diff --git a/apps/storefront/src/lib/abandonedCart.ts b/apps/storefront/src/lib/abandonedCart.ts
index 298da62..8789a7e 100644
--- a/apps/storefront/src/lib/abandonedCart.ts
+++ b/apps/storefront/src/lib/abandonedCart.ts
@@ -4,6 +4,7 @@ import { useCart, useLanguage, type CartLineItem } from "@funky/ui";
 import { authStore } from "./auth.ts";
 import { mergeCartLineItemsByMaxQuantity } from "@funky/ui";
 import { isBackendConfigured, restUrl } from "@funky/sdk";
+import { cacheRestRouteUnavailableFromResponse, isRestRouteAvailable } from "./restRouteAvailability.ts";
 import {
   ABANDONED_CART_CONFIG,
   ABANDONED_CART_ENDPOINT,
@@ -204,13 +205,19 @@ async function fetchAbandonedCartPublicConfig(
   backendLanguageCode: string,
   configuredLanguageCodes: readonly string[] = [],
 ): Promise<AbandonedCartPublicConfig | null> {
-  const endpoint = restUrl("funkycommerce/v1/abandoned-carts/config");
+  const route = "/funkycommerce/v1/abandoned-carts/config";
+  const endpoint = restUrl(route);
   if (!endpoint || !isBackendConfigured) return null;
 
   const key = publicConfigCacheKey(languageCode, backendLanguageCode);
-  const cached = publicConfigCache.get(key);
-  if (cached) return cached;
+  if (publicConfigCache.has(key)) return publicConfigCache.get(key) ?? null;
   if (publicConfigInFlight.has(key)) return publicConfigInFlight.get(key)!;
+  if (await isRestRouteAvailable(route) !== true) {
+    publicConfigCache.set(key, null);
+    return null;
+  }
+  const pendingRequest = publicConfigInFlight.get(key);
+  if (pendingRequest) return pendingRequest;
 
   const url = new URL(endpoint);
   url.searchParams.set("language", languageCode);
@@ -218,6 +225,7 @@ async function fetchAbandonedCartPublicConfig(
 
   const request = fetch(url.toString(), { cache: "no-store" })
     .then(async (response) => {
+      await cacheRestRouteUnavailableFromResponse(route, "GET", response);
       if (!response.ok) return null;
       const raw = (await response.json().catch(() => null)) as AbandonedCartPublicConfigSource | null;
       const normalized = normalizeAbandonedCartPublicConfig(raw, {
diff --git a/apps/storefront/src/lib/archiveSettings.test.ts b/apps/storefront/src/lib/archiveSettings.test.ts
index af7b89d..9ec37e3 100644
--- a/apps/storefront/src/lib/archiveSettings.test.ts
+++ b/apps/storefront/src/lib/archiveSettings.test.ts
@@ -118,7 +118,6 @@ test("Store API pagination accepts empty catalogs and unavailable Woo, but not p
   assert.deepEqual(await fetchRestArchiveNodes("https://cms.test/products", async () =>
     new Response(null, { status: 404 })), []);
   for (const response of [
-    new Response("[]"),
     new Response("[]", { headers: { "x-wp-totalpages": "2" } }),
     new Response("{}", { headers: { "x-wp-totalpages": "1" } }),
     new Response(null, { status: 500 }),
@@ -127,6 +126,22 @@ test("Store API pagination accepts empty catalogs and unavailable Woo, but not p
   }
 });
 
