user_prompt},
+    ]
+
+    result = client._chat_completion(
+        messages=messages,
+        temperature=0.8,
+        max_tokens=512,
+    )
+
+    if result:
+        titles = _parse_titles_from_response(result)
+        if len(titles) >= 2:  # 至少解析出2个才算成功
+            titles = titles[:count]
+            logger.info(
+                "豆包智能标题生成成功: style=%s count=%d description=%s...",
+                style,
+                len(titles),
+                description[:20],
+            )
+            return {
+                "titles": titles,
+                "style": style,
+                "source": "doubao",
+                "description": description,
+            }
+        logger.warning("豆包返回内容解析失败，降级到本地生成: %s", result[:100])
+
+    # 降级到本地生成
+    titles = _generate_titles_fallback(description, style, count)
+    return {
+        "titles": titles,
+        "style": style,
+        "source": "fallback",
+        "description": description,
+    }
+
+
+# ── 单例入口 ─────────────────────────────────────────────────────────────────
+
+
+def get_ai_service() -> "AIService":
+    """获取 AI 服务单例."""
+    global _ai_service
+    if _ai_service is None:
+        _ai_service = AIService()
+    return _ai_service
+
+
+_ai_service: Optional["AIService"] = None
+
+
+class AIService:
+    """AI 服务统一入口，便于后续扩展更多能力."""
+
+    def __init__(self) -> None:
+        self._client = DoubaoAIClient()
+
+    @property
+    def is_available(self) -> bool:
+        return self._client.is_available
+
+    def generate_titles(
+        self,
+        description: str,
+        style: str = "viral",
+        count: int = 5,
+    ) -> Dict[str, Any]:
+        return generate_smart_titles(description, style, count)

tests/unit/test_ai_service.py

@@ -0,0 +1,299 @@
+"""AI 服务层单元测试.
+
+测试覆盖：
+- DoubaoAIClient 可用性检测
+- 智能标题生成（降级模式）
+- 标题解析（多种返回格式）
+- 风格校验
+- 参数边界
+"""
+
+from __future__ import annotations
+
+import json
+import sys
+import unittest
+from unittest.mock import MagicMock, patch
+
+sys.path.insert(0, "apps/api")
+
+from app.services.ai_service import (  # noqa: E402
+    DoubaoAIClient,
+    TITLE_STYLES,
+    _generate_titles_fallback,
+    _parse_titles_from_response,
+    generate_smart_titles,
+)
+
+
+class TestDoubaoAIClient(unittest.TestCase):
+    """豆包客户端基础测试."""
+
+    def test_client_availability_without_key(self):
+        """未配置 API Key 时不可用."""
+        with patch("app.services.ai_service.get_settings") as mock_settings:
+            mock_settings.return_value = MagicMock(
+                DOUBAO_API_KEY="",
+                DOUBAO_MODEL="test-model",
+                DOUBAO_BASE_URL="https://test.com",
+                DOUBAO_TIMEOUT=30,
+                DOUBAO_MAX_RETRIES=2,
+            )
+            client = DoubaoAIClient()
+            self.assertFalse(client.is_available)
+
+    def test_client_availability_with_key(self):
+        """配置了 API Key 时可用."""
+        with patch("app.services.ai_service.get_settings") as mock_settings:
+            mock_settings.return_value = MagicMock(
+                DOUBAO_API_KEY="sk-test-123",
+                DOUBAO_MODEL="test-model",
+                DOUBAO_BASE_URL="https://test.com",
+                DOUBAO_TIMEOUT=30,
+                DOUBAO_MAX_RETRIES=2,
+            )
+            client = DoubaoAIClient()
+            self.assertTrue(client.is_available)
+
+    def test_chat_completion_not_available_returns_none(self):
+        """不可用时调用返回 None."""
+        with patch("app.services.ai_service.get_settings") as mock_settings:
+            mock_settings.return_value = MagicMock(
+                DOUBAO_API_KEY="",
+                DOUBAO_MODEL="test-model",
+                DOUBAO_BASE_URL="https://test.com",
+                DOUBAO_TIMEOUT=30,
+                DOUBAO_MAX_RETRIES=2,
+            )
+            client = DoubaoAIClient()
+            result = client._chat_completion([{"role": "user", "content": "hi"}])
+            self.assertIsNone(result)
+
+
+class TestTitleParsing(unittest.TestCase):
+    """标题解析测试 — 覆盖多种返回格式."""
+
+    def test_parse_json_array(self):
+        """解析 JSON 数组格式."""
