Implement artwork download and cache

backend/test/e2e/app.e2e-spec.ts

@@ -14,6 +14,7 @@ import { Test } from '@nestjs/testing';
 import { AppModule } from '../../src/app.module';
 import { AssetsController } from '../../src/modules/assets/assets.controller';
 import { AssetDownloadQueryDto } from '../../src/modules/assets/assets.dto';
+import { ArtworkController } from '../../src/modules/artwork/artwork.controller';
 import { AppConfigService } from '../../src/modules/config/config.service';
 import { DevicesController } from '../../src/modules/devices/devices.controller';
 import { HealthController } from '../../src/modules/health/health.controller';
@@ -62,6 +63,7 @@ function createPrismaMock() {
   const devices = new Map<string, any>();
   const tracks = new Map<string, any>();
   const audioAssets = new Map<string, any>();
+  const artworkAssets = new Map<string, any>();
   const uploadSessions = new Map<string, any>();
   const libraryEvents = new Map<bigint, any>();
   let nextLibraryEventId = 1n;
@@ -133,6 +135,9 @@ function createPrismaMock() {
             primaryAudioAsset: track.primaryAudioAssetId
               ? audioAssets.get(track.primaryAudioAssetId) ?? null
               : null,
+            artworkAsset: track.artworkAssetId
+              ? artworkAssets.get(track.artworkAssetId) ?? null
+              : null,
           }));
       }),
       findUnique: jest.fn().mockImplementation(async ({ where }) => {
@@ -209,6 +214,11 @@ function createPrismaMock() {
         return updated;
       }),
     },
+    artworkAsset: {
+      findUnique: jest.fn().mockImplementation(async ({ where }) => {
+        return artworkAssets.get(where.id) ?? null;
+      }),
+    },
     uploadSession: {
       create: jest.fn().mockImplementation(async ({ data }) => {
         const now = new Date();
@@ -266,6 +276,7 @@ function createPrismaMock() {
       devices,
       tracks,
       audioAssets,
+      artworkAssets,
       uploadSessions,
       libraryEvents,
     },
@@ -275,6 +286,7 @@ function createPrismaMock() {
 describe('Velody API wiring (e2e)', () => {
   let app: INestApplication;
   let assetsController: AssetsController;
+  let artworkController: ArtworkController;
   let healthController: HealthController;
   let devicesController: DevicesController;
   let libraryController: LibraryController;
@@ -315,6 +327,7 @@ describe('Velody API wiring (e2e)', () => {
     await app.init();
 
     assetsController = moduleRef.get(AssetsController);
+    artworkController = moduleRef.get(ArtworkController);
     healthController = moduleRef.get(HealthController);
     devicesController = moduleRef.get(DevicesController);
     libraryController = moduleRef.get(LibraryController);
@@ -490,6 +503,107 @@ describe('Velody API wiring (e2e)', () => {
     ).rejects.toBeInstanceOf(NotFoundException);
   });
 
