diff --git a/.env.example b/.env.example
index 8453460b..affa5e38 100644
--- a/.env.example
+++ b/.env.example
@@ -40,8 +40,10 @@ AI_IMAGE_MODEL=gemini-2.5-flash-image
 AI_VIDEO_MODEL=kling-v2-5-turbo
 
 # ── 积分定价 ──
-QUOTA_REGISTER_GIFT_AMOUNT=100
-QUOTA_INVITE_REWARD_AMOUNT=50
+QUOTA_REGISTER_GIFT_AMOUNT=300
+QUOTA_INVITE_REWARD_AMOUNT=200
+QUOTA_INVITE_REWARD_DAILY_LIMIT=3
+QUOTA_INVITE_CODE_TTL_DAYS=30
 QUOTA_GENERATE_IMAGE_COST=10
 QUOTA_GENERATE_ACTION_COST=50
 
diff --git a/backend/packages/app/src/windup_app/bootstrap/app.py b/backend/packages/app/src/windup_app/bootstrap/app.py
index 586c8b2d..b08dec5c 100644
--- a/backend/packages/app/src/windup_app/bootstrap/app.py
+++ b/backend/packages/app/src/windup_app/bootstrap/app.py
@@ -21,8 +21,7 @@
 from windup_app.server.character.service import service as character_service
 from windup_app.server.orchestrator.dispatcher import GenerationDispatcher
 from windup_app.server.project.model import Project  # noqa: F401
-from windup_app.server.quota.model import CreditAccount, CreditTransaction  # noqa: F401
-# InviteCode, InviteRecord, TokenUsage 暂不实现
+from windup_app.server.quota.model import CreditAccount, CreditTransaction, InviteCode, InviteRecord  # noqa: F401
 from windup_app.server.user.model import User  # noqa: F401
 from windup_app.server.workflow_run.model import WorkflowRun  # noqa: F401
 from windup_app.web.api.auth import router as auth_router
diff --git a/backend/packages/app/src/windup_app/server/quota/interface.py b/backend/packages/app/src/windup_app/server/quota/interface.py
index c419c466..25b88e66 100644
--- a/backend/packages/app/src/windup_app/server/quota/interface.py
+++ b/backend/packages/app/src/windup_app/server/quota/interface.py
@@ -10,6 +10,8 @@
 from windup_app.server.quota.model import (
     CreditAccountView,
     CreditTransactionView,
+    InviteCode,
+    InviteCodeView,
 )
 
 
@@ -35,7 +37,12 @@ def reserve_credit(
 
     @abstractmethod
     def capture_credit(
-        self, session: Session, user_id: int, actual_amount: int, ref_id: str, frozen_amount: int
+        self,
+        session: Session,
+        user_id: int,
+        actual_amount: int,
+        ref_id: str,
+        frozen_amount: int,
     ) -> None:
         """预付费扣减：冻结转消耗。
 
@@ -65,7 +72,12 @@ def release_credit(
 
     @abstractmethod
     def credit(
-        self, session: Session, user_id: int, amount: int, reason: int, ref_id: str | None = None
+        self,
+        session: Session,
+        user_id: int,
+        amount: int,
+        reason: int,
+        ref_id: str | None = None,
     ) -> None:
         """入账：增加可用余额与累计获得。"""
 
@@ -78,18 +90,22 @@ def list_transactions(
         """分页查询积分流水，返回 (列表, 总数)。"""
 
     # -- 邀请码 -----------------------------------------------------------
-    # TODO 目前先不实现。
-    # @abstractmethod
-    # def get_invite_code(self, session: Session, user_id: int) -> InviteCodeView | None:
-    #     """获取用户当前邀请码。"""
-    #
-    # @abstractmethod
-    # def generate_invite_code(self, session: Session, user_id: int) -> InviteCodeView:
-    #     """生成新邀请码（替换旧码）。"""
-    #
-    # @abstractmethod
-    # def redeem_invite_code(self, session: Session, user_id: int, code: str) -> None:
-    #     """兑换邀请码，双方各得积分。
-    #
-    #     :raises BizException: 邀请码无效 / 已达上限 / 已填过码。
-    #     """
+
+    @abstractmethod
+    def get_invite_code(self, session: Session, user_id: int) -> InviteCodeView:
+        """获取当前未过期邀请码；没有或已过期则签发新行。"""
+
+    @abstractmethod
+    def generate_invite_code(self, session: Session, user_id: int) -> InviteCodeView:
+        """签发新邀请码：插入新行，仍有效的旧码立即过期但保留。"""
+
+    @abstractmethod
+    def require_active_invite(self, session: Session, code: str) -> InviteCode:
+        """注册前校验邀请码存在且未过期。非法返回「邀请码无效」，过期返回「邀请码已过期」。"""
+
+    @abstractmethod
+    def redeem_invite_code(self, session: Session, user_id: int, code: str) -> None:
+        """注册时兑换邀请码。被邀请人始终得邀请奖励；邀请人受每日人数上限。
+
+        :raises BizException: 邀请码无效 / 已过期 / 已填过码 / 不能填自己的码。
+        """
diff --git a/backend/packages/app/src/windup_app/server/quota/model.py b/backend/packages/app/src/windup_app/server/quota/model.py
index 45e82ff4..e04a0ff3 100644
--- a/backend/packages/app/src/windup_app/server/quota/model.py
+++ b/backend/packages/app/src/windup_app/server/quota/model.py
@@ -15,11 +15,19 @@
 """
 
 from dataclasses import dataclass, field
-from datetime import datetime, timezone
-
-from sqlalchemy import BigInteger, DateTime, Integer, SmallInteger, String, UniqueConstraint
+from datetime import datetime, timedelta, timezone
+
+from sqlalchemy import (
+    BigInteger,
+    DateTime,
+    Integer,
+    SmallInteger,
+    String,
+    UniqueConstraint,
+)
 from sqlalchemy.orm import Mapped, mapped_column
 
+from windup_framework.config.quota import settings as quota_settings
 from windup_framework.db import Base
 
 
@@ -107,18 +115,70 @@ class CreditTransaction(Base):
     )
 
 
-# -- 以下 ORM 暂不实现（枚举 / 接口已预留）----------------------------------
-#
-# class InviteCode(Base):
-#     """邀请码。"""
-#     __tablename__ = "windup_invite_code"
-#     ...
-#
-# class InviteRecord(Base):
-#     """邀请记录。"""
-#     __tablename__ = "windup_invite_record"
-#     ...
-#
+class InviteCode(Base):
+    """用户邀请码。只增不删；轮换插入新行，旧行保留。"""
+
+    __tablename__ = "windup_invite_code"
+
+    id: Mapped[int] = mapped_column(
+        BigInteger().with_variant(Integer, "sqlite"),
+        primary_key=True,
+        autoincrement=True,
+    )
+    user_id: Mapped[int] = mapped_column(
+        BigInteger().with_variant(Integer, "sqlite"),
+        index=True,
+        nullable=False,
+    )
+    code: Mapped[str] = mapped_column(String(16), unique=True, nullable=False)
+    used_count: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+    expires_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+        default=lambda: datetime.now(timezone.utc)
+        + timedelta(days=quota_settings.invite_code_ttl_days),
+    )
+    create_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+        default=lambda: datetime.now(timezone.utc),
+    )
+    update_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+        default=lambda: datetime.now(timezone.utc),
+        onupdate=lambda: datetime.now(timezone.utc),
+    )
+
+
+class InviteRecord(Base):
+    """一次成功的邀请关系。被邀请人只能出现一次。"""
+
+    __tablename__ = "windup_invite_record"
+
+    id: Mapped[int] = mapped_column(
+        BigInteger().with_variant(Integer, "sqlite"),
+        primary_key=True,
+        autoincrement=True,
+    )
+    inviter_id: Mapped[int] = mapped_column(
+        BigInteger().with_variant(Integer, "sqlite"),
+        nullable=False,
+        index=True,
+    )
+    invitee_id: Mapped[int] = mapped_column(
+        BigInteger().with_variant(Integer, "sqlite"),
+        unique=True,
+        nullable=False,
+    )
+    code: Mapped[str] = mapped_column(String(16), nullable=False)
+    create_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+        default=lambda: datetime.now(timezone.utc),
+    )
+
+
 # class TokenUsage(Base):
 #     """Token 用量记录。"""
 #     __tablename__ = "windup_token_usage"
@@ -156,9 +216,12 @@ class CreditTransactionView:
     create_at: datetime = field(default_factory=lambda: datetime.now(timezone.utc))
 
 
-# -- 暂不实现 --
-#
-# @dataclass
-# class InviteCodeView:
-#     """邀请码视图。"""
-#     ...
+@dataclass
+class InviteCodeView:
+    """邀请码视图。"""
+
+    code: str
+    used_count: int = 0
+    expires_at: datetime = field(default_factory=lambda: datetime.now(timezone.utc))
+    create_at: datetime = field(default_factory=lambda: datetime.now(timezone.utc))
+    update_at: datetime = field(default_factory=lambda: datetime.now(timezone.utc))
diff --git a/backend/packages/app/src/windup_app/server/quota/service.py b/backend/packages/app/src/windup_app/server/quota/service.py
index 5fcb63bf..e7a8d72f 100644
--- a/backend/packages/app/src/windup_app/server/quota/service.py
+++ b/backend/packages/app/src/windup_app/server/quota/service.py
@@ -12,8 +12,12 @@
 """
 
 import logging
+import re
+import secrets
+from datetime import datetime, timedelta, timezone
 
 from sqlalchemy import func, select
+from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm import Session
 
 from windup_common.enums.biz_code import BizCode
@@ -26,10 +30,68 @@
     CreditAccountView,
     CreditTransaction,
     CreditTransactionView,
+    InviteCode,
+    InviteCodeView,
+    InviteRecord,
 )
+from windup_app.server.user.model import User
+from windup_framework.config.quota import settings as quota_settings
 
 logger = logging.getLogger("windup.quota.service")
 
