I Built an AI Dubbing App with Claude Code Agents — Here's What I Learned

1 OVERVIEW GitHub: https://github.com/jin-wook-lee-96/ai-dubbing ⭐ Upload audio or video → get a dubbed MP3 in 7 languages. Built with Next.js 16, ElevenLabs STT/TTS, GPT-4o-mini, and a 5-agent Claude Code workflow. 2 Pipeline File upload → ElevenLabs STT → GPT-4o-mini translation → ElevenLabs TTS → MP3 3 Problems Worth Sharing 1. Vercel's 4.5 MB request limit Never send the file to the API. Client uploads directly to Vercel Blob; API receives only the URL. 2. SSRF on the Blob URL input Allowlist before any fetch — https: protocol + hostname must end with blob.vercel-storage.com . Same for targetLang to block prompt injection. 3. Large files Files over 60s are cropped client-side using Web Audio API + MediaRecorder before upload. Works on iOS Safari via webkitAudioContext fallback. Server never sees the oversized file. 4-Agent Claude Code Workflow Agent Role senior-web-designer UI/UX frontend-senior-dev Components code-error-fixer Bugs & build errors security-auditor OWASP, SSRF, injec