How I repackaged the official Windows Codex MSIX into a working Linux .deb

I wanted a real Linux desktop app for Codex. At first, this looked like it should be straightforward: take the official Windows package, unpack it, swap in Linux Electron, rebuild whatever was platform-specific, and turn it into a .deb . That is not what happened. What actually worked was more pragmatic: preserve the official Codex payload, branding, and resources from the Windows MSIX, but replace the runtime shell with a small Linux Electron wrapper that opens Codex in its own desktop window. This post is the write-up I wish I had before I started. The Goal The target was simple: install Codex on Ubuntu as a .deb get a desktop launcher and icon make it feel like a native app avoid relying on a browser tab keep the build repeatable I already had something similar working for ChatGPT, so I assumed Codex would follow the same path. That assumption was wrong. What I started with The source payload was the official Windows MSIX: OpenAI.Codex_26.313.5234.0_x64__2p2nqsd0c76g0.Msix The repo