diff --git a/apps/desktop/package.json b/apps/desktop/package.json
index e8b42e09..1bc32019 100644
--- a/apps/desktop/package.json
+++ b/apps/desktop/package.json
@@ -18,6 +18,7 @@
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "lucide-react": "^1.20.0",
+    "pdfjs-dist": "6.1.200",
     "react": "^19.2.4",
     "react-dom": "^19.2.7",
     "tailwind-merge": "^3.6.0",
diff --git a/apps/desktop/src/features/score/ScoreViewer.test.tsx b/apps/desktop/src/features/score/ScoreViewer.test.tsx
new file mode 100644
index 00000000..297e1d42
--- /dev/null
+++ b/apps/desktop/src/features/score/ScoreViewer.test.tsx
@@ -0,0 +1,329 @@
+import { act, fireEvent, render, screen, waitFor } from "@testing-library/react";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import type { PDFDocumentLoadingTask, PDFDocumentProxy } from "pdfjs-dist";
+import { ScoreViewer } from "./ScoreViewer";
+import { loadScorePdf } from "./pdfjs";
+
+vi.mock("./pdfjs", () => ({
+  loadScorePdf: vi.fn()
+}));
+
+vi.mock("../../i18n", () => ({
+  createTranslator: () => (key: string) =>
+    ({
+      scoreViewerEmpty: "No score PDF attached. Attach a validated score PDF to view it here.",
+      scoreViewerLoading: "Loading score PDF...",
+      scoreViewerFailedTitle: "Could not display the score",
+      scoreViewerRetry: "Retry",
+      scoreViewerPrevPage: "Previous page",
+      scoreViewerNextPage: "Next page",
+      scoreViewerPageIndicator: "Page {current} of {total}",
+      scoreViewerZoomIn: "Zoom in",
+      scoreViewerZoomOut: "Zoom out",
+      scoreViewerFitWidth: "Fit width"
+    })[key] ?? key,
+  detectPreferredLocale: () => "en"
+}));
+
+interface Deferred<T> {
+  promise: Promise<T>;
+  resolve: (value: T) => void;
+  reject: (reason: unknown) => void;
+}
+
+function createDeferred<T>(): Deferred<T> {
+  let resolve!: (value: T) => void;
+  let reject!: (reason: unknown) => void;
+  const promise = new Promise<T>((res, rej) => {
+    resolve = res;
+    reject = rej;
+  });
+  return { promise, resolve, reject };
+}
+
+function createFakePage(renderPromise: Promise<void> = Promise.resolve()) {
+  const renderTask = { promise: renderPromise, cancel: vi.fn() };
+  return {
+    renderTask,
+    getViewport: vi.fn(({ scale }: { scale: number }) => ({
+      width: 600 * scale,
+      height: 800 * scale
+    })),
+    render: vi.fn(() => renderTask)
+  };
+}
+
+function createFakeDocument(numPages = 3, page = createFakePage()) {
+  return {
+    page,
+    doc: {
+      numPages,
+      getPage: vi.fn(() => Promise.resolve(page))
+    } as unknown as PDFDocumentProxy
+  };
+}
+
+function mockLoadTaskOnce(
+  promise: Promise<unknown>,
+  destroy: () => Promise<void> = () => Promise.resolve()
+) {
+  const destroyMock = vi.fn(destroy);
+  vi.mocked(loadScorePdf).mockReturnValueOnce({
+    promise,
+    destroy: destroyMock
+  } as unknown as PDFDocumentLoadingTask);
+  return { destroy: destroyMock };
+}
+
+const SAMPLE_BYTES = new Uint8Array([0x25, 0x50, 0x44, 0x46]);
+
+describe("ScoreViewer", () => {
+  beforeEach(() => {
+    vi.mocked(loadScorePdf).mockReset();
+  });
+
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it("renders the empty placeholder without loading when no data is attached", () => {
+    const onStatusChange = vi.fn();
+    render(<ScoreViewer data={null} onStatusChange={onStatusChange} />);
+
+    expect(
+      screen.getByText("No score PDF attached. Attach a validated score PDF to view it here.")
+    ).toBeInTheDocument();
+    expect(loadScorePdf).not.toHaveBeenCalled();
+    expect(onStatusChange).not.toHaveBeenCalled();
+  });
+
+  it("transitions from LOADING to READY and renders the first page", async () => {
+    const deferred = createDeferred<PDFDocumentProxy>();
+    mockLoadTaskOnce(deferred.promise);
+    const { doc, page } = createFakeDocument(3);
+    const onStatusChange = vi.fn();
+
+    render(<ScoreViewer data={SAMPLE_BYTES} onStatusChange