Pick the system you will build across five weeks. It should be something that answers questions or does tasks over a body of knowledge you care about, because that shape carries cleanly through RAG, agents, evals, and memory.

Good seeds: an assistant over your company's docs, a research tool for a domain you know, a support agent for a real product.

Write one page: what it does, who uses it, and the single question or task it must handle well first. That first capability is your Week 1 build.