feat(player): let multi-disc games boot every disc at once

frontend/src/locales/bg_BG/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Всички дискове",
   "all-saves": "Всички записи",
   "all-states": "Всички бързи записи",
   "back-to-gallery": "Към галерията",

frontend/src/locales/cs_CZ/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Všechny disky",
   "all-saves": "Všechny uložené pozice",
   "all-states": "Všechny stavy",
   "back-to-gallery": "Zpět do galerie",

frontend/src/locales/de_DE/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Alle Discs",
   "all-saves": "Alle Spielstände",
   "all-states": "Alle Zustände",
   "back-to-gallery": "Zurück zur Plattformübersicht",

frontend/src/locales/en_GB/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "All discs",
   "all-saves": "All saves",
   "all-states": "All states",
   "back-to-gallery": "Back to gallery",

frontend/src/locales/en_US/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "All discs",
   "all-saves": "All saves",
   "all-states": "All states",
   "back-to-gallery": "Back to gallery",

frontend/src/locales/es_ES/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Todos los discos",
   "all-saves": "Todas las partidas",
   "all-states": "Todos los estados",
   "back-to-gallery": "Volver a galería",

frontend/src/locales/fr_FR/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Tous les disques",
   "all-saves": "Toutes les sauvegardes",
   "all-states": "Tous les états",
   "back-to-gallery": "Retour à la galerie",

frontend/src/locales/hu_HU/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Összes lemez",
   "all-saves": "Összes mentés",
   "all-states": "Összes állás",
   "back-to-gallery": "Vissza a galériába",

frontend/src/locales/it_IT/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Tutti i dischi",
   "all-saves": "Tutti i salvataggi",
   "all-states": "Tutti gli stati",
   "back-to-gallery": "Ritorna alla galleria",

frontend/src/locales/ja_JP/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "すべてのディスク",
   "all-saves": "すべてのセーブ",
   "all-states": "すべてのステートセーブ",
   "back-to-gallery": "ギャラリーへ戻る",

frontend/src/locales/ko_KR/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "모든 디스크",
   "all-saves": "모든 세이브",
   "all-states": "모든 상태",
   "back-to-gallery": "갤러리로 가기",

frontend/src/locales/pl_PL/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Wszystkie płyty",
   "all-saves": "Wszystkie zapisy",
   "all-states": "Wszystkie stany",
   "back-to-gallery": "Powrót do galerii",

frontend/src/locales/pt_BR/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Todos os discos",
   "all-saves": "Todos os saves",
   "all-states": "Todos os states",
   "back-to-gallery": "Voltar à galeria",

frontend/src/locales/ro_RO/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Toate discurile",
   "all-saves": "Toate salvările",
   "all-states": "Toate stările",
   "back-to-gallery": "Înapoi la galerie",

frontend/src/locales/ru_RU/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Все диски",
   "all-saves": "Все сохранения",
   "all-states": "Все состояния",
   "back-to-gallery": "Вернуться в галерею",

frontend/src/locales/tr_TR/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "Tüm diskler",
   "all-saves": "Tüm kayıtlar",
   "all-states": "Tüm durum kayıtları",
   "back-to-gallery": "Galeriye dön",

frontend/src/locales/zh_CN/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "所有光盘",
   "all-saves": "所有存档",
   "all-states": "所有状态",
   "back-to-gallery": "返回游戏库",

frontend/src/locales/zh_TW/play.json

@@ -1,4 +1,5 @@
 {
+  "all-discs": "所有光碟",
   "all-saves": "所有存檔",
   "all-states": "所有即時存檔",
   "back-to-gallery": "返回遊戲庫",

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

@@ -1,50 +1,113 @@
 import { describe, expect, it } from "vitest";
-import { resolveStoredDisc } from "./playerDisc";
+import {
+  ALL_DISCS,
+  bootDiscId,
+  defaultDisc,
+  resolveStoredDisc,
+} from "./playerDisc";
 
-// Only `id` is read off each file; minimal stubs stand in for RomFileSchema.
-const files = (...ids: number[]) => ids.map((id) => ({ id }));
+// Only `id` and `file_name` are read off each file; minimal stubs stand in for
+// RomFileSchema. Ids default to a `.chd` name, which is not a playlist.
+const files = (...ids: number[]) =>
+  ids.map((id) => ({ id, file_name: `Game (Disc ${id}).chd` }));
+const withM3u = (...ids: number[]) => [
+  ...files(...ids),
+  { id: 99, file_name: "Game.m3u" },
+];
 
 describe("resolveStoredDisc", () => {
   it("keeps a stored id that still belongs to the rom", () => {
     expect(resolveStoredDisc("2", files(1, 2, 3))).toEqual({
-      discId: 2,
+      disc: 2,
       stale: false,
     });
   });
 