+_INVITE_ALPHABET = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789"
+_INVITE_CODE_LENGTH = 8
+_INVITE_CODE_RE = re.compile(rf"^[{re.escape(_INVITE_ALPHABET)}]{{4,16}}$")
+
+
+def normalize_invite_code(code: str) -> str:
+    return code.strip().upper()
+
+
+def parse_invite_code(code: str) -> str:
+    """解析邀请链接传入的邀请码，字符集与前端 INVITE_CODE_PATTERN 一致。"""
+    normalized = normalize_invite_code(code)
+    if _INVITE_CODE_RE.fullmatch(normalized) is None:
+        raise BizException("邀请码无效", code=BizCode.BAD_REQUEST)
+    return normalized
+
+
+def _new_invite_code() -> str:
+    return "".join(secrets.choice(_INVITE_ALPHABET) for _ in range(_INVITE_CODE_LENGTH))
+
+
+def _is_invitee_unique_violation(exc: IntegrityError) -> bool:
+    text = f"{getattr(exc, 'orig', '')} {exc}".lower()
+    return "invitee" in text or "windup_invite_record" in text
+
+
+def _now() -> datetime:
+    return datetime.now(timezone.utc)
+
+
+def _utc_day_start(now: datetime | None = None) -> datetime:
+    current = now or _now()
+    if current.tzinfo is None:
+        current = current.replace(tzinfo=timezone.utc)
+    return current.astimezone(timezone.utc).replace(
+        hour=0, minute=0, second=0, microsecond=0
+    )
+
+
+def _is_expired(expires_at: datetime) -> bool:
+    exp = expires_at if expires_at.tzinfo else expires_at.replace(tzinfo=timezone.utc)
+    return exp <= _now()
+
+
+def _to_invite_view(row: InviteCode) -> InviteCodeView:
+    return InviteCodeView(
+        code=row.code,
+        used_count=row.used_count,
+        expires_at=row.expires_at,
+        create_at=row.create_at,
+        update_at=row.update_at,
+    )
+
 
 def _to_account_view(account: CreditAccount) -> CreditAccountView:
     return CreditAccountView(
@@ -120,17 +182,30 @@ def reserve_credit(
         session.flush()
 
         self._write_txn(
-            session, user_id, -amount, CreditReason.FROZEN,
-            BillingMode.PREPAID, account.balance, ref_id,
+            session,
+            user_id,
+            -amount,
+            CreditReason.FROZEN,
+            BillingMode.PREPAID,
+            account.balance,
+            ref_id,
         )
 
         logger.info(
             "[WINDUP] 积分冻结 | user_id=%s amount=%s ref_id=%s balance=%s",
-            user_id, amount, ref_id, account.balance,
+            user_id,
+            amount,
+            ref_id,
+            account.balance,
         )
 
     def capture_credit(
-        self, session: Session, user_id: int, actual_amount: int, ref_id: str, frozen_amount: int
+        self,
+        session: Session,
+        user_id: int,
+        actual_amount: int,
+        ref_id: str,
+        frozen_amount: int,
     ) -> None:
         """预付费扣减：frozen -= frozen_amount, total_spent += actual_amount。
 
@@ -158,20 +233,34 @@ def capture_credit(
 
         # 写扣减流水
         self._write_txn(
-            session, user_id, -actual_amount, CreditReason.CAPTURED,
-            BillingMode.PREPAID, account.balance, ref_id,
+            session,
+            user_id,
+            -actual_amount,
+            CreditReason.CAPTURED,
+            BillingMode.PREPAID,
+            account.balance,
+            ref_id,
         )
 
         # 有差额退回时写退款流水（用不同 reason 区分，ref_id 加后缀去重）
         if refund > 0:
             self._write_txn(
-                session, user_id, refund, CreditReason.REFUND,
-                BillingMode.PREPAID, account.balance, f"{ref_id}:refund",
+                session,
+                user_id,
+                refund,
+                CreditReason.REFUND,
+                BillingMode.PREPAID,
+                account.balance,
+                f"{ref_id}:refund",
             )
 
         logger.info(
             "[WINDUP] 积分扣减 | user_id=%s actual=%s frozen=%s refund=%s balance=%s",
-            user_id, actual_amount, frozen_amount, refund, account.balance,
+            user_id,
+            actual_amount,
+            frozen_amount,
+            refund,
+            account.balance,
         )
 
     def release_credit(
@@ -191,13 +280,21 @@ def release_credit(
         session.flush()
 
         self._write_txn(
-            session, user_id, amount, CreditReason.REFUND,
-            BillingMode.PREPAID, account.balance, f"{ref_id}:release",
+            session,
+            user_id,
+            amount,
+            CreditReason.REFUND,
+            BillingMode.PREPAID,
+            account.balance,
+            f"{ref_id}:release",
         )
 
         logger.info(
             "[WINDUP] 积分解冻 | user_id=%s amount=%s ref_id=%s balance=%s",
-            user_id, amount, ref_id, account.balance,
+            user_id,
+            amount,
+            ref_id,
+            account.balance,
         )
 
     # -- 后付费：原子扣减（暂不实现，AGENT_TOKEN / POSTPAID 枚举已预留）------
@@ -211,7 +308,12 @@ def release_credit(
     # -- 入账（赠送 / 奖励 / 管理员调整）----------------------------------
 
     def credit(
-        self, session: Session, user_id: int, amount: int, reason: int, ref_id: str | None = None
+        self,
+        session: Session,
+        user_id: int,
+        amount: int,
+        reason: int,
+        ref_id: str | None = None,
     ) -> None:
         """入账：balance += amount, total_earned += amount。"""
         if amount <= 0:
@@ -223,13 +325,21 @@ def credit(
         session.flush()
 
         self._write_txn(
-            session, user_id, amount, reason,
-            BillingMode.PREPAID, account.balance, ref_id,
+            session,
+            user_id,
+            amount,
+            reason,
+            BillingMode.PREPAID,
+            account.balance,
+            ref_id,
         )
 
         logger.info(
             "[WINDUP] 积分入账 | user_id=%s amount=%s reason=%s balance=%s",
-            user_id, amount, reason, account.balance,
+            user_id,
+            amount,
+            reason,
+            account.balance,
         )
 
     # -- 流水查询 ---------------------------------------------------------
@@ -254,8 +364,128 @@ def list_transactions(
 
         return [_to_txn_view(r) for r in rows], total or 0
 
-    # -- 邀请码（暂不实现）-------------------------------------------------
-    # TODO: get_invite_code / generate_invite_code / redeem_invite_code
+    # -- 邀请码 -----------------------------------------------------------
+
+    def get_invite_code(self, session: Session, user_id: int) -> InviteCodeView:
+        row = session.scalar(
+            select(InviteCode)
+            .where(InviteCode.user_id == user_id, InviteCode.expires_at > _now())
+            .order_by(InviteCode.id.desc())
+        )
+        if row is not None:
+            return _to_invite_view(row)
+        return self.generate_invite_code(session, user_id)
+
+    def generate_invite_code(self, session: Session, user_id: int) -> InviteCodeView:
+        if session.get(User, user_id) is None:
+            raise BizException("用户不存在", code=BizCode.NOT_FOUND)
+
+        now = _now()
+        existing = session.scalars(
+            select(InviteCode)
+            .where(InviteCode.user_id == user_id)
+            .with_for_update()
+        ).all()
+        for row in existing:
+            if not _is_expired(row.expires_at):
+                row.expires_at = now
+
+        row = InviteCode(
+            user_id=user_id,
+            code=self._allocate_invite_code(session),
+            used_count=0,
+            expires_at=now
+            + timedelta(days=quota_settings.invite_code_ttl_days),
+        )
+        session.add(row)
+        session.flush()
+        logger.info("[WINDUP] 生成邀请码 | user_id=%s code=%s", user_id, row.code)
+        return _to_invite_view(row)
+
+    def _allocate_invite_code(self, session: Session) -> str:
+        for _ in range(16):
+            code = _new_invite_code()
+            if session.scalar(select(InviteCode.id).where(InviteCode.code == code)) is None:
+                return code
+        raise BizException("邀请码生成失败，请稍后重试", code=BizCode.BAD_REQUEST)
+
+    def require_active_invite(self, session: Session, code: str) -> InviteCode:
+        normalized = parse_invite_code(code)
+        invite = session.scalar(
+            select(InviteCode).where(InviteCode.code == normalized)
+        )
+        if invite is None:
+            raise BizException("邀请码无效", code=BizCode.BAD_REQUEST)
+        if _is_expired(invite.expires_at):
+            raise BizException("邀请码已过期", code=BizCode.NOT_FOUND)
+        return invite
+
+    def redeem_invite_code(self, session: Session, user_id: int, code: str) -> None:
+        invite = self.require_active_invite(session, code)
+        if invite.user_id == user_id:
+            raise BizException("不能填写自己的邀请码", code=BizCode.BAD_REQUEST)
+        if session.get(User, user_id) is None:
+            raise BizException("用户不存在", code=BizCode.NOT_FOUND)
+
+        existing = session.scalar(
+            select(InviteRecord.id).where(InviteRecord.invitee_id == user_id)
+        )
+        if existing is not None:
+            raise BizException("已填写过邀请码", code=BizCode.BAD_REQUEST)
+
+        self._get_account_for_update(session, invite.user_id)
+
+        record = InviteRecord(
+            inviter_id=invite.user_id,
+            invitee_id=user_id,
+            code=invite.code,
+        )
+        session.add(record)
+        invite.used_count += 1
+        try:
+            session.flush()
+        except IntegrityError as exc:
+            if _is_invitee_unique_violation(exc):
+                raise BizException("已填写过邀请码", code=BizCode.BAD_REQUEST) from exc
+            raise
+
+        reward = quota_settings.invite_reward_amount
+        today_count = session.scalar(
+            select(func.count())
+            .select_from(InviteRecord)
+            .where(
+                InviteRecord.inviter_id == invite.user_id,
+                InviteRecord.create_at >= _utc_day_start(),
+            )
+        ) or 0
+        if today_count <= quota_settings.invite_reward_daily_limit:
+            self.credit(
+                session,
+                invite.user_id,
+                reward,
+                int(CreditReason.INVITE_REWARD),
+                f"invite:{user_id}:inviter",
+            )
+        else:
+            logger.info(
+                "[WINDUP] 邀请人日限额已满，跳过邀请人奖励 | inviter=%s invitee=%s count=%s",
+                invite.user_id,
+                user_id,
+                today_count,
+            )
+        self.credit(
+            session,
+            user_id,
+            reward,
+            int(CreditReason.INVITE_REWARD),
+            f"invite:{user_id}:invitee",
+        )
+        logger.info(
+            "[WINDUP] 兑换邀请码 | invitee=%s inviter=%s code=%s",
+            user_id,
+            invite.user_id,
+            invite.code,
+        )
 
 
 service = SqlAlchemyQuotaService()
diff --git a/backend/packages/app/src/windup_app/server/user/interface.py b/backend/packages/app/src/windup_app/server/user/interface.py
index c8c0d0d2..6ea3d826 100644
--- a/backend/packages/app/src/windup_app/server/user/interface.py
+++ b/backend/packages/app/src/windup_app/server/user/interface.py
@@ -27,9 +27,9 @@ class UserService(ABC):
 
     @abstractmethod
     def register_by_email(self, session: Session, input: RegisterInput) -> LoginResult:
-        """邮箱+密码注册，注册成功即登录。
+        """邮箱+验证码+密码注册。邀请码选填。
 
-        :raises windup_common.exceptions.BizException: 邮箱已注册。
+        :raises windup_common.exceptions.BizException: 邮箱已注册 / 邀请码无效。
         """
 
     # -- 登录 ------------------------------------------------------------
@@ -53,9 +53,9 @@ def send_verification_code(self, email: str, purpose: str) -> None:
 
     @abstractmethod
     def login_by_code(self, session: Session, input: LoginByCodeInput) -> LoginResult:
-        """邮箱+验证码登录。内测期间不自动建号。
+        """邮箱+验证码登录。未知邮箱自动建号并赠送注册积分。
 
-        :raises windup_common.exceptions.BizException: 验证码错误 / 已过期 / 账号不存在 / 账号已封禁。
+        :raises windup_common.exceptions.BizException: 验证码错误 / 已过期 / 账号已封禁。
         """
 
     # -- 登出 ------------------------------------------------------------
diff --git a/backend/packages/app/src/windup_app/server/user/model.py b/backend/packages/app/src/windup_app/server/user/model.py
index 31b51464..c7460228 100644
--- a/backend/packages/app/src/windup_app/server/user/model.py
+++ b/backend/packages/app/src/windup_app/server/user/model.py
@@ -115,6 +115,7 @@ class RegisterInput:
     password: str
     code: str
     nickname: str | None = None
+    invite_code: str | None = None
 
