_collect_emulator_extras ran three passes in one body: the undeclared
files a platform's cores need, a second copy of an archive under the
subdirectory some cores read, and the scan a filename-agnostic core
allows. The last two are named now, complexity 98 to 54.
The archive-prefix pass had no test, and extracting it surfaced why that
mattered: it read an index from the enclosing scope, so on its own it
would have raised. Three tests cover it, including the case it exists to
prevent - claiming a prefixed path for an archive the collection does
not hold.
A filename-agnostic core accepts any name for its BIOS, so the builder
scans the directory holding the candidates. It picked that directory
from a first-hit lookup by name, the one piece of evidence that lands
in another emulator's tree: five files answer to GameIndex.yaml and one
belongs to an Android package, rom1.bin is a PS2 ROM and a Roland
SC-55 ROM. One wrong match became every file beside it, flattened into
the BIOS root of platforms that do not run that emulator: 45 files in
the Recalbox pack, 170 in the RetroArch one.
Four things decide it now. A destination and the repo layout meet on a
tail, so the path index is tried from the longest tail down and never
to the bare filename; that alone corrects seven files, among them the
Japanese GameCube slot, which held the US dump. A seed has to declare
the shape it is looking for, since no shape means the whole directory.
An ambiguous name needs the profile's other files to agree before the
scan walks anywhere. What the scan emits carries the SHA-1 it selected,
so packing never resolves it by name again.
Abdessamad Derraz