   it("falls back to the first file and marks stale when the id is gone", () => {
     // Classic post-rescan case: files were reimported with new ids.
     expect(resolveStoredDisc("2", files(10, 11, 12))).toEqual({
-      discId: 10,
+      disc: 10,
       stale: true,
     });
   });
 
   it("falls back to the first file without staleness when nothing was stored", () => {
     expect(resolveStoredDisc(null, files(5, 6))).toEqual({
-      discId: 5,
+      disc: 5,
       stale: false,
     });
   });
 
   it("treats a non-numeric stored value as stale garbage to forget", () => {
     expect(resolveStoredDisc("not-a-number", files(1))).toEqual({
-      discId: 1,
+      disc: 1,
       stale: true,
     });
   });
 
-  it("returns a null disc id (and no staleness) for a rom with no files", () => {
+  it("returns a null disc (and no staleness) for a rom with no files", () => {
     expect(resolveStoredDisc(null, [])).toEqual({
-      discId: null,
+      disc: null,
       stale: false,
     });
   });
 
   it("still clears a stored id when the rom now has no files", () => {
     expect(resolveStoredDisc("2", [])).toEqual({
-      discId: null,
+      disc: null,
       stale: true,
     });
   });
+
+  it("keeps a stored all-discs choice while the rom is multi-file", () => {
+    expect(resolveStoredDisc(ALL_DISCS, files(1, 2))).toEqual({
+      disc: ALL_DISCS,
+      stale: false,
+    });
+  });
+
+  it("drops a stored all-discs choice once the rom is single-file", () => {
+    expect(resolveStoredDisc(ALL_DISCS, files(7))).toEqual({
+      disc: 7,
+      stale: true,
+    });
+  });
+});
+
+describe("defaultDisc", () => {
+  it("boots every file together when the set ships its own playlist", () => {
+    expect(defaultDisc(withM3u(1, 2))).toBe(ALL_DISCS);
+  });
+
+  it("matches the playlist extension case-insensitively", () => {
+    expect(
+      defaultDisc([
+        { id: 1, file_name: "Game (Disc 1).chd" },
+        { id: 2, file_name: "Game.M3U" },
+      ]),
+    ).toBe(ALL_DISCS);
+  });
+
+  it("boots the first file when a multi-file set has no playlist", () => {
+    expect(defaultDisc(files(3, 4))).toBe(3);
+  });
+
+  it("boots the only file of a single-file rom carrying a playlist", () => {
+    expect(defaultDisc([{ id: 1, file_name: "Game.m3u" }])).toBe(1);
+  });
+
+  it("returns null for a rom with no files", () => {
+    expect(defaultDisc([])).toBeNull();
+  });
+});
+
+describe("bootDiscId", () => {
+  it("downloads a single file when one disc is selected", () => {
+    expect(bootDiscId(4)).toBe(4);
+  });
+
+  it("downloads the rom whole for all-discs and for no selection", () => {
+    expect(bootDiscId(ALL_DISCS)).toBeNull();
+    expect(bootDiscId(null)).toBeNull();
+  });
 });

frontend/src/v2/utils/playerDisc.ts

@@ -6,22 +6,63 @@
 // with that stale id makes the download endpoint 404, which EmulatorJS surfaces
 // as a generic "Network Error" (issue #3938). Validate the saved id against the
 // rom's current files before using it, and report when it must be forgotten.
+//
+// A multi-file rom can also be booted whole (issue #3985): asking the download
+// endpoint for no file in particular returns every file zipped together with a
+// generated .m3u playlist, which EmulatorJS boots with its in-game disc
+// switcher. That choice is stored as `ALL_DISCS`.
+export const ALL_DISCS = "all";
+
+// A file id to boot on its own, ALL_DISCS to boot every file together, or null
+// when the rom has no files to boot at all.
+export type DiscSelection = number | typeof ALL_DISCS | null;
+
+interface DiscFile {
+  id: number;
+  file_name: string;
+}
+
 export interface ResolvedDisc {
-  // The file id to boot, or null when the rom has no files.
-  discId: number | null;
-  // True when a value was stored but no longer matches a current file, so the
+  disc: DiscSelection;
+  // True when a value was stored but no longer matches the rom's files, so the
   // caller should drop the stale localStorage entry.
   stale: boolean;
 }
 
