The weekend builder's playbook: shipping FOMO Sun in stolen hours

The reality of building a side project in 2026

I have a job. I have a life. FOMO Sun gets my weekends and evenings. And yet we shipped 36 versions in two days and have a working product with live weather data, 200+ destinations, and users.

Here is how.

The two-agent trick

I do not write most of the code. Two AI agents do: Claude (Anthropic) handles architecture, auditing, documentation, and precise specs. GPT/Codex handles rapid implementation, turning specs into deployed code in minutes. My job is taste, direction, and quality control.

This means a weekend session looks like: I spend 20 minutes describing what I want. Claude writes a detailed prompt. I paste it into GPT. GPT ships 3-5 versions. I review each deploy on my phone, give feedback, and repeat. In a good session, I ship 8-10 versions in 4 hours.

Notion as the brain that never sleeps

The critical piece is that both agents and I share a single Notion workspace. It contains the release changelog (every version, every commit SHA), the PM journal (every decision, every piece of feedback), the blog posts you are reading, and the architecture docs. When I pick up the project after a week away, Claude reads the Notion docs and knows exactly where we left off. No context is lost between sessions.

What works about weekends

Weekend building has one huge advantage: you are the user. On a foggy Saturday morning in Basel, I open FOMO Sun and immediately know what is broken, what is confusing, and what is missing. The feedback loop is instant because you are frustrated by the same fog that the app is trying to solve.

What does not work

Momentum. After a productive weekend, Monday comes and the project sits untouched for five days. The trick is using those five days passively: I collect feedback in Notion, draft the next prompt in my head, and save screenshots of UX annoyances. When the next weekend arrives, I have a clear list.

The meta lesson

The biggest shift in building side projects in 2026 is that the bottleneck is no longer code. It is taste and direction. If you know what you want and can articulate it clearly, AI agents can build it faster than you can type. The skill is not programming. It is product management.

This is part of the FOMO Sun build-in-public series. The app is live at fomosun.com. I build on weekends and evenings. Follow along.