Anthropic hired this engineer at $250K–$750K a year because he knows how to build harnesses for multi-agent systems In a 15-minute workshop, he shows exactly how to build one from scratch AI → Agents → Harness → Loops → Graphs step 1 → start with the Claude Agent SDK — the harness handles loops, context, and sandboxing step 2 → separate the brain from the hands — reasoning in one place, tools in a sandbox, 60% faster to first token step 3 → run it server-side and log every step — close your laptop and it keeps running, crashes resume from the log step 4 → make failure cheap — retry dead sandboxes and replay lost context instead of starting over step 5 → turn yesterday's logs into new memory and skills — the harness wakes up smarter Anthropic calls this "dreaming" Most people spend weeks building this by hand You don't have to Bookmark and watch it Then read the full Opus 5.5 harness engineering guide below ↓