The author distinguishes between vibe coding, a reckless approach where developers prompt and accept AI output without review, and agentic engineering, a disciplined professional workflow. While vibe coding is useful for rapid prototyping and MVPs, it lacks the rigor required for scalable or secure systems. Agentic engineering involves orchestrating AI agents under strict human oversight, treating them as fast but unreliable junior developers who require architectural direction and relentless testing.
Key points:
- Distinction between vibe coding (prototyping) and agentic engineering (professional discipline).
- The importance of design docs, rigorous code reviews, and comprehensive test suites in AI workflows.
- How AI-assisted development rewards strong engineering fundamentals rather than replacing them.
- The risk of skill atrophy among junior developers who rely on prompting without understanding underlying principles.
Key points:
- Distinction between vibe coding (prototyping) and agentic engineering (professional discipline).
- The importance of design docs, rigorous code reviews, and comprehensive test suites in AI workflows.
- How AI-assisted development rewards strong engineering fundamentals rather than replacing them.
- The risk of skill atrophy among junior developers who rely on prompting without understanding underlying principles.
Simon Willison details creating a custom macOS presentation app, "Present," in just 45 minutes using Swift and SwiftUI. Frustrated with the risk of browser crashes when presenting a series of web pages, he built an app that displays URLs as slides, offering features like full-screen mode, keyboard navigation, and automatic URL saving. He even added remote control functionality via a web server and Tailscale.
The project highlights the power of AI-assisted coding and expands his skillset, demonstrating how experienced software engineers can quickly learn new languages and tools to solve personal problems. The resulting app is a simple, effective solution tailored to his specific needs.
The project highlights the power of AI-assisted coding and expands his skillset, demonstrating how experienced software engineers can quickly learn new languages and tools to solve personal problems. The resulting app is a simple, effective solution tailored to his specific needs.
Simon Willison’s annual review of the major trends, breakthroughs, and cultural moments in the large language model ecosystem in 2025, covering reasoning models, coding agents, CLI tools, Chinese open‑weight models, image editing, academic competition wins, and the rise of AI‑enabled browsers.