+test("Store API pagination uses page lengths when cross-origin headers are unavailable", async () => {
+  const calls: number[] = [];
+  const nodes = await fetchRestArchiveNodes<number>("https://cms.test/products", async (input) => {
+    const page = Number(new URL(String(input)).searchParams.get("page"));
+    calls.push(page);
+    return new Response(JSON.stringify(page === 1
+      ? Array.from({ length: ARCHIVE_BATCH_SIZE }, (_, index) => index)
+      : [100]), {
+      headers: page === 1 ? {} : { "x-wp-totalpages": "unavailable" },
+    });
+  });
+
+  assert.equal(nodes.length, ARCHIVE_BATCH_SIZE + 1);
+  assert.deepEqual(calls, [1, 2]);
+});
+
 test("archive batching loads multiple cursor pages up to the requested total", async () => {
   const calls: { first: number; after: string | null }[] = [];
   const pages = [
diff --git a/apps/storefront/src/lib/archiveSettings.ts b/apps/storefront/src/lib/archiveSettings.ts
index e0fadd6..b315f04 100644
--- a/apps/storefront/src/lib/archiveSettings.ts
+++ b/apps/storefront/src/lib/archiveSettings.ts
@@ -60,12 +60,13 @@ export async function fetchRestArchiveNodes<TNode>(endpoint: string, request: ty
     if (!Array.isArray(payload)) throw new Error("WooCommerce Store API catalog returned a non-array payload");
     const totalPagesHeader = response.headers.get("x-wp-totalpages");
     const totalPages = Number(totalPagesHeader);
-    if (totalPagesHeader === null || !Number.isSafeInteger(totalPages) || totalPages < 0) {
-      throw new Error("WooCommerce Store API catalog returned invalid pagination headers");
-    }
     nodes.push(...payload);
-    if (page >= totalPages) return nodes;
-    if (!payload.length) throw new Error("WooCommerce Store API catalog returned an incomplete page");
+    if (totalPagesHeader !== null && Number.isSafeInteger(totalPages) && totalPages >= 0) {
+      if (page >= totalPages) return nodes;
+      if (!payload.length) throw new Error("WooCommerce Store API catalog returned an incomplete page");
+    } else if (payload.length < ARCHIVE_BATCH_SIZE) {
+      return nodes;
+    }
   }
   throw new Error("WooCommerce Store API catalog exceeded 1,000 pagination batches");
 }
diff --git a/apps/storefront/src/lib/commerce.ts b/apps/storefront/src/lib/commerce.ts
index 7eef463..b3423e4 100644
--- a/apps/storefront/src/lib/commerce.ts
+++ b/apps/storefront/src/lib/commerce.ts
@@ -42,6 +42,7 @@ import {
   type RawLocalizedTermTranslation,
 } from "./commerceTaxonomyLanguage.ts";
 import { ARCHIVE_BATCH_SIZE, fetchArchiveNodesInBatches, fetchRestArchiveNodes } from "./archiveSettings.ts";
+import { isRestRouteAvailable } from "./restRouteAvailability.ts";
 
 export type { ProductPriceBehavior, ResolvedProductPriceMode } from "./productPriceMode.ts";
 export { resolveProductPriceMode } from "./productPriceMode.ts";
@@ -1245,7 +1246,9 @@ export function mapStoreApiCatalogProduct(product: StoreApiCatalogProduct): RawP
 }
 
 async function getStoreApiCatalogProducts(): Promise<RawProductCard[]> {
-  const endpoint = restUrl("wc/store/v1/products");
+  const route = "/wc/store/v1/products";
+  if (await isRestRouteAvailable(route) !== true) return [];
+  const endpoint = restUrl(route);
   if (!endpoint) return [];
   const products = await fetchRestArchiveNodes<StoreApiCatalogProduct>(endpoint);
   return products.map(mapStoreApiCatalogProduct);
@@ -1434,6 +1437,7 @@ export async function getProductByUriOrSlug(identifier: string): Promise<CmsProd
 }
 
 async function getStoreApiProductDetail(slug: string): Promise<CmsProductDetail | null> {
+  if (await isRestRouteAvailable("/wc/store/v1/products") !== true) return null;
   const endpoint = restUrl(`wc/store/v1/products?slug=${encodeURIComponent(slug)}&per_page=1`);
   if (!endpoint) return null;
   const response = await fetch(endpoint, { headers: { Accept: "application/json" } });
diff --git a/apps/storefront/src/lib/commerceCompatibility.test.ts b/apps/storefront/src/lib/commerceCompatibility.test.ts
index 37ca856..ddd1dca 100644
--- a/apps/storefront/src/lib/commerceCompatibility.test.ts
+++ b/apps/storefront/src/lib/commerceCompatibility.test.ts
@@ -85,6 +85,7 @@ test("single-locale catalogs merge current Store API products with GraphQL produ
   assert.match(source, /const storeApiProducts = configuredLanguageCodes\.length <= 1\s*\?\s*await getOptionalStoreApiCatalogProducts\("catalog"\)/);
   assert.match(source, /\.\.\.storeApiProducts\.filter/);
   assert.match(source, /fetchRestArchiveNodes<StoreApiCatalogProduct>\(endpoint\)/);
+  assert.match(source, /isRestRouteAvailable\(route\) !== true/);
   assert.match(source, /Store API \$\{context\} enrichment failed; preserving authoritative GraphQL data/);
 });
 