 export function resolveStoredDisc(
   storedDisc: string | null,
-  files: readonly { id: number }[],
+  files: readonly DiscFile[],
 ): ResolvedDisc {
+  if (storedDisc === ALL_DISCS) {
+    // Nothing left to boot together once the rom is down to a single file.
+    return files.length > 1
+      ? { disc: ALL_DISCS, stale: false }
+      : { disc: defaultDisc(files), stale: true };
+  }
+
   const storedDiscId = storedDisc ? parseInt(storedDisc) : null;
   if (storedDiscId !== null && files.some((f) => f.id === storedDiscId)) {
-    return { discId: storedDiscId, stale: false };
+    return { disc: storedDiscId, stale: false };
   }
   // NaN (non-numeric storage) counts as stored garbage worth forgetting.
-  return { discId: files[0]?.id ?? null, stale: storedDiscId !== null };
+  return { disc: defaultDisc(files), stale: storedDiscId !== null };
+}
+
+// Sets that ship their own .m3u are curated multi-disc releases, so boot them
+// whole and let the user swap discs from the emulator menu. Every other set
+// keeps booting a single file: pulling the whole set can mean hundreds of extra
+// MB over the wire, and EmulatorJS only prefers the playlist over a bare .chd /
+// .iso for cue-based sets anyway.
+export function defaultDisc(files: readonly DiscFile[]): DiscSelection {
+  if (files.length > 1 && files.some(isM3uFile)) return ALL_DISCS;
+  return files[0]?.id ?? null;
+}
+
+// The file id to download, or null to download the rom whole.
+export function bootDiscId(disc: DiscSelection): number | null {
+  return typeof disc === "number" ? disc : null;
+}
+
+function isM3uFile(file: DiscFile): boolean {
+  return file.file_name.toLowerCase().endsWith(".m3u");
 }

frontend/src/v2/views/Player/EmulatorJS.vue

@@ -57,7 +57,12 @@ import {
   resolveBezelUrl,
   resolveStoredBezelVisible,
 } from "@/v2/utils/playerBezel";
-import { resolveStoredDisc } from "@/v2/utils/playerDisc";
+import {
+  ALL_DISCS,
+  bootDiscId,
+  resolveStoredDisc,
+  type DiscSelection,
+} from "@/v2/utils/playerDisc";
 import { installIOSFullscreenShim } from "@/views/Player/EmulatorJS/utils";
 
 // Reuse v1's heavy emulator integration — do NOT rewrite this. Lazy so the
@@ -121,7 +126,7 @@ const heroRom = computed<DetailedRom | SimpleRom | null>(
 );
 const isSavesTabSelected = ref(true);
 const selectedState = ref<StateSchema | null>(null);
-const selectedDisc = ref<number | null>(null);
+const selectedDisc = ref<DiscSelection>(null);
 const selectedCore = ref<string | null>(null);
 const selectedFirmware = ref<FirmwareSchema | null>(null);
 const supportedCores = ref<string[]>([]);
@@ -191,6 +196,16 @@ const compatibleStates = computed(
     ) ?? [],
 );
 
+// Booting every file at once hands EmulatorJS the whole set plus an .m3u
+// playlist, which unlocks its in-game disc switcher for multi-disc games.
+const discItems = computed<{ title: string; value: DiscSelection }[]>(() => [
+  { title: t("play.all-discs"), value: ALL_DISCS },
+  ...(rom.value?.files ?? []).map((f) => ({
+    title: f.file_name,
+    value: f.id,
+  })),
+]);
+
 const setBgArt = useBackgroundArt();
 
 // The hero cover is the shared GameCover (same component as gallery +
@@ -421,11 +436,11 @@ onMounted(async () => {
   // Validate the saved disc against the rom's current files: a rescan can
   // leave a stale id behind that would 404 the download (issue #3938).
   const storedDisc = localStorage.getItem(`player:${rom.value.id}:disc`);
-  const { discId, stale } = resolveStoredDisc(storedDisc, rom.value.files);
+  const { disc, stale } = resolveStoredDisc(storedDisc, rom.value.files);
   if (stale) {
     localStorage.removeItem(`player:${rom.value.id}:disc`);
   }
-  selectedDisc.value = discId;
+  selectedDisc.value = disc;
 
   // Prefer the core saved for this game, then the platform default, validating
   // each candidate so a stale entry falls through instead of masking the next
@@ -714,15 +729,9 @@ const selectedAsset = computed<SaveSchema | StateSchema | null>(() =>
             variant="outlined"
             density="comfortable"
             prepend-inner-icon="mdi-disc"
-            clearable
             hide-details
             :label="t('rom.file')"
-            :items="
-              (rom?.files ?? []).map((f) => ({
-                title: f.file_name,
-                value: f.id,
-              }))
-            "
+            :items="discItems"
           />
           <RSelect
             v-if="supportedCores.length > 1"
@@ -788,7 +797,7 @@ const selectedAsset = computed<SaveSchema | StateSchema | null>(() =>
         :save="selectedSave"
         :bios="selectedFirmware"
         :core="selectedCore"
-        :disc="selectedDisc"
+        :disc="bootDiscId(selectedDisc)"
       />
       <!-- Bezel overlay drawn around the game canvas. Purely decorative and
            click-through, so pointer events reach the emulator underneath. In