 
 @dataclass
diff --git a/backend/packages/app/src/windup_app/server/user/service.py b/backend/packages/app/src/windup_app/server/user/service.py
index d5bc1b03..572cf099 100644
--- a/backend/packages/app/src/windup_app/server/user/service.py
+++ b/backend/packages/app/src/windup_app/server/user/service.py
@@ -49,7 +49,7 @@
 
 JWT_SECRET = jwt_settings.secret.get_secret_value()
 JWT_ALGORITHM = "HS256"
-ACCESS_TOKEN_EXPIRE_SECONDS = 15 * 60        # 15 分钟
+ACCESS_TOKEN_EXPIRE_SECONDS = 15 * 60  # 15 分钟
 REFRESH_TOKEN_EXPIRE_SECONDS = 7 * 24 * 3600  # 7 天
 
 # -- 密码哈希 -------------------------------------------------------------
@@ -64,6 +64,7 @@ def _verify_password(password: str, hashed: str) -> bool:
     """验证密码。"""
     return bcrypt.checkpw(password.encode(), hashed.encode())
 
+
 # -- Redis key 前缀 -------------------------------------------------------
 
 VERIFY_COOLDOWN_KEY = "verify:cooldown:{email}"
@@ -72,12 +73,12 @@ def _verify_password(password: str, hashed: str) -> bool:
 LOGIN_FAIL_KEY = "login:fail:{email}"
 LOGIN_LOCK_KEY = "login:lock:{email}"
 
-VERIFY_CODE_TTL = 300   # 5 分钟
-COOLDOWN_TTL = 60       # 60 秒
+VERIFY_CODE_TTL = 300  # 5 分钟
+COOLDOWN_TTL = 60  # 60 秒
 
-LOGIN_FAIL_LIMIT = 5            # 连续错误密码上限
-LOGIN_FAIL_WINDOW = 15 * 60     # 失败计数窗口 15 分钟
-LOGIN_LOCK_DURATION = 15 * 60   # 锁定时长 15 分钟
+LOGIN_FAIL_LIMIT = 5  # 连续错误密码上限
+LOGIN_FAIL_WINDOW = 15 * 60  # 失败计数窗口 15 分钟
+LOGIN_LOCK_DURATION = 15 * 60  # 锁定时长 15 分钟
 
 
 def _hash_token(token: str) -> str:
@@ -166,11 +167,18 @@ def redis(self) -> redis_lib.Redis:
 
     # -- 注册 ------------------------------------------------------------
 
-    def register_by_email(
-        self, session: Session, input: RegisterInput
-    ) -> LoginResult:
-        """邮箱+验证码+密码注册。"""
-        # 校验验证码
+    def register_by_email(self, session: Session, input: RegisterInput) -> LoginResult:
+        """邮箱+验证码+密码注册。邀请码选填。"""
+        from windup_app.server.quota.service import (
+            parse_invite_code,
+            service as quota_service,
+        )
+
+        raw_invite = (input.invite_code or "").strip()
+        invite_code = parse_invite_code(raw_invite) if raw_invite else None
+        if invite_code is not None:
+            quota_service.require_active_invite(session, invite_code)
+
         self._verify_code(input.email, input.code, "register")
 
         # 检查邮箱唯一
@@ -184,13 +192,17 @@ def register_by_email(
             email=input.email,
             password_hash=_hash_password(input.password),
             nickname=input.nickname,
-            email_verified_at=datetime.now(timezone.utc),  # 注册即验证（已通过验证码校验）
+            email_verified_at=datetime.now(
+                timezone.utc
+            ),  # 注册即验证（已通过验证码校验）
         )
         session.add(user)
         session.flush()
 
-        # 注册送积分
+        # 注册送积分；有邀请码再发双方邀请奖励
         self._create_credit_account(session, user.id)
+        if invite_code is not None:
+            quota_service.redeem_invite_code(session, user.id, invite_code)
 
         # 注册即登录，签发 token
         access_token = create_access_token(user.id, user.email)
@@ -270,13 +282,12 @@ def login_by_password(
 
     def send_verification_code(self, email: str, purpose: str) -> None:
         """发送邮箱验证码。"""
-        if purpose == "register":
-            raise BizException("内测期间暂不开放注册", code=BizCode.BAD_REQUEST)
-
         # 频率限制
         cooldown_key = VERIFY_COOLDOWN_KEY.format(email=email)
         if self.redis.get(cooldown_key):
-            raise BizException("发送过于频繁，请稍后再试", code=BizCode.TOO_MANY_REQUESTS)
+            raise BizException(
+                "发送过于频繁，请稍后再试", code=BizCode.TOO_MANY_REQUESTS
+            )
 
         code = _generate_code()
         code_key = VERIFY_CODE_KEY.format(purpose=purpose, email=email)
@@ -302,20 +313,26 @@ def _verify_code(self, email: str, code: str, purpose: str) -> None:
         # 验证通过，删除验证码
         self.redis.delete(code_key)
 
-    def login_by_code(
-        self, session: Session, input: LoginByCodeInput
-    ) -> LoginResult:
-        """邮箱+验证码登录。内测期间不自动建号。"""
+    def login_by_code(self, session: Session, input: LoginByCodeInput) -> LoginResult:
+        """邮箱+验证码登录。未知邮箱自动建号并赠送注册积分。"""
         # 校验验证码
         self._verify_code(input.email, input.code, "login")
 
         user = session.scalar(select(User).where(User.email == input.email))
         if user is None:
-            raise BizException("账号不存在", code=BizCode.NOT_FOUND)
-        if user.status == UserStatus.BANNED:
-            raise BizException("账号已被封禁", code=BizCode.BAD_REQUEST)
-        if user.email_verified_at is None:
-            user.email_verified_at = datetime.now(timezone.utc)
+            user = User(
+                email=input.email,
+                password_hash="",
+                email_verified_at=datetime.now(timezone.utc),
+            )
+            session.add(user)
+            session.flush()
+            self._create_credit_account(session, user.id)
+        else:
+            if user.status == UserStatus.BANNED:
+                raise BizException("账号已被封禁", code=BizCode.BAD_REQUEST)
+            if user.email_verified_at is None:
+                user.email_verified_at = datetime.now(timezone.utc)
 
         user.last_login_at = datetime.now(timezone.utc)
         session.flush()
@@ -443,9 +460,7 @@ def change_password(
         self._revoke_all_user_tokens(user_id)
         logger.info("[WINDUP] 密码已修改 | user_id=%s", user_id)
 
-    def reset_password(
-        self, session: Session, input: ResetPasswordInput
-    ) -> None:
+    def reset_password(self, session: Session, input: ResetPasswordInput) -> None:
         """邮箱+验证码重置密码（忘记密码场景）。"""
         # 校验验证码（purpose 必须为 reset_password）
         self._verify_code(input.email, input.code, "reset_password")
@@ -517,7 +532,8 @@ def _create_credit_account(self, session: Session, user_id: int) -> None:
 
         logger.info(
             "[WINDUP] 注册送积分 | user_id=%s amount=%s",
-            user_id, quota_settings.register_gift_amount,
+            user_id,
+            quota_settings.register_gift_amount,
         )
 
     def _store_refresh_token(self, jti: str, user_id: int) -> None:
diff --git a/backend/packages/app/src/windup_app/web/api/auth.py b/backend/packages/app/src/windup_app/web/api/auth.py
index 72504c2f..eb76d7db 100644
--- a/backend/packages/app/src/windup_app/web/api/auth.py
+++ b/backend/packages/app/src/windup_app/web/api/auth.py
@@ -6,14 +6,20 @@
 import logging
 
 from fastapi import APIRouter, Depends, Request
-from pydantic import BaseModel, ConfigDict, Field, EmailStr
+from pydantic import BaseModel, ConfigDict, Field, EmailStr, field_validator
 from sqlalchemy.orm import Session
 
 from windup_common.result import Response
 
 from windup_framework.db import get_session
 
-from windup_app.server.user.model import ResetPasswordInput, UpdateNicknameInput, User, UserView
+from windup_app.server.user.model import (
+    RegisterInput,
+    ResetPasswordInput,
+    UpdateNicknameInput,
+    User,
+    UserView,
+)
 from windup_app.server.user.service import service
 
 logger = logging.getLogger("windup.auth.api")
@@ -31,6 +37,18 @@ class RegisterRequest(BaseModel):
     password: str = Field(min_length=8, max_length=128)
     code: str = Field(min_length=6, max_length=6, description="邮箱验证码")
     nickname: str | None = Field(default=None, max_length=50)
+    invite_code: str | None = Field(
+        default=None,
+        max_length=16,
+        description="邀请链接中的邀请码，选填；有则发双方邀请奖励",
+    )
+
+    @field_validator("invite_code", mode="before")
+    @classmethod
+    def blank_invite_code(cls, value: object) -> object:
+        if isinstance(value, str) and not value.strip():
+            return None
+        return value
 
 
 class LoginRequest(BaseModel):
@@ -77,7 +95,9 @@ class ResetPasswordRequest(BaseModel):
     """重置密码请求（忘记密码场景）。"""
 
     email: EmailStr
-    code: str = Field(min_length=6, max_length=6, description="reset_password 用途的验证码")
+    code: str = Field(
+        min_length=6, max_length=6, description="reset_password 用途的验证码"
+    )
     new_password: str = Field(min_length=8, max_length=128)
 
 
@@ -111,15 +131,25 @@ class UserOut(BaseModel):
 
 @router.post("/register", response_model=Response[TokenResponse])
 def register(body: RegisterRequest, session: Session = Depends(get_session)):
-    """邮箱+验证码+密码注册。
-
-    内测期间关闭公开注册，路由与请求模型保留以便以后重新开放。
-    """
-    from windup_common.enums.biz_code import BizCode
-    from windup_common.exceptions import BizException
-
-    del body, session
-    raise BizException("内测期间暂不开放注册", code=BizCode.BAD_REQUEST)
+    """邮箱+验证码+密码注册。邀请码选填。"""
+    result = service.register_by_email(
+        session,
+        RegisterInput(
+            email=body.email,
+            password=body.password,
+            code=body.code,
+            nickname=body.nickname,
+            invite_code=body.invite_code,
+        ),
+    )
+    return Response.success(
+        TokenResponse(
+            access_token=result.access_token,
+            refresh_token=result.refresh_token,
+            user=result.user,
+        ),
+        message="注册成功",
+    )
 
 
 @router.post("/login", response_model=Response[TokenResponse])
@@ -127,7 +157,9 @@ def login(body: LoginRequest, session: Session = Depends(get_session)):
     """邮箱+密码+验证码登录。"""
     result = service.login_by_password(
         session,
-        type("LoginByPasswordInput", (), {"email": body.email, "password": body.password})(),
+        type(
+            "LoginByPasswordInput", (), {"email": body.email, "password": body.password}
+        )(),
     )
     return Response.success(
         TokenResponse(
@@ -148,7 +180,7 @@ def send_code(body: SendCodeRequest):
 
 @router.post("/login-by-code", response_model=Response[TokenResponse])
 def login_by_code(body: LoginByCodeRequest, session: Session = Depends(get_session)):
-    """验证码登录。内测期间不自动注册。"""
+    """验证码登录。未知邮箱自动建号并赠送注册积分。"""
     result = service.login_by_code(
         session,
         type("LoginByCodeInput", (), {"email": body.email, "code": body.code})(),
@@ -191,26 +223,37 @@ def get_me(request: Request, session: Session = Depends(get_session)):
     if user is None:
         from windup_common.enums.biz_code import BizCode
         from windup_common.exceptions import BizException
+
         raise BizException("用户不存在", code=BizCode.NOT_FOUND)
     return Response.success(
         UserOut(
             id=user.id,
             email=user.email,
             nickname=user.nickname,
-            email_verified_at=user.email_verified_at.isoformat() if user.email_verified_at else None,
+            email_verified_at=user.email_verified_at.isoformat()
+            if user.email_verified_at
+            else None,
             status=user.status,
         )
     )
 
