I am processing a MAME romset along with CHDs, and am noticing that the CHD files do not keep their extension (Pleasuredome DATs).

Script excerpt:

npx igir@latest copy zip clean test \
    --dat "dat/mame_*" \
    --input "${input_dir}" \
    --input "${output_dir}" \
    --output "${output_dir}" \
    --overwrite-invalid \
    --merge-roms merged

Output dir:

roms-sorted/MAME
├── kinst
│ └── kinst
├── kinst2
│ └── kinst2

The problem is without the extension, Retroarch does not find the CHD and the game load fails.

For now I just run:

> find "${output_dir}/mame" -mindepth 2 -type f ! -name "*.*" \ -exec mv "{}" "{}.chd" \;

Which works around it.