+        content = json.dumps(["标题一", "标题二", "标题三"])
+        result = _parse_titles_from_response(content)
+        self.assertEqual(len(result), 3)
+        self.assertEqual(result[0], "标题一")
+
+    def test_parse_json_with_titles_key(self):
+        """解析带 titles 字段的 JSON 对象."""
+        content = json.dumps({"titles": ["标题A", "标题B"]})
+        result = _parse_titles_from_response(content)
+        self.assertEqual(len(result), 2)
+
+    def test_parse_markdown_code_block_json(self):
+        """解析 markdown 代码块包裹的 JSON."""
+        content = "```json\n[\"标题1\", \"标题2\"]\n```"
+        result = _parse_titles_from_response(content)
+        self.assertEqual(len(result), 2)
+
+    def test_parse_numbered_list(self):
+        """解析编号列表."""
+        content = "1. 第一个标题\n2. 第二个标题\n3. 第三个标题"
+        result = _parse_titles_from_response(content)
+        self.assertEqual(len(result), 3)
+        self.assertIn("第一个标题", result)
+
+    def test_parse_dash_list(self):
+        """解析破折号列表."""
+        content = "- 标题甲\n- 标题乙\n- 标题丙"
+        result = _parse_titles_from_response(content)
+        self.assertEqual(len(result), 3)
+
+    def test_parse_chinese_numbered(self):
+        """解析中文数字编号."""
+        content = "1、标题一\n2、标题二"
+        result = _parse_titles_from_response(content)
+        self.assertEqual(len(result), 2)
+
+    def test_parse_empty_content(self):
+        """空内容返回空列表."""
+        result = _parse_titles_from_response("")
+        self.assertEqual(result, [])
+
+    def test_parse_filters_long_lines(self):
+        """过滤过长的行."""
+        long_title = "这是一个非常长的标题" * 15  # 超过100字
+        content = f"1. 正常标题\n2. {long_title}\n3. 另一个标题"
+        result = _parse_titles_from_response(content)
+        self.assertEqual(len(result), 2)
+        self.assertNotIn(long_title, result)
+
+    def test_parse_invalid_json_falls_back_to_lines(self):
+        """无效 JSON 回退到按行解析."""
+        content = '["标题1", "标题2", 无效'
+        result = _parse_titles_from_response(content)
+        # 至少能解析出一些内容
+        self.assertTrue(len(result) >= 0)
+
+
+class TestFallbackGeneration(unittest.TestCase):
+    """降级生成测试."""
+
+    def test_fallback_returns_requested_count(self):
+        """返回请求的数量."""
+        result = _generate_titles_fallback("测试内容", "viral", 5)
+        self.assertEqual(len(result), 5)
+
+    def test_fallback_max_10(self):
+        """最多返回10个."""
+        result = _generate_titles_fallback("测试内容", "viral", 20)
+        self.assertEqual(len(result), 10)
+
+    def test_fallback_different_styles(self):
+        """不同风格都能生成."""
+        for style in ["viral", "emotional", "informative"]:
+            result = _generate_titles_fallback("测试", style, 3)
+            self.assertEqual(len(result), 3)
+            for title in result:
+                self.assertTrue(len(title) > 0)
+
+    def test_fallback_contains_keyword(self):
+        """标题包含关键词."""
+        result = _generate_titles_fallback("旅行攻略", "viral", 5)
+        has_keyword = any("旅行" in t for t in result)
+        self.assertTrue(has_keyword)
+
+
+class TestGenerateSmartTitles(unittest.TestCase):
+    """智能标题生成集成测试."""
+
+    def test_generate_without_api_key_fallback(self):
+        """无 API Key 时走降级路径."""
+        with patch("app.services.ai_service.get_settings") as mock_settings:
+            mock_settings.return_value = MagicMock(
+                DOUBAO_API_KEY="",
+                DOUBAO_MODEL="test",
+                DOUBAO_BASE_URL="https://test.com",
+                DOUBAO_TIMEOUT=30,
+                DOUBAO_MAX_RETRIES=2,
+            )
+            result = generate_smart_titles("测试视频内容", "viral", 5)
+            self.assertEqual(result["source"], "fallback")
+            self.assertEqual(result["style"], "viral")
+            self.assertEqual(len(result["titles"]), 5)
+
+    def test_generate_invalid_style_defaults_to_viral(self):
+        """无效风格默认 viral."""
+        with patch("app.services.ai_service.get_settings") as mock_settings:
+            mock_settings.return_value = MagicMock(
+                DOUBAO_API_KEY="",
+                DOUBAO_MODEL="test",
+                DOUBAO_BASE_URL="https://test.com",
+                DOUBAO_TIMEOUT=30,
+                DOUBAO_MAX_RETRIES=2,
+            )
+            result = generate_smart_titles("测试", "invalid_style", 5)
+            self.assertEqual(result["style"], "viral")
+
+    def test_generate_count_bounds(self):
+        """数量边界处理."""
