D014 - A data root and a cache root

Status: decided Date: 2026-08-30

Paths::data_root holds what cannot be regenerated without the hardware or a person: configuration, saves, established names, hardware measurements, overrides. Paths::cache_root holds what can: models, runtimes, compiled shaders, packages, traces and logs. In a portable run both are the same directory.

Why: on Windows the data root roams and is synchronised at logon; gigabytes of downloadable material do not belong there. Linux and macOS make the same split.

Rejected:

• A single root: puts rebuildable bulk in the roaming profile.