diff --git a/apps/api/app/api/routes/auth.py b/apps/api/app/api/routes/auth.py
index 5e8234484..0c268d92d 100755
--- a/apps/api/app/api/routes/auth.py
+++ b/apps/api/app/api/routes/auth.py
@@ -84,6 +84,7 @@ class CurrentUserResponse(BaseModel):
     phone: str = ""
     phone_verified: bool = False
     binding_complete: bool = False
+    wechat_bound: bool = False
 
 
 class PasswordResetRequestModel(BaseModel):
@@ -272,6 +273,7 @@ async def get_current_user_info(
         phone=user.phone or "",
         phone_verified=user.phone_verified,
         binding_complete=binding_complete,
+        wechat_bound=bool(user.wechat_openid),
     )
 
 
@@ -492,6 +494,122 @@ async def wechat_callback(
     )
 
 
+# ==================== 微信账号绑定/解绑（已登录用户） ====================
+
+
+class WechatBindUrlResponse(BaseModel):
+    auth_url: str
+    state: str
+
+
+class WechatBindCompleteRequest(BaseModel):
+    code: str
+    state: str = ""
+
+
+class WechatBindUserProfile(BaseModel):
+    """绑定/解绑后返回的用户信息（字段对齐 /auth/me，前端 normalizeUser 直接消费）"""
+
+    user_id: str
+    email: str
+    username: str
+    display_name: str
+    email_verified: bool
+    phone: str = ""
+    phone_verified: bool = False
+    binding_complete: bool = False
+    wechat_bound: bool = False
+
+
+class WechatBindCompleteResponse(BaseModel):
+    success: bool
+    user: WechatBindUserProfile
+
+
+class WechatUnbindResponse(BaseModel):
+    success: bool
+
+
+def _wechat_user_profile(user) -> WechatBindUserProfile:
+    binding_complete = bool(
+        user.phone_verified and user.email_verified and user.email and "@wechat.local" not in user.email
+    )
+    return WechatBindUserProfile(
+        user_id=user.id,
+        email=user.email,
+        username=user.username,
+        display_name=user.display_name,
+        email_verified=user.email_verified,
+        phone=user.phone or "",
+        phone_verified=user.phone_verified,
+        binding_complete=binding_complete,
+        wechat_bound=bool(user.wechat_openid),
+    )
+
+
+@router.get("/wechat/bind/url", response_model=WechatBindUrlResponse)
+async def get_wechat_bind_url(
+    current_user: AuthenticatedUser = Depends(get_current_user),
+) -> WechatBindUrlResponse:
+    """获取微信绑定授权链接（已登录用户场景）。state 经 Redis 存储做 CSRF 校验。"""
+    from packages.application.auth.wechat_oauth_service import get_wechat_oauth_service
+
+    oauth_service = get_wechat_oauth_service()
+    auth_url, state = oauth_service.generate_auth_url()
+    logger.info("[微信绑定] 用户 %s 请求绑定授权链接", current_user.user.id)
+    return WechatBindUrlResponse(auth_url=auth_url, state=state)
+
+
+@router.post("/wechat/bind", response_model=WechatBindCompleteResponse)
+async def wechat_bind(
+    request: WechatBindCompleteRequest,
+    current_user: AuthenticatedUser = Depends(get_current_user),
+    user_repository: UserRepository = Depends(get_user_repository),
+) -> WechatBindCompleteResponse:
+    """微信绑定完成：扫码回调后用 code 换 openid，绑定到当前登录账号（不创建新用户）。"""
+    from packages.application.auth.wechat_bind_use_case import WechatBindRequest, WechatBindUseCase
+    from packages.application.auth.wechat_oauth_service import get_wechat_oauth_service
+
+    oauth_service = get_wechat_oauth_service()
+    wechat_user, err = oauth_service.handle_callback(request.code, request.state)
+    if err:
+        logger.warning("[微信绑定] 用户 %s 换取微信信息失败: %s", current_user.user.id, err)
+        raise HTTPException(status_code=400, detail=err)
+
+    use_case = WechatBindUseCase(user_repository=user_repository)
+    result, error, http_status = use_case.bind(
