feat(torrents): add global open-file limit

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.