+  it('downloads artwork bytes for the owning device user with the stored image mime type', async () => {
+    const registerResponse = await devicesController.register({
+      platform: 'IPHONE',
+      deviceName: 'Artwork iPhone',
+      appVersion: '0.1.0',
+    });
+    const artworkId = randomUUID();
+    const trackId = randomUUID();
+    const bytes = Buffer.from(
+      'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVQIW2P8z8DwHwAFgwJ/lBi4NwAAAABJRU5ErkJggg==',
+      'base64',
+    );
+    const storageKey = join('library', 'artwork', `${artworkId}.png`);
+
+    prismaState.artworkAssets.set(artworkId, {
+      id: artworkId,
+      sha256: sha256Hex(bytes),
+      storageKey,
+      mimeType: 'image/png',
+      width: 1,
+      height: 1,
+      fileSizeBytes: BigInt(bytes.length),
+      createdAt: new Date('2026-05-29T08:00:00.000Z'),
+      track: {
+        userId: prismaState.defaultUser.id,
+      },
+    });
+    prismaState.tracks.set(trackId, {
+      id: trackId,
+      userId: prismaState.defaultUser.id,
+      primaryAudioAssetId: null,
+      artworkAssetId: artworkId,
+      title: 'Artwork Track',
+      artist: 'Velody',
+      album: null,
+      albumArtist: null,
+      genre: null,
+      discNumber: null,
+      trackNumber: null,
+      year: null,
+      durationMs: null,
+      status: 'ACTIVE',
+      deletedAt: null,
+      createdAt: new Date('2026-05-29T08:00:00.000Z'),
+      updatedAt: new Date('2026-05-29T08:02:00.000Z'),
+    });
+
+    const filePath = join(storageRoot, storageKey);
+    await mkdir(dirname(filePath), { recursive: true });
+    await writeFile(filePath, bytes);
+
+    const headers = new Map<string, string>();
+    const responseMock = {
+      setHeader(name: string, value: string) {
+        headers.set(name.toLowerCase(), String(value));
+      },
+    } as any;
+
+    const streamable = await artworkController.download(
+      artworkId,
+      { deviceId: registerResponse.deviceId },
+      responseMock,
+    );
+    const downloadedBytes = await streamToBuffer(streamable.getStream());
+
+    expect(downloadedBytes.equals(bytes)).toBe(true);
+    expect(headers.get('content-type')).toBe('image/png');
+    expect(headers.get('content-length')).toBe(String(bytes.length));
+  });
+
+  it('returns not found when the requested artwork file is missing', async () => {
+    const registerResponse = await devicesController.register({
+      platform: 'IPHONE',
+      deviceName: 'Artwork iPhone',
+      appVersion: '0.1.0',
+    });
+    const artworkId = randomUUID();
+
+    prismaState.artworkAssets.set(artworkId, {
+      id: artworkId,
+      sha256: 'sha-missing-artwork',
+      storageKey: join('library', 'artwork', `${artworkId}.png`),
+      mimeType: 'image/png',
+      width: 1,
+      height: 1,
+      fileSizeBytes: BigInt(10),
+      createdAt: new Date('2026-05-29T08:00:00.000Z'),
+      track: {
+        userId: prismaState.defaultUser.id,
+      },
+    });
+
+    await expect(
+      artworkController.download(
+        artworkId,
+        { deviceId: registerResponse.deviceId },
+        { setHeader() {} } as any,
+      ),
+    ).rejects.toBeInstanceOf(NotFoundException);
+  });
+
   it('rejects an invalid asset download device id query', async () => {
     const validationPipe = new ValidationPipe({
       whitelist: true,
@@ -523,6 +637,7 @@ describe('Velody API wiring (e2e)', () => {
     const secondaryDeviceId = randomUUID();
     const primaryTrackId = randomUUID();
     const primaryAssetId = randomUUID();
+    const primaryArtworkId = randomUUID();
     const secondaryTrackId = randomUUID();
     const secondaryAssetId = randomUUID();
 
@@ -552,6 +667,16 @@ describe('Velody API wiring (e2e)', () => {
       sourceDeviceId: primaryDevice.deviceId,
       createdAt: new Date('2026-05-29T08:00:00.000Z'),
     });
+    prismaState.artworkAssets.set(primaryArtworkId, {
+      id: primaryArtworkId,
+      sha256: 'artwork-sha-default',
+      storageKey: `library/artwork/${primaryArtworkId}.png`,
+      mimeType: 'image/png',
+      width: 512,
+      height: 512,
+      fileSizeBytes: BigInt(128),
+      createdAt: new Date('2026-05-29T08:00:30.000Z'),
+    });
     prismaState.audioAssets.set(secondaryAssetId, {
       id: secondaryAssetId,
       userId: secondUserId,
@@ -571,7 +696,7 @@ describe('Velody API wiring (e2e)', () => {
       id: primaryTrackId,
       userId: prismaState.defaultUser.id,
       primaryAudioAssetId: primaryAssetId,
-      artworkAssetId: null,
+      artworkAssetId: primaryArtworkId,
       title: 'Default User Track',
       artist: 'Velody',
       album: null,
@@ -621,6 +746,13 @@ describe('Velody API wiring (e2e)', () => {
           assetId: primaryAssetId,
           createdAt: '2026-05-29T08:00:00.000Z',
           updatedAt: '2026-05-29T08:02:00.000Z',
+          artwork: {
+            artworkId: primaryArtworkId,
+            sha256: 'artwork-sha-default',
+            mimeType: 'image/png',
+            width: 512,
+            height: 512,
+          },
         },
       ],
     });