+        WechatBindRequest(
+            user_id=current_user.user.id,
+            openid=wechat_user.openid,
+            unionid=wechat_user.unionid or "",
+        )
+    )
+    if error:
+        logger.warning("[微信绑定] 用户 %s 绑定失败: %s", current_user.user.id, error)
+        raise HTTPException(status_code=http_status, detail=error)
+
+    logger.info("[微信绑定] 用户 %s 绑定成功 openid=%s", current_user.user.id, wechat_user.openid[:8])
+    return WechatBindCompleteResponse(success=True, user=_wechat_user_profile(result.user))
+
+
+@router.delete("/wechat/bind", response_model=WechatUnbindResponse)
+async def wechat_unbind(
+    current_user: AuthenticatedUser = Depends(get_current_user),
+    user_repository: UserRepository = Depends(get_user_repository),
+) -> WechatUnbindResponse:
+    """解绑微信：需账号仍有其他登录方式（密码/手机/真实邮箱），否则拒绝。"""
+    from packages.application.auth.wechat_bind_use_case import WechatUnbindUseCase
+
+    use_case = WechatUnbindUseCase(user_repository=user_repository)
+    result, error, http_status = use_case.unbind(current_user.user.id)
+    if error:
+        logger.warning("[微信解绑] 用户 %s 解绑失败: %s", current_user.user.id, error)
+        raise HTTPException(status_code=http_status, detail=error)
+
+    logger.info("[微信解绑] 用户 %s 解绑成功", current_user.user.id)
+    return WechatUnbindResponse(success=True)
+
+
 # ==================== 验证码 & 绑定 ====================
 
 
diff --git a/packages/application/auth/wechat_bind_use_case.py b/packages/application/auth/wechat_bind_use_case.py
new file mode 100644
index 000000000..4b9cce0bb
--- /dev/null
+++ b/packages/application/auth/wechat_bind_use_case.py
@@ -0,0 +1,115 @@
+"""
+微信账号绑定/解绑 Use Case（已登录用户场景）
+
+与 wechat_sync_use_case（登录/注册，系统级）不同：
+- bind：把微信 openid/unionid 绑定到【当前登录账号】，不创建新用户；
+  微信身份若已绑定其他账号则冲突（409）。
+- unbind：解除当前账号的微信绑定；若账号没有其他登录方式（手机/邮箱/密码），
+  解绑后将无法登录，因此拒绝解绑。
+"""
+
+from __future__ import annotations
+
+from typing import Optional
+
+from packages.domain.entities import User
+
+
+class WechatBindRequest:
+    """微信绑定请求"""
+
+    def __init__(self, user_id: str, openid: str, unionid: str = ""):
+        self.user_id = user_id
+        self.openid = (openid or "").strip()
+        self.unionid = (unionid or "").strip()
+
+
+class WechatBindResult:
+    """微信绑定/解绑结果"""
+
+    def __init__(self, user: User):
+        self.user = user
+
+
+class WechatBindUseCase:
+    """已登录用户绑定微信用例"""
+
+    def __init__(self, user_repository):
+        self.user_repository = user_repository
+
+    def bind(self, request: WechatBindRequest) -> tuple[Optional[WechatBindResult], Optional[str], int]:
+        """
+        绑定微信到当前登录账号。
+
+        Returns:
+            (结果, 错误信息, http状态码) - 成功时错误信息为 None、状态码为 200；
+            冲突返回 409，客户端/服务端错误返回 400/404。
+        """
+        if not request.openid:
+            return None, "缺少微信 openid", 400
+
+        user = self.user_repository.find_by_id(request.user_id)
+        if user is None:
+            return None, "当前用户不存在", 404
+
+        # 已绑定同一个微信：幂等成功
+        if user.wechat_openid == request.openid:
+            return WechatBindResult(user=user), None, 200
+
+        # 当前账号已绑定其他微信
+        if user.wechat_openid:
+            return None, "当前账号已绑定微信，请先解绑", 409
+
+        # openid 已被其他账号占用
+        existing = self.user_repository.find_by_wechat_openid(request.openid)
+        if existing is not None and existing.id != user.id:
+            return None, "该微信已绑定其他账号，请先在原账号解绑", 409
+
+        # unionid 冲突：同主体微信已绑其他账号
+        if request.unionid:
