fix(downloads): resume interrupted Xtream VOD transfers (#1329)

* fix(downloads): resume interrupted Xtream VOD transfers

* fix(downloads): validate partials before resuming

* fix(downloads): propagate headers to episode transfers

apps/electron-backend-e2e/src/download-reliability.e2e.ts

@@ -0,0 +1,117 @@
+import { mkdirSync, readFileSync, statSync } from 'fs';
+import { join } from 'path';
+import type { Page } from '@playwright/test';
+import {
+    addXtreamPortal,
+    closeElectronApp,
+    expect,
+    launchElectronApp,
+    resetMockServers,
+    test,
+    waitForXtreamWorkspaceReady,
+} from './electron-test-fixtures';
+import {
+    createInterruptedRangeServer,
+    INTERRUPTED_RANGE_SERVER_ETAG,
+    startDownload,
+} from './downloads.e2e-support';
+
+async function openDownloadsPage(page: Page): Promise<void> {
+    await page.getByRole('button', { name: 'Open downloads' }).click();
+    await page.waitForURL(/\/workspace\/downloads(?:\?.*)?$/);
+}
+
+async function getPlaylistId(page: Page, title: string): Promise<string> {
+    const playlists = await page.evaluate(
+        async () => (await window.electron?.dbGetAppPlaylistMetas?.()) ?? []
+    );
+    const playlist = playlists.find((entry) => entry.title === title);
+    expect(playlist, `playlist "${title}" should exist`).toBeDefined();
+    return playlist?._id ?? '';
+}
+
+test.describe('Electron download reliability', () => {
+    test('@downloads @electron retains a network-interrupted partial and retries it with HTTP Range', async ({
+        dataDir,
+        request,
+    }) => {
+        await resetMockServers(request, ['xtream']);
+        const rangeServer = await createInterruptedRangeServer();
+        const app = await launchElectronApp(dataDir);
+
+        try {
+            await addXtreamPortal(app.mainWindow, {
+                name: 'Reset Portal',
+                username: 'user1',
+                password: 'pass1',
+            });
+            await waitForXtreamWorkspaceReady(app.mainWindow);
+            await openDownloadsPage(app.mainWindow);
+
+            const downloadsDir = join(dataDir, 'e2e-reset-downloads');
+            mkdirSync(downloadsDir, { recursive: true });
+            await app.electronApp.evaluate(({ dialog }, folder) => {
+                dialog.showOpenDialog = async () =>
+                    ({
+                        canceled: false,
+                        filePaths: [folder],
+                    }) as Awaited<ReturnType<typeof dialog.showOpenDialog>>;
+            }, downloadsDir);
+            await app.mainWindow
+                .getByRole('button', { name: 'Change Folder' })
+                .click();
+
+            const playlistId = await getPlaylistId(
+                app.mainWindow,
+                'Reset Portal'
+            );
+            const downloadId = await startDownload(app.mainWindow, {
+                playlistId,
+                xtreamId: 9801,
+                contentType: 'vod',
+                title: 'E2E Reset Movie',
+                url: rangeServer.url,
+                downloadFolder: downloadsDir,
+            });
+            const item = app.mainWindow.getByTestId(
+                `download-queue-item-${downloadId}`
+            );
+            await expect(item.locator('.download-queue__status')).toContainText(
+                'Failed',
+                { timeout: 30000 }
+            );
+            await expect(item.locator('.download-queue__error')).toContainText(
+                'DOWNLOAD_NETWORK_INTERRUPTED (ECONNRESET)'
+            );
+
+            const partialPath = join(downloadsDir, 'E2E Reset Movie.mp4.part');
+            expect(statSync(partialPath).size).toBe(
+                rangeServer.interruptedBytes
+            );
+
+            await item
+                .getByRole('button', { name: 'Retry E2E Reset Movie' })
+                .click();
+            await expect(
+                app.mainWindow.getByTestId(
+                    `download-library-movie-${downloadId}`
+                )
+            ).toBeVisible({ timeout: 30000 });
+
+            const resumeRequest = rangeServer.requests.find(
+                (entry) => entry.range
+            );
+            expect(resumeRequest?.range).toBe(
+                `bytes=${rangeServer.interruptedBytes}-`
+            );
+            expect(resumeRequest?.ifRange).toBe(INTERRUPTED_RANGE_SERVER_ETAG);
+            const finalFile = readFileSync(
+                join(downloadsDir, 'E2E Reset Movie.mp4')
+            );
+            expect(finalFile.equals(rangeServer.payload)).toBe(true);
+        } finally {
+            await closeElectronApp(app);
+            await rangeServer.close();
+        }
+    });
+});

