diff --git a/web/src/services/diagnostics/client-diagnostics.ts b/web/src/services/diagnostics/client-diagnostics.ts
index f4c37e0d0..8a71b35d1 100644
--- a/web/src/services/diagnostics/client-diagnostics.ts
+++ b/web/src/services/diagnostics/client-diagnostics.ts
@@ -124,7 +124,7 @@ export function recordDiagnosticEvent(input: DiagnosticEventInput) {
         category: input.category,
         code: redactClientText(input.code),
         message: redactClientText(input.message) || "未命名诊断事件",
-        route: normalizeRoute(input.route || (typeof window !== "undefined" ? window.location.pathname : "")),
+        route: normalizeRoute(input.route || browserLocation()?.pathname || ""),
         durationMs: input.durationMs === undefined ? undefined : clampNumber(input.durationMs, 0, 86_400_000),
         httpStatus: input.httpStatus === undefined ? undefined : clampNumber(input.httpStatus, 0, 599),
         requestId: safeDiagnosticId(input.requestId),
@@ -177,11 +177,17 @@ function readHeader(headers: unknown, key: string) {
     return typeof value === "string" ? value : undefined;
 }
 
+// 诊断只在真实浏览器里有地址。测试与 SSR 环境里 `window` 可能存在但 `window.location` 不存在
+// （bun test 就是这样），所以两个都要探测，不能只看 typeof window。
+function browserLocation(): Location | undefined {
+    return typeof window !== "undefined" && window.location ? window.location : undefined;
+}
+
 function normalizeRoute(value?: string) {
     const raw = String(value || "").trim();
-    if (!raw) return typeof window !== "undefined" ? window.location.pathname : "/";
+    if (!raw) return browserLocation()?.pathname || "/";
     try {
-        const parsed = new URL(raw, typeof window !== "undefined" ? window.location.origin : "http://localhost");
+        const parsed = new URL(raw, browserLocation()?.origin || "http://localhost");
         return parsed.pathname || "/";
     } catch {
         return raw.split(/[?#]/, 1)[0] || "/";