+            existing_union = self.user_repository.find_by_wechat_unionid(request.unionid)
+            if existing_union is not None and existing_union.id != user.id:
+                return None, "该微信主体已绑定其他账号，请先在原账号解绑", 409
+
+        user.wechat_openid = request.openid
+        if request.unionid and not user.wechat_unionid:
+            user.wechat_unionid = request.unionid
+        self.user_repository.save(user)
+
+        return WechatBindResult(user=user), None, 200
+
+
+class WechatUnbindUseCase:
+    """已登录用户解绑微信用例"""
+
+    def __init__(self, user_repository):
+        self.user_repository = user_repository
+
+    def unbind(self, user_id: str) -> tuple[Optional[WechatBindResult], Optional[str], int]:
+        """
+        解除当前账号的微信绑定。
+
+        解绑前置条件：账号必须还有其他登录方式（密码 / 已验证手机 / 真实邮箱），
+        否则解绑后将永远无法登录。
+        """
+        user = self.user_repository.find_by_id(user_id)
+        if user is None:
+            return None, "当前用户不存在", 404
+
+        if not user.wechat_openid:
+            return None, "当前账号未绑定微信", 400
+
+        # 守卫：解绑后账号必须仍有可实际使用的登录方式。
+        # 注意：微信注册用户带的是【随机密码】（用户不知道、无法用密码登录，
+        # 且 @wechat.local 占位邮箱收不到重置邮件），故 password_hash 不作为兜底依据，
+        # 口径与 /auth/me 的 binding_complete 一致。
+        has_phone = bool(user.phone and user.phone_verified)
+        has_real_email = bool(user.email and user.email_verified and "@wechat.local" not in user.email)
+        if not (has_phone or has_real_email):
+            return None, "账号需要至少一种其他登录方式（已验证手机或真实邮箱）后才能解绑微信", 400
+
+        user.wechat_openid = None
+        user.wechat_unionid = None
+        self.user_repository.save(user)
+
+        return WechatBindResult(user=user), None, 200
diff --git a/tests/unit/test_wechat_bind_routes_1719.py b/tests/unit/test_wechat_bind_routes_1719.py
new file mode 100644
index 000000000..37df5fada
--- /dev/null
+++ b/tests/unit/test_wechat_bind_routes_1719.py
@@ -0,0 +1,233 @@
+"""#1719：微信绑定/解绑路由层测试（直接驱动路由函数）。
+
+覆盖：
+- GET  /wechat/bind/url：调 oauth 生成链接、记日志
+- POST /wechat/bind：oauth 失败→400；绑定成功→success+user.wechat_bound=True；
+  use case 返回冲突→对应状态码透传
+- DELETE /wechat/bind：成功→success=True；use case 报错→状态码透传
+- /auth/me 返回 wechat_bound 字段
+"""
+
+from __future__ import annotations
+
+import asyncio
+import os
+import sys
+from pathlib import Path
+from types import SimpleNamespace
+from unittest.mock import MagicMock
+
+import pytest
+
+os.environ.setdefault("JWT_SECRET_KEY", "unit-test-secret-key-for-testing")
+os.environ.setdefault("DATABASE_URL", "sqlite:///test.db")
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "apps" / "api"))
+
+from app.api.routes import auth as auth_route  # noqa: E402
+from fastapi import HTTPException  # noqa: E402
+
+
+def _auth_user(user_id="u-1", openid=None):
+    user = SimpleNamespace(
+        id=user_id,
+        wechat_openid=openid,
+        email="user@example.com",
+        email_verified=True,
+        username="user",
+        display_name="用户",
+        phone="",
+        phone_verified=False,
+    )
+    return SimpleNamespace(user=user, session_id="s-1", token_type="user_auth")
+
+
+def _patched_bind(result, error, status):
+    """构造打了补丁的 wechat_bind_use_case 模块"""
+    mod = SimpleNamespace(
+        WechatBindRequest=lambda **kw: SimpleNamespace(**kw),
+        WechatBindUseCase=MagicMock(),
+        WechatUnbindUseCase=MagicMock(),
+    )
+    fake_bind_uc = MagicMock()
+    fake_bind_uc.bind.return_value = (result, error, status)
+    mod.WechatBindUseCase.return_value = fake_bind_uc
+    return mod
+
+
+def test_get_bind_url_returns_url_and_state():
