Nutshell subscribes you to RSS feeds and emails you a daily digest. Each morning it fetches new articles, runs them through an LLM, and sends you a summary to your inbox. The main configurable piece is the summary format. You can set writing style (bullet points, narrative, technical, casual, or a free-form custom system prompt) and reading length (short ~1-2 min, medium ~5-10 min, long ~10-20 min). Changes take effect on the next send, no re-generating history.