feat(torrents): add global open-file limit

src/bindings/PersistedSettings.ts

@@ -11,4 +11,4 @@ import type { SiteLogin } from "./SiteLogin";
 import type { Theme } from "./Theme";
 import type { WindowControlStyle } from "./WindowControlStyle";
 
-export type PersistedSettings = { theme: Theme, fontFamily: FontFamily, windowControlStyle: WindowControlStyle, calendarPreference: CalendarPreference, language: string, baseDownloadFolder: string, categorySubfoldersEnabled: boolean, categorySubfolders: { [key in string]: string }, categoryDirectoryOverrides: { [key in string]: string }, approvedDownloadRoots: Array<string>, maxConcurrentDownloads: number, globalSpeedLimit: string, speedLimitPresetValues: Array<number>, logsEnabled: boolean, isSidebarVisible: boolean, sidebarPosition: string, activeSettingsTab: SettingsTab, scheduler: SchedulerSettings, schedulerRunning: boolean, schedulerActiveDownloadIds: Array<string>, schedulerLastStartKey: string, schedulerLastStopKey: string, lastCustomSpeedLimitKiB: number, lastCustomSpeedLimitUnit: string, perServerConnections: number, maxAutomaticRetries: number, showNotifications: boolean, playCompletionSound: boolean, autoAddClipboardLinks: boolean, appFontSize: AppFontSize, listRowDensity: ListRowDensity, showDockBadge: boolean, showMenuBarIcon: boolean, proxyMode: ProxyMode, proxyHost: string, proxyPort: number, torrentEnableDht: boolean, torrentEnableDht6: boolean, torrentEnablePex: boolean, torrentEnableLpd: boolean, customUserAgent: string, askWhereToSaveEachFile: boolean, rememberLastUsedDownloadDirectory: boolean, preventsSleepWhileDownloading: boolean, preventsDisplaySleepWhileDownloading: boolean, mediaCookieSource: MediaCookieSource, siteLogins: Array<SiteLogin>, autoCheckUpdates: boolean, keychainAccessGranted: boolean, };
+export type PersistedSettings = { theme: Theme, fontFamily: FontFamily, windowControlStyle: WindowControlStyle, calendarPreference: CalendarPreference, language: string, baseDownloadFolder: string, categorySubfoldersEnabled: boolean, categorySubfolders: { [key in string]: string }, categoryDirectoryOverrides: { [key in string]: string }, approvedDownloadRoots: Array<string>, maxConcurrentDownloads: number, globalSpeedLimit: string, speedLimitPresetValues: Array<number>, logsEnabled: boolean, isSidebarVisible: boolean, sidebarPosition: string, activeSettingsTab: SettingsTab, scheduler: SchedulerSettings, schedulerRunning: boolean, schedulerActiveDownloadIds: Array<string>, schedulerLastStartKey: string, schedulerLastStopKey: string, lastCustomSpeedLimitKiB: number, lastCustomSpeedLimitUnit: string, perServerConnections: number, maxAutomaticRetries: number, showNotifications: boolean, playCompletionSound: boolean, autoAddClipboardLinks: boolean, appFontSize: AppFontSize, listRowDensity: ListRowDensity, showDockBadge: boolean, showMenuBarIcon: boolean, proxyMode: ProxyMode, proxyHost: string, proxyPort: number, torrentEnableDht: boolean, torrentEnableDht6: boolean, torrentEnablePex: boolean, torrentEnableLpd: boolean, torrentMaxOpenFiles: number, customUserAgent: string, askWhereToSaveEachFile: boolean, rememberLastUsedDownloadDirectory: boolean, preventsSleepWhileDownloading: boolean, preventsDisplaySleepWhileDownloading: boolean, mediaCookieSource: MediaCookieSource, siteLogins: Array<SiteLogin>, autoCheckUpdates: boolean, keychainAccessGranted: boolean, };

src/components/SettingsView.tsx

@@ -34,6 +34,11 @@ import {
 import { usePlatformInfo } from '../utils/platform';
 import { isTrustedFirelinkReleaseUrl } from '../utils/releaseUrls';
 import { normalizeCustomProxy } from '../store/useDownloadStore';
+import {
+  MAX_TORRENT_MAX_OPEN_FILES,
+  MIN_TORRENT_MAX_OPEN_FILES,
+  normalizeTorrentMaxOpenFiles
+} from '../utils/downloads';
 import { useTranslation } from 'react-i18next';
 import { localeDirection, resolveAppLocale } from '../i18n';
 