+    fake_oauth = MagicMock()
+    fake_oauth.generate_auth_url.return_value = ("https://open.weixin.qq.com/qrconnect?xxx", "state-bind-1")
+
+    import packages.application.auth.wechat_oauth_service as oauth_mod
+
+    orig = oauth_mod.get_wechat_oauth_service
+    oauth_mod.get_wechat_oauth_service = MagicMock(return_value=fake_oauth)
+    try:
+        resp = asyncio.run(auth_route.get_wechat_bind_url(current_user=_auth_user()))
+    finally:
+        oauth_mod.get_wechat_oauth_service = orig
+
+    assert resp.auth_url.startswith("https://open.weixin.qq.com")
+    assert resp.state == "state-bind-1"
+
+
+def test_bind_oauth_error_returns_400():
+    fake_oauth = MagicMock()
+    fake_oauth.handle_callback.return_value = (None, "无效的 state 参数")
+
+    import packages.application.auth.wechat_oauth_service as oauth_mod
+
+    orig = oauth_mod.get_wechat_oauth_service
+    oauth_mod.get_wechat_oauth_service = MagicMock(return_value=fake_oauth)
+    try:
+        with pytest.raises(HTTPException) as exc:
+            asyncio.run(
+                auth_route.wechat_bind(
+                    SimpleNamespace(code="c-1", state="s-1"),
+                    current_user=_auth_user(),
+                    user_repository=MagicMock(),
+                )
+            )
+    finally:
+        oauth_mod.get_wechat_oauth_service = orig
+
+    assert exc.value.status_code == 400
+    assert "state" in exc.value.detail
+
+
+def test_bind_success_returns_user_with_wechat_bound():
+    fake_oauth = MagicMock()
+    fake_oauth.handle_callback.return_value = (
+        SimpleNamespace(openid="wx-openid-1", unionid="wx-union-1"),
+        None,
+    )
+
+    bound_user = SimpleNamespace(
+        id="u-1",
+        wechat_openid="wx-openid-1",
+        email="user@example.com",
+        email_verified=True,
+        username="user",
+        display_name="用户",
+        phone="",
+        phone_verified=False,
+    )
+
+    import packages.application.auth.wechat_oauth_service as oauth_mod
+    from packages.application.auth import wechat_bind_use_case as bind_mod
+
+    orig_oauth = oauth_mod.get_wechat_oauth_service
+    fake_bind_uc = MagicMock()
+    fake_bind_uc.bind.return_value = (SimpleNamespace(user=bound_user), None, 200)
+    orig_bind = bind_mod.WechatBindUseCase
+    bind_mod.WechatBindUseCase = MagicMock(return_value=fake_bind_uc)
+    oauth_mod.get_wechat_oauth_service = MagicMock(return_value=fake_oauth)
+    try:
+        resp = asyncio.run(
+            auth_route.wechat_bind(
+                SimpleNamespace(code="c-1", state="s-1"),
+                current_user=_auth_user(),
+                user_repository=MagicMock(),
+            )
+        )
+    finally:
+        oauth_mod.get_wechat_oauth_service = orig_oauth
+        bind_mod.WechatBindUseCase = orig_bind
+
+    assert resp.success is True
+    assert resp.user.wechat_bound is True
+    assert resp.user.user_id == "u-1"
+    # 绑定请求应带上当前用户 id 与微信 openid
+    call_kwargs = fake_bind_uc.bind.call_args[0][0]
+    assert call_kwargs.user_id == "u-1"
+    assert call_kwargs.openid == "wx-openid-1"
+
+
+def test_bind_conflict_propagates_409():
+    fake_oauth = MagicMock()
+    fake_oauth.handle_callback.return_value = (
+        SimpleNamespace(openid="wx-openid-1", unionid=""),
+        None,
+    )
+
+    import packages.application.auth.wechat_oauth_service as oauth_mod
+    from packages.application.auth import wechat_bind_use_case as bind_mod
+
+    orig_oauth = oauth_mod.get_wechat_oauth_service
+    fake_bind_uc = MagicMock()