 
 @router.post("/change-password", response_model=Response[None])
-def change_password(body: ChangePasswordRequest, request: Request, session: Session = Depends(get_session)):
+def change_password(
+    body: ChangePasswordRequest,
+    request: Request,
+    session: Session = Depends(get_session),
+):
     """修改密码。"""
     current_user = request.state.current_user
     service.change_password(
         session,
         current_user.id,
-        type("ChangePasswordInput", (), {"old_password": body.old_password, "new_password": body.new_password})(),
+        type(
+            "ChangePasswordInput",
+            (),
+            {"old_password": body.old_password, "new_password": body.new_password},
+        )(),
     )
     return Response.success(None, message="密码修改成功")
 
@@ -220,13 +263,19 @@ def reset_password(body: ResetPasswordRequest, session: Session = Depends(get_se
     """邮箱+验证码重置密码（忘记密码）。"""
     service.reset_password(
         session,
-        ResetPasswordInput(email=body.email, code=body.code, new_password=body.new_password),
+        ResetPasswordInput(
+            email=body.email, code=body.code, new_password=body.new_password
+        ),
     )
     return Response.success(None, message="密码重置成功")
 
 
 @router.patch("/profile", response_model=Response[UserOut])
-def update_nickname(body: UpdateNicknameRequest, request: Request, session: Session = Depends(get_session)):
+def update_nickname(
+    body: UpdateNicknameRequest,
+    request: Request,
+    session: Session = Depends(get_session),
+):
     """修改当前用户昵称。"""
     current_user = request.state.current_user
     user_view = service.update_nickname(
@@ -237,7 +286,9 @@ def update_nickname(body: UpdateNicknameRequest, request: Request, session: Sess
             id=user_view.id,
             email=user_view.email,
             nickname=user_view.nickname,
-            email_verified_at=user_view.email_verified_at.isoformat() if user_view.email_verified_at else None,
+            email_verified_at=user_view.email_verified_at.isoformat()
+            if user_view.email_verified_at
+            else None,
             status=user_view.status,
         ),
         message="昵称修改成功",
diff --git a/backend/packages/app/src/windup_app/web/api/quota.py b/backend/packages/app/src/windup_app/web/api/quota.py
index 90d3f56c..85e6c257 100644
--- a/backend/packages/app/src/windup_app/web/api/quota.py
+++ b/backend/packages/app/src/windup_app/web/api/quota.py
@@ -4,11 +4,8 @@
 --------
 GET  /quota/balance          查询积分余额
 GET  /quota/transactions     查询积分流水（分页）
-
-暂不实现：
-POST /quota/invite/redeem    兑换邀请码
 GET  /quota/invite/code      获取我的邀请码
-POST /quota/invite/generate  生成新邀请码
+POST /quota/invite/generate  签发新邀请码
 """
 
 from __future__ import annotations
@@ -63,15 +60,14 @@ class CreditTransactionOut(BaseModel):
     create_at: datetime
 
 
-# -- 暂不实现 ----------------------------------------------------------------
-#
-# class InviteCodeOut(BaseModel):
-#     """邀请码响应。"""
-#     ...
-#
-# class RedeemRequest(BaseModel):
-#     """兑换邀请码请求。"""
-#     ...
+class InviteCodeOut(BaseModel):
+    """邀请码响应。"""
+
+    code: str
+    used_count: int
+    expires_at: datetime
+    create_at: datetime
+    update_at: datetime
 
 
 # -- 端点 ----------------------------------------------------------------
@@ -102,7 +98,9 @@ def list_transactions(
 ) -> ListResponse[CreditTransactionOut]:
     """查询积分流水（分页）。"""
     user_id = request.state.current_user.id
-    txns, total = service.list_transactions(session, user_id, page=page, page_size=page_size)
+    txns, total = service.list_transactions(
+        session, user_id, page=page, page_size=page_size
+    )
     return ListResponse.success(
         [CreditTransactionOut.model_validate(t) for t in txns],
         total=total,
@@ -111,13 +109,38 @@ def list_transactions(
     )
 
 
-# -- 邀请码端点（暂不实现）--------------------------------------------------
-#
-# @router.get("/invite/code")
-# def get_invite_code(...): ...
-#
-# @router.post("/invite/generate")
-# def generate_invite_code(...): ...
-#
-# @router.post("/invite/redeem")
-# def redeem_invite_code(...): ...
+@router.get("/invite/code", response_model=Response[InviteCodeOut])
+def get_invite_code(
+    request: Request,
+    session: Session = Depends(get_session),
+) -> Response[InviteCodeOut]:
+    """获取当前用户未过期邀请码；没有或已过期则签发新行。"""
+    view = service.get_invite_code(session, request.state.current_user.id)
+    return Response.success(
+        InviteCodeOut(
+            code=view.code,
+            used_count=view.used_count,
+            expires_at=view.expires_at,
+            create_at=view.create_at,
+            update_at=view.update_at,
+        )
+    )
+
+
+@router.post("/invite/generate", response_model=Response[InviteCodeOut])
+def generate_invite_code(
+    request: Request,
+    session: Session = Depends(get_session),
+) -> Response[InviteCodeOut]:
+    """签发新邀请码。旧码立即过期，行保留。"""
+    view = service.generate_invite_code(session, request.state.current_user.id)
+    return Response.success(
+        InviteCodeOut(
+            code=view.code,
+            used_count=view.used_count,
+            expires_at=view.expires_at,
+            create_at=view.create_at,
+            update_at=view.update_at,
+        ),
+        message="邀请码已更新",
+    )
diff --git a/backend/packages/framework/src/windup_framework/config/quota.py b/backend/packages/framework/src/windup_framework/config/quota.py
index 3d648feb..af1ca72c 100644
--- a/backend/packages/framework/src/windup_framework/config/quota.py
+++ b/backend/packages/framework/src/windup_framework/config/quota.py
@@ -9,7 +9,7 @@
 class QuotaSettings(BaseSettings):
     """积分定价配置。
 
-    环境变量前缀 ``QUOTA_``，例如 ``QUOTA_REGISTER_GIFT_AMOUNT=100``。
+    环境变量前缀 ``QUOTA_``，例如 ``QUOTA_REGISTER_GIFT_AMOUNT=300``。
     """
 
     model_config = SettingsConfigDict(
@@ -20,8 +20,10 @@ class QuotaSettings(BaseSettings):
     )
 
     # -- 注册 / 邀请 -------------------------------------------------------
-    register_gift_amount: int = 100         # 注册赠送积分
-    invite_reward_amount: int = 50          # 邀请奖励（双方各得）
+    register_gift_amount: int = 300         # 注册赠送积分
+    invite_reward_amount: int = 200         # 邀请奖励（双方各得）
+    invite_reward_daily_limit: int = 3      # 邀请人每日可获奖励的邀请人数（3×200=600）
+    invite_code_ttl_days: int = 30          # 邀请码有效期（天）
 
     # -- 生成任务 -----------------------------------------------------------
     generate_image_cost: int = 10           # 生成角色参考图
diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
index 10ecb720..714cbfba 100644
--- a/backend/tests/conftest.py
+++ b/backend/tests/conftest.py
@@ -22,7 +22,12 @@
 from windup_app.bootstrap.app import create_app
 from windup_app.server.character.model import Character
 from windup_app.server.project.model import Project
-from windup_app.server.quota.model import CreditAccount, CreditTransaction
+from windup_app.server.quota.model import (
+    CreditAccount,
+    CreditTransaction,
+    InviteCode,
+    InviteRecord,
+)
 from windup_app.server.user.model import User
 from windup_app.server.orchestrator.model import GenerationTaskRecord
 from windup_app.server.workflow_run.model import WorkflowRun
@@ -53,7 +58,19 @@ def _disable_generation_execution(app):
     app.state.run_image_task = lambda *args: None
 
 
-def seed_credit_account(session, user_id: int, *, balance: int | None = None) -> CreditAccount:
+def seed_invite_code(session, code: str = "AB23CD45") -> str:
+    """预置一个可重复使用的邀请码，供注册测试使用。"""
+    inviter = User(email=f"inviter-{code.lower()}@example.com", password_hash="x")
+    session.add(inviter)
+    session.flush()
+    session.add(InviteCode(user_id=inviter.id, code=code, used_count=0))
+    seed_credit_account(session, inviter.id)
+    return code
+
+
+def seed_credit_account(
+    session, user_id: int, *, balance: int | None = None
+) -> CreditAccount:
     """给测试用户补一张积分账户（注册赠送口径）。"""
     gift = quota_settings.register_gift_amount
     account = CreditAccount(
@@ -85,15 +102,29 @@ def _enable_sqlite_foreign_keys(dbapi_connection, _connection_record):
     return engine
 
 
+@pytest.fixture()
+def invite_code(db_session):
+    return seed_invite_code(db_session)
+
+
 @pytest.fixture()
 def engine():
     """建好 ``windup_project`` 和 ``windup_user`` 表的内存 engine。"""
     engine = _make_engine()
-    Base.metadata.create_all(engine, tables=[
-        Project.__table__, User.__table__, Character.__table__, WorkflowRun.__table__,
-        CreditAccount.__table__, CreditTransaction.__table__,
-        GenerationTaskRecord.__table__,
-    ])
+    Base.metadata.create_all(
+        engine,
+        tables=[
+            Project.__table__,
+            User.__table__,
+            Character.__table__,
+            WorkflowRun.__table__,
+            CreditAccount.__table__,
+            CreditTransaction.__table__,
+            InviteCode.__table__,
+            InviteRecord.__table__,
+            GenerationTaskRecord.__table__,
+        ],
+    )
     yield engine
     engine.dispose()
 
diff --git a/backend/tests/test_auth_api.py b/backend/tests/test_auth_api.py
index 16094461..1eb8cff9 100644
--- a/backend/tests/test_auth_api.py
+++ b/backend/tests/test_auth_api.py
@@ -4,6 +4,8 @@
 
 import pytest
 
+from conftest import seed_invite_code
+
 from windup_app.server.user.model import User
 from windup_app.server.user.service import _hash_password, service
 
@@ -91,6 +93,62 @@ def test_reset_password_endpoint(auth_client, seeded_user, mock_user_redis):
     assert body["message"] == "密码重置成功"
 