@@ -318,6 +323,10 @@ const engineRunId = useRef(0);
     () => String(settings.maxConcurrentDownloads)
   );
   const [proxyPortInput, setProxyPortInput] = useState(() => String(settings.proxyPort));
+  const [torrentMaxOpenFilesInput, setTorrentMaxOpenFilesInput] = useState(
+    () => String(settings.torrentMaxOpenFiles)
+  );
+  const torrentMaxOpenFilesCommitRef = useRef(0);
 
   useEffect(() => {
     setPerServerConnectionsInput(String(settings.perServerConnections));
@@ -331,6 +340,10 @@ const engineRunId = useRef(0);
     setProxyPortInput(String(settings.proxyPort));
   }, [settings.proxyPort]);
 
+  useEffect(() => {
+    setTorrentMaxOpenFilesInput(String(settings.torrentMaxOpenFiles));
+  }, [settings.torrentMaxOpenFiles]);
+
   // Local state for adding site login
   const [loginPattern, setLoginPattern] = useState('');
   const [loginUser, setLoginUser] = useState('');
@@ -346,6 +359,22 @@ const engineRunId = useRef(0);
 
   // Toast notifications
   const { addToast } = useToast();
+  const commitTorrentMaxOpenFiles = (raw: string) => {
+    const next = normalizeTorrentMaxOpenFiles(raw) ?? settings.torrentMaxOpenFiles;
+    const requestId = ++torrentMaxOpenFilesCommitRef.current;
+    setTorrentMaxOpenFilesInput(String(next));
+    void settings.setTorrentMaxOpenFiles(next).catch(error => {
+      if (requestId !== torrentMaxOpenFilesCommitRef.current) return;
+      setTorrentMaxOpenFilesInput(String(settings.torrentMaxOpenFiles));
+      addToast({
+        message: t($ => $.settings.network.torrentMaxOpenFilesUpdateFailed, {
+          detail: error instanceof Error ? error.message : String(error)
+        }),
+        variant: 'error',
+        isActionable: true
+      });
+    });
+  };
   const [isCheckingForUpdates, setIsCheckingForUpdates] = useState(false);
   const [manualUpdateStatus, setManualUpdateStatus] = useState<ManualUpdateStatus>({ type: 'idle' });
 
@@ -1212,6 +1241,27 @@ runEngineChecks(false);
                 </p>
               </div>
 
+              <h2 className="settings-section-title">{t($ => $.settings.network.torrentResourceLimits)}</h2>
+              <div className="mac-settings-group">
+                <div className="mac-settings-row settings-network-row">
+                  <div className="settings-row-label">
+                    <span>{t($ => $.settings.network.torrentMaxOpenFiles)}</span>
+                    <small>{t($ => $.settings.network.torrentMaxOpenFilesDescription)}</small>
+                  </div>
+                  <input
+                    type="number"
+                    min={MIN_TORRENT_MAX_OPEN_FILES}
+                    max={MAX_TORRENT_MAX_OPEN_FILES}
+                    step={1}
+                    value={torrentMaxOpenFilesInput}
+                    onChange={(event) => setTorrentMaxOpenFilesInput(event.target.value)}
+                    onBlur={(event) => commitTorrentMaxOpenFiles(event.target.value)}
+                    className="app-control settings-port-input text-center"
+                    aria-label={t($ => $.settings.network.torrentMaxOpenFiles)}
+                  />
+                </div>
+              </div>
+
               <h2 className="settings-section-title">{t($ => $.settings.network.identity)}</h2>
               <div className="mac-settings-group settings-popup-group">
                 <div className="mac-settings-row settings-network-row">