diff --git a/apps/storefront/src/lib/protectedPages.test.ts b/apps/storefront/src/lib/protectedPages.test.ts
index 143eada..3001875 100644
--- a/apps/storefront/src/lib/protectedPages.test.ts
+++ b/apps/storefront/src/lib/protectedPages.test.ts
@@ -13,6 +13,7 @@ test("protected pages use authenticated non-cacheable REST access and strict log
   assert.match(client, /X-WPGraphQL-Login-Token/);
   assert.match(client, /X-FunkyCommerce-Page-Proof/);
   assert.match(client, /cachePrivate:\s*true/);
+  assert.match(client, /isRestRouteAvailable\(PROTECTED_PAGE_ROUTE/);
   assert.match(gate, /parseStorefrontAuthRef\(`\$\{pathname\}\$\{search\}\$\{hash\}`\)/);
   assert.match(gate, /role="alert"/);
   assert.match(gate, /aria-labelledby="protected-page-title"/);
diff --git a/apps/storefront/src/lib/protectedPages.ts b/apps/storefront/src/lib/protectedPages.ts
index d887ea7..8bed598 100644
--- a/apps/storefront/src/lib/protectedPages.ts
+++ b/apps/storefront/src/lib/protectedPages.ts
@@ -1,8 +1,10 @@
 import { BACKEND_ORIGIN } from "@funky/sdk";
 import { authStore } from "./auth.ts";
 import type { CmsPage } from "./pages.ts";
+import { isRestRouteAvailable } from "./restRouteAvailability.ts";
 
 const PROOF_PREFIX = "funkycommerce-page-proof:";
+const PROTECTED_PAGE_ROUTE = "/funkycommerce/v1/protected-page";
 
 export class ProtectedPageError extends Error {
   readonly kind: "auth-required" | "password-required" | "invalid-password";
@@ -28,7 +30,10 @@ function storedProof(uri: string): string | null {
 