+    fake_bind_uc.bind.return_value = (None, "该微信已绑定其他账号，请先在原账号解绑", 409)
+    orig_bind = bind_mod.WechatBindUseCase
+    bind_mod.WechatBindUseCase = MagicMock(return_value=fake_bind_uc)
+    oauth_mod.get_wechat_oauth_service = MagicMock(return_value=fake_oauth)
+    try:
+        with pytest.raises(HTTPException) as exc:
+            asyncio.run(
+                auth_route.wechat_bind(
+                    SimpleNamespace(code="c-1", state="s-1"),
+                    current_user=_auth_user(),
+                    user_repository=MagicMock(),
+                )
+            )
+    finally:
+        oauth_mod.get_wechat_oauth_service = orig_oauth
+        bind_mod.WechatBindUseCase = orig_bind
+
+    assert exc.value.status_code == 409
+    assert "已绑定其他账号" in exc.value.detail
+
+
+def test_unbind_success_returns_success_true():
+    unbound_user = SimpleNamespace(
+        id="u-1",
+        wechat_openid=None,
+        email="user@example.com",
+        email_verified=True,
+        username="user",
+        display_name="用户",
+        phone="",
+        phone_verified=False,
+    )
+
+    from packages.application.auth import wechat_bind_use_case as bind_mod
+
+    fake_uc = MagicMock()
+    fake_uc.unbind.return_value = (SimpleNamespace(user=unbound_user), None, 200)
+    orig = bind_mod.WechatUnbindUseCase
+    bind_mod.WechatUnbindUseCase = MagicMock(return_value=fake_uc)
+    try:
+        resp = asyncio.run(
+            auth_route.wechat_unbind(current_user=_auth_user(openid="wx-old"), user_repository=MagicMock())
+        )
+    finally:
+        bind_mod.WechatUnbindUseCase = orig
+
+    assert resp.success is True
+    fake_uc.unbind.assert_called_once_with("u-1")
+
+
+def test_unbind_rejected_no_other_login_propagates_400():
+    from packages.application.auth import wechat_bind_use_case as bind_mod
+
+    fake_uc = MagicMock()
+    fake_uc.unbind.return_value = (None, "账号需要至少一种其他登录方式（已验证手机或真实邮箱）后才能解绑微信", 400)
+    orig = bind_mod.WechatUnbindUseCase
+    bind_mod.WechatUnbindUseCase = MagicMock(return_value=fake_uc)
+    try:
+        with pytest.raises(HTTPException) as exc:
+            asyncio.run(auth_route.wechat_unbind(current_user=_auth_user(openid="wx-old"), user_repository=MagicMock()))
+    finally:
+        bind_mod.WechatUnbindUseCase = orig
+
+    assert exc.value.status_code == 400
+    assert "登录方式" in exc.value.detail
+
+
+def test_me_includes_wechat_bound_flag():
+    # 已绑定用户
+    resp = asyncio.run(auth_route.get_current_user_info(authenticated_user=_auth_user(openid="wx-openid-1")))
+    assert resp.wechat_bound is True
+
+    # 未绑定用户
+    resp2 = asyncio.run(auth_route.get_current_user_info(authenticated_user=_auth_user(openid=None)))
+    assert resp2.wechat_bound is False
diff --git a/tests/unit/test_wechat_bind_use_case_1719.py b/tests/unit/test_wechat_bind_use_case_1719.py
new file mode 100644
index 000000000..e933f8a25
--- /dev/null
+++ b/tests/unit/test_wechat_bind_use_case_1719.py
@@ -0,0 +1,251 @@
+"""#1719：已登录用户微信绑定/解绑 Use Case 测试。
+
+覆盖：
+- bind：幂等重复绑定、未绑定成功、当前账号已绑其他微信、openid/unionid 冲突 409、用户不存在
+- unbind：成功清 openid+unionid、未绑定拒绝、无其他登录方式拒绝、密码/手机/真实邮箱各兜底放行、用户不存在
+"""
+
+from __future__ import annotations
+
+from types import SimpleNamespace
+
+import pytest
+
+from packages.application.auth.wechat_bind_use_case import (
+    WechatBindRequest,
+    WechatBindUseCase,
+    WechatUnbindUseCase,
+)
+
+
+def _user(
+    user_id="u-1",
+    wechat_openid=None,
+    wechat_unionid=None,
+    password_hash="hashed-pw",
+    phone=None,
+    phone_verified=False,