src/i18n/catalogs/en.ts

@@ -799,6 +799,10 @@ const common = {
       torrentLpd: 'Local Peer Discovery (LPD)',
       torrentLpdDescription: 'Discover compatible peers on the local network. This increases local network visibility.',
       torrentPeerDiscoveryRestartNote: 'These options are global to Aria2 and take effect after Firelink restarts. Aria2 still disables peer discovery for private torrents.',
+      torrentResourceLimits: 'BitTorrent resource limits',
+      torrentMaxOpenFiles: 'Maximum open Torrent files',
+      torrentMaxOpenFilesDescription: 'Global Aria2 limit for files open at once in multi-file Torrents. Lower values reduce file-descriptor use; the default is 100. Changes apply to new Torrents without restarting Aria2, and this does not raise your operating system limit.',
+      torrentMaxOpenFilesUpdateFailed: 'Could not apply the Torrent open-file limit: {{detail}}',
       identity: 'Identity',
       customUserAgent: 'Custom User-Agent',
       userAgentDescription: 'Applied to metadata fetches and download engines.',

src/i18n/catalogs/fa.ts

@@ -799,6 +799,10 @@ const fa = {
       torrentLpd: 'کشف همتای محلی (LPD)',
       torrentLpdDescription: 'همتاهای سازگار در شبکه محلی را پیدا می‌کند و دیده‌شدن ترافیک در شبکه محلی را افزایش می‌دهد.',
       torrentPeerDiscoveryRestartNote: 'این گزینه‌ها سراسری و مربوط به Aria2 هستند و پس از راه‌اندازی مجدد Firelink اعمال می‌شوند. Aria2 همچنان کشف همتا را برای تورنت‌های خصوصی خاموش می‌کند.',
+      torrentResourceLimits: 'محدودیت منابع بیت‌تورنت',
+      torrentMaxOpenFiles: 'حداکثر فایل‌های باز تورنت',
+      torrentMaxOpenFilesDescription: 'حداکثر سراسری Aria2 برای تعداد فایل‌های هم‌زمان باز در تورنت‌های چندفایلی. مقدار کمتر مصرف file descriptor را کم می‌کند؛ پیش‌فرض ۱۰۰ است. تغییرات برای تورنت‌های جدید و بدون راه‌اندازی مجدد Aria2 اعمال می‌شوند و محدودیت سیستم‌عامل را افزایش نمی‌دهند.',
+      torrentMaxOpenFilesUpdateFailed: 'اعمال محدودیت فایل‌های باز تورنت ممکن نشد: {{detail}}',
       identity: 'هویت',
       customUserAgent: 'User-Agent سفارشی',
       userAgentDescription: 'در دریافت‌های متادیتا و موتورهای دانلود اعمال می‌شود.',

src/i18n/catalogs/he.ts

@@ -799,6 +799,10 @@ const he = {
       torrentLpd: 'גילוי עמיתים מקומיים (LPD)',
       torrentLpdDescription: 'מאתר עמיתים תואמים ברשת המקומית ומגדיל את החשיפה המקומית של התעבורה.',
       torrentPeerDiscoveryRestartNote: 'האפשרויות האלה הן כלליות ל-Aria2 ונכנסות לתוקף לאחר הפעלה מחדש של Firelink. Aria2 עדיין משבית גילוי עמיתים בטורנטים פרטיים.',
+      torrentResourceLimits: 'מגבלות משאבי BitTorrent',
+      torrentMaxOpenFiles: 'מספר קובצי Torrent פתוחים מרבי',
+      torrentMaxOpenFilesDescription: 'מגבלה כללית של Aria2 על מספר הקבצים הפתוחים בו-זמנית בטורנטים מרובי קבצים. ערך נמוך יותר מפחית שימוש ב-file descriptors; ברירת המחדל היא 100. השינויים חלים על טורנטים חדשים ללא הפעלה מחדש של Aria2, ואינם מגדילים את מגבלת מערכת ההפעלה.',
+      torrentMaxOpenFilesUpdateFailed: 'לא ניתן להחיל את מגבלת הקבצים הפתוחים של Torrent: {{detail}}',
       identity: 'זהות',
       customUserAgent: 'User-Agent מותאם אישית',
       userAgentDescription: 'מוחל על משיכות מטא נתונים ומנועי הורדה.',

