diff --git a/src/__tests__/download.test.ts b/src/__tests__/download.test.ts
index 9a4d9dc..d3d5f4e 100644
--- a/src/__tests__/download.test.ts
+++ b/src/__tests__/download.test.ts
@@ -874,4 +874,283 @@ describe('DownloadService', () => {
       expect(result.filePath).toBeDefined();
     });
   });
+
+  describe('downloadItem — SponsorBlock arg construction', () => {
+    function setupForArgs(deps: ReturnType<typeof createMockDeps>) {
+      const outputPath = join(tmpDir, 'media', 'youtube', 'Test Channel', 'Test Video Title.mp4');
+      mkdirSync(join(tmpDir, 'media', 'youtube', 'Test Channel'), { recursive: true });
+      writeFileSync(outputPath, 'data');
+      execYtDlpMock.mockResolvedValueOnce({ stdout: outputPath, stderr: '', exitCode: 0 });
+      statMock.mockResolvedValueOnce({ size: 1000 });
+      return outputPath;
+    }
+
+    it('produces --sponsorblock-remove with comma-separated categories', async () => {
+      const deps = createMockDeps();
+      const service = new DownloadService(
+        db, deps.rateLimiter, deps.fileOrganizer,
+        deps.qualityAnalyzer, deps.cookieManager
+      );
+      setupForArgs(deps);
+
+      const profile: FormatProfile = {
+        id: 20, name: 'SB Test', videoResolution: null, audioCodec: null, audioBitrate: null,
+        containerFormat: null, isDefault: false, subtitleLanguages: null, embedSubtitles: false,
+        embedChapters: false, embedThumbnail: false,
+        sponsorBlockRemove: 'sponsor,selfpromo',
+        outputTemplate: null, createdAt: '', updatedAt: '',
+      };
+
+      await service.downloadItem(testContentItem, testChannel, profile);
+
+      const args = execYtDlpMock.mock.calls[0][0] as string[];
+      const sbIdx = args.indexOf('--sponsorblock-remove');
+      expect(sbIdx).toBeGreaterThanOrEqual(0);
+      expect(args[sbIdx + 1]).toBe('sponsor,selfpromo');
+    });
+
+    it('does not include --sponsorblock-remove when sponsorBlockRemove is null', async () => {
+      const deps = createMockDeps();
+      const service = new DownloadService(
+        db, deps.rateLimiter, deps.fileOrganizer,
+        deps.qualityAnalyzer, deps.cookieManager
+      );
+      setupForArgs(deps);
+
+      const profile: FormatProfile = {
+        id: 21, name: 'No SB', videoResolution: null, audioCodec: null, audioBitrate: null,
+        containerFormat: null, isDefault: false, subtitleLanguages: null, embedSubtitles: false,
+        embedChapters: false, embedThumbnail: false,
+        sponsorBlockRemove: null,
+        outputTemplate: null, createdAt: '', updatedAt: '',
+      };
+
+      await service.downloadItem(testContentItem, testChannel, profile);
+
+      const args = execYtDlpMock.mock.calls[0][0] as string[];
+      expect(args).not.toContain('--sponsorblock-remove');
+    });
+
+    it('does not include --sponsorblock-remove when value is empty/whitespace', async () => {
+      const deps = createMockDeps();
+      const service = new DownloadService(
+        db, deps.rateLimiter, deps.fileOrganizer,
+        deps.qualityAnalyzer, deps.cookieManager
+      );
+      setupForArgs(deps);
+
+      const profile: FormatProfile = {
+        id: 22, name: 'Empty SB', videoResolution: null, audioCodec: null, audioBitrate: null,
+        containerFormat: null, isDefault: false, subtitleLanguages: null, embedSubtitles: false,
+        embedChapters: false, embedThumbnail: false,
+        sponsorBlockRemove: '  ',
+        outputTemplate: null, createdAt: '', updatedAt: '',
+      };
+
+      await service.downloadItem(testContentItem, testChannel, profile);
+
+      const args = execYtDlpMock.mock.calls[0][0] as string[];
+      expect(args).not.toContain('--sponsorblock-remove');
+    });
+
+    it('handles all SponsorBlock category types', async () => {
+      const deps = createMockDeps();
+      const service = new DownloadService(
+        db, deps.rateLimiter, deps.fileOrganizer,
+        deps.qualityAnalyzer, deps.cookieManager
+      );
+      setupForArgs(deps);
+
