diff --git a/src/core/login.py b/src/core/login.py
new file mode 100644
index 0000000..1520f77
--- /dev/null
+++ b/src/core/login.py
@@ -0,0 +1,466 @@
+"""
+登录流程引擎
+从 register.py 中拆分的登录专属方法
+"""
+
+import urllib.parse
+import base64
+import json as json_module
+from datetime import datetime
+from typing import Optional, Dict, Any
+
+from .register import RegistrationEngine, RegistrationResult
+from ..config.constants import OPENAI_API_ENDPOINTS
+
+
+class LoginEngine(RegistrationEngine):
+    """
+    登录引擎
+    继承 RegistrationEngine，包含登录流程专属方法：
+    - _follow_login_redirects
+    - _submit_login_form
+    - _send_verification_code_passwordless
+    - _get_workspace_id
+    - _select_workspace
+    - _follow_redirects
+    - _handle_oauth_callback
+    """
+
+    def _follow_login_redirects(self, start_url: str) -> bool:
+        """跟随重定向链，寻找回调 URL"""
+        try:
+            current_url = start_url
+            max_redirects = 6
+
+            for i in range(max_redirects):
+                self._log(f"重定向 {i+1}/{max_redirects}: {current_url[:100]}...")
+
+                response = self.session.get(
+                    current_url,
+                    allow_redirects=False,
+                    timeout=15
+                )
+
+                location = response.headers.get("Location") or ""
+
+                # 如果不是重定向状态码，停止
+                if response.status_code == 200:
+                    self._log(f"非重定向状态码: {response.status_code}")
+                    return True
+
+                if not location:
+                    self._log("重定向响应缺少 Location 头")
+                    break
+
+                # 构建下一个 URL
+                next_url = urllib.parse.urljoin(current_url, location)
+
+                # 检查是否包含回调参数
+                if "code=" in next_url and "state=" in next_url:
+                    self._log(f"找到回调 URL: {next_url[:100]}...")
+
+                current_url = next_url
+
+            self._log("未能在重定向链中找到最终 URL")
+            return False
+
+        except Exception as e:
+            self._log(f"跟随重定向失败: {e}", "error")
+            return False
+
+    def _submit_login_form(self, did: str, sen_token) -> bool:
+        """处理 免密登录"""
+        try:
+            self._log("处理免密登录...")
+            login_body = f'{{"username":{{"value":"{self.email}","kind":"email"}}}}'
+            headers = {
+                "referer": "https://auth.openai.com/log-in",
+                "accept": "application/json",
+                "content-type": "application/json",
+            }
+
+            if sen_token:
+                sentinel = f'{{"p": "", "t": "", "c": "{sen_token}", "id": "{did}", "flow": "authorize_continue"}}'
+                headers["openai-sentinel-token"] = sentinel
+
+            response = self.session.post(
+                OPENAI_API_ENDPOINTS["signup"],
+                headers=headers,
+                data=login_body,
+            )
+            self._log(f"提交登录表单状态: {response.status_code}")
+            if response.status_code == 200:
+                return True
+            return False
+
+        except Exception as e:
+            self._log(f"处理登录失败: {e}", "error")
+            return False
+
+    def _send_verification_code_passwordless(self) -> bool:
+        """发送验证码"""
+        try:
+            import time
+            # 记录发送时间戳
+            self._otp_sent_at = time.time()
+            response = self.session.post(
+                OPENAI_API_ENDPOINTS["passwordless_send_otp"],
+                headers={
+                    "referer": "https://auth.openai.com/log-in/password",
+                    "accept": "application/json"
+                }
+            )
+
+            self._log(f"验证码发送状态: {response.status_code}")
+            return response.status_code == 200
+
+        except Exception as e:
+            self._log(f"发送验证码失败: {e}", "error")
+            return False
+
+    def _get_workspace_id(self) -> Optional[str]:
+        """获取 Workspace ID"""
+        try:
+            auth_cookie = self.session.cookies.get("oai-client-auth-session")
+            if not auth_cookie:
+                self._log("未能获取到授权 Cookie", "error")
+                return None
+
+            try:
+                segments = auth_cookie.split(".")