src/i18n/catalogs/ru.ts

@@ -799,6 +799,10 @@ const ru = {
       torrentLpd: 'Локальное обнаружение пиров (LPD)',
       torrentLpdDescription: 'Ищет подходящие пиры в локальной сети и увеличивает видимость трафика в ней.',
       torrentPeerDiscoveryRestartNote: 'Эти параметры являются глобальными для Aria2 и применяются после перезапуска Firelink. Aria2 по-прежнему отключает обнаружение пиров для приватных торрентов.',
+      torrentResourceLimits: 'Ограничения ресурсов BitTorrent',
+      torrentMaxOpenFiles: 'Максимум открытых файлов Torrent',
+      torrentMaxOpenFilesDescription: 'Глобальный лимит Aria2 на одновременно открытые файлы в многофайловых торрентах. Меньшие значения снижают расход дескрипторов; по умолчанию 100. Изменения применяются к новым торрентам без перезапуска Aria2 и не повышают лимит операционной системы.',
+      torrentMaxOpenFilesUpdateFailed: 'Не удалось применить лимит открытых файлов Torrent: {{detail}}',
       identity: 'Идентификация',
       customUserAgent: 'Собственный User-Agent',
       userAgentDescription: 'Применяется при получении метаданных и работе движков загрузки.',

src/i18n/catalogs/uk.ts

@@ -799,6 +799,10 @@ const uk = {
       torrentLpd: 'Локальний пошук пірів (LPD)',
       torrentLpdDescription: 'Шукає сумісних пірів у локальній мережі та збільшує видимість трафіку в ній.',
       torrentPeerDiscoveryRestartNote: 'Ці параметри є глобальними для Aria2 і застосовуються після перезапуску Firelink. Aria2 і надалі вимикає пошук пірів для приватних торрентів.',
+      torrentResourceLimits: 'Обмеження ресурсів BitTorrent',
+      torrentMaxOpenFiles: 'Максимум відкритих файлів Torrent',
+      torrentMaxOpenFilesDescription: 'Глобальне обмеження Aria2 на одночасно відкриті файли в багатофайлових торрентах. Менші значення зменшують використання дескрипторів; типове значення — 100. Зміни застосовуються до нових торрентів без перезапуску Aria2 і не підвищують обмеження операційної системи.',
+      torrentMaxOpenFilesUpdateFailed: 'Не вдалося застосувати обмеження відкритих файлів Torrent: {{detail}}',
       identity: 'Ідентифікація',
       customUserAgent: 'Власний User-Agent',
       userAgentDescription: 'Застосовується до запитів метаданих та рушіїв завантаження.',

src/i18n/catalogs/zh-CN.ts

@@ -799,6 +799,10 @@ const zhCN = {
       torrentLpd: '本地节点发现（LPD）',
       torrentLpdDescription: '在本地网络中发现兼容节点，这会增加本地网络中的流量可见性。',
       torrentPeerDiscoveryRestartNote: '这些选项是 Aria2 的全局设置，需要重启 Firelink 后生效。Aria2 仍会对私有 Torrent 禁用节点发现。',
+      torrentResourceLimits: 'BitTorrent 资源限制',
+      torrentMaxOpenFiles: 'Torrent 最大打开文件数',
+      torrentMaxOpenFilesDescription: 'Aria2 对多文件 Torrent 同时打开文件数的全局限制。较低的值可减少文件描述符占用；默认值为 100。修改会在不重启 Aria2 的情况下应用于新 Torrent，且不会提高操作系统的限制。',
+      torrentMaxOpenFilesUpdateFailed: '无法应用 Torrent 打开文件数限制：{{detail}}',
       identity: '身份',
       customUserAgent: '自定义 User-Agent',
       userAgentDescription: '应用于元数据获取和下载引擎。',

