fix: return a real 404 for nonexistent athlete pages

app/e2e/athlete-404.spec.ts

@@ -0,0 +1,22 @@
+import { test, expect } from "@playwright/test";
+
+// Regression guard for the athlete-page soft-404. A loading.tsx at
+// app/src/app/athlete/[slug]/ created an implicit Suspense boundary that made
+// Next stream the shell with a 200 status before the page's notFound() ran, so
+// a nonexistent athlete returned HTTP 200 with the not-found UI (a soft 404 —
+// bad for SEO). Removing that loading.tsx lets Next resolve notFound() before
+// flushing the status. These assertions fail (miss returns 200) if it comes back.
+
+test("nonexistent athlete returns a real 404 status", async ({ page }) => {
+  const res = await page.goto("/athlete/no-such-person--zz-x");
+  expect(res?.status()).toBe(404);
+  await expect(page.getByText("Page not found")).toBeVisible();
+});
+
+test("existing athlete returns 200 and renders the profile", async ({ page }) => {
+  // Rootul Patel is present in the committed athlete index (see
+  // athlete-search.spec.ts, which relies on the same athlete).
+  const res = await page.goto("/athlete/rootul-patel--us-m");
+  expect(res?.status()).toBe(200);
+  await expect(page.getByText("Rootul Patel")).toBeVisible();
+});

app/src/app/athlete/[slug]/page.tsx

@@ -13,6 +13,14 @@ import AthleteRaceList from "@/components/AthleteRaceList";
 // Web APIs only, no fs/zlib (see @/lib/athlete-shards).
 export const runtime = "edge";
 
+// NOTE: deliberately no loading.tsx for this segment. A loading.tsx creates an
+// implicit Suspense boundary that makes Next stream the shell with a 200 status
+// before this page runs, so notFound() for a nonexistent athlete could only
+// produce a soft 404 (HTTP 200 with the not-found UI) — bad for SEO. Without
+// it, Next resolves the page (and notFound()) before flushing the status, so
+// missing athletes return a real 404. See e2e/athlete-404.spec.ts. The shard
+// fetch is fast on the edge, so the lost skeleton costs little.
+
 interface PageProps {
   params: Promise<{ slug: string }>;
 }