+    email="user@example.com",
+    email_verified=True,
+):
+    return SimpleNamespace(
+        id=user_id,
+        wechat_openid=wechat_openid,
+        wechat_unionid=wechat_unionid,
+        password_hash=password_hash,
+        phone=phone,
+        phone_verified=phone_verified,
+        email=email,
+        email_verified=email_verified,
+    )
+
+
+class _FakeRepo:
+    """内存仓储：按 id/openid/unionid 建索引，save 原地更新。"""
+
+    def __init__(self, users):
+        self.users = {u.id: u for u in users}
+        self.saved = []
+
+    def find_by_id(self, user_id):
+        return self.users.get(user_id)
+
+    def find_by_wechat_openid(self, openid):
+        for u in self.users.values():
+            if u.wechat_openid == openid:
+                return u
+        return None
+
+    def find_by_wechat_unionid(self, unionid):
+        if not unionid:
+            return None
+        for u in self.users.values():
+            if u.wechat_unionid == unionid:
+                return u
+        return None
+
+    def save(self, user):
+        self.saved.append(user)
+
+
+# ==================== bind ====================
+
+
+def test_bind_success_when_not_bound():
+    user = _user()
+    repo = _FakeRepo([user])
+    result, err, status = WechatBindUseCase(repo).bind(
+        WechatBindRequest(user_id="u-1", openid="wx-openid-1", unionid="wx-union-1")
+    )
+    assert err is None
+    assert status == 200
+    assert result.user.wechat_openid == "wx-openid-1"
+    assert result.user.wechat_unionid == "wx-union-1"
+    assert repo.saved == [user]
+
+
+def test_bind_idempotent_same_openid():
+    user = _user(wechat_openid="wx-openid-1", wechat_unionid="wx-union-1")
+    repo = _FakeRepo([user])
+    result, err, status = WechatBindUseCase(repo).bind(
+        WechatBindRequest(user_id="u-1", openid="wx-openid-1", unionid="wx-union-1")
+    )
+    assert err is None
+    assert status == 200
+    assert result.user is user
+    assert repo.saved == []  # 幂等不写库
+
+
+def test_bind_conflict_user_already_bound_other_wechat():
+    user = _user(wechat_openid="wx-old")
+    repo = _FakeRepo([user])
+    result, err, status = WechatBindUseCase(repo).bind(WechatBindRequest(user_id="u-1", openid="wx-new"))
+    assert result is None
+    assert status == 409
+    assert "已绑定微信" in err
+
+
+def test_bind_conflict_openid_used_by_other_user():
+    user = _user(user_id="u-1")
+    other = _user(user_id="u-2", wechat_openid="wx-openid-1")
+    repo = _FakeRepo([user, other])
+    result, err, status = WechatBindUseCase(repo).bind(WechatBindRequest(user_id="u-1", openid="wx-openid-1"))
+    assert result is None
+    assert status == 409
+    assert "已绑定其他账号" in err
+    assert user.wechat_openid is None  # 未写库
+
+
+def test_bind_conflict_unionid_used_by_other_user():
+    user = _user(user_id="u-1")
+    # openid 不同，但 unionid 指向同一微信主体
+    other = _user(user_id="u-2", wechat_openid="wx-other", wechat_unionid="wx-union-x")
+    repo = _FakeRepo([user, other])
+    result, err, status = WechatBindUseCase(repo).bind(
+        WechatBindRequest(user_id="u-1", openid="wx-openid-1", unionid="wx-union-x")
+    )
+    assert result is None
+    assert status == 409
+    assert "微信主体" in err
+
+
+def test_bind_missing_openid_returns_400():
+    repo = _FakeRepo([_user()])
+    result, err, status = WechatBindUseCase(repo).bind(WechatBindRequest(user_id="u-1", openid=""))
+    assert result is None
+    assert status == 400
+    assert "openid" in err
+
+
+def test_bind_user_not_found_returns_404():