src/ipc.ts

@@ -77,6 +77,7 @@ type CommandMap = {
     result: void;
   };
   get_torrent_peers: { args: { id: string }; result: TorrentPeerDiagnostics };
+  set_torrent_max_open_files: { args: { max_open_files: number }; result: void };
   set_global_speed_limit: { args: { limit: string | null }; result: void };
   request_automation_permission: { args: undefined; result: void };
   check_automation_permission: { args: undefined; result: void };

src/store/useSettingsStore.test.ts

@@ -6,6 +6,10 @@ import {
 } from './useSettingsStore';
 import * as ipc from '../ipc';
 import type { PairingTokenHydration } from '../bindings/PairingTokenHydration';
+import {
+  DEFAULT_TORRENT_MAX_OPEN_FILES,
+  MAX_TORRENT_MAX_OPEN_FILES
+} from '../utils/downloads';
 
 vi.mock('../ipc', () => ({
   invokeCommand: vi.fn()
@@ -57,6 +61,66 @@ describe('Torrent peer discovery preferences', () => {
   });
 });
 
+describe('Torrent open-file limit preference', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    useSettingsStore.setState({ torrentMaxOpenFiles: DEFAULT_TORRENT_MAX_OPEN_FILES });
+  });
+
+  it('applies a bounded global limit before persisting it', async () => {
+    vi.mocked(ipc.invokeCommand).mockResolvedValue(undefined);
+
+    await useSettingsStore.getState().setTorrentMaxOpenFiles(256);
+
+    expect(ipc.invokeCommand).toHaveBeenCalledWith('set_torrent_max_open_files', {
+      max_open_files: 256
+    });
+    expect(useSettingsStore.getState().torrentMaxOpenFiles).toBe(256);
+  });
+
+  it('rejects unsafe values without changing the saved limit', async () => {
+    await expect(useSettingsStore.getState().setTorrentMaxOpenFiles(0)).rejects.toThrow();
+    await expect(
+      useSettingsStore.getState().setTorrentMaxOpenFiles(MAX_TORRENT_MAX_OPEN_FILES + 1)
+    ).rejects.toThrow();
+
+    expect(ipc.invokeCommand).not.toHaveBeenCalledWith(
+      'set_torrent_max_open_files',
+      expect.anything()
+    );
+    expect(useSettingsStore.getState().torrentMaxOpenFiles)
+      .toBe(DEFAULT_TORRENT_MAX_OPEN_FILES);
+  });
+
+  it('serializes rapid updates so the native global option cannot reorder', async () => {
+    let releaseFirst!: () => void;
+    const firstUpdate = new Promise<void>(resolve => {
+      releaseFirst = resolve;
+    });
+    const events: string[] = [];
+    vi.mocked(ipc.invokeCommand).mockImplementation(async (command: string, args?: unknown) => {
+      if (command !== 'set_torrent_max_open_files') return undefined;
+      const value = (args as { max_open_files: number }).max_open_files;
+      events.push(`start:${value}`);
+      if (value === 256) await firstUpdate;
+      events.push(`finish:${value}`);
+      return undefined;
+    });
+
+    const first = useSettingsStore.getState().setTorrentMaxOpenFiles(256);
+    const second = useSettingsStore.getState().setTorrentMaxOpenFiles(512);
+    await vi.waitFor(() => expect(events).toEqual(['start:256']));
+    expect(useSettingsStore.getState().torrentMaxOpenFiles)
+      .toBe(DEFAULT_TORRENT_MAX_OPEN_FILES);
+
+    releaseFirst();
+    await Promise.all([first, second]);
+
+    expect(events).toEqual(['start:256', 'finish:256', 'start:512', 'finish:512']);
+    expect(useSettingsStore.getState().torrentMaxOpenFiles).toBe(512);
+  });
+});
+
 describe('calendar preference', () => {
   it('keeps Gregorian as the default and persists explicit calendar choices', async () => {
     vi.clearAllMocks();

