⚡ perf: dedupe concurrent fetch requests in OG API route

src/app/api/og/[username]/route.test.ts

@@ -149,6 +149,35 @@ describe("OG Image Route", () => {
     expect(res.status).toBe(429);
     expect(res.headers.get("Retry-After")).toBe("0");
   });
+
+  it("should dedupe concurrent fetches for the same username", async () => {
+    // Create a delayed fetch so multiple concurrent GETs will hit the inflight map
+    let callCount = 0;
+    const mockFetch = vi.spyOn(global, "fetch").mockImplementation(() => {
+      callCount++;
+      return new Promise((resolve) => {
+        setTimeout(() => {
+          resolve(new Response(JSON.stringify({ name: "Concurrent User" }), { status: 200 }));
+        }, 10);
+      });
+    });
+
+    const req1 = new NextRequest("http://localhost/api/og/concurrentuser");
+    const req2 = new NextRequest("http://localhost/api/og/concurrentuser");
+
+    // Fire concurrently
+    const [res1, res2] = await Promise.all([
+      GET(req1, { params: Promise.resolve({ username: "concurrentuser" }) }),
+      GET(req2, { params: Promise.resolve({ username: "concurrentuser" }) })
+    ]);
+
+    expect(res1.status).toBe(200);
+    expect(res2.status).toBe(200);
+    expect(callCount).toBe(1); // fetch should only be called once
+    expect(mockFetch).toHaveBeenCalledTimes(1);
+
+    // We should restore fetch, though afterEach does that
+  });
 });
 
 function collectText(node: unknown): string[] {

src/app/api/og/[username]/route.tsx

@@ -7,6 +7,7 @@
 import { getClientIp } from "@/lib/rateLimit";
 
 export const runtime = "edge";
+const inflightFetch = new Map<string, Promise<Response>>();
 const rateLimiter = new RateLimiter(50, 60 * 1000);
 const ONE_HOUR_IN_SECONDS = 60 * 60;
 const ONE_DAY_IN_SECONDS = 24 * ONE_HOUR_IN_SECONDS;
@@ -42,13 +43,25 @@
   let publicRepos = 0;
 
   try {
-    const res = await fetch(`https://api.github.com/users/${encodeURIComponent(username)}`, {
-      headers: {
-        Accept: "application/vnd.github.v3+json",
-        "User-Agent": "github-user-summary",
-      },
-      next: { revalidate: ONE_DAY_IN_SECONDS },
-    });
+    const url = `https://api.github.com/users/${encodeURIComponent(username)}`;
+    let fetchPromise = inflightFetch.get(url);
+    if (!fetchPromise) {
+      fetchPromise = fetch(url, {
+        headers: {
+          Accept: "application/vnd.github.v3+json",
+          "User-Agent": "github-user-summary",
+        },
+        next: { revalidate: ONE_DAY_IN_SECONDS },
+      }).finally(() => {
+        inflightFetch.delete(url);
+      });
+      inflightFetch.set(url, fetchPromise);
+    }
+
+    // We clone the response because multiple concurrent requests
+    // will need to read the body stream independently
+    const res = (await fetchPromise).clone();
+
     if (res.ok) {
       const data = await res.json();
       name = data.name ?? username;
@@ -84,7 +97,7 @@
           }}
         >
           {avatarUrl && (
             <img
               src={sanitizeUrl(avatarUrl)}
               alt=""
               width={120}