+                if len(segments) < 1:
+                    self._log("授权 Cookie 格式错误", "error")
+                    return None
+
+                # 解码第一个 segment
+                payload = segments[0]
+                pad = "=" * ((4 - (len(payload) % 4)) % 4)
+                decoded = base64.urlsafe_b64decode((payload + pad).encode("ascii"))
+                auth_json = json_module.loads(decoded.decode("utf-8"))
+
+                workspaces = auth_json.get("workspaces") or []
+                if not workspaces:
+                    self._log("授权 Cookie 里没有 workspace 信息", "error")
+                    return None
+
+                workspace_id = str((workspaces[0] or {}).get("id") or "").strip()
+                if not workspace_id:
+                    self._log("无法解析 workspace_id", "error")
+                    return None
+
+                self._log(f"Workspace ID: {workspace_id}")
+                return workspace_id
+
+            except Exception as e:
+                self._log(f"解析授权 Cookie 失败: {e}", "error")
+                return None
+
+        except Exception as e:
+            self._log(f"获取 Workspace ID 失败: {e}", "error")
+            return None
+
+    def _select_workspace(self, workspace_id: str) -> Optional[str]:
+        """选择 Workspace"""
+        try:
+            select_body = f'{{"workspace_id":"{workspace_id}"}}'
+
+            response = self.session.post(
+                OPENAI_API_ENDPOINTS["select_workspace"],
+                headers={
+                    "referer": "https://auth.openai.com/sign-in-with-chatgpt/codex/consent",
+                    "content-type": "application/json",
+                },
+                data=select_body,
+            )
+
+            if response.status_code != 200:
+                self._log(f"选择 workspace 失败: {response.status_code}", "error")
+                self._log(f"响应: {response.text[:200]}", "warning")
+                return None
+
+            continue_url = str((response.json() or {}).get("continue_url") or "").strip()
+            if not continue_url:
+                self._log("workspace/select 响应里缺少 continue_url", "error")
+                return None
+
+            self._log(f"Continue URL: {continue_url[:100]}...")
+            return continue_url
+
+        except Exception as e:
+            self._log(f"选择 Workspace 失败: {e}", "error")
+            return None
+
+    def _follow_redirects(self, start_url: str) -> Optional[str]:
+        """跟随重定向链，寻找回调 URL"""
+        try:
+            current_url = start_url
+            max_redirects = 6
+
+            for i in range(max_redirects):
+                self._log(f"重定向 {i+1}/{max_redirects}: {current_url[:100]}...")
+
+                response = self.session.get(
+                    current_url,
+                    allow_redirects=False,
+                    timeout=15
+                )
+
+                location = response.headers.get("Location") or ""
+
+                # 如果不是重定向状态码，停止
+                if response.status_code not in [301, 302, 303, 307, 308]:
+                    self._log(f"非重定向状态码: {response.status_code}")
+                    break
+
+                if not location:
+                    self._log("重定向响应缺少 Location 头")
+                    break
+
+                # 构建下一个 URL
+                next_url = urllib.parse.urljoin(current_url, location)
+
+                # 检查是否包含回调参数
+                if "code=" in next_url and "state=" in next_url:
+                    self._log(f"找到回调 URL: {next_url[:100]}...")
+                    return next_url
+
+                current_url = next_url
+
+            self._log("未能在重定向链中找到回调 URL", "error")
+            return None
+
+        except Exception as e:
+            self._log(f"跟随重定向失败: {e}", "error")
+            return None
+
+    def _handle_oauth_callback(self, callback_url: str) -> Optional[Dict[str, Any]]:
+        """处理 OAuth 回调"""
+        try:
+            if not self.oauth_start:
+                self._log("OAuth 流程未初始化", "error")
+                return None
+
+            self._log("处理 OAuth 回调...")
+            token_info = self.oauth_manager.handle_callback(
+                callback_url=callback_url,
+                expected_state=self.oauth_start.state,
+                code_verifier=self.oauth_start.code_verifier
+            )
+
+            self._log("OAuth 授权成功")
+            return token_info
+
+        except Exception as e:
+            self._log(f"处理 OAuth 回调失败: {e}", "error")
+            return None
+
+    def run(self) -> RegistrationResult:
+        """
+        执行完整的注册流程
+
+        支持已注册账号自动登录：
+        - 如果检测到邮箱已注册，自动切换到登录流程
+        - 已注册账号跳过：设置密码、发送验证码、创建用户账户
+        - 共用步骤：获取验证码、验证验证码、Workspace 和 OAuth 回调
+
+        Returns:
+            RegistrationResult: 注册结果
+        """
+        result = RegistrationResult(success=False, logs=self.logs)
+
+        try:
+            self._log("=" * 60)
+            self._log("开始注册流程")
+            self._log("=" * 60)
+
+            # 1. 检查 IP 地理位置
+            self._log("1. 检查 IP 地理位置...")
+            ip_ok, location = self._check_ip_location()
+            if not ip_ok:
+                result.error_message = f"IP 地理位置不支持: {location}"
+                self._log(f"IP 检查失败: {location}", "error")
+                return result
+
+            self._log(f"IP 位置: {location}")
+
+            # 2. 创建邮箱
+            self._log("2. 创建邮箱...")
+            if not self._create_email():
+                result.error_message = "创建邮箱失败"
+                return result
+
+            result.email = self.email
+
+            # 3. 初始化会话
+            self._log("3. 初始化会话...")
+            if not self._init_session():
+                result.error_message = "初始化会话失败"
+                return result
+
+            # 4. 开始 OAuth 流程
+            self._log("4. 开始 OAuth 授权流程...")
+            if not self._start_oauth():
+                result.error_message = "开始 OAuth 流程失败"
+                return result
+
+            # 5. 获取 Device ID
+            self._log("5. 获取 Device ID...")
+            did = self._get_device_id()
+            if not did:
+                result.error_message = "获取 Device ID 失败"
+                return result
+
+            # 6. 检查 Sentinel 拦截
+            self._log("6. 检查 Sentinel 拦截...")
