1@README.md
2
3## For agents
4
5- The design rationale for `mesen.nix` lives in its header comment, with
6  file:line citations into the Mesen 2 source (tag 2.1.1, reference clone at
7  `~/src/github.com/SourMesen/Mesen2`). Re-check those citations when the
8  nixpkgs pin moves Mesen to a new version.
9- Test wrapper changes with an isolated `HOME`/`XDG_CONFIG_HOME` and
10  `--testRunner`, against a copy of a real Mesen-written settings.json — that
11  file carries a UTF-8 BOM, a bare seed does not, and both paths must work.
12- Running the wrapper merges keys into `${XDG_CONFIG_HOME:-$HOME/.config}/Mesen2/settings.json`.
13  Under your real `HOME` that is the user's live config; see the repo
14  CLAUDE.md before running it anywhere but a scratch `HOME`.