diff --git a/frontend/src/app/site-finder/page.tsx b/frontend/src/app/site-finder/page.tsx
index 04a74bc5..2a20afc0 100644
--- a/frontend/src/app/site-finder/page.tsx
+++ b/frontend/src/app/site-finder/page.tsx
@@ -1,8 +1,9 @@
 "use client";
 
-import { useState } from "react";
+import { Suspense, useEffect, useState } from "react";
 import dynamic from "next/dynamic";
 import Link from "next/link";
+import { usePathname, useRouter, useSearchParams } from "next/navigation";
 import type { FeatureCollection } from "geojson";
 
 import { CadInput } from "@/components/site-finder/CadInput";
@@ -47,6 +48,12 @@ const TABS: Array<{ id: TabId; label: string }> = [
   { id: "market", label: "Рынок" },
 ];
 
+const TAB_IDS = TABS.map((t) => t.id);
+
+function isTabId(v: string | null | undefined): v is TabId {
+  return !!v && (TAB_IDS as readonly string[]).includes(v);
+}
+
 // ── KPI helpers ───────────────────────────────────────────────────────────────
 
 type KpiColor = "neutral" | "amber" | "green" | "red" | "blue";
@@ -73,12 +80,44 @@ function scoreKpiColor(score: number, max: number): KpiColor {
 
 // ── Page ──────────────────────────────────────────────────────────────────────
 
-export default function SiteFinderPage() {
+function SiteFinderContent() {
+  const router = useRouter();
+  const pathname = usePathname();
+  const searchParams = useSearchParams();
+
   const { mutate, data, isPending, error, isIdle } = useSiteAnalysis();
   const [isochrones, setIsochrones] = useState<FeatureCollection | undefined>(
     undefined,
   );
-  const [tab, setTab] = useState<TabId>("overview");
+  // Lazy init: считаем initialTab один раз на mount (useState всё равно
+  // игнорирует initializer после первого render — не тратим CPU).
+  const [tab, setTabState] = useState<TabId>(() => {
+    const t = searchParams.get("tab");
+    return isTabId(t) ? t : "overview";
+  });
+
+  // Sync tab → URL query (?tab=env). overview = default, не пишем в URL.
+  function setTab(next: TabId) {
+    setTabState(next);
+    const params = new URLSearchParams(searchParams.toString());
+    if (next === "overview") {
+      params.delete("tab");
+    } else {
+      params.set("tab", next);
+    }
+    const qs = params.toString();
+    // Используем pathname вместо голого "?" — Next 15 App Router не всегда
+    // чисто чистит query при `router.replace("?")` (dangling `?` остаётся).
+    router.replace(qs ? `${pathname}?${qs}` : pathname, { scroll: false });
+  }
+
+  // Listen to back/forward navigation — reflect URL tab in state.
+  // setState с тем же значением React сам бэйлит через Object.is, поэтому
+  // guard по tab не нужен (и не вводит stale-closure через eslint-disable).
+  useEffect(() => {
+    const urlTab = searchParams.get("tab");
+    setTabState(isTabId(urlTab) ? urlTab : "overview");
+  }, [searchParams]);
 
   function handleAnalyze(cadNum: string) {
     setIsochrones(undefined);
@@ -342,3 +381,13 @@ export default function SiteFinderPage() {
     </main>
   );
 }
+
+// useSearchParams() в Next 15 App Router throw'ит при static rendering без
+// <Suspense> boundary — поэтому оборачиваем page-level.
+export default function SiteFinderPage() {
+  return (
+    <Suspense fallback={null}>
+      <SiteFinderContent />
+    </Suspense>
+  );
+}