 
+def test_register_endpoint_success(client, db_session, mock_user_redis):
+    seed_invite_code(db_session)
+    db_session.commit()
+    mock_user_redis.get.return_value = "123456"
+
+    resp = client.post(
+        "/auth/register",
+        json={
+            "email": "invitee@example.com",
+            "password": "password123",
+            "code": "123456",
+            "invite_code": "AB23CD45",
+            "nickname": "受邀用户",
+        },
+    )
+    assert resp.status_code == 200
+    body = resp.json()
+    assert body["code"] == 200
+    assert body["message"] == "注册成功"
+    assert body["data"]["user"]["email"] == "invitee@example.com"
+    assert body["data"]["access_token"]
+
+
+def test_register_endpoint_success_without_invite_code(client, mock_user_redis):
+    mock_user_redis.get.return_value = "123456"
+    resp = client.post(
+        "/auth/register",
+        json={
+            "email": "open@example.com",
+            "password": "password123",
+            "code": "123456",
+        },
+    )
+    assert resp.status_code == 200
+    body = resp.json()
+    assert body["code"] == 200
+    assert body["data"]["user"]["email"] == "open@example.com"
+    assert body["data"]["access_token"]
+
+
+def test_login_by_code_endpoint_creates_unknown_email(client, db_session, mock_user_redis):
+    mock_user_redis.get.return_value = "123456"
+    resp = client.post(
+        "/auth/login-by-code",
+        json={"email": "fresh@example.com", "code": "123456"},
+    )
+    assert resp.status_code == 200
+    body = resp.json()
+    assert body["code"] == 200
+    assert body["data"]["user"]["email"] == "fresh@example.com"
+    assert (
+        db_session.query(User).filter(User.email == "fresh@example.com").one_or_none()
+        is not None
+    )
+
+
 def test_update_nickname_endpoint(auth_client, seeded_user, mock_user_redis):
     resp = auth_client.patch("/auth/profile", json={"nickname": "新昵称"})
     assert resp.status_code == 200
diff --git a/backend/tests/test_auth_registration_closed.py b/backend/tests/test_auth_registration_closed.py
index aa77c335..28fa99df 100644
--- a/backend/tests/test_auth_registration_closed.py
+++ b/backend/tests/test_auth_registration_closed.py
@@ -1,30 +1,25 @@
-"""内测关闭公开注册：公开建号路径必须被拒绝。"""
+"""无效邀请码不得建号。"""
 
 from windup_common.enums.biz_code import BizCode
 
+from windup_app.server.user.model import User
 
-def test_register_endpoint_rejects_public_signup(client):
+
+def test_register_endpoint_rejects_invalid_invite_code(client, db_session):
     resp = client.post(
         "/auth/register",
         json={
             "email": "new@example.com",
             "password": "password123",
             "code": "123456",
+            "invite_code": "NOPE1234",
         },
     )
     assert resp.status_code == 200
     body = resp.json()
     assert body["code"] == BizCode.BAD_REQUEST
-    assert body["message"] == "内测期间暂不开放注册"
-    assert body["data"] is None
-
-
-def test_send_code_rejects_register_purpose(client):
-    resp = client.post(
-        "/auth/send-code",
-        json={"email": "new@example.com", "purpose": "register"},
+    assert body["message"] == "邀请码无效"
+    assert (
+        db_session.query(User).filter(User.email == "new@example.com").one_or_none()
+        is None
     )
-    assert resp.status_code == 200
-    body = resp.json()
-    assert body["code"] == BizCode.BAD_REQUEST
-    assert body["message"] == "内测期间暂不开放注册"
diff --git a/backend/tests/test_quota.py b/backend/tests/test_quota.py
index 64364464..775c8176 100644
--- a/backend/tests/test_quota.py
+++ b/backend/tests/test_quota.py
@@ -106,18 +106,25 @@ def test_get_nonexistent_account(self, db_session, quota_service):
 class TestReserveCredit:
     def test_reserve_success(self, db_session, quota_service, user_with_account):
         uid = user_with_account.id
-        quota_service.reserve_credit(db_session, uid, quota_settings.generate_image_cost, "task:1")
+        quota_service.reserve_credit(
+            db_session, uid, quota_settings.generate_image_cost, "task:1"
+        )
 
         account = db_session.scalar(
             select(CreditAccount).where(CreditAccount.user_id == uid)
         )
-        assert account.balance == quota_settings.register_gift_amount - quota_settings.generate_image_cost
+        assert (
+            account.balance
+            == quota_settings.register_gift_amount - quota_settings.generate_image_cost
+        )
         assert account.frozen == quota_settings.generate_image_cost
 
     def test_reserve_insufficient(self, db_session, quota_service, user_with_account):
         uid = user_with_account.id
         with pytest.raises(BizException, match="积分不足"):
-            quota_service.reserve_credit(db_session, uid, quota_settings.register_gift_amount + 1, "task:2")
+            quota_service.reserve_credit(
+                db_session, uid, quota_settings.register_gift_amount + 1, "task:2"
+            )
 
     def test_reserve_nonexistent_account(self, db_session, quota_service):
         with pytest.raises(BizException, match="积分账户不存在"):
@@ -125,11 +132,14 @@ def test_reserve_nonexistent_account(self, db_session, quota_service):
 
     def test_reserve_writes_txn(self, db_session, quota_service, user_with_account):
         uid = user_with_account.id
-        quota_service.reserve_credit(db_session, uid, quota_settings.generate_image_cost, "task:3")
+        quota_service.reserve_credit(
+            db_session, uid, quota_settings.generate_image_cost, "task:3"
+        )
 
         txn = db_session.scalar(
-            select(CreditTransaction)
-            .where(CreditTransaction.user_id == uid, CreditTransaction.ref_id == "task:3")
+            select(CreditTransaction).where(
+                CreditTransaction.user_id == uid, CreditTransaction.ref_id == "task:3"
+            )
         )
         assert txn is not None
         assert txn.delta == -quota_settings.generate_image_cost
@@ -157,8 +167,12 @@ def test_capture_full(self, db_session, quota_service, user_with_account):
     def test_capture_partial_refund(self, db_session, quota_service, user_with_account):
         """冻结 50，实际扣 30，差额 20 退回。"""
         uid = user_with_account.id
-        quota_service.reserve_credit(db_session, uid, quota_settings.generate_action_cost, "task:4")
-        quota_service.capture_credit(db_session, uid, 30, "task:4", quota_settings.generate_action_cost)
+        quota_service.reserve_credit(
+            db_session, uid, quota_settings.generate_action_cost, "task:4"
+        )
+        quota_service.capture_credit(
+            db_session, uid, 30, "task:4", quota_settings.generate_action_cost
+        )
 
         account = db_session.scalar(
             select(CreditAccount).where(CreditAccount.user_id == uid)
@@ -167,11 +181,17 @@ def test_capture_partial_refund(self, db_session, quota_service, user_with_accou
         assert account.frozen == 0
         assert account.total_spent == 30
 
-    def test_capture_writes_txn_and_refund(self, db_session, quota_service, user_with_account):
+    def test_capture_writes_txn_and_refund(
+        self, db_session, quota_service, user_with_account
+    ):
         """有差额退回时应写两条流水：扣减 + 退款。"""
         uid = user_with_account.id
-        quota_service.reserve_credit(db_session, uid, quota_settings.generate_action_cost, "task:5")
-        quota_service.capture_credit(db_session, uid, 30, "task:5", quota_settings.generate_action_cost)
+        quota_service.reserve_credit(
+            db_session, uid, quota_settings.generate_action_cost, "task:5"
+        )
+        quota_service.capture_credit(
+            db_session, uid, 30, "task:5", quota_settings.generate_action_cost
+        )
 
         txns = db_session.scalars(
             select(CreditTransaction).where(CreditTransaction.user_id == uid)
@@ -180,10 +200,14 @@ def test_capture_writes_txn_and_refund(self, db_session, quota_service, user_wit
         assert CreditReason.CAPTURED in reasons
         assert CreditReason.REFUND in reasons
 
-    def test_capture_insufficient_frozen(self, db_session, quota_service, user_with_account):
+    def test_capture_insufficient_frozen(
+        self, db_session, quota_service, user_with_account
+    ):
         """冻结额度不足时应抛异常。"""
         uid = user_with_account.id
-        quota_service.reserve_credit(db_session, uid, quota_settings.generate_image_cost, "task:6")
+        quota_service.reserve_credit(
+            db_session, uid, quota_settings.generate_image_cost, "task:6"
+        )
         with pytest.raises(BizException, match="冻结额度不足"):
             quota_service.capture_credit(db_session, uid, 100, "task:6", 100)
 
@@ -198,8 +222,12 @@ def test_capture_nonexistent_account(self, db_session, quota_service):
 class TestReleaseCredit:
     def test_release_success(self, db_session, quota_service, user_with_account):
         uid = user_with_account.id
-        quota_service.reserve_credit(db_session, uid, quota_settings.generate_image_cost, "task:7")
-        quota_service.release_credit(db_session, uid, quota_settings.generate_image_cost, "task:7")
+        quota_service.reserve_credit(
+            db_session, uid, quota_settings.generate_image_cost, "task:7"
+        )
+        quota_service.release_credit(
+            db_session, uid, quota_settings.generate_image_cost, "task:7"
+        )
 
         account = db_session.scalar(
             select(CreditAccount).where(CreditAccount.user_id == uid)
@@ -209,17 +237,25 @@ def test_release_success(self, db_session, quota_service, user_with_account):
 
     def test_release_writes_txn(self, db_session, quota_service, user_with_account):
         uid = user_with_account.id
-        quota_service.reserve_credit(db_session, uid, quota_settings.generate_image_cost, "task:8")
-        quota_service.release_credit(db_session, uid, quota_settings.generate_image_cost, "task:8")
+        quota_service.reserve_credit(
+            db_session, uid, quota_settings.generate_image_cost, "task:8"
+        )
+        quota_service.release_credit(
+            db_session, uid, quota_settings.generate_image_cost, "task:8"
+        )
 
         txn = db_session.scalar(
-            select(CreditTransaction)
-            .where(CreditTransaction.user_id == uid, CreditTransaction.reason == CreditReason.REFUND)
+            select(CreditTransaction).where(
+                CreditTransaction.user_id == uid,
+                CreditTransaction.reason == CreditReason.REFUND,
+            )
         )
         assert txn is not None
         assert txn.delta == quota_settings.generate_image_cost
 
-    def test_release_insufficient_frozen(self, db_session, quota_service, user_with_account):
+    def test_release_insufficient_frozen(
+        self, db_session, quota_service, user_with_account
+    ):
         uid = user_with_account.id
         with pytest.raises(BizException, match="冻结额度不足"):
             quota_service.release_credit(db_session, uid, 100, "task:9")
@@ -248,8 +284,9 @@ def test_credit_writes_txn(self, db_session, quota_service, user_with_account):
         quota_service.credit(db_session, uid, 50, CreditReason.ADMIN_ADJUST, "admin:2")
 
         txn = db_session.scalar(
-            select(CreditTransaction)
-            .where(CreditTransaction.user_id == uid, CreditTransaction.ref_id == "admin:2")
+            select(CreditTransaction).where(
+                CreditTransaction.user_id == uid, CreditTransaction.ref_id == "admin:2"
+            )
         )
         assert txn is not None
         assert txn.delta == 50
@@ -290,8 +327,16 @@ def test_list_empty(self, db_session, quota_service, user_with_account):
 
     def test_list_after_operations(self, db_session, quota_service, user_with_account):
         uid = user_with_account.id
-        quota_service.reserve_credit(db_session, uid, quota_settings.generate_image_cost, "task:10")
-        quota_service.capture_credit(db_session, uid, quota_settings.generate_image_cost, "task:10", quota_settings.generate_image_cost)
+        quota_service.reserve_credit(
+            db_session, uid, quota_settings.generate_image_cost, "task:10"
+        )
+        quota_service.capture_credit(
+            db_session,
+            uid,
+            quota_settings.generate_image_cost,
+            "task:10",
+            quota_settings.generate_image_cost,
+        )
 
         txns, total = quota_service.list_transactions(db_session, uid)
         assert total >= 2
@@ -300,13 +345,19 @@ def test_list_after_operations(self, db_session, quota_service, user_with_accoun
     def test_list_pagination(self, db_session, quota_service, user_with_account):
         uid = user_with_account.id
         for i in range(5):
-            quota_service.credit(db_session, uid, 10, CreditReason.ADMIN_ADJUST, f"page:{i}")
+            quota_service.credit(
+                db_session, uid, 10, CreditReason.ADMIN_ADJUST, f"page:{i}"
+            )
 
