# 数据库设计文档

## Android 本地数据库（Room）

### User 表
```kotlin
@Entity(tableName = "users")
data class User(
    @PrimaryKey val id: String,
    val nickname: String,
    val avatarUrl: String?,
    val subscriptionType: String,  // free, premium
    val createdAt: Long
)
```

### Conversation 表
```kotlin
@Entity(tableName = "conversations")
data class Conversation(
    @PrimaryKey val id: String,
    val userId: String,
    val startedAt: Long,
    val endedAt: Long?,
    val durationSeconds: Int,
    val summary: String?,
    val currentTopic: String?,  // 当前话题
    val conversationStage: String?  // CHILDHOOD, EDUCATION, CAREER, FAMILY, BELIEFS, SUMMARY
)
```

### ConversationSegment 表
```kotlin
@Entity(tableName = "conversation_segments")
data class ConversationSegment(
    @PrimaryKey val id: String,
    val conversationId: String,
    val audioPath: String?,
    val transcriptText: String,
    val createdAt: Long,
    val processed: Boolean,
    val topicCategory: String?  // 话题分类
)
```

### Chapter 表
```kotlin
@Entity(tableName = "chapters")
data class Chapter(
    @PrimaryKey val id: String,
    val title: String,
    val content: String,
    val orderIndex: Int,
    val status: String,  // draft, completed
    val updatedAt: Long,
    val category: String  // 章节分类
)
```

### Book 表
```kotlin
@Entity(tableName = "books")
data class Book(
    @PrimaryKey val id: String,
    val userId: String,
    val title: String,
    val totalPages: Int,
    val totalWords: Int,
    val updatedAt: Long
)
```

## 后端数据库（SQLAlchemy）

### users 表
- id (String, Primary Key)
- openid (String, Unique) - 微信 OpenID
- nickname (String)
- avatar_url (String, Nullable)
- subscription_type (String) - free, premium
- created_at (DateTime)

### conversations 表
- id (String, Primary Key)
- user_id (String, Foreign Key -> users.id)
- started_at (DateTime)
- ended_at (DateTime, Nullable)
- duration_seconds (Integer)
- summary (String, Nullable)
- status (String) - active, ended, processing
- current_topic (String, Nullable)
- conversation_stage (String, Nullable) - childhood, education, career, family, beliefs, summary

### segments 表
- id (String, Primary Key)
- conversation_id (String, Foreign Key -> conversations.id)
- audio_url (String, Nullable)
- transcript_text (Text)
- created_at (DateTime)
- processed (Boolean, Default False)
- topic_category (String, Nullable)
- agent_response (Text, Nullable)

### chapters 表
- id (String, Primary Key)
- user_id (String, Foreign Key -> users.id)
- title (String)
- content (Text)
- order_index (Integer)
- status (String) - draft, completed
- images (JSON, Nullable) - 图片 URL 列表
- updated_at (DateTime)
- category (String) - 章节分类

### books 表
- id (String, Primary Key)
- user_id (String, Foreign Key -> users.id)
- title (String)
- total_pages (Integer)
- total_words (Integer)
- cover_image_url (String, Nullable)
- updated_at (DateTime)