+    repo = _FakeRepo([])
+    result, err, status = WechatBindUseCase(repo).bind(WechatBindRequest(user_id="ghost", openid="wx-openid-1"))
+    assert result is None
+    assert status == 404
+
+
+def test_bind_fills_unionid_when_existing_user_has_none():
+    # 用户历史上只绑了 openid（unionid 为空），再次绑定时补齐 unionid 不冲突
+    user = _user(wechat_openid="wx-openid-1", wechat_unionid=None)
+    repo = _FakeRepo([user])
+    result, err, status = WechatBindUseCase(repo).bind(
+        WechatBindRequest(user_id="u-1", openid="wx-openid-1", unionid="wx-union-new")
+    )
+    # openid 相同 → 幂等成功（不覆盖 unionid，保持数据稳定）
+    assert err is None
+    assert status == 200
+
+
+# ==================== unbind ====================
+
+
+def test_unbind_success_with_real_verified_email():
+    # 默认 _user 即 real@example.com 且 email_verified=True
+    user = _user(wechat_openid="wx-openid-1", wechat_unionid="wx-union-1")
+    repo = _FakeRepo([user])
+    result, err, status = WechatUnbindUseCase(repo).unbind("u-1")
+    assert err is None
+    assert status == 200
+    assert result.user.wechat_openid is None
+    assert result.user.wechat_unionid is None
+    assert repo.saved == [user]
+
+
+def test_unbind_rejected_when_only_random_password_hash():
+    # 微信注册用户：随机密码 hash 存在、邮箱是 @wechat.local 占位、无手机 → 不允许解绑
+    user = _user(
+        wechat_openid="wx-openid-1",
+        password_hash="random-secret-hash",
+        email="abc@wechat.local",
+        email_verified=True,
+    )
+    repo = _FakeRepo([user])
+    result, err, status = WechatUnbindUseCase(repo).unbind("u-1")
+    assert result is None
+    assert status == 400
+    assert "登录方式" in err
+    assert user.wechat_openid == "wx-openid-1"  # 未写库
+
+
+def test_unbind_allowed_with_verified_phone_even_without_password():
+    user = _user(
+        wechat_openid="wx-openid-1",
+        password_hash="",
+        phone="13800000000",
+        phone_verified=True,
+        email="wx@wechat.local",
+        email_verified=True,
+    )
+    repo = _FakeRepo([user])
+    result, err, status = WechatUnbindUseCase(repo).unbind("u-1")
+    assert err is None
+    assert status == 200
+    assert result.user.wechat_openid is None
+
+
+def test_unbind_rejected_when_no_other_login_method():
+    # 无手机、邮箱占位 → 唯一登录方式就是微信，禁止解绑
+    user = _user(
+        wechat_openid="wx-openid-1",
+        password_hash="",
+        email="abc@wechat.local",
+        email_verified=True,
+    )
+    repo = _FakeRepo([user])
+    result, err, status = WechatUnbindUseCase(repo).unbind("u-1")
+    assert result is None
+    assert status == 400
+    assert "登录方式" in err
+    assert user.wechat_openid == "wx-openid-1"  # 未写库
+
+
+def test_unbind_not_bound_returns_400():
+    user = _user()  # 未绑定
+    repo = _FakeRepo([user])
+    result, err, status = WechatUnbindUseCase(repo).unbind("u-1")
+    assert result is None
+    assert status == 400
+    assert "未绑定" in err
+
+
+def test_unbind_user_not_found_returns_404():
+    repo = _FakeRepo([])
+    result, err, status = WechatUnbindUseCase(repo).unbind("ghost")
+    assert result is None
+    assert status == 404
+
+
+def test_unbind_unverified_phone_does_not_count():
+    # 手机未验证不算有效登录方式
+    user = _user(
+        wechat_openid="wx-openid-1",
+        password_hash="",
+        phone="13800000000",
+        phone_verified=False,
+        email="abc@wechat.local",
+        email_verified=True,
+    )
+    repo = _FakeRepo([user])
+    result, err, status = WechatUnbindUseCase(repo).unbind("u-1")
+    assert result is None
+    assert status == 400