diff --git a/backend/crates/gateway-api/src/admin/auth.rs b/backend/crates/gateway-api/src/admin/auth.rs
index 6d7c96a47..0a7ad0fc2 100644
--- a/backend/crates/gateway-api/src/admin/auth.rs
+++ b/backend/crates/gateway-api/src/admin/auth.rs
@@ -216,9 +216,11 @@ where
         .route("/api/admin/auth/logout", post(logout::<S>))
 }
 
-/// 登录失败限流以 socket 对端 IP 为计数桶，使不同来源的失败互不影响；
+/// 登录失败限流以 socket 对端为计数桶，使不同来源的失败互不影响；
 /// 转发头（X-Forwarded-For 等）可由客户端伪造，不参与来源判定。
 /// 经反向代理部署时所有请求同源于代理地址，退化为共享单桶。
+/// IPv6 按 /64 前缀聚合——单前缀内 2^64 地址不应各得独立配额，否则
+/// 直连 IPv6 客户端可逐地址轮换绕过限流。
 async fn attach_login_source(mut request: Request, next: Next) -> Response {
     if let Some(ConnectInfo(peer)) = request
         .extensions()
@@ -227,11 +229,21 @@ async fn attach_login_source(mut request: Request, next: Next) -> Response {
     {
         request
             .extensions_mut()
-            .insert(AdminLoginSource::new(peer.ip().to_string()));
+            .insert(AdminLoginSource::new(login_bucket_key(peer.ip())));
     }
     next.run(request).await
 }
 
+fn login_bucket_key(ip: std::net::IpAddr) -> String {
+    match ip {
+        std::net::IpAddr::V4(v4) => v4.to_string(),
+        std::net::IpAddr::V6(v6) => {
+            let prefix = u128::from(v6) & !((1_u128 << 64) - 1);
+            format!("{}/64", std::net::Ipv6Addr::from(prefix))
+        }
+    }
+}
+
 async fn login<S>(
     State(state): State<S>,
     source: Option<Extension<AdminLoginSource>>,
diff --git a/backend/crates/gateway-api/tests/admin/auth.rs b/backend/crates/gateway-api/tests/admin/auth.rs
index 62b49677c..3759d4974 100644
--- a/backend/crates/gateway-api/tests/admin/auth.rs
+++ b/backend/crates/gateway-api/tests/admin/auth.rs
@@ -226,3 +226,62 @@ async fn login_route_should_bucket_throttling_by_client_ip() {
         axum::http::StatusCode::UNAUTHORIZED
     );
 }
+
+#[tokio::test]
+async fn login_route_should_aggregate_ipv6_sources_by_64_prefix() {
+    use std::net::{Ipv6Addr, SocketAddr};
+
+    use axum::{body::Body, extract::ConnectInfo, http::Request};
+    use tower::ServiceExt as _;
+
+    #[derive(Clone)]
+    struct AuthState(gateway_admin::AdminServices);
+
+    impl gateway_api::admin::AdminSessionState for AuthState {
+        fn admin_services(&self) -> &gateway_admin::AdminServices {
+            &self.0
+        }
+    }
+
+    let fixture = AdminTestFixture::new().await;
+    let app = gateway_api::admin::auth::router::<AuthState>()
+        .with_state(AuthState(fixture.services.clone()));
+
+    let failed_login_from = |ip: Ipv6Addr| {
+        let app = app.clone();
+        async move {
+            let mut request = Request::builder()
+                .method("POST")
+                .uri("/api/admin/auth/login")
+                .header("content-type", "application/json")
+                .body(Body::from(
+                    r#"{"username":"admin_1","password":"wrong-password"}"#,
+                ))
+                .expect("build login request");
+            request
+                .extensions_mut()
+                .insert(ConnectInfo(SocketAddr::from((ip, 50_000))));
+            app.oneshot(request).await.expect("login response").status()
+        }
+    };
+
+    // 同一 /64 内轮换低 64 位不应各得独立配额：五次即触发限流。
+    for suffix in 0..4 {
+        assert_eq!(
+            failed_login_from(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, suffix)).await,
+            axum::http::StatusCode::UNAUTHORIZED
+        );
+    }
+    assert_eq!(
+        failed_login_from(Ipv6Addr::new(
+            0x2001, 0xdb8, 0, 0, 0xffff, 0xffff, 0xffff, 0xffff
+        ))
+        .await,
+        axum::http::StatusCode::TOO_MANY_REQUESTS
+    );
+    // 不同 /64 前缀是独立桶。
+    assert_eq!(
+        failed_login_from(Ipv6Addr::new(0x2001, 0xdb8, 0, 1, 0, 0, 0, 1)).await,
+        axum::http::StatusCode::UNAUTHORIZED
+    );
+}
diff --git a/backend/crates/gateway-store/tests/support.rs b/backend/crates/gateway-store/tests/support.rs
index 24c57bef8..7912ca27b 100644
--- a/backend/crates/gateway-store/tests/support.rs
+++ b/backend/crates/gateway-store/tests/support.rs
@@ -5,8 +5,16 @@
 pub(crate) fn test_env(name: &str) -> Option<String> {
     let value = std::env::var(name).ok();
     assert!(
-        value.is_some() || std::env::var_os("CI").is_none(),
+        value.is_some() || !running_in_ci(),
         "{name} must be set in CI: store integration tests are not allowed to skip silently"
     );
     value
 }
+
+/// 按 is-ci 约定判定 CI：`CI` 存在且非 falsey（`0`/`false`/空）。
+/// 开发者用 `CI=false` 显式声明「非 CI」时不应把跳过变成 panic。
+fn running_in_ci() -> bool {
+    std::env::var("CI")
+        .ok()
+        .is_some_and(|value| !matches!(value.as_str(), "" | "0" | "false"))
+}