Got you.

Based on your exact problem statement, your time limit (4–5 days), and the "must win the hackathon" angle →

here is the best, no-bullshit recommendation:

✅ Use: WebTransport over HTTP/3 + FEC + Priority Streams

This is the perfect sweet spot between:

✅ modern & impressive

✅ extremely resilient on unstable links

✅ easiest to implement

✅ fastest to finish in 4–5 days

✅ supports real-time status naturally

✅ supports browser UI (huge demo boost)

✅ very hackathon-friendly

And MOST IMPORTANT: It directly matches every requirement in your problem statement.

✅ Let me prove it to you very cleanly

✅ Requirement #1 — “fast file mover”

WebTransport ✔ because:

• built on QUIC
• low-latency streams
• parallel transfer