+            sen_token = self._check_sentinel(did)
+            if sen_token:
+                self._log("Sentinel 检查通过")
+            else:
+                self._log("Sentinel 检查失败或未启用", "warning")
+
+            # 7. 提交注册表单 + 解析响应判断账号状态
+            self._log("7. 提交注册表单...")
+            signup_result = self._submit_signup_form(did, sen_token)
+            if not signup_result.success:
+                result.error_message = f"提交注册表单失败: {signup_result.error_message}"
+                return result
+
+            # 8. 检测到已注册账号 → 直接终止任务
+            if self._is_existing_account:
+                self._log(f"8. 邮箱 {self.email} 在 OpenAI 已注册，跳过注册流程", "warning")
+                result.error_message = f"邮箱 {self.email} 已在 OpenAI 注册"
+                return result
+            else:
+                self._log("8. 注册密码...")
+                password_ok, password = self._register_password()
+                if not password_ok:
+                    result.error_message = "注册密码失败"
+                    return result
+
+            # 9. 发送验证码
+            self._log("9. 发送验证码...")
+            if not self._send_verification_code():
+                result.error_message = "发送验证码失败"
+                return result
+
+            # 10. 获取验证码（超时后重发一次）
+            self._log("10. 等待验证码...")
+            code = self._get_verification_code()
+            if not code:
+                self._log("10. 验证码超时，重新发送...")
+                if self._send_verification_code():
+                    code = self._get_verification_code()
+            if not code:
+                result.error_message = "获取验证码失败"
+                return result
+
+            # 11. 验证验证码
+            self._log("11. 验证验证码...")
+            if not self._validate_verification_code(code):
+                result.error_message = "验证验证码失败"
+                return result
+
+            # 12. 创建用户账户
+            self._log("12. 创建用户账户...")
+            if not self._create_user_account():
+                result.error_message = "创建用户账户失败"
+                return result
+
+            self._log("13-1. 结束注册,启用登录流程...")
+            if not self._follow_login_redirects(self.oauth_start.auth_url):
+                result.error_message = "跟随重定向链失败"
+                return result
+
+            self._log("13-2. 提交登陆表单")
+            if not self._submit_login_form(did, sen_token):
+                result.error_message = "提交登陆表单失败"
+                return result
+
+            self._log("14. 发送验证码...")
+            if not self._send_verification_code_passwordless():
+                result.error_message = "发送验证码失败"
+                return result
+
+            self._log("15. 等待验证码...")
+            code = self._get_verification_code()
+            if not code:
+                self._log("15. 验证码超时，重新发送...")
+                if self._send_verification_code_passwordless():
+                    code = self._get_verification_code()
+            if not code:
+                result.error_message = "获取验证码失败"
+                return result
+
+            self._log("16. 验证验证码...")
+            if not self._validate_verification_code(code):
+                result.error_message = "验证验证码失败"
+                return result
+
+            # 13. 获取 Workspace ID
+            self._log("17. 获取 Workspace ID...")
+            workspace_id = self._get_workspace_id()
+            if not workspace_id:
+                result.error_message = "获取 Workspace ID 失败"
+                return result
+
+            result.workspace_id = workspace_id
+
+            # 14. 选择 Workspace
+            self._log("18. 选择 Workspace...")
+            continue_url = self._select_workspace(workspace_id)
+            if not continue_url:
+                result.error_message = "选择 Workspace 失败"
+                return result
+
+            # 15. 跟随重定向链
+            self._log("19. 跟随重定向链...")
+            callback_url = self._follow_redirects(continue_url)
+            if not callback_url:
+                result.error_message = "跟随重定向链失败"
+                return result
+
+            # 16. 处理 OAuth 回调
+            self._log("20. 处理 OAuth 回调...")
+            token_info = self._handle_oauth_callback(callback_url)
+            if not token_info:
+                result.error_message = "处理 OAuth 回调失败"
+                return result
+
+            # 提取账户信息
+            result.account_id = token_info.get("account_id", "")
+            result.access_token = token_info.get("access_token", "")
+            result.refresh_token = token_info.get("refresh_token", "")
+            result.id_token = token_info.get("id_token", "")
+            result.password = self.password or ""  # 保存密码（已注册账号为空）
+
+            # 设置来源标记
+            result.source = "register"
+
+            # 尝试获取 session_token 从 cookie
+            session_cookie = self.session.cookies.get("__Secure-next-auth.session-token")
+            if session_cookie:
+                self.session_token = session_cookie
+                result.session_token = session_cookie
+                self._log(f"获取到 Session Token")
+
+            # 17. 完成
+            self._log("=" * 60)
+            self._log("注册成功!")
+            self._log(f"邮箱: {result.email}")
+            self._log(f"Account ID: {result.account_id}")
+            self._log(f"Workspace ID: {result.workspace_id}")
+            self._log("=" * 60)
+
+            result.success = True
+            result.metadata = {
+                "email_service": self.email_service.service_type.value,
+                "proxy_used": self.proxy_url,
+                "registered_at": datetime.now().isoformat(),
+            }
+
+            return result
+
+        except Exception as e:
+            self._log(f"注册过程中发生未预期错误: {e}", "error")
+            result.error_message = str(e)
+            return result