First 90 days as a junior engineer on an AI-heavy team: what to learn first

You took the offer. The team uses Cursor or Copilot for almost every PR, runs an internal RAG bot over the docs, and at least one senior engineer is building agent workflows on the side. Your onboarding doc is half-written because the person who owned it left, and the codebase has roughly 40% more surface area than the org chart suggests, because LLMs have made it cheap to ship adapters, scripts, and one-off services nobody fully owns. This is the environment most junior engineers walk into in...