fix(Docs): Add cache-control and default to HTML content (#43989)

apps/docs/app/api/guides-md/[...slug]/route.ts

@@ -14,7 +14,10 @@ export async function GET(_request: Request, { params }: { params: Promise<{ slu
   try {
     const content = await fs.readFile(filePath, 'utf-8')
     return new NextResponse(content, {
-      headers: { 'Content-Type': 'text/markdown; charset=utf-8' },
+      headers: {
+        'Content-Type': 'text/markdown; charset=utf-8',
+        'Cache-Control': 'public, max-age=86400, stale-while-revalidate=3600',
+      },
     })
   } catch {
     return new NextResponse('Not found', { status: 404 })

apps/docs/components/GuidesSidebar.tsx

@@ -30,7 +30,15 @@ function AiTools({ className }: { className?: string }) {
 
     try {
       const res = await fetch(mdUrl)
-      const text = await res.text()
+      let text: string
+
+      if (res.ok) {
+        text = await res.text()
+      } else {
+        // Default to HTML content within the article when no .md file is available.
+        text = document.getElementById('sb-docs-guide-main-article')?.innerHTML ?? ''
+      }
+
       await navigator.clipboard.writeText(text)
       setCopied(true)
       setTimeout(() => setCopied(false), 2000)