fix(site): add explicit not-found page

apps/site/tools/site-e2e.mjs

@@ -32,8 +32,8 @@ const GEOMETRY_WIDTHS = [320, 390, 768, 1024, 1440, 1920, 2560];
 const CAPTURE_WIDTHS = new Set([390, 1440]);
 const HEIGHTS = new Map([[320, 844], [390, 844], [768, 1024], [1024, 900], [1440, 1000], [1920, 1080], [2560, 1440]]);
 const AXE_TAGS = ["wcag2a", "wcag2aa", "wcag21a", "wcag21aa", "wcag22aa"];
-const EXPECTED_SCENARIOS = 80;
-const EXPECTED_ASSERTIONS = 995;
+const EXPECTED_SCENARIOS = 81;
+const EXPECTED_ASSERTIONS = 1009;
 const EXPECTED_CAPTURES = 8;
 
 function parseArguments(argv) {
@@ -1394,6 +1394,62 @@ async function main() {
     console.log(`Serving ${serveRoot}`);
     console.log(`Evidence ${evidenceRoot}\n`);
 
+    const notFoundScope = "404 artifact and recovery";
+    await results.scenario(notFoundScope, async () => {
+      const artifact = path.join(serveRoot, "404.html");
+      results.equal(notFoundScope, "top-level 404 artifact exists", true, fs.existsSync(artifact));
+      const opened = await openPage(browser, server.origin, { path: "/404.html" }, { width: 390 });
+      try {
+        const state = await opened.page.evaluate(() => {
+          const robots = [...document.querySelectorAll("meta[name='robots']")].map((element) => element.getAttribute("content") || "");
+          const h1s = [...document.querySelectorAll("h1")].map((element) => element.textContent?.replace(/\s+/g, " ").trim() || "");
+          const englishCopy = [...document.querySelectorAll("[lang='en']")].some((element) => /Page not found\./.test(element.textContent || ""));
+          const links = [...document.querySelectorAll("main a[href]")].map((element) => ({
+            href: element.getAttribute("href"),
+            lang: element.getAttribute("lang"),
+            text: element.textContent?.replace(/\s+/g, " ").trim() || "",
+          }));
+          const executableScripts = [...document.scripts].filter((script) => {
+            const type = (script.getAttribute("type") || "").trim().toLowerCase();
+            return !["application/ld+json", "application/json", "importmap"].includes(type);
+          }).length;
+          return {
+            lang: document.documentElement.lang,
+            mainCount: document.querySelectorAll("main").length,
+            h1s,
+            robots,
+            englishCopy,
+            links,
+            executableScripts,
+            viewportWidth: innerWidth,
+            documentWidth: document.documentElement.scrollWidth,
+          };
+        });
+        const axe = await runAxe(opened.page);
+        results.equal(notFoundScope, "local artifact route responds", 200, opened.status);
+        results.equal(notFoundScope, "document language is Korean", "ko", state.lang);
+        results.equal(notFoundScope, "one main landmark", 1, state.mainCount);
+        results.equal(notFoundScope, "one unique h1", 1, state.h1s.length);
+        results.equal(notFoundScope, "h1 identifies the missing page", "페이지를 찾을 수 없습니다", state.h1s[0]);
+        results.equal(notFoundScope, "English explanation is language tagged", true, state.englishCopy);
+        results.equal(notFoundScope, "one robots directive", 1, state.robots.length);
+        results.check(notFoundScope, "robots directive prevents indexing", state.robots[0]?.split(",").some((value) => value.trim().toLowerCase() === "noindex"), {
+          expected: "noindex",
+          actual: state.robots,
+        });
+        results.check(notFoundScope, "Korean home recovery link exists", state.links.some((link) => link.href === "/" && link.text.endsWith("한국어 홈")), { actual: state.links });
+        results.check(notFoundScope, "English home recovery link exists and is language tagged", state.links.some((link) => link.href === "/en/" && link.lang === "en" && link.text === "EN English home"), { actual: state.links });
+        results.equal(notFoundScope, "no executable scripts", 0, state.executableScripts);
+        results.check(notFoundScope, "no horizontal document overflow", state.documentWidth <= state.viewportWidth + 1, {
+          expected: `<= ${state.viewportWidth + 1}`,
+          actual: state.documentWidth,
+        });
+        results.empty(notFoundScope, "axe WCAG A/AA violations", axe);
+      } finally {
+        await closePage(opened.page);
+      }
+    });
+
     // Four routes across the complete local preflight width matrix. Only the
     // 390/1440 states create visual evidence; every width gets the full geometry gate.
     for (const route of ROUTES) {