tl;dr: Building on Sunil Pai's "senior engineer death spiral," the author argues that great senior engineers share a habit of first principles thinking—asking why something is being built and connecting code to user outcomes—which helps them stay unstuck. This mindset is especially valuable in the shift to agentic development, where engineers need to set aside prior assumptions and constraints to explore what's actually possible with AI. Combining first principles with small, momentum-building steps creates faster learning loops when working with agents.