 async function protectedPageRequest(uri: string, password?: string): Promise<Response | null> {
   if (!BACKEND_ORIGIN) return null;
-  const endpoint = new URL("/wp-json/funkycommerce/v1/protected-page", BACKEND_ORIGIN);
+  if (await isRestRouteAvailable(PROTECTED_PAGE_ROUTE, password === undefined ? "GET" : "POST") !== true) {
+    return null;
+  }
+  const endpoint = new URL(`/wp-json${PROTECTED_PAGE_ROUTE}`, BACKEND_ORIGIN);
   const token = authStore.getToken() || authStore.load()?.authToken;
   const headers: Record<string, string> = {
     Accept: "application/json",
diff --git a/apps/storefront/src/lib/restRouteAvailability.test.ts b/apps/storefront/src/lib/restRouteAvailability.test.ts
new file mode 100644
index 0000000..7b3dd0d
--- /dev/null
+++ b/apps/storefront/src/lib/restRouteAvailability.test.ts
@@ -0,0 +1,35 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import { createRestRouteAvailability, restIndexHasRoute } from "./restRouteAvailability.ts";
+
+test("REST route discovery checks registered methods and reuses the REST index", async () => {
+  const requests: string[] = [];
+  const availability = createRestRouteAvailability("https://cms.test", async (input) => {
+    requests.push(String(input));
+    return new Response(JSON.stringify({
+      routes: {
+        "/funkycommerce/v1/protected-page": {
+          endpoints: [{ methods: ["GET", "POST"] }],
+        },
+      },
+    }));
+  });
+
+  assert.equal(await availability.isAvailable("/funkycommerce/v1/protected-page", "GET"), true);
+  assert.equal(await availability.isAvailable("/funkycommerce/v1/protected-page", "POST"), true);
+  assert.equal(await availability.isAvailable("/funkycommerce/v1/abandoned-carts/config"), false);
+  assert.equal(requests.length, 1);
+  assert.equal(requests[0], "https://cms.test/wp-json/");
+});
+
+test("REST route discovery treats a missing or method-incompatible route as unavailable", () => {
+  const index = {
+    routes: {
+      "/wc/store/v1/products": { endpoints: [{ methods: ["GET"] }] },
+    },
+  };
+
+  assert.equal(restIndexHasRoute(index, "/wc/store/v1/products"), true);
+  assert.equal(restIndexHasRoute(index, "/wc/store/v1/products", "POST"), false);
+  assert.equal(restIndexHasRoute(index, "/funkycommerce/v1/protected-page"), false);
+});
diff --git a/apps/storefront/src/lib/restRouteAvailability.ts b/apps/storefront/src/lib/restRouteAvailability.ts
new file mode 100644
index 0000000..1bc46e7
--- /dev/null
+++ b/apps/storefront/src/lib/restRouteAvailability.ts
@@ -0,0 +1,80 @@
+import { BACKEND_ORIGIN } from "@funky/sdk";
+
+type RestEndpoint = {
+  methods?: string[];
+};
+
+type RestRoute = RestEndpoint & {
+  endpoints?: RestEndpoint[];
+};
+
+type RestIndex = {
+  routes?: Record<string, RestRoute>;
+};
+
+function normalizeRoute(route: string): string {
+  return `/${route.replace(/^\/+|\/+$/g, "")}`;
+}
+
+export function restIndexHasRoute(index: unknown, route: string, method = "GET"): boolean {
+  if (!index || typeof index !== "object") return false;
+  const routes = (index as RestIndex).routes;
+  const entry = routes?.[normalizeRoute(route)];
+  if (!entry) return false;
+  const normalizedMethod = method.toUpperCase();
+  return [entry, ...(entry.endpoints || [])].some((endpoint) =>
+    endpoint.methods?.some((registeredMethod) => registeredMethod.toUpperCase() === normalizedMethod),
+  );
+}
+
+export function createRestRouteAvailability(
+  backendOrigin: string | undefined,
+  request: typeof fetch = fetch,
+) {
+  const unavailableRoutes = new Set<string>();
+  let restIndexRequest: Promise<RestIndex | null> | undefined;
+
+  function getRestIndex(): Promise<RestIndex | null> {
+    if (!backendOrigin) return Promise.resolve(null);
+    if (!restIndexRequest) {
+      restIndexRequest = request(new URL("/wp-json/", backendOrigin), {
+        headers: { Accept: "application/json" },
+        cache: "no-store",
+      })
+        .then(async (response) => {
+          if (!response.ok) return null;
+          const payload: unknown = await response.json().catch(() => null);
+          return payload && typeof payload === "object" ? payload as RestIndex : null;
+        })
+        .catch(() => null);
+    }
+    return restIndexRequest;
+  }
+
+  async function isAvailable(route: string, method = "GET"): Promise<boolean | null> {
+    if (!backendOrigin) return false;
+    const normalizedMethod = method.toUpperCase();
+    const key = `${normalizedMethod}:${normalizeRoute(route)}`;
+    if (unavailableRoutes.has(key)) return false;
+    const index = await getRestIndex();
+    if (!index) return null;
+    const available = restIndexHasRoute(index, route, normalizedMethod);
+    if (!available) unavailableRoutes.add(key);
+    return available;
+  }
+
+  async function cacheUnavailableFromResponse(route: string, method: string, response: Response): Promise<void> {
+    if (response.status !== 404) return;
+    const payload: unknown = await response.clone().json().catch(() => null);
+    if (payload && typeof payload === "object" && "code" in payload && payload.code === "rest_no_route") {
+      unavailableRoutes.add(`${method.toUpperCase()}:${normalizeRoute(route)}`);
+    }
+  }
+
+  return { isAvailable, cacheUnavailableFromResponse };
+}
+
+const backendRestRoutes = createRestRouteAvailability(BACKEND_ORIGIN);
+
+export const isRestRouteAvailable = backendRestRoutes.isAvailable;
+export const cacheRestRouteUnavailableFromResponse = backendRestRoutes.cacheUnavailableFromResponse;
diff --git a/apps/storefront/src/lib/routePrefetch.test.ts b/apps/storefront/src/lib/routePrefetch.test.ts
index 19ec3c1..912bc28 100644
--- a/apps/storefront/src/lib/routePrefetch.test.ts
+++ b/apps/storefront/src/lib/routePrefetch.test.ts
@@ -15,7 +15,7 @@ test("commerce taxonomy prefetch bypasses generic and protected page lookup", ()
   assert.match(documentWarmupSource, /await Promise\.all\(boundedAssets\.map\(loadHydrationAsset\)\)/);
   assert.match(documentWarmupSource, /signal: AbortSignal\.timeout\(2_000\)/);
   assert.match(source, /content-node:v3:/);
-  assert.match(source, /\["product-category", "pro-cat", "pro-category"\]/);
+  assert.match(source, /\["product-category", "kategoria-produktu", "pro-cat", "pro-category"\]/);
   assert.match(source, /\["product-tag", "pro-tag"\]/);
   assert.match(source, /const taxonomy = commerceTaxonomyForPath\(pathname, languageCodes\)/);
   assert.match(source, /if \(taxonomy\) \{[\s\S]*getProductArchive\([\s\S]*return;/);
diff --git a/apps/storefront/src/lib/routePrefetch.ts b/apps/storefront/src/lib/routePrefetch.ts
index bc8cb9e..81fefef 100644
--- a/apps/storefront/src/lib/routePrefetch.ts
+++ b/apps/storefront/src/lib/routePrefetch.ts
@@ -14,7 +14,7 @@ function commerceTaxonomyForPath(pathname: string, languageCodes: readonly strin
   const routeSegments = languageCodes.some((code) => code.toLowerCase() === firstSegment)
     ? segments.slice(1)
     : segments;
-  if (["product-category", "pro-cat", "pro-category"].includes(routeSegments[0])) return "category";
+  if (["product-category", "kategoria-produktu", "pro-cat", "pro-category"].includes(routeSegments[0])) return "category";
   if (["product-tag", "pro-tag"].includes(routeSegments[0])) return "tag";
   if (["brand", "product-brand"].includes(routeSegments[0])) return "brand";
   if (routeSegments[0] === "shop" && routeSegments[1] === "category") return "category";