Build Decision Log

Summary

Decisions that apply across more than one build, so they don’t get re-litigated per project. This is what projects/references/ is for: notes supporting multiple projects, rather than belonging to any one of them.

Standing decisions

Always measure before enclosing

Confirmed on hallway-display-build. Any power or thermal assumption gets measured on a breadboard before anything is glued, screwed or mounted. A wrong number found at the breadboard costs an afternoon; found after mounting it costs the build.

“Already owned” is not free

From kitchen-tablet-dashboard, abandoned partly on this. Reusing a device you already have has real costs — power, mounting, degradation, and the constraints the original design imposes. Price them before treating reuse as the cheap option.

Pin firmware on anything hard to reach

If reflashing means standing on a chair or removing a mount, pin the version and record why. Applies to hallway-display; will apply to office-air-quality-sensor if it ends up mounted.

Mains changes the design, so don’t inherit battery constraints

Noted while planning office-air-quality-sensor. The hallway build’s design was shaped almost entirely by having no power socket. The office has one — so deep-sleep current, wake intervals and e-ink stop being requirements. Copying a good design into a different constraint set is a common way to build the wrong thing.

Why these live here

Each of these came out of one project but binds the next one. Left on the originating project page they’d be found only by someone already reading that page — which is nobody, at the moment they’d be useful.