6/ Design call I liked: auth-checked streaming beats a presigned URL with a TTL here. Slightly more API load per segment, but access control lives in one place instead of leaking into URL expiry math.

3/ Stack: Fastify + TS, Prisma/Postgres for video lifecycle (UPLOADING → PROCESSED), Zod validation, JWT + bcrypt auth, React 19 + Vite client with upload progress.