-        txns_p1, total = quota_service.list_transactions(db_session, uid, page=1, page_size=2)
+        txns_p1, total = quota_service.list_transactions(
+            db_session, uid, page=1, page_size=2
+        )
         assert total == 5
         assert len(txns_p1) == 2
 
-        txns_p3, _ = quota_service.list_transactions(db_session, uid, page=3, page_size=2)
+        txns_p3, _ = quota_service.list_transactions(
+            db_session, uid, page=3, page_size=2
+        )
         assert len(txns_p3) == 1  # 最后一页只有 1 条
 
     def test_list_other_user_empty(self, db_session, quota_service, user_with_account):
@@ -409,7 +460,9 @@ def test_list_transactions_empty(self, auth_quota_client):
         assert data["data"] == []
         assert data["total"] == 0
 
-    def test_list_transactions_pagination(self, auth_quota_client, db_session, user_with_account):
+    def test_list_transactions_pagination(
+        self, auth_quota_client, db_session, user_with_account
+    ):
         """先写入几条流水，再通过 API 分页查询。"""
         uid = user_with_account.id
         service = SqlAlchemyQuotaService()
@@ -423,7 +476,9 @@ def test_list_transactions_pagination(self, auth_quota_client, db_session, user_
         assert data["total"] == 5
         assert len(data["data"]) == 2
 
-    def test_list_transactions_default_pagination(self, auth_quota_client, db_session, user_with_account):
+    def test_list_transactions_default_pagination(
+        self, auth_quota_client, db_session, user_with_account
+    ):
         """默认分页参数。"""
         uid = user_with_account.id
         service = SqlAlchemyQuotaService()
@@ -441,3 +496,346 @@ def test_unauthenticated_access(self, client):
         assert resp.status_code == 200
         data = resp.json()
         assert data["code"] == 401
+
+
+def _gift_account(session: Session, user_id: int) -> None:
+    session.add(
+        CreditAccount(
+            user_id=user_id,
+            balance=quota_settings.register_gift_amount,
+            frozen=0,
+            total_earned=quota_settings.register_gift_amount,
+            total_spent=0,
+        )
+    )
+    session.flush()
+
+
+class TestInviteCode:
+    """邀请码生成、查询与兑换。"""
+
+    def test_get_invite_code_creates_when_missing(self, auth_quota_client):
+        resp = auth_quota_client.get("/quota/invite/code")
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["code"] == 200
+        assert len(data["data"]["code"]) == 8
+        assert data["data"]["used_count"] == 0
+
+        again = auth_quota_client.get("/quota/invite/code")
+        assert again.json()["data"]["code"] == data["data"]["code"]
+        assert again.json()["data"]["expires_at"]
+
+    def test_generate_invite_code_rotates(self, auth_quota_client):
+        first = auth_quota_client.get("/quota/invite/code").json()["data"]["code"]
+        second = auth_quota_client.post("/quota/invite/generate").json()["data"]["code"]
+        assert second != first
+        assert len(second) == 8
+        assert auth_quota_client.get("/quota/invite/code").json()["data"]["code"] == second
+
+    def test_generate_invite_code_locks_existing_row(
+        self, db_session, quota_service, monkeypatch
+    ):
+        from sqlalchemy.sql.selectable import Select
+        from windup_app.server.user.model import User
+
+        host = User(email="lock-host@example.com", password_hash="x")
+        db_session.add(host)
+        db_session.flush()
+        quota_service.generate_invite_code(db_session, host.id)
+
+        locked = []
+        original = Select.with_for_update
+
+        def tracking(self, *args, **kwargs):
+            locked.append(True)
+            return original(self, *args, **kwargs)
+
+        monkeypatch.setattr(Select, "with_for_update", tracking)
+        quota_service.generate_invite_code(db_session, host.id)
+        assert locked, "轮换已有邀请码时应对该行加 FOR UPDATE"
+
+    def test_generate_invite_code_keeps_old_row(self, db_session, quota_service):
+        from datetime import datetime, timezone
+        from sqlalchemy import select
+        from windup_app.server.quota.model import InviteCode
+        from windup_app.server.user.model import User
+
+        host = User(email="append-host@example.com", password_hash="x")
+        db_session.add(host)
+        db_session.flush()
+        first = quota_service.generate_invite_code(db_session, host.id)
+        second = quota_service.generate_invite_code(db_session, host.id)
+        rows = db_session.scalars(
+            select(InviteCode).where(InviteCode.user_id == host.id)
+        ).all()
+        assert {row.code for row in rows} == {first.code, second.code}
+        old = next(row for row in rows if row.code == first.code)
+        now = datetime.now(timezone.utc)
+        exp = old.expires_at if old.expires_at.tzinfo else old.expires_at.replace(
+            tzinfo=timezone.utc
+        )
+        assert exp <= now
+
+    def test_get_invite_code_issues_new_row_after_expiry(
+        self, db_session, quota_service
+    ):
+        from datetime import datetime, timedelta, timezone
+        from sqlalchemy import select
+        from windup_app.server.quota.model import InviteCode
+        from windup_app.server.user.model import User
+
+        host = User(email="expire-host@example.com", password_hash="x")
+        db_session.add(host)
+        db_session.flush()
+        first = quota_service.generate_invite_code(db_session, host.id)
+        row = db_session.scalar(
+            select(InviteCode).where(InviteCode.code == first.code)
+        )
+        row.expires_at = datetime.now(timezone.utc) - timedelta(seconds=1)
+        db_session.flush()
+
+        second = quota_service.get_invite_code(db_session, host.id)
+        assert second.code != first.code
+        assert (
+            db_session.scalar(
+                select(InviteCode).where(InviteCode.code == first.code)
+            )
+            is not None
+        )
+
+    def test_redeem_unique_violation_is_already_redeemed(
+        self, db_session, quota_service, monkeypatch
+    ):
+        """并发双兑时 unique(invitee_id) 应收敛为「已填写过邀请码」，而不是 500。"""
+        from sqlalchemy.exc import IntegrityError
+        from windup_app.server.user.model import User
+        from windup_common.exceptions import BizException
+
+        host = User(email="race-host@example.com", password_hash="x")
+        guest = User(email="race-guest@example.com", password_hash="x")
+        db_session.add_all([host, guest])
+        db_session.flush()
+        _gift_account(db_session, host.id)
+        _gift_account(db_session, guest.id)
+        view = quota_service.generate_invite_code(db_session, host.id)
+
+        from windup_app.server.quota.model import InviteRecord
+
+        orig_flush = db_session.flush
+
+        def boom(*_args, **_kwargs):
+            if any(isinstance(obj, InviteRecord) for obj in db_session.new):
+                raise IntegrityError(
+                    "INSERT",
+                    {},
+                    Exception(
+                        "UNIQUE constraint failed: windup_invite_record.invitee_id"
+                    ),
+                )
+            return orig_flush(*_args, **_kwargs)
+
+        monkeypatch.setattr(db_session, "flush", boom)
+
+        with pytest.raises(BizException, match="已填写过邀请码"):
+            quota_service.redeem_invite_code(db_session, guest.id, view.code)
+
+    def test_redeem_invite_code_rewards_both_users(self, db_session, quota_service):
+        from windup_app.server.user.model import User
+
+        inviter = User(email="host@example.com", password_hash="x")
+        invitee = User(email="guest@example.com", password_hash="x")
+        db_session.add_all([inviter, invitee])
+        db_session.flush()
+        _gift_account(db_session, inviter.id)
+        _gift_account(db_session, invitee.id)
+        view = quota_service.generate_invite_code(db_session, inviter.id)
+
+        quota_service.redeem_invite_code(db_session, invitee.id, view.code.lower())
+
+        host = quota_service.get_account(db_session, inviter.id)
+        guest = quota_service.get_account(db_session, invitee.id)
+        assert (
+            host.balance
+            == quota_settings.register_gift_amount + quota_settings.invite_reward_amount
+        )
+        assert (
+            guest.balance
+            == quota_settings.register_gift_amount + quota_settings.invite_reward_amount
+        )
+
+    def test_inviter_daily_reward_stops_after_three_invites(
+        self, db_session, quota_service
+    ):
+        from windup_app.server.quota.model import InviteRecord
+        from windup_app.server.user.model import User
+
+        inviter = User(email="cap-host@example.com", password_hash="x")
+        db_session.add(inviter)
+        db_session.flush()
+        _gift_account(db_session, inviter.id)
+        view = quota_service.generate_invite_code(db_session, inviter.id)
+
+        guests = []
+        for i in range(4):
+            guest = User(email=f"cap-guest-{i}@example.com", password_hash="x")
+            db_session.add(guest)
+            db_session.flush()
+            _gift_account(db_session, guest.id)
+            quota_service.redeem_invite_code(db_session, guest.id, view.code)
+            guests.append(guest)
+
+        host = quota_service.get_account(db_session, inviter.id)
+        assert host.balance == quota_settings.register_gift_amount + (
+            quota_settings.invite_reward_amount * 3
+        )
+        assert (
+            db_session.scalar(
+                select(InviteRecord.id).where(
+                    InviteRecord.invitee_id == guests[3].id
+                )
+            )
+            is not None
+        )
+        fourth = quota_service.get_account(db_session, guests[3].id)
+        assert (
+            fourth.balance
+            == quota_settings.register_gift_amount + quota_settings.invite_reward_amount
+        )
+
+    def test_inviter_daily_reward_resets_next_utc_day(
+        self, db_session, quota_service
+    ):
+        from datetime import timedelta
+        from windup_app.server.quota.model import InviteRecord
+        from windup_app.server.quota.service import _now
+        from windup_app.server.user.model import User
+
+        inviter = User(email="nextday-host@example.com", password_hash="x")
+        db_session.add(inviter)
+        db_session.flush()
+        _gift_account(db_session, inviter.id)
+        view = quota_service.generate_invite_code(db_session, inviter.id)
+
+        for i in range(3):
+            guest = User(email=f"old-guest-{i}@example.com", password_hash="x")
+            db_session.add(guest)
+            db_session.flush()
+            _gift_account(db_session, guest.id)
+            quota_service.redeem_invite_code(db_session, guest.id, view.code)
+
+        yesterday = _now() - timedelta(days=1)
+        for row in db_session.scalars(
+            select(InviteRecord).where(InviteRecord.inviter_id == inviter.id)
+        ).all():
+            row.create_at = yesterday
+        db_session.flush()
+
+        today_guest = User(email="today-guest@example.com", password_hash="x")
+        db_session.add(today_guest)
+        db_session.flush()
+        _gift_account(db_session, today_guest.id)
+        quota_service.redeem_invite_code(db_session, today_guest.id, view.code)
+
+        host = quota_service.get_account(db_session, inviter.id)
+        assert host.balance == quota_settings.register_gift_amount + (
+            quota_settings.invite_reward_amount * 4
+        )
+
+    def test_redeem_rejects_own_code_and_repeat(self, db_session, quota_service):
+        from windup_app.server.user.model import User
+        from windup_common.exceptions import BizException
+
+        host = User(email="self@example.com", password_hash="x")
+        guest = User(email="once@example.com", password_hash="x")
+        db_session.add_all([host, guest])
+        db_session.flush()
+        _gift_account(db_session, host.id)
+        _gift_account(db_session, guest.id)
+        view = quota_service.generate_invite_code(db_session, host.id)
+
+        with pytest.raises(BizException, match="不能填写自己的邀请码"):
+            quota_service.redeem_invite_code(db_session, host.id, view.code)
+
+        quota_service.redeem_invite_code(db_session, guest.id, view.code)
+        with pytest.raises(BizException, match="已填写过邀请码"):
+            quota_service.redeem_invite_code(db_session, guest.id, view.code)
+
+    def test_generate_invite_code_rejects_missing_user(self, db_session, quota_service):
+        from windup_common.exceptions import BizException
+
+        with pytest.raises(BizException, match="用户不存在"):
+            quota_service.generate_invite_code(db_session, 999999)
+
+    def test_allocate_invite_code_gives_up_on_collision(
+        self, db_session, quota_service, monkeypatch
+    ):
+        from windup_app.server.quota import service as quota_mod
+        from windup_app.server.user.model import User
+        from windup_common.exceptions import BizException
+
+        taken = User(email="taken@example.com", password_hash="x")
+        host = User(email="alloc@example.com", password_hash="x")
+        db_session.add_all([taken, host])
+        db_session.flush()
+        occupied = quota_service.generate_invite_code(db_session, taken.id)
+        monkeypatch.setattr(quota_mod, "_new_invite_code", lambda: occupied.code)
+
+        with pytest.raises(BizException, match="邀请码生成失败"):
+            quota_service.generate_invite_code(db_session, host.id)
+
+    def test_redeem_rejects_blank_or_unknown_code(self, db_session, quota_service):
+        from windup_app.server.user.model import User
+        from windup_common.exceptions import BizException
+
+        guest = User(email="blank@example.com", password_hash="x")
+        db_session.add(guest)
+        db_session.flush()
+        _gift_account(db_session, guest.id)
+
+        with pytest.raises(BizException, match="邀请码无效"):
+            quota_service.redeem_invite_code(db_session, guest.id, "   ")
+        with pytest.raises(BizException, match="邀请码无效"):
+            quota_service.redeem_invite_code(db_session, guest.id, "IO01")
+        with pytest.raises(BizException, match="邀请码无效"):
+            quota_service.redeem_invite_code(db_session, guest.id, "NOPE1234")
+
+    def test_redeem_rejects_expired_code(self, db_session, quota_service):
+        from datetime import datetime, timedelta, timezone
+        from sqlalchemy import select
+        from windup_app.server.quota.model import InviteCode
+        from windup_app.server.user.model import User
+        from windup_common.enums.biz_code import BizCode
+        from windup_common.exceptions import BizException
+
+        host = User(email="stale-host@example.com", password_hash="x")
+        guest = User(email="stale-guest@example.com", password_hash="x")
+        db_session.add_all([host, guest])
+        db_session.flush()
+        _gift_account(db_session, host.id)
+        _gift_account(db_session, guest.id)
+        view = quota_service.generate_invite_code(db_session, host.id)
+        row = db_session.scalar(select(InviteCode).where(InviteCode.code == view.code))
+        row.expires_at = datetime.now(timezone.utc) - timedelta(seconds=1)
+        db_session.flush()
+
+        with pytest.raises(BizException, match="邀请码已过期") as exc:
+            quota_service.redeem_invite_code(db_session, guest.id, view.code)
+        assert exc.value.code == BizCode.NOT_FOUND
+
+    def test_redeem_rejects_missing_invitee(self, db_session, quota_service):
+        from windup_app.server.user.model import User
+        from windup_common.exceptions import BizException
+
+        host = User(email="orphan-host@example.com", password_hash="x")
+        db_session.add(host)
+        db_session.flush()
+        _gift_account(db_session, host.id)
+        view = quota_service.generate_invite_code(db_session, host.id)
+
+        with pytest.raises(BizException, match="用户不存在"):
+            quota_service.redeem_invite_code(db_session, 999999, view.code)
+
+    def test_invite_redeem_endpoint_removed(self, auth_quota_client):
+        resp = auth_quota_client.post("/quota/invite/redeem", json={"code": "AB23CD45"})
+        assert resp.status_code == 404
diff --git a/backend/tests/test_user_service.py b/backend/tests/test_user_service.py
index 671a677a..31cc1761 100644
--- a/backend/tests/test_user_service.py
+++ b/backend/tests/test_user_service.py
@@ -31,6 +31,12 @@
 # -- Fixtures ------------------------------------------------------------
 
