fix(compare): restore SSR content and canonical, 301 reverse-pair to alphabetical

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

@@ -107,10 +107,19 @@ export async function generateMetadata({
   params: Promise<Params>;
 }): Promise<Metadata> {
   const { slug } = await params;
+  // Run the same gating logic as the page render so non-canonical and
+  // invalid slugs short-circuit at the metadata phase, BEFORE Next.js
+  // streams the loading.tsx fallback. Without this the SSR HTML ends
+  // up with the root layout's homepage title and description plus the
+  // skeleton body, which is exactly what crawlers index. Routing here
+  // produces a real 308 / 404 response from the route layer instead of
+  // a 200 wrapping the streamed skeleton.
+  const canonicalTarget = canonicalisationTarget(slug);
+  if (canonicalTarget) redirect(`/compare/${canonicalTarget}`);
   const pair = getComparePair(slug) ?? (await resolveAdHocPair(slug));
-  if (!pair) return {};
+  if (!pair) notFound();
   const { a, b } = await loadPairProviders(pair);
-  if (!a || !b) return {};
+  if (!a || !b) notFound();
 
   const title = `${a.name} vs ${b.name}: live OpenChainBench benchmark data`;
   const description = capDescription(

src/middleware.ts

@@ -1,7 +1,7 @@
 import { NextResponse, type NextRequest } from "next/server";
 
 /**
- * Edge middleware. Three jobs:
+ * Edge middleware. Four jobs:
  *
  * 1. **Cache-key normalisation** on public read-only API routes that
  *    don't use query params. Vercel keys the edge cache on the full URL,
@@ -15,15 +15,26 @@ import { NextResponse, type NextRequest } from "next/server";
  *    on dev / staging only (bridge-revenue, evm-quote-latency, etc.).
  *    On prod they hit `notFound()` and return a 404. Sustained 404 on
  *    previously-indexed URLs gets read as a soft-404 signal that bleeds
- *    into surrounding bench rankings — likely the dominant driver of
- *    the recent brand-search collapse. Returning 410 explicitly tells
- *    Google "this URL is gone for good", and the cluster recovers.
+ *    into surrounding bench rankings, likely the dominant driver of the
+ *    recent brand-search collapse. Returning 410 explicitly tells Google
+ *    "this URL is gone for good", and the cluster recovers.
  *
  *    Only fires on production (`VERCEL_ENV === "production"`) so that
  *    staging / preview / local dev still render the bench pages from
  *    their YAML files normally.
  *
- * 3. **(future)** any cross-route concerns - kept lightweight.
+ * 3. **Canonical-order redirect on /compare/<a>-vs-<b>.** Pair pages
+ *    have a single canonical URL: the alphabetical ordering of the two
+ *    provider slugs. Without this, `/compare/base-vs-arbitrum` and
+ *    `/compare/arbitrum-vs-base` both 200 with separate streamed
+ *    Suspense fallbacks, which Google indexes as two empty shells of
+ *    the same comparison. The page component also calls `redirect()`
+ *    on non-canonical slugs but that fires after the loading.tsx
+ *    boundary has streamed its skeleton, so the response goes out as
+ *    200 with the skeleton HTML and the homepage metadata. Doing it at
+ *    the edge here short-circuits before any render starts.
+ *
+ * 4. **(future)** any cross-route concerns. Kept lightweight.
  */
 
 const CANONICAL_NO_QUERY = new Set([
@@ -45,6 +56,12 @@ const REMOVED_BENCH_SLUGS = new Set([
 ]);
 
 const BENCH_PATH = /^\/benchmarks\/([a-z0-9][a-z0-9-]{0,79})\/?$/;
+// `/compare/<a>-vs-<b>` with both sides as standard provider slug
+// shapes (lowercase alphanumeric + hyphens). The `-vs-` delimiter is
+// matched literally; provider slugs themselves can contain hyphens
+// (e.g. `helius-sender`, `phantom-perps`), so split on the first
+// occurrence at parse time, not on every `-`.
+const COMPARE_PATH = /^\/compare\/([a-z0-9][a-z0-9-]{0,79})\/?$/;
 
 export function middleware(req: NextRequest) {
   const { pathname, search } = req.nextUrl;
@@ -65,15 +82,39 @@ export function middleware(req: NextRequest) {
     }
   }
 
+  const compareMatch = pathname.match(COMPARE_PATH);
+  if (compareMatch) {
+    const canonical = canonicalComparePath(compareMatch[1]);
+    if (canonical && canonical !== compareMatch[1]) {
+      const url = req.nextUrl.clone();
+      url.pathname = `/compare/${canonical}`;
+      return NextResponse.redirect(url, 308);
+    }
+  }
+
   return NextResponse.next();
 }
 
+/** Returns the alphabetical canonical form of a `<a>-vs-<b>` slug, or
+ *  null when the slug isn't a valid pair shape. When the slug is already
+ *  canonical the return value equals the input. */
+function canonicalComparePath(slug: string): string | null {
+  const idx = slug.indexOf("-vs-");
+  if (idx <= 0) return null;
+  const a = slug.slice(0, idx);
+  const b = slug.slice(idx + "-vs-".length);
+  if (!a || !b || a === b) return null;
+  const [first, second] = [a, b].sort();
+  return `${first}-vs-${second}`;
+}
+
 export const config = {
   matcher: [
     "/api/citable",
     "/api/llm-context",
     "/api/freshness",
     "/api/openapi.json",
     "/benchmarks/:slug*",
+    "/compare/:slug*",
   ],
 };