diff --git a/docs/backend/profile.md b/docs/backend/profile.md
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+告诉前端这次只改了 GET /api/user/profile 的响应，新增每日免费额度信息，原有字段不变。
+接口：GET https://api.cozsweet.com/api/user/profile
+新增字段：
+{
+  "dailyFreeChatLimit": 10,
+  "dailyFreeChatUsed": 0,
+  "dailyFreeChatRemaining": 10,
+  "dailyFreePrivateLimit": 0,
+  "dailyFreePrivateUsed": 0,
+  "dailyFreePrivateRemaining": 0,
+  "dailyQuotas": {
+    "chat": {
+      "limit": 10,
+      "used": 0,
+      "remaining": 10
+    },
+    "privateMessage": {
+      "limit": 0,
+      "used": 0,
+      "remaining": 0
+    }
+  }
+}
+含义：
+dailyFreeChatLimit：今天免费聊天总次数
+dailyFreeChatUsed：今天已用免费聊天次数
+dailyFreeChatRemaining：今天剩余免费聊天次数
+dailyFreePrivateLimit：今天免费私密消息总次数
+dailyFreePrivateUsed：今天已用免费私密消息次数
+dailyFreePrivateRemaining：今天剩余免费私密消息次数
+dailyQuotas：同样数据的结构化版本，前端想用对象也可以直接用它
+当前额度规则：
+游客/未注册：聊天 10，私密 0
+注册用户：聊天 30，私密 2
+注意：
+聊天优先消耗 dailyFreeChatRemaining
+私密消息优先消耗 dailyFreePrivateRemaining
+聊天剩余为 0 时，前端应阻止继续聊天或展示后端返回的额度用完提示
+私密剩余为 0 时，前端不要展示私密内容，按锁定私密消息处理。
+16:19
+profile完整字段发给前端 
+16:20
+发给前端这版：
+GET https://api.cozsweet.com/api/user/profile
+Authorization: Bearer <token>
+完整响应结构：
+interface ProfileResponse {
+  code: number;
+  message: string;
+  success: boolean;
+  data: UserProfile;
+}
+
+interface UserProfile {
+  id: string;
+  username: string;
+  email: string | null;
+  platform: string;
+
+  intimacy: number;
+  dolBalance: number;
+  creditBalance: number;
+
+  isTestAccount: boolean;
+
+  personalityTraits: Record<string, number> | null;
+  preferredLanguage: string | null;
+
+  createdAt: string | null;
+  lastMessageAt: string | null;
+
+  country: string | null;
+  countryCode: string | null;
+
+  dailyFreeChatLimit: number;
+  dailyFreeChatUsed: number;
+  dailyFreeChatRemaining: number;
+
+  dailyFreePrivateLimit: number;
+  dailyFreePrivateUsed: number;
+  dailyFreePrivateRemaining: number;
+
+  dailyQuotas: {
+    chat: {
+      limit: number;
+      used: number;
+      remaining: number;
+    };
+    privateMessage: {
+      limit: number;
+      used: number;
+      remaining: number;
+    };
+  };
+}
+示例：
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "id": "user-id",
+    "username": "guest_codex",
+    "email": "device_xxx@guest.local",
+    "platform": "web",
+    "intimacy": 0,
+    "dolBalance": 0,
+    "creditBalance": 0,
+    "isTestAccount": false,
+    "personalityTraits": {
+      "caring": 0.5,
+      "playful": 0.5,
+      "serious": 0.5,
+      "cheerful": 0.5,
+      "romantic": 0.5
+    },
+    "preferredLanguage": "ja",
+    "createdAt": "2026-07-03T16:12:01.591264+08:00",
+    "lastMessageAt": null,
+    "country": "Japan",
+    "countryCode": "JP",
+    "dailyFreeChatLimit": 10,
+    "dailyFreeChatUsed": 0,
+    "dailyFreeChatRemaining": 10,
+    "dailyFreePrivateLimit": 0,
+    "dailyFreePrivateUsed": 0,
+    "dailyFreePrivateRemaining": 0,
+    "dailyQuotas": {
+      "chat": {
+        "limit": 10,
+        "used": 0,
+        "remaining": 10
+      },
+      "privateMessage": {
+        "limit": 0,
+        "used": 0,
+        "remaining": 0
+      }
+    }
+  }
+}
+额度规则：
+游客：dailyFreeChatLimit = 10，dailyFreePrivateLimit = 0
+注册用户：dailyFreeChatLimit = 30，dailyFreePrivateLimit = 2
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