+      const allCategories = 'sponsor,selfpromo,interaction,intro,outro,preview,music_offtopic,filler';
+      const profile: FormatProfile = {
+        id: 23, name: 'All SB', videoResolution: null, audioCodec: null, audioBitrate: null,
+        containerFormat: null, isDefault: false, subtitleLanguages: null, embedSubtitles: false,
+        embedChapters: false, embedThumbnail: false,
+        sponsorBlockRemove: allCategories,
+        outputTemplate: null, createdAt: '', updatedAt: '',
+      };
+
+      await service.downloadItem(testContentItem, testChannel, profile);
+
+      const args = execYtDlpMock.mock.calls[0][0] as string[];
+      const sbIdx = args.indexOf('--sponsorblock-remove');
+      expect(sbIdx).toBeGreaterThanOrEqual(0);
+      expect(args[sbIdx + 1]).toBe(allCategories);
+    });
+  });
+
+  describe('downloadItem — subtitle arg construction', () => {
+    function setupForArgs(deps: ReturnType<typeof createMockDeps>) {
+      const outputPath = join(tmpDir, 'media', 'youtube', 'Test Channel', 'Test Video Title.mp4');
+      mkdirSync(join(tmpDir, 'media', 'youtube', 'Test Channel'), { recursive: true });
+      writeFileSync(outputPath, 'data');
+      execYtDlpMock.mockResolvedValueOnce({ stdout: outputPath, stderr: '', exitCode: 0 });
+      statMock.mockResolvedValueOnce({ size: 1000 });
+      return outputPath;
+    }
+
+    it('produces --write-subs and --sub-langs when subtitleLanguages is set', async () => {
+      const deps = createMockDeps();
+      const service = new DownloadService(
+        db, deps.rateLimiter, deps.fileOrganizer,
+        deps.qualityAnalyzer, deps.cookieManager
+      );
+      setupForArgs(deps);
+
+      const profile: FormatProfile = {
+        id: 30, name: 'Sub Test', videoResolution: null, audioCodec: null, audioBitrate: null,
+        containerFormat: null, isDefault: false,
+        subtitleLanguages: 'en,es',
+        embedSubtitles: false, embedChapters: false, embedThumbnail: false,
+        sponsorBlockRemove: null, outputTemplate: null, createdAt: '', updatedAt: '',
+      };
+
+      await service.downloadItem(testContentItem, testChannel, profile);
+
+      const args = execYtDlpMock.mock.calls[0][0] as string[];
+      expect(args).toContain('--write-subs');
+      const slIdx = args.indexOf('--sub-langs');
+      expect(slIdx).toBeGreaterThanOrEqual(0);
+      expect(args[slIdx + 1]).toBe('en,es');
+      // embedSubtitles is false, so no --embed-subs
+      expect(args).not.toContain('--embed-subs');
+    });
+
+    it('produces --embed-subs when embedSubtitles=true AND subtitleLanguages is set', async () => {
+      const deps = createMockDeps();
+      const service = new DownloadService(
+        db, deps.rateLimiter, deps.fileOrganizer,
+        deps.qualityAnalyzer, deps.cookieManager
+      );
+      setupForArgs(deps);
+
+      const profile: FormatProfile = {
+        id: 31, name: 'Embed Sub', videoResolution: null, audioCodec: null, audioBitrate: null,
+        containerFormat: null, isDefault: false,
+        subtitleLanguages: 'en,es',
+        embedSubtitles: true,
+        embedChapters: false, embedThumbnail: false,
+        sponsorBlockRemove: null, outputTemplate: null, createdAt: '', updatedAt: '',
+      };
+
+      await service.downloadItem(testContentItem, testChannel, profile);
+
+      const args = execYtDlpMock.mock.calls[0][0] as string[];
+      expect(args).toContain('--write-subs');
+      expect(args).toContain('--sub-langs');
+      expect(args).toContain('--embed-subs');
+    });
+
+    it('does NOT produce --embed-subs when embedSubtitles=true but subtitleLanguages is null', async () => {
+      const deps = createMockDeps();
+      const service = new DownloadService(
+        db, deps.rateLimiter, deps.fileOrganizer,
+        deps.qualityAnalyzer, deps.cookieManager
+      );
+      setupForArgs(deps);
+
+      const profile: FormatProfile = {
+        id: 32, name: 'No Lang', videoResolution: null, audioCodec: null, audioBitrate: null,
+        containerFormat: null, isDefault: false,
+        subtitleLanguages: null,
