diff --git a/backend/internal/service/ratelimit_service.go b/backend/internal/service/ratelimit_service.go
index d12824ec..ecbd86d1 100644
--- a/backend/internal/service/ratelimit_service.go
+++ b/backend/internal/service/ratelimit_service.go
@@ -248,17 +248,15 @@ func (s *RateLimitService) HandleUpstreamError(ctx context.Context, account *Acc
 				shouldDisable = true
 				break
 			}
-			// 2. 设置 expires_at 为当前时间，强制下次请求刷新 token
-			if account.Credentials == nil {
-				account.Credentials = make(map[string]any)
-			}
-			account.Credentials["expires_at"] = time.Now().Format(time.RFC3339)
-			if err := persistAccountCredentials(ctx, s.accountRepo, account, account.Credentials); err != nil {
-				slog.Warn("oauth_401_force_refresh_update_failed", "account_id", account.ID, "error", err)
-			} else {
-				slog.Info("oauth_401_force_refresh_set", "account_id", account.ID, "platform", account.Platform)
-			}
-			// 3. 临时不可调度，替代 SetError（保持 status=active 让刷新服务能拾取）
+			// 2. 临时不可调度，替代 SetError（保持 status=active 让刷新服务能拾取）
+			// 注意：此处不再写回 account.Credentials/expires_at。
+			// 原实现使用请求开始时的 account 快照整列覆盖 credentials JSONB（见
+			// persistAccountCredentials → accountRepository.UpdateCredentials → SetCredentials），
+			// 在另一个 worker 刚刷新完 refresh_token 的窄窗口内会把新 refresh_token 回滚为旧值，
+			// 导致下一周期用旧 refresh_token 调上游拿到 invalid_grant 后，
+			// tryRecoverFromRefreshRace 重读 DB 发现 currentRT == usedRT 也救不回来，账号被错误 disable。
+			// 这里仅依赖 InvalidateToken + SetTempUnschedulable 让账号在冷却期内不被调度，
+			// 冷却结束后由 token_provider 的 NeedsRefresh / token_refresh_service 走带分布式锁的正路刷新。
 			msg := "Authentication failed (401): invalid or expired credentials"
 			if upstreamMsg != "" {
 				msg = "OAuth 401: " + upstreamMsg
diff --git a/backend/internal/service/ratelimit_service_401_test.go b/backend/internal/service/ratelimit_service_401_test.go
index a964775e..873aaf33 100644
--- a/backend/internal/service/ratelimit_service_401_test.go
+++ b/backend/internal/service/ratelimit_service_401_test.go
@@ -129,7 +129,10 @@ func TestRateLimitService_HandleUpstreamError_OAuth401SetsTempUnschedulable(t *t
 }
 
 // TestRateLimitService_HandleUpstreamError_OAuth401InvalidatorError
-// OpenAI OAuth 401 缓存失效出错时仍走 temp_unschedulable
+// OpenAI OAuth 401 缓存失效出错时仍走 temp_unschedulable。
+// 注意：401 handler 不再回写 credentials(避免请求开始时的快照整列覆盖 DB
+// 把另一个 worker 刚刷新出来的新 refresh_token 回滚为旧值),
+// 因此 updateCredentialsCalls 应当为 0。
 func TestRateLimitService_HandleUpstreamError_OAuth401InvalidatorError(t *testing.T) {
 	repo := &rateLimitAccountRepoStub{}
 	invalidator := &tokenCacheInvalidatorRecorder{err: errors.New("boom")}
@@ -149,7 +152,7 @@ func TestRateLimitService_HandleUpstreamError_OAuth401InvalidatorError(t *testin
 	require.True(t, shouldDisable)
 	require.Equal(t, 0, repo.setErrorCalls)
 	require.Equal(t, 1, repo.tempCalls)
-	require.Equal(t, 1, repo.updateCredentialsCalls)
+	require.Equal(t, 0, repo.updateCredentialsCalls)
 	require.Len(t, invalidator.accounts, 1)
 }
 
@@ -171,7 +174,12 @@ func TestRateLimitService_HandleUpstreamError_NonOAuth401(t *testing.T) {
 	require.Empty(t, invalidator.accounts)
 }
 
-func TestRateLimitService_HandleUpstreamError_OAuth401UsesCredentialsUpdater(t *testing.T) {
+// TestRateLimitService_HandleUpstreamError_OAuth401DoesNotOverwriteCredentials
+// 回归测试:确保 401 handler 不再使用请求开始时的 account 快照写回 credentials。
+// 原实现会通过 persistAccountCredentials → UpdateCredentials → SetCredentials
+// 整列覆盖 credentials JSONB,在另一个 worker 刚刷新完 refresh_token 的窄窗口内
+// 会把新 refresh_token 回滚为快照中的旧值,导致下一周期拿 invalid_grant 被错误 disable。
+func TestRateLimitService_HandleUpstreamError_OAuth401DoesNotOverwriteCredentials(t *testing.T) {
 	repo := &rateLimitAccountRepoStub{}
 	service := NewRateLimitService(repo, nil, &config.Config{}, nil, nil)
 	account := &Account{
@@ -187,8 +195,9 @@ func TestRateLimitService_HandleUpstreamError_OAuth401UsesCredentialsUpdater(t *
 	shouldDisable := service.HandleUpstreamError(context.Background(), account, 401, http.Header{}, []byte("unauthorized"))
 
 	require.True(t, shouldDisable)
-	require.Equal(t, 1, repo.updateCredentialsCalls)
-	require.NotEmpty(t, repo.lastCredentials["expires_at"])
+	require.Equal(t, 0, repo.updateCredentialsCalls, "401 handler must not write credentials back from the request-start snapshot")
+	require.Equal(t, 1, repo.tempCalls, "401 handler should still set temp-unschedulable cooldown")
+	require.Nil(t, repo.lastCredentials, "no credentials should have been persisted")
 }
 
 // 缺少 refresh_token 的 OAuth 账号 401 应直接 SetError 永久禁用，