feat(auth): M2 POST /wechat/conflict/continue(继续绑定=登录老账号)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/api/v1/auth.py

@@ -13,6 +13,7 @@ from __future__ import annotations
 import logging
 
 from fastapi import APIRouter, HTTPException, Request, status
+from sqlalchemy.exc import IntegrityError
 
 from app.api.deps import CurrentUser, DbSession
 from app.core import test_account
@@ -46,6 +47,8 @@ from app.schemas.auth import (
     WechatBindPhoneJverifyRequest,
     WechatBindPhoneSmsRequest,
     WechatBindResultResponse,
+    WechatConflictContinueRequest,
+    WechatConflictRebindRequest,
     WechatLoginRequest,
     WechatLoginResponse,
 )
@@ -352,6 +355,53 @@ def wechat_bind_phone_jverify(
     )
 
 
+# ===================== 微信占用冲突(M2) =====================
+
+@router.post(
+    "/wechat/conflict/continue",
+    response_model=WechatBindResultResponse,
+    summary="微信占用冲突·继续绑定(登录老账号,能绑就绑)",
+)
+def wechat_conflict_continue(
+    req: WechatConflictContinueRequest, request: Request, db: DbSession
+) -> WechatBindResultResponse:
+    try:
+        claims = decode_conflict_ticket(req.conflict_ticket)
+    except TokenError as e:
+        raise HTTPException(status_code=401, detail="操作超时,请重新用微信登录") from e
+
+    enforce_rate_limit(
+        request, scope="wechat-conflict-device", subject=req.device_id,
+        limit=SMS_LOGIN_MAX_PER_HOUR, window_sec=3600, detail="操作过于频繁,请稍后再试",
+    )
+
+    user = user_repo.get_user_by_phone(db, claims["phone"])
+    if user is None:
+        # P 期间被腾空(老账号改号/注销)→ 前提已变,让前端重走
+        raise HTTPException(status_code=409, detail="账号状态已变化,请重新登录")
+    if user.status != "active":
+        raise HTTPException(status_code=403, detail="account disabled")
+
+    if user.wechat_openid is None:
+        try:
+            user_repo.attach_wechat_to_user(
+                db, user, openid=claims["openid"],
+                wechat_nickname=claims["wnk"], wechat_avatar_url=claims["wav"],
+            )
+        except IntegrityError:
+            db.rollback()  # openid 被别处绑走 → 只登入不绑
+            user_repo.touch_last_login(db, user)
+    else:
+        user_repo.touch_last_login(db, user)  # X 已绑别的微信 → 只登入,丢弃本次 openid
+
+    completed = onboarding_repo.is_completed(db, user_id=user.id, device_id=req.device_id)
+    logger.info("wechat conflict continue user_id=%d openid=%s***", user.id, claims["openid"][:6])
+    return WechatBindResultResponse(
+        status="logged_in",
+        token=_login_response(user, onboarding_completed=completed),
+    )
+
+
 # ===================== Refresh =====================
 
 @router.post("/refresh", response_model=TokenPair, summary="用 refresh_token 换新 token 对")