fix: sitemap aggregate timeout + CDN caching

src/app/api/aggregate/route.ts

@@ -11,9 +11,17 @@
 // of kv.openchainbench.com to get near-zero latency from any Vercel
 // function in the same region.
 export const runtime = "nodejs";
+// ISR: generate once, serve from Vercel Data Cache for 60 s, regenerate
+// in background. Keeps s-maxage in the response (Next.js strips it when
+// the route uses cache:"no-store" fetches internally, which makes the
+// route dynamic and prevents CDN caching — removing that flag fixes it).
+export const revalidate = 60;
 
 const UPSTREAM = "https://kv.openchainbench.com/aggregate/latest.json";
-const UPSTREAM_TIMEOUT_MS = 25_000;
+// Paris VPS → IAD1 with 7.3 MB payload: measured 37-49 s uncompressed.
+// With Accept-Encoding:gzip Caddy compresses to ~2.3 MB in ~18 s. Set
+// the timeout to 70 s so cold-cache first requests always complete.
+const UPSTREAM_TIMEOUT_MS = 70_000;
 
 export async function GET() {
   // Retry once: some Vercel function instances can't reach the Paris VPS
@@ -28,7 +36,10 @@ export async function GET() {
       upstream = await fetch(UPSTREAM, {
         signal: AbortSignal.timeout(UPSTREAM_TIMEOUT_MS),
         headers: { "Accept-Encoding": "gzip, br" },
-        cache: "no-store",
+        // No cache:"no-store" here: that flag opts the route into
+        // dynamic mode and causes Next.js to strip s-maxage from our
+        // response headers, breaking Vercel CDN caching. The ISR
+        // revalidate=60 above handles freshness instead.
       });
     } catch (err) {
       lastErr = String(err);

src/lib/aggregate-blob.ts

@@ -35,7 +35,11 @@ const DEFAULT_URL =
   process.env.VERCEL_ENV
     ? "https://openchainbench.com/api/aggregate"
     : "https://kv.openchainbench.com/aggregate/latest.json";
-const FETCH_TIMEOUT_MS = 20_000;
+// Needs to be > the Paris VPS response time (measured 18 s compressed,
+// 37-49 s uncompressed). Set to 65 s so cold-cache ISR misses on
+// /api/aggregate have enough headroom to complete before we give up and
+// fall through to the Redis fan-out path.
+const FETCH_TIMEOUT_MS = 65_000;
 const MIN_BENCHES = 40;
 
 type AggregateEnvelope = {

src/lib/sitemap-builder.ts

@@ -577,11 +577,14 @@ async function buildFullSitemap(): Promise<MetadataRoute.Sitemap> {
 
 export async function buildSitemap(): Promise<MetadataRoute.Sitemap> {
   try {
-    // 20 s: tight enough to reply well within the smoke-test's 90 s window
-    // even if the static fallback itself takes a few seconds. The Vercel
-    // maxDuration on the route is 60 s; this leaves 40 s of headroom.
+    // 55 s: the Vercel maxDuration on the route is 60 s. With /api/aggregate
+    // ISR-cached (revalidate=60 on that route) warm requests return in <1 ms
+    // and the full sitemap completes in ~10 s. Cold-start requests (first hit
+    // after deployment) may take 18-49 s for the aggregate; 55 s gives enough
+    // headroom while leaving 5 s for buildStaticFallback() before Vercel kills
+    // the function.
     const timeout = new Promise<never>((_, reject) =>
-      setTimeout(() => reject(new Error("sitemap build timeout")), 20_000),
+      setTimeout(() => reject(new Error("sitemap build timeout")), 55_000),
     );
     // Attach a no-op .catch() to prevent unhandled-rejection crashes if
     // buildFullSitemap() rejects AFTER the race has already settled (via