src/store/useSettingsStore.ts

@@ -20,7 +20,13 @@ import {
   DEFAULT_CATEGORY_SUBFOLDERS,
   normalizeDownloadLocationSettings
 } from '../utils/downloadLocations';
-import { normalizeSpeedLimitForBackend } from '../utils/downloads';
+import {
+  DEFAULT_TORRENT_MAX_OPEN_FILES,
+  MAX_TORRENT_MAX_OPEN_FILES,
+  MIN_TORRENT_MAX_OPEN_FILES,
+  normalizeSpeedLimitForBackend,
+  normalizeTorrentMaxOpenFiles
+} from '../utils/downloads';
 import i18n from '../i18n';
 import { isAppLocalePreference, type AppLocalePreference } from '../i18n/locales';
 import {
@@ -30,6 +36,7 @@ import {
 } from '../utils/dateTime';
 
 let settingsQueue: Promise<void> = Promise.resolve();
+let torrentMaxOpenFilesQueue: Promise<void> = Promise.resolve();
 let pairingTokenHydrationRequest: Promise<PairingTokenHydration> | null = null;
 const settingsPersistenceErrorListeners = new Set<() => void>();
 let settingsPersistenceFailed = false;
@@ -238,6 +245,7 @@ export interface SettingsState {
   torrentEnableDht6: boolean;
   torrentEnablePex: boolean;
   torrentEnableLpd: boolean;
+  torrentMaxOpenFiles: number;
   customUserAgent: string;
   askWhereToSaveEachFile: boolean;
   preventsSleepWhileDownloading: boolean;
@@ -292,6 +300,7 @@ export interface SettingsState {
   setTorrentEnableDht6: (enabled: boolean) => void;
   setTorrentEnablePex: (enabled: boolean) => void;
   setTorrentEnableLpd: (enabled: boolean) => void;
+  setTorrentMaxOpenFiles: (value: number) => Promise<void>;
   setCustomUserAgent: (userAgent: string) => void;
   setAskWhereToSaveEachFile: (ask: boolean) => void;
   setPreventsSleepWhileDownloading: (prevent: boolean) => void;
@@ -372,6 +381,7 @@ export const useSettingsStore = create<SettingsState>()(
       torrentEnableDht6: false,
       torrentEnablePex: true,
       torrentEnableLpd: false,
+      torrentMaxOpenFiles: DEFAULT_TORRENT_MAX_OPEN_FILES,
       customUserAgent: '',
       askWhereToSaveEachFile: false,
       preventsSleepWhileDownloading: true,
@@ -470,6 +480,22 @@ export const useSettingsStore = create<SettingsState>()(
       setTorrentEnableDht6: (torrentEnableDht6) => set({ torrentEnableDht6 }),
       setTorrentEnablePex: (torrentEnablePex) => set({ torrentEnablePex }),
       setTorrentEnableLpd: (torrentEnableLpd) => set({ torrentEnableLpd }),
+      setTorrentMaxOpenFiles: (value) => {
+        const normalized = normalizeTorrentMaxOpenFiles(value);
+        if (normalized === undefined) {
+          return Promise.reject(new Error(
+            `Torrent maximum open files must be between ${MIN_TORRENT_MAX_OPEN_FILES} and ${MAX_TORRENT_MAX_OPEN_FILES}`
+          ));
+        }
+        const apply = async () => {
+          await invoke('set_torrent_max_open_files', { max_open_files: normalized });
+          info('Settings updated: torrentMaxOpenFiles');
+          set({ torrentMaxOpenFiles: normalized });
+        };
+        const result = torrentMaxOpenFilesQueue.then(apply, apply);
+        torrentMaxOpenFilesQueue = result.then(() => undefined, () => undefined);
+        return result;
+      },
       setCustomUserAgent: (customUserAgent) => set({ customUserAgent }),
       setAskWhereToSaveEachFile: (askWhereToSaveEachFile) => set({ askWhereToSaveEachFile }),
       setPreventsSleepWhileDownloading: (preventsSleepWhileDownloading) => {
@@ -655,6 +681,7 @@ export const useSettingsStore = create<SettingsState>()(
         torrentEnableDht6: state.torrentEnableDht6,
         torrentEnablePex: state.torrentEnablePex,
         torrentEnableLpd: state.torrentEnableLpd,
+        torrentMaxOpenFiles: state.torrentMaxOpenFiles,
         customUserAgent: state.customUserAgent,
         askWhereToSaveEachFile: state.askWhereToSaveEachFile,
         preventsSleepWhileDownloading: state.preventsSleepWhileDownloading,
@@ -704,6 +731,8 @@ export const useSettingsStore = create<SettingsState>()(
           torrentEnableDht6: persistedBoolean(persisted.torrentEnableDht6, currentState.torrentEnableDht6),
           torrentEnablePex: persistedBoolean(persisted.torrentEnablePex, currentState.torrentEnablePex),
           torrentEnableLpd: persistedBoolean(persisted.torrentEnableLpd, currentState.torrentEnableLpd),
+          torrentMaxOpenFiles: normalizeTorrentMaxOpenFiles(persisted.torrentMaxOpenFiles)
+            ?? currentState.torrentMaxOpenFiles,
           sidebarPosition: isAllowedSetting(SIDEBAR_POSITION_VALUES, persisted.sidebarPosition)
             ? persisted.sidebarPosition
             : currentState.sidebarPosition,

