fix(accounts): preserve rolling window usage

Co-authored-by: Codex <noreply@openai.com>

backend/crates/gateway-admin/src/model/provider_credentials.rs

@@ -608,8 +608,9 @@ pub struct ProviderQuota {
 impl ProviderQuota {
     /// 返回账号展开面板使用的当前额度窗口用量。
     ///
-    /// 只选择具备完整时间边界且可按账号归属的窗口；优先级与 Dashboard
-    /// 代表性额度窗口一致，同一优先级保持 Provider 投影顺序。
+    /// Provider 已提供账号级本地用量时，固定窗口和无固定重置点的滚动窗口
+    /// 都可作为代表用量；优先级与 Dashboard 代表性额度窗口一致，
+    /// 同一优先级保持 Provider 投影顺序。
     #[must_use]
     pub fn representative_window_usage(&self) -> Option<&AccountUsage> {
         self.windows
@@ -618,7 +619,6 @@ impl ProviderQuota {
             .filter(|(_, window)| {
                 window.local_usage_attribution == QuotaLocalUsageAttribution::AccountWide
                     && window.window_seconds.is_some()
-                    && window.reset_at.is_some()
                     && window.local_usage.is_some()
             })
             .min_by_key(|(index, window)| (quota_usage_priority(window), *index))

backend/crates/gateway-admin/tests/main.rs

@@ -6,6 +6,7 @@ use gateway_core::engine::credential::OpaqueProviderData;
 use gateway_admin::{
     model::{
         PageSize, Revision,
+        accounts::AccountUsage,
         auth::LoginCommand,
         client_keys::ClientKeyPageSize,
         observability::{DecimalAmount, RequestOutcome, TimeRange},
@@ -135,6 +136,51 @@ fn representative_quota_should_prefer_short_window_and_highest_usage() {
     assert_eq!(quota.representative_used_percent(), Some(45.0));
 }
 
+#[test]
+fn representative_window_usage_should_accept_account_wide_rolling_window_without_reset() {
+    let usage = AccountUsage {
+        account_id: "acct_xai".to_owned(),
+        request_count: 5,
+        success_count: 5,
+        input_tokens: Some(100),
+        output_tokens: Some(20),
+        cached_tokens: Some(80),
+        cache_write_tokens: Some(0),
+        reasoning_tokens: Some(0),
+        image_input_tokens: Some(0),
+        image_output_tokens: Some(0),
+        image_request_count: 0,
+        image_request_failed_count: 0,
+        total_tokens: Some(120),
+        cost_coverage: Default::default(),
+        costs: Vec::new(),
+        last_used_at: Some(Utc::now()),
+        request_buckets: Vec::new(),
+        models: Vec::new(),
+    };
+    let quota = ProviderQuota {
+        observed_at: None,
+        refresh_token_expires_at: None,
+        windows: vec![ProviderQuotaWindow {
+            key: "free-rolling-24h".to_owned(),
+            group: "shortTerm".to_owned(),
+            label: "日限额".to_owned(),
+            source: None,
+            local_usage_attribution: QuotaLocalUsageAttribution::AccountWide,
+            window_seconds: Some(86_400),
+            used_percent: None,
+            reset_at: None,
+            limit_reached: false,
+            local_usage: Some(usage.clone()),
+            provider_data: None,
+        }],
+        limit_reached: false,
+        provider_data: None,
+    };
+
+    assert_eq!(quota.representative_window_usage(), Some(&usage));
+}
+
 #[test]
 fn exhausted_quota_should_project_full_usage_to_only_the_representative_window() {
     let mut quota = ProviderQuota {