I Vibe Coded an Entire Operating System From Scratch Using AI — Here's What I Learned

I've always considered building an operating system the Mount Everest of programming. Not the "follow a tutorial and boot into Hello World" kind — I mean the real thing: UEFI boot, page tables, preemptive multitasking, a filesystem, a window manager, user-space applications, and a desktop environment. The kind of project that touches every layer of the stack and punishes every wrong assumption. So naturally, I decided to see if Claude could help me build one. The result is ASOS — a hobbyist x86-64 operating system written in C and Assembly, runs on 128MB of RAM, built from absolute scratch. No Linux kernel underneath. No libc. No safety net. 25,709 lines of code (excluding ported DOOM), 82 commits over 8 days, booting from UEFI firmware all the way to a desktop environment with a window manager, four GUI applications, an interactive shell, and yes — a playable port of the original 1993 DOOM. This post isn't about OS development theory. It's about what actually happened when I sat down