apps/electron-backend-e2e/src/downloads.e2e-support.ts

@@ -31,6 +31,10 @@ interface ThrottledRangeServer {
     url: string;
 }
 
+interface InterruptedRangeServer extends ThrottledRangeServer {
+    interruptedBytes: number;
+}
+
 interface TruncatedDownloadServer {
     close: () => Promise<void>;
     payload: Buffer;
@@ -39,6 +43,7 @@ interface TruncatedDownloadServer {
 }
 
 export const RANGE_SERVER_ETAG = '"e2e-range-etag"';
+export const INTERRUPTED_RANGE_SERVER_ETAG = '"e2e-reset-etag"';
 const downloadPlayCaptureKey = '__iptvnatorE2eDownloadPlayPaths';
 
 export function getStalkerSeriesDownloadTarget(
@@ -172,6 +177,63 @@ export async function createThrottledRangeServer(
     };
 }
 
+/**
+ * Resets the first full response after writing a valid prefix, then serves the
+ * remainder to a Range retry. This matches a provider/proxy connection drop
+ * without manufacturing a clean EOF.
+ */
+export async function createInterruptedRangeServer(): Promise<InterruptedRangeServer> {
+    const payload = Buffer.alloc(64 * 1024, 9);
+    const interruptedBytes = 16 * 1024;
+    const requests: RangeServerRequest[] = [];
+
+    const server = createServer((req, res) => {
+        const range = req.headers.range;
+        const ifRange = req.headers['if-range'];
+        requests.push({
+            ifRange: typeof ifRange === 'string' ? ifRange : undefined,
+            range: typeof range === 'string' ? range : undefined,
+        });
+
+        const offset = range
+            ? Number(/^bytes=(\d+)-$/.exec(range)?.[1] ?? Number.NaN)
+            : 0;
+        if (range && Number.isFinite(offset)) {
+            res.writeHead(206, {
+                'Content-Length': payload.length - offset,
+                'Content-Range': `bytes ${offset}-${payload.length - 1}/${payload.length}`,
+                'Content-Type': 'video/mp4',
+                ETag: INTERRUPTED_RANGE_SERVER_ETAG,
+            });
+            res.end(payload.subarray(offset));
+            return;
+        }
+
+        res.writeHead(200, {
+            'Content-Length': payload.length,
+            'Content-Type': 'video/mp4',
+            ETag: INTERRUPTED_RANGE_SERVER_ETAG,
+        });
+        res.write(payload.subarray(0, interruptedBytes), () => {
+            setTimeout(() => res.socket?.destroy(), 20);
+        });
+    });
+
+    await new Promise<void>((resolve) =>
+        server.listen(0, '127.0.0.1', resolve)
+    );
+    const { port } = server.address() as AddressInfo;
+
+    return {
+        close: () =>
+            new Promise<void>((resolve) => server.close(() => resolve())),
+        interruptedBytes,
+        payload,
+        requests,
+        url: `http://127.0.0.1:${port}/media/e2e-reset-movie.mp4`,
+    };
+}
+
 /**
  * Ends a chunked response cleanly while Content-Range advertises a larger
  * representation. The runtime therefore retains the valid .part for a Range