+        embedSubtitles: true,
+        embedChapters: false, embedThumbnail: false,
+        sponsorBlockRemove: null, outputTemplate: null, createdAt: '', updatedAt: '',
+      };
+
+      await service.downloadItem(testContentItem, testChannel, profile);
+
+      const args = execYtDlpMock.mock.calls[0][0] as string[];
+      expect(args).not.toContain('--write-subs');
+      expect(args).not.toContain('--sub-langs');
+      expect(args).not.toContain('--embed-subs');
+    });
+
+    it('does not produce subtitle args when no format profile', async () => {
+      const deps = createMockDeps();
+      const service = new DownloadService(
+        db, deps.rateLimiter, deps.fileOrganizer,
+        deps.qualityAnalyzer, deps.cookieManager
+      );
+      setupForArgs(deps);
+
+      await service.downloadItem(testContentItem, testChannel);
+
+      const args = execYtDlpMock.mock.calls[0][0] as string[];
+      expect(args).not.toContain('--write-subs');
+      expect(args).not.toContain('--sub-langs');
+      expect(args).not.toContain('--embed-subs');
+    });
+
+    it('handles single subtitle language', async () => {
+      const deps = createMockDeps();
+      const service = new DownloadService(
+        db, deps.rateLimiter, deps.fileOrganizer,
+        deps.qualityAnalyzer, deps.cookieManager
+      );
+      setupForArgs(deps);
+
+      const profile: FormatProfile = {
+        id: 33, name: 'Single Lang', videoResolution: null, audioCodec: null, audioBitrate: null,
+        containerFormat: null, isDefault: false,
+        subtitleLanguages: 'en',
+        embedSubtitles: true,
+        embedChapters: false, embedThumbnail: false,
+        sponsorBlockRemove: null, outputTemplate: null, createdAt: '', updatedAt: '',
+      };
+
+      await service.downloadItem(testContentItem, testChannel, profile);
+
+      const args = execYtDlpMock.mock.calls[0][0] as string[];
+      expect(args).toContain('--write-subs');
+      const slIdx = args.indexOf('--sub-langs');
+      expect(args[slIdx + 1]).toBe('en');
+      expect(args).toContain('--embed-subs');
+    });
+  });
+
+  describe('downloadItem — combined SponsorBlock + subtitle args', () => {
+    it('includes both SponsorBlock and subtitle args when both are configured', async () => {
+      const deps = createMockDeps();
+      const service = new DownloadService(
+        db, deps.rateLimiter, deps.fileOrganizer,
+        deps.qualityAnalyzer, deps.cookieManager
+      );
+
+      const outputPath = join(tmpDir, 'media', 'youtube', 'Test Channel', 'Test Video Title.mp4');
+      mkdirSync(join(tmpDir, 'media', 'youtube', 'Test Channel'), { recursive: true });
+      writeFileSync(outputPath, 'data');
+      execYtDlpMock.mockResolvedValueOnce({ stdout: outputPath, stderr: '', exitCode: 0 });
+      statMock.mockResolvedValueOnce({ size: 1000 });
+
+      const profile: FormatProfile = {
+        id: 40, name: 'Full Features', videoResolution: '1080p', audioCodec: null, audioBitrate: null,
+        containerFormat: 'mkv', isDefault: false,
+        subtitleLanguages: 'en,es,fr',
+        embedSubtitles: true,
+        embedChapters: true, embedThumbnail: true,
+        sponsorBlockRemove: 'sponsor,selfpromo,intro,outro',
+        outputTemplate: null, createdAt: '', updatedAt: '',
+      };
+
+      await service.downloadItem(testContentItem, testChannel, profile);
+
+      const args = execYtDlpMock.mock.calls[0][0] as string[];
+
+      // Subtitle args
+      expect(args).toContain('--write-subs');
+      const slIdx = args.indexOf('--sub-langs');
+      expect(args[slIdx + 1]).toBe('en,es,fr');
+      expect(args).toContain('--embed-subs');
+
+      // SponsorBlock args
+      const sbIdx = args.indexOf('--sponsorblock-remove');
+      expect(sbIdx).toBeGreaterThanOrEqual(0);
+      expect(args[sbIdx + 1]).toBe('sponsor,selfpromo,intro,outro');
+
+      // Chapter + thumbnail embedding
+      expect(args).toContain('--embed-chapters');
+      expect(args).toContain('--embed-thumbnail');
+    });
+  });
 });