src/utils/downloads.test.ts

@@ -9,6 +9,7 @@ import {
   isValidTorrentExcludeTrackerList,
   isValidTorrentTrackerList,
   normalizeTorrentEncryptionPolicy,
+  normalizeTorrentMaxOpenFiles,
   normalizeTorrentPrioritizePiece,
   normalizeTorrentTrackerInterval,
   normalizeTorrentTrackerTimeout,
@@ -126,6 +127,19 @@ describe('Torrent tracker timing validation', () => {
   });
 });
 
+describe('Torrent open-file limit validation', () => {
+  it('accepts bounded integer limits', () => {
+    expect(normalizeTorrentMaxOpenFiles(1)).toBe(1);
+    expect(normalizeTorrentMaxOpenFiles(4096)).toBe(4096);
+  });
+
+  it('rejects zero, fractional, and oversized limits', () => {
+    expect(normalizeTorrentMaxOpenFiles(0)).toBeUndefined();
+    expect(normalizeTorrentMaxOpenFiles('1.5')).toBeUndefined();
+    expect(normalizeTorrentMaxOpenFiles(4097)).toBeUndefined();
+  });
+});
+
 describe('download connection resolution', () => {
   it('uses a clamped fallback for legacy rows without a saved value', () => {
     expect(resolveDownloadConnections(undefined, 8)).toBe(8);

src/utils/downloads.ts

@@ -67,6 +67,9 @@ export const normalizeTorrentEncryptionPolicy = (
 
 export const MAX_TORRENT_TRACKER_TIMEOUT = 604800;
 export const MAX_TORRENT_TRACKER_INTERVAL = 604800;
+export const DEFAULT_TORRENT_MAX_OPEN_FILES = 100;
+export const MIN_TORRENT_MAX_OPEN_FILES = 1;
+export const MAX_TORRENT_MAX_OPEN_FILES = 4096;
 
 const parseIntegerOption = (value: unknown): number | undefined => {
   if (typeof value === 'number') {
@@ -93,6 +96,15 @@ export const normalizeTorrentTrackerInterval = (value: unknown): number | undefi
     : undefined;
 };
 
+export const normalizeTorrentMaxOpenFiles = (value: unknown): number | undefined => {
+  const parsed = parseIntegerOption(value);
+  return parsed !== undefined
+    && parsed >= MIN_TORRENT_MAX_OPEN_FILES
+    && parsed <= MAX_TORRENT_MAX_OPEN_FILES
+    ? parsed
+    : undefined;
+};
+
 // Keep every filename component within the common cross-platform filesystem
 // limit. Count UTF-8 bytes because POSIX filesystems enforce bytes, while this
 // bound is also conservative for Windows filename components.