Merge pull request #4848 from rommapp/fix/player-default-descriptor-file

fix(player): boot cue/gdi/ccd/mds disc sets whole by default

frontend/src/v2/utils/playerDisc.test.ts

@@ -92,6 +92,32 @@ describe("defaultDisc", () => {
     ).toBe(ALL_DISCS);
   });
 
+  it.each(["cue", "gdi", "ccd", "mds", "CUE"])(
+    "boots every file together when the set has a .%s sheet",
+    (extension) => {
+      expect(
+        defaultDisc([
+          file(1, `Game.${extension}`),
+          file(2, "Game (Track 1).bin"),
+          file(3, "Game (Track 2).bin"),
+        ]),
+      ).toBe(ALL_DISCS);
+    },
+  );
+
+  it("boots a lone sheet when it is the rom's only file", () => {
+    expect(defaultDisc([file(1, "Game.cue")])).toBe(1);
+  });
+
+  it("keeps a remembered track over the sheet default", () => {
+    const cueSet = [file(1, "Game.cue"), file(2, "Game.iso")];
+    expect(resolveStoredDisc("2", cueSet)).toEqual({ disc: 2, stale: false });
+    expect(resolveStoredDisc(null, cueSet)).toEqual({
+      disc: ALL_DISCS,
+      stale: false,
+    });
+  });
+
   it("boots the first file when a multi-file set has no playlist", () => {
     expect(defaultDisc(files(3, 4))).toBe(3);
   });

frontend/src/v2/utils/playerDisc.ts

@@ -87,10 +87,19 @@ export function selectableDiscFiles<T extends DiscFile>(
   return bootableFiles(files).filter((f) => !isM3uFile(f));
 }
 
-// A set shipping its own .m3u is a curated multi-disc release, so boot it whole;
-// anything else boots one file to avoid pulling hundreds of unused MB.
+// Sheets that point at sibling track files, so neither the sheet nor a track
+// boots alone (issue #4209). Kept in step with backend/utils/m3u.py.
+const DESCRIPTOR_EXTENSIONS: readonly string[] = ["cue", "gdi", "ccd", "mds"];
+
+function isDescriptorFile(file: DiscFile): boolean {
+  const extension = file.file_name.toLowerCase().split(".").pop() ?? "";
+  return isM3uFile(file) || DESCRIPTOR_EXTENSIONS.includes(extension);
+}
+
+// A set carrying a playlist or disc sheet only boots whole; anything else boots
+// one file to avoid pulling hundreds of unused MB.
 export function defaultDisc(files: readonly DiscFile[]): DiscSelection {
-  if (files.length > 1 && files.some(isM3uFile)) return ALL_DISCS;
+  if (files.length > 1 && files.some(isDescriptorFile)) return ALL_DISCS;
   return bootableFiles(files)[0]?.id ?? null;
 }