Check the real environment before you build

Built the backend for the split-flap board assuming a normal server-capable host, because that's the default shape most examples assume. The actual hosting target — a static export with no server runtime — couldn't run any of it. Nothing was broken in the code, there was just nowhere for it to live.

Confirming the real deployment target before writing backend code would have saved a full re-platform. Doing it late didn't kill the project, but it's a needless tax to keep paying — and it's become the first thing I check now, before any backend code gets written.

A smaller version of the same mistake showed up again a few nights later: `command-a && command-b` works in bash, but PowerShell needs each command on its own line (or `;`, with different failure behaviour). One character, and it turned a clean copy-paste into a dead-end error message at the point in the night when patience was thinnest.

Same lesson both times, just at different scales — confirm what's actually running the thing (the hosting platform, the shell) before handing over code or commands built for a different assumption.