Building a Real-Time Progress Bar with Server-Sent Events in Next.js

When spectr-ai analyzes a smart contract, it's not instant. The LLM needs time to reason through the code, identify vulnerabilities, and generate structured output. That analysis can take 10-30 seconds depending on the model and contract size. Staring at a spinner for 30 seconds feels broken. Users need to see progress. I considered WebSockets, but they're overkill for this. The communication is one-directional — the server sends progress updates, the client displays them. That's exactly what Se