+        with patch("app.services.ai_service.get_settings") as mock_settings:
+            mock_settings.return_value = MagicMock(
+                DOUBAO_API_KEY="",
+                DOUBAO_MODEL="test",
+                DOUBAO_BASE_URL="https://test.com",
+                DOUBAO_TIMEOUT=30,
+                DOUBAO_MAX_RETRIES=2,
+            )
+            # 小于最小值
+            result = generate_smart_titles("测试", "viral", 1)
+            self.assertEqual(len(result["titles"]), 3)
+            # 大于最大值
+            result = generate_smart_titles("测试", "viral", 100)
+            self.assertEqual(len(result["titles"]), 10)
+
+    def test_generate_with_api_success(self):
+        """API 调用成功路径."""
+        with patch("app.services.ai_service.get_settings") as mock_settings:
+            mock_settings.return_value = MagicMock(
+                DOUBAO_API_KEY="sk-test-123",
+                DOUBAO_MODEL="test-model",
+                DOUBAO_BASE_URL="https://test.com",
+                DOUBAO_TIMEOUT=30,
+                DOUBAO_MAX_RETRIES=0,
+            )
+            mock_response = MagicMock()
+            mock_response.status_code = 200
+            mock_response.json.return_value = {
+                "choices": [
+                    {
+                        "message": {
+                            "content": json.dumps(["AI标题1", "AI标题2", "AI标题3", "AI标题4", "AI标题5"])
+                        }
+                    }
+                ]
+            }
+            mock_response.raise_for_status = MagicMock()
+
+            with patch("httpx.post", return_value=mock_response):
+                result = generate_smart_titles("测试视频", "viral", 5)
+                self.assertEqual(result["source"], "doubao")
+                self.assertEqual(len(result["titles"]), 5)
+                self.assertIn("AI标题1", result["titles"])
+
+    def test_generate_with_api_failure_fallback(self):
+        """API 调用失败时降级."""
+        with patch("app.services.ai_service.get_settings") as mock_settings:
+            mock_settings.return_value = MagicMock(
+                DOUBAO_API_KEY="sk-test-123",
+                DOUBAO_MODEL="test-model",
+                DOUBAO_BASE_URL="https://test.com",
+                DOUBAO_TIMEOUT=1,
+                DOUBAO_MAX_RETRIES=0,
+            )
+            with patch("httpx.post", side_effect=Exception("API Error")):
+                result = generate_smart_titles("测试视频", "viral", 5)
+                self.assertEqual(result["source"], "fallback")
+                self.assertEqual(len(result["titles"]), 5)
+
+    def test_generate_api_returns_unparseable_fallback(self):
+        """API 返回无法解析时降级."""
+        with patch("app.services.ai_service.get_settings") as mock_settings:
+            mock_settings.return_value = MagicMock(
+                DOUBAO_API_KEY="sk-test-123",
+                DOUBAO_MODEL="test-model",
+                DOUBAO_BASE_URL="https://test.com",
+                DOUBAO_TIMEOUT=30,
+                DOUBAO_MAX_RETRIES=0,
+            )
+            mock_response = MagicMock()
+            mock_response.status_code = 200
+            # 返回无法解析的内容（只有一个标题且格式异常）
+            mock_response.json.return_value = {
+                "choices": [{"message": {"content": "一段文字说明，不是标题列表"}}]
+            }
+            mock_response.raise_for_status = MagicMock()
+
+            with patch("httpx.post", return_value=mock_response):
+                result = generate_smart_titles("测试视频", "viral", 5)
+                # 只有1个有效标题，不足2个触发降级
+                self.assertEqual(result["source"], "fallback")
+
+
+class TestTitleStyles(unittest.TestCase):
+    """标题风格定义测试."""
+
+    def test_all_styles_have_required_fields(self):
+        """所有风格都有必要字段."""
+        for key, info in TITLE_STYLES.items():
+            self.assertIn("name", info)
+            self.assertIn("description", info)
+            self.assertIn("examples", info)
+            self.assertTrue(len(info["examples"]) >= 2)
+
+    def test_three_styles_defined(self):
+        """定义了三种风格."""
+        self.assertEqual(len(TITLE_STYLES), 3)
+        self.assertIn("viral", TITLE_STYLES)
+        self.assertIn("emotional", TITLE_STYLES)
+        self.assertIn("informative", TITLE_STYLES)
+
+
+if __name__ == "__main__":
+    unittest.main()