 
+@pytest.fixture(autouse=True)
+def _seed_invite(request):
+    if "db_session" in request.fixturenames:
+        request.getfixturevalue("invite_code")
+
+
 @pytest.fixture()
 def mock_redis():
     """Mock Redis 客户端。"""
@@ -129,6 +135,7 @@ def test_register_success(db_session, service, mock_email):
         email="new@example.com",
         password="password123",
         code="123456",
+        invite_code="AB23CD45",
     )
 
     result = service.register_by_email(db_session, input_data)
@@ -148,6 +155,7 @@ def test_public_methods_accept_session(db_session, service, mock_email):
             email="public@example.com",
             password="password123",
             code="123456",
+            invite_code="AB23CD45",
         ),
     )
 
@@ -191,19 +199,21 @@ def test_register_creates_credit_account(db_session, service, mock_email):
         email="credit@example.com",
         password="password123",
         code="123456",
+        invite_code="AB23CD45",
     )
 
     result = service.register_by_email(db_session, input_data)
     user_id = result.user.id
+    expected = quota_settings.register_gift_amount + quota_settings.invite_reward_amount
 
     # 验证积分账户已创建
     account = db_session.scalar(
         select(CreditAccount).where(CreditAccount.user_id == user_id)
     )
     assert account is not None
-    assert account.balance == quota_settings.register_gift_amount
+    assert account.balance == expected
     assert account.frozen == 0
-    assert account.total_earned == quota_settings.register_gift_amount
+    assert account.total_earned == expected
     assert account.total_spent == 0
 
     # 验证赠送流水已记录
@@ -222,7 +232,12 @@ def test_register_creates_credit_account(db_session, service, mock_email):
 def test_register_duplicate_email(db_session, service):
     # 先注册一个用户
     service._redis.get.return_value = "123456"
-    input_data = RegisterInput(email="dup@example.com", password="pass123", code="123456")
+    input_data = RegisterInput(
+        email="dup@example.com",
+        password="pass123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     service.register_by_email(db_session, input_data)
 
     # 尝试重复注册
@@ -237,6 +252,7 @@ def test_register_wrong_code(db_session, service):
         email="new@example.com",
         password="password123",
         code="999999",  # 错误验证码
+        invite_code="AB23CD45",
     )
 
     with pytest.raises(BizException, match="验证码错误"):
@@ -250,19 +266,84 @@ def test_register_expired_code(db_session, service):
         email="new@example.com",
         password="password123",
         code="123456",
+        invite_code="AB23CD45",
     )
 
     with pytest.raises(BizException, match="验证码已过期"):
         service.register_by_email(db_session, input_data)
 
 
+def test_register_blank_invite_code_only_gives_register_gift(db_session, service):
+    """未带邀请码时只发注册赠送，不挡注册。"""
+    from sqlalchemy import select
+    from windup_app.server.quota.model import CreditAccount
+    from windup_framework.config.quota import settings as quota_settings
+
+    service._redis.get.return_value = "123456"
+    input_data = RegisterInput(
+        email="blank-invite@example.com",
+        password="password123",
+        code="123456",
+        invite_code="   ",
+    )
+
+    result = service.register_by_email(db_session, input_data)
+    account = db_session.scalar(
+        select(CreditAccount).where(CreditAccount.user_id == result.user.id)
+    )
+    assert account is not None
+    assert account.balance == quota_settings.register_gift_amount
+
+
+def test_register_rejects_invite_code_outside_link_charset(db_session, service):
+    """前端邀请链接用 A-H/J-N/P-Z/2-9，含 I/O/0/1 的码不会进注册请求。"""
+    service._redis.get.return_value = "123456"
+    input_data = RegisterInput(
+        email="bad-charset@example.com",
+        password="password123",
+        code="123456",
+        invite_code="IIII",
+    )
+
+    with pytest.raises(BizException, match="邀请码无效"):
+        service.register_by_email(db_session, input_data)
+
+
+def test_register_expired_invite_code(db_session, service):
+    from datetime import datetime, timedelta, timezone
+    from sqlalchemy import select
+    from windup_app.server.quota.model import InviteCode
+    from windup_common.enums.biz_code import BizCode
+
+    row = db_session.scalar(select(InviteCode).where(InviteCode.code == "AB23CD45"))
+    row.expires_at = datetime.now(timezone.utc) - timedelta(days=1)
+    db_session.flush()
+
+    service._redis.get.return_value = "123456"
+    input_data = RegisterInput(
+        email="late@example.com",
+        password="password123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
+    with pytest.raises(BizException, match="邀请码已过期") as exc:
+        service.register_by_email(db_session, input_data)
+    assert exc.value.code == BizCode.NOT_FOUND
+    assert db_session.scalar(select(User).where(User.email == "late@example.com")) is None
+
+
 # -- 登录测试 ------------------------------------------------------------
 
 
 def test_login_success(db_session, service, mock_email):
     # 先注册
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="login@example.com", password="pass123", code="123456")
+    register_input = RegisterInput(
+        email="login@example.com",
+        password="pass123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     service.register_by_email(db_session, register_input)
 
     # 登录（不需要验证码）
@@ -277,7 +358,12 @@ def test_login_success(db_session, service, mock_email):
 def test_login_wrong_password(db_session, service, mock_email):
     # 先注册
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="login@example.com", password="pass123", code="123456")
+    register_input = RegisterInput(
+        email="login@example.com",
+        password="pass123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     service.register_by_email(db_session, register_input)
 
     # 密码错误
@@ -301,11 +387,17 @@ def test_login_nonexistent_user(db_session, service):
 def test_login_banned_user(db_session, service, mock_email):
     # 先注册
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="banned@example.com", password="pass123", code="123456")
+    register_input = RegisterInput(
+        email="banned@example.com",
+        password="pass123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     service.register_by_email(db_session, register_input)
 
     # 封禁用户
     from sqlalchemy import select
+
     user = db_session.scalar(select(User).where(User.email == "banned@example.com"))
     user.status = UserStatus.BANNED
     db_session.flush()
@@ -321,29 +413,36 @@ def test_login_banned_user(db_session, service, mock_email):
 # -- 验证码登录测试 ------------------------------------------------------
 
 
-def test_login_by_code_unknown_email_does_not_create_user(db_session, service, mock_email):
-    """内测关闭公开注册后，验证码登录不得自动建号。"""
+def test_login_by_code_unknown_email_creates_user_and_gifts(
+    db_session, service, mock_email
+):
+    """未知邮箱验证码登录自动建号，并只发注册赠送。"""
     from sqlalchemy import select
+    from windup_app.server.quota.model import CreditAccount
+    from windup_framework.config.quota import settings as quota_settings
 
     service._redis.get.return_value = "123456"
     input_data = LoginByCodeInput(email="code@example.com", code="123456")
 
-    with pytest.raises(BizException, match="账号不存在") as exc:
-        service.login_by_code(db_session, input_data)
-
-    from windup_common.enums.biz_code import BizCode
+    result = service.login_by_code(db_session, input_data)
 
