Daniel Fabbri

After reading Karpathy's YC talk and year-end review, it's clear that there's a real, defensible layer between foundation models and end users. The pattern he calls out is "Cursor for X". It's what Cursor revealed about how LLM apps should be architected. Karpathy identifies four things these apps do: 1. Context engineering. The app decides what goes into the context window. You don't manually copy-paste code files and error logs. The app does the retrieval, embedding, and curation. This is a ton of hidden work. 2. Multi-call orchestration. Under the hood, there are embedding models for your files, chat models for reasoning, models that apply diffs. The user sees one experience. The app runs a whole orchestra. 3. Application-specific GUI. This is undersold. Text is hard to audit. Seeing red/green diffs uses your visual system, which is way faster than reading. Command+Y to accept, Command+N to reject. You're not typing "yes I accept this change" into a chat box. 4. Autonomy slider. Cmd+K changes a small chunk. Cmd+L changes a file. Cmd+I does more autonomous work. The user controls how much the AI does at once. The human verification step is the bottleneck. AI generates instantly. But you're still responsible for the output. If you get a 1,000 line diff, you have to verify it actually works, introduces no bugs, and has no security issues. That takes time. So there are two levers: - Speed up verification (GUIs, visual diffs, good UX) - Keep the AI on a leash (smaller chunks, clearer prompts) If your prompt is vague, AI does something unexpected, verification fails, you re-prompt. You're now spinning in a loop. Better to spend more time on a precise prompt that increases the probability of successful verification on the first pass. "This is the decade of agents" Right now, with where models are, you want suits. Partial autonomy products where the human stays in the loop, the generation-verification cycle is fast, and there's an autonomy slider you can push right over time. Suits augment. Robots operate autonomously. The suit still has a human making decisions. The robot flies around on its own. Build Iron Man suits, not Iron Man robots.