⚡ Bolt: Optimize sitemap generation with parallel fetching

This commit optimizes the `app/sitemap.ts` generation by replacing the
sequential data fetching inside the `for...of` loop with mapped
`Promise.all` calls. This significantly reduces the time it takes to
generate the sitemap for all available editions, making build times
faster and more efficient. Individual API fetches are also updated with
`.catch(() => [])` to handle partial failures gracefully without
breaking the build.

Co-authored-by: anyulled <100741+anyulled@users.noreply.github.com>

Author: google-labs-jules[bot]

.jules/bolt.md

@@ -12,3 +12,8 @@
 
 **Learning:** Found `useEffect` fetching static content (Speakers) in a Client Component (`Section5`) on the homepage. This caused unnecessary layout shifts and delayed LCP.
 **Action:** Move data fetching to the parent Server Component (`page.tsx`) and pass data as props. This leverages ISR caching and eliminates client-side waterfall.
+
+## 2026-03-15 - Parallel Data Fetching in Sitemap
+
+**Learning:** Sequential data fetching inside loops (like `for...of`) significantly delays sitemap generation or static param generation as the number of years/entries grows.
+**Action:** Always use `Promise.all` mapped over the loop iterations and apply `.catch(() => [])` to individual fetches to prevent a single API failure from breaking the whole process.

app/sitemap.ts

@@ -28,8 +28,10 @@ export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
     });
   }
 
-  for (const year of years) {
-    urls.push({
+  const yearPromises = years.map(async (year) => {
+    const yearUrls: MetadataRoute.Sitemap = [];
+
+    yearUrls.push({
       url: `${baseUrl}/${year}`,
       lastModified: new Date(),
       changeFrequency: "daily",
@@ -38,28 +40,28 @@ export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
 
     const yearPages = ["speakers", "talks", "schedule", "job-offers", "cfp", "diversity", "sponsorship", "travel"];
     for (const page of yearPages) {
-      urls.push({
+      yearUrls.push({
         url: `${baseUrl}/${year}/${page}`,
         lastModified: new Date(),
         changeFrequency: "weekly",
         priority: 0.8,
       });
     }
 
-    const speakers = await getSpeakers(year);
+    const [speakers, sessionGroups] = await Promise.all([getSpeakers(year).catch(() => []), getTalks(year).catch(() => [])]);
+
     for (const speaker of speakers) {
-      urls.push({
+      yearUrls.push({
         url: `${baseUrl}/${year}/speakers/${speaker.id}`,
         lastModified: new Date(),
         changeFrequency: "weekly",
         priority: 0.7,
       });
     }
 
-    const sessionGroups = await getTalks(year);
     for (const group of sessionGroups) {
       for (const talk of group.sessions) {
-        urls.push({
+        yearUrls.push({
           url: `${baseUrl}/${year}/talks/${talk.id}`,
           lastModified: new Date(),
           changeFrequency: "weekly",
@@ -70,14 +72,19 @@ export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
 
     const companies = getJobOffersByYear(year);
     for (const company of companies) {
-      urls.push({
+      yearUrls.push({
         url: `${baseUrl}/${year}/job-offers/${slugify(company.name)}`,
         lastModified: new Date(),
         changeFrequency: "monthly",
         priority: 0.5,
       });
     }
-  }
+
+    return yearUrls;
+  });
+
+  const yearsUrlsArrays = await Promise.all(yearPromises);
+  urls.push(...yearsUrlsArrays.flat());
 
   return urls;
 }