-    assert exc.value.code == BizCode.NOT_FOUND
-    assert db_session.scalar(select(User).where(User.email == "code@example.com")) is None
+    user = db_session.scalar(select(User).where(User.email == "code@example.com"))
+    assert user is not None
+    assert result.user.id == user.id
+    assert result.user.email_verified_at is not None
+    account = db_session.scalar(
+        select(CreditAccount).where(CreditAccount.user_id == user.id)
+    )
+    assert account is not None
+    assert account.balance == quota_settings.register_gift_amount
 
 
-def test_send_verification_code_rejects_register_purpose(service, mock_email):
+def test_send_verification_code_allows_register_purpose(service, mock_email):
     service._redis.get.return_value = None
 
-    with pytest.raises(BizException, match="内测期间暂不开放注册"):
-        service.send_verification_code("new@example.com", "register")
+    service.send_verification_code("new@example.com", "register")
 
-    mock_email.send_verification_code.assert_not_called()
+    mock_email.send_verification_code.assert_called_once()
 
 
 def test_login_by_code_banned_user(db_session, service, mock_email):
@@ -352,9 +451,16 @@ def test_login_by_code_banned_user(db_session, service, mock_email):
     service._redis.get.return_value = "123456"
     service.register_by_email(
         db_session,
-        RegisterInput(email="banned-code@example.com", password="pass123", code="123456"),
+        RegisterInput(
+            email="banned-code@example.com",
+            password="pass123",
+            code="123456",
+            invite_code="AB23CD45",
+        ),
+    )
+    user = db_session.scalar(
+        select(User).where(User.email == "banned-code@example.com")
     )
-    user = db_session.scalar(select(User).where(User.email == "banned-code@example.com"))
     user.status = UserStatus.BANNED
     db_session.flush()
 
@@ -384,7 +490,12 @@ def test_login_by_code_marks_unverified_email(db_session, service):
 def test_login_by_code_existing_user(db_session, service, mock_email):
     # 先注册
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="exist@example.com", password="pass123", code="123456")
+    register_input = RegisterInput(
+        email="exist@example.com",
+        password="pass123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     service.register_by_email(db_session, register_input)
 
     # 验证码登录
@@ -490,16 +601,25 @@ def test_refresh_tokens_concurrent_reuse(service, mock_redis):
 def test_change_password(db_session, service, mock_email):
     # 先注册
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="change@example.com", password="oldpass123", code="123456")
+    register_input = RegisterInput(
+        email="change@example.com",
+        password="oldpass123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     result = service.register_by_email(db_session, register_input)
 
     # 修改密码
-    change_input = ChangePasswordInput(old_password="oldpass123", new_password="newpass123")
+    change_input = ChangePasswordInput(
+        old_password="oldpass123", new_password="newpass123"
+    )
     service.change_password(db_session, result.user.id, change_input)
 
     # 用新密码登录
     service._redis.get.return_value = None
-    login_input = LoginByPasswordInput(email="change@example.com", password="newpass123")
+    login_input = LoginByPasswordInput(
+        email="change@example.com", password="newpass123"
+    )
     login_result = service.login_by_password(db_session, login_input)
 
     assert login_result.user.email == "change@example.com"
@@ -508,7 +628,12 @@ def test_change_password(db_session, service, mock_email):
 def test_change_password_wrong_old(db_session, service, mock_email):
     # 先注册
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="change@example.com", password="oldpass123", code="123456")
+    register_input = RegisterInput(
+        email="change@example.com",
+        password="oldpass123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     result = service.register_by_email(db_session, register_input)
 
     # 旧密码错误
@@ -524,7 +649,13 @@ def test_change_password_wrong_old(db_session, service, mock_email):
 def test_update_nickname(db_session, service, mock_email):
     """修改昵称后立即生效。"""
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="nick@example.com", password="pass1234", code="123456", nickname="旧昵称")
+    register_input = RegisterInput(
+        email="nick@example.com",
+        password="pass1234",
+        code="123456",
+        nickname="旧昵称",
+        invite_code="AB23CD45",
+    )
     result = service.register_by_email(db_session, register_input)
 
     update_input = UpdateNicknameInput(nickname="新昵称")
@@ -537,7 +668,12 @@ def test_update_nickname(db_session, service, mock_email):
 def test_update_nickname_max_length(db_session, service, mock_email):
     """昵称长度上限 50。"""
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="nick2@example.com", password="pass1234", code="123456")
+    register_input = RegisterInput(
+        email="nick2@example.com",
+        password="pass1234",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     result = service.register_by_email(db_session, register_input)
 
     long_nickname = "a" * 50
@@ -562,12 +698,19 @@ def test_reset_password(db_session, service, mock_email):
     """邮箱+验证码重置密码后，新密码可登录。"""
     # 先注册
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="reset@example.com", password="oldpass123", code="123456")
+    register_input = RegisterInput(
+        email="reset@example.com",
+        password="oldpass123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     service.register_by_email(db_session, register_input)
 
     # 重置密码（验证码 purpose 为 reset_password）
     service._redis.get.return_value = "654321"
-    reset_input = ResetPasswordInput(email="reset@example.com", code="654321", new_password="newpass123")
+    reset_input = ResetPasswordInput(
+        email="reset@example.com", code="654321", new_password="newpass123"
+    )
     service.reset_password(db_session, reset_input)
 
     # 用新密码登录
@@ -581,12 +724,19 @@ def test_reset_password(db_session, service, mock_email):
 def test_reset_password_wrong_code(db_session, service, mock_email):
     """验证码错误时拒绝重置。"""
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="reset2@example.com", password="oldpass123", code="123456")
+    register_input = RegisterInput(
+        email="reset2@example.com",
+        password="oldpass123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     service.register_by_email(db_session, register_input)
 
     # 验证码错误
     service._redis.get.return_value = None  # 验证码过期
-    reset_input = ResetPasswordInput(email="reset2@example.com", code="000000", new_password="newpass123")
+    reset_input = ResetPasswordInput(
+        email="reset2@example.com", code="000000", new_password="newpass123"
+    )
 
     with pytest.raises(BizException, match="验证码已过期"):
         service.reset_password(db_session, reset_input)
@@ -595,7 +745,9 @@ def test_reset_password_wrong_code(db_session, service, mock_email):
 def test_reset_password_user_not_found(db_session, service):
     """用户不存在时拒绝重置。"""
     service._redis.get.return_value = "654321"
-    reset_input = ResetPasswordInput(email="noexist@example.com", code="654321", new_password="newpass123")
+    reset_input = ResetPasswordInput(
+        email="noexist@example.com", code="654321", new_password="newpass123"
+    )
 
     with pytest.raises(BizException, match="用户不存在"):
         service.reset_password(db_session, reset_input)
@@ -608,7 +760,12 @@ def test_login_account_locked(db_session, service, mock_email):
     """账号被锁定后拒绝登录（即使密码正确）。"""
     # 先注册
     service._redis.get.return_value = "123456"
-    register_input = RegisterInput(email="lock@example.com", password="pass123", code="123456")
+    register_input = RegisterInput(
+        email="lock@example.com",
+        password="pass123",
+        code="123456",
+        invite_code="AB23CD45",
+    )
     service.register_by_email(db_session, register_input)
 
     # 模拟账号锁定
diff --git a/openapi.json b/openapi.json
index 0e5d0242..33cc2cde 100644
--- a/openapi.json
+++ b/openapi.json
@@ -720,6 +720,43 @@
         "title": "HTTPValidationError",
         "type": "object"
       },
+      "InviteCodeOut": {
+        "description": "邀请码响应。",
+        "properties": {
+          "code": {
+            "title": "Code",
+            "type": "string"
+          },
+          "create_at": {
+            "format": "date-time",
+            "title": "Create At",
+            "type": "string"
+          },
+          "expires_at": {
+            "format": "date-time",
+            "title": "Expires At",
+            "type": "string"
+          },
+          "update_at": {
+            "format": "date-time",
+            "title": "Update At",
+            "type": "string"
+          },
+          "used_count": {
+            "title": "Used Count",
+            "type": "integer"
+          }
+        },
+        "required": [
+          "code",
+          "used_count",
+          "expires_at",
+          "create_at",
+          "update_at"
+        ],
+        "title": "InviteCodeOut",
+        "type": "object"
+      },
       "ListResponse_CharacterOut_": {
         "properties": {
           "code": {
@@ -1242,6 +1279,19 @@
             "title": "Email",
             "type": "string"
           },
+          "invite_code": {
+            "anyOf": [
+              {
+                "maxLength": 16,
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "邀请链接中的邀请码，选填；有则发双方邀请奖励",
+            "title": "Invite Code"
+          },
           "nickname": {
             "anyOf": [
               {
@@ -1425,6 +1475,48 @@
         "title": "Response[GenerationTaskOut]",
         "type": "object"
       },
+      "Response_InviteCodeOut_": {
+        "properties": {
+          "code": {
+            "default": 200,
+            "description": "业务状态码:成功 200,失败非 200",
+            "title": "Code",
+            "type": "integer"
+          },
+          "data": {
+            "anyOf": [
+              {
+                "$ref": "#/components/schemas/InviteCodeOut"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "业务数据"
+          },
+          "message": {
+            "default": "success",
+            "description": "提示信息",
+            "title": "Message",
+            "type": "string"
+          },
+          "timestamp": {
+            "anyOf": [
+              {
+                "format": "date-time",
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "响应时间;默认不携带,不携带时省略",
+            "title": "Timestamp"
+          }
+        },
+        "title": "Response[InviteCodeOut]",
+        "type": "object"
+      },
       "Response_MediaUploadResult_": {
         "properties": {
           "code": {
@@ -2095,7 +2187,7 @@
     },
     "/auth/login-by-code": {
       "post": {
-        "description": "验证码登录。内测期间不自动注册。",
+        "description": "验证码登录。未知邮箱自动建号并赠送注册积分。",
         "operationId": "login_by_code_auth_login_by_code_post",
         "requestBody": {
           "content": {
@@ -2285,7 +2377,7 @@
     },
     "/auth/register": {
       "post": {
-        "description": "邮箱+验证码+密码注册。\n\n内测期间关闭公开注册，路由与请求模型保留以便以后重新开放。",
+        "description": "邮箱+验证码+密码注册。邀请码选填。",
         "operationId": "register_auth_register_post",
         "requestBody": {
           "content": {
@@ -3106,6 +3198,50 @@
         ]
       }
     },
+    "/quota/invite/code": {
+      "get": {
+        "description": "获取当前用户未过期邀请码；没有或已过期则签发新行。",
+        "operationId": "get_invite_code_quota_invite_code_get",
+        "responses": {
+          "200": {
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Response_InviteCodeOut_"
+                }
+              }
+            },
+            "description": "Successful Response"
+          }
+        },
+        "summary": "Get Invite Code",
+        "tags": [
+          "quota"
+        ]
+      }
+    },
+    "/quota/invite/generate": {
+      "post": {
+        "description": "签发新邀请码。旧码立即过期，行保留。",
+        "operationId": "generate_invite_code_quota_invite_generate_post",
+        "responses": {
+          "200": {
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Response_InviteCodeOut_"
+                }
+              }
+            },
+            "description": "Successful Response"
+          }
+        },
+        "summary": "Generate Invite Code",
+        "tags": [
+          "quota"
+        ]
+      }
+    },
     "/quota/transactions": {
       "get": {
         "description": "查询积分流水（分页）。",