diff --git a/frontend/src/components/downloadRow.dom.test.tsx b/frontend/src/components/downloadRow.dom.test.tsx
new file mode 100644
index 00000000..be5d62b3
--- /dev/null
+++ b/frontend/src/components/downloadRow.dom.test.tsx
@@ -0,0 +1,87 @@
+// @vitest-environment jsdom
+//
+// Library-row metadata (E7·S1): the completed row surfaces the concrete container/format alongside the
+// already-shown size. The format chip reads the raw `asset.container` (uppercased in the UI), so it must
+// render when present and be absent when the asset has no container yet (queued/running before the worker
+// fills it). i18n is key-passthrough here.
+import { describe, it, expect, afterEach, vi } from "vitest";
+import { render, screen, cleanup } from "@testing-library/react";
+
+vi.mock("react-i18next", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("react-i18next")>();
+  return { ...actual, useTranslation: () => ({ t: (key: string) => key }) };
+});
+
+import { DownloadRow } from "./downloadRow";
+import type { DownloadJob } from "../lib/api";
+
+const baseJob: DownloadJob = {
+  id: 1,
+  status: "done",
+  progress: 100,
+  speed_bps: null,
+  eta_s: null,
+  phase: null,
+  error: null,
+  error_code: null,
+  queue_pos: 0,
+  created_at: null,
+  source_kind: "youtube",
+  source_ref: "abc",
+  source_url: null,
+  poster_url: null,
+  profile_id: null,
+  spec: {
+    mode: "av",
+    max_height: null,
+    container: null,
+    audio_format: null,
+    vcodec: null,
+    embed_subs: false,
+    embed_chapters: false,
+    embed_thumbnail: false,
+    sponsorblock: false,
+  },
+  display_name: "Clip",
+  display_uploader: null,
+  display_uploader_url: null,
+  extra_links: [],
+  can_download: true,
+  expired: false,
+  asset: null,
+};
+
+const withAsset = (container: string | null): DownloadJob => ({
+  ...baseJob,
+  asset: {
+    id: 10,
+    status: "ready",
+    title: "Clip",
+    uploader: null,
+    uploader_url: null,
+    upload_date: null,
+    duration_s: 90,
+    size_bytes: 148_800_000,
+    width: 1920,
+    height: 1080,
+    container,
+    thumbnail_url: null,
+    expires_at: null,
+  },
+});
+
+afterEach(cleanup);
+
+describe("DownloadRow format chip", () => {
+  it("shows the uppercased container next to the size when ready", () => {
+    render(<DownloadRow job={withAsset("mp4")} />);
+    // Raw container is stored lowercase; the row uppercases it via CSS, so the text node stays "mp4".
+    expect(screen.getByText(/·\s*mp4/i)).toBeTruthy();
+    expect(screen.getByText(/142 MB/)).toBeTruthy();
+  });
+
+  it("omits the format chip when the asset has no container yet", () => {
+    const { container } = render(<DownloadRow job={withAsset(null)} />);
+    expect(container.textContent).not.toMatch(/·\s*(mp4|m4a|webm)/i);
+  });
+});
diff --git a/frontend/src/components/downloadRow.tsx b/frontend/src/components/downloadRow.tsx
index 53f00711..45a918f7 100644
--- a/frontend/src/components/downloadRow.tsx
+++ b/frontend/src/components/downloadRow.tsx
@@ -215,6 +215,11 @@ export function DownloadRow({
         <ChannelLine job={job} />
         <div className="flex items-center gap-2 mt-1 text-xs">
           <StatusPill job={job} />
+          {job.asset?.container ? (
+            // Concrete container (mp4 / m4a / webm …) — reads as the file format, and its audio-vs-video
+            // extension is the video/audio distinction the running-only phase pill can't show at rest.
+            <span className="text-muted uppercase">· {job.asset.container}</span>
+          ) : null}
           {job.asset?.size_bytes ? (
             <span className="text-muted">· {formatBytes(job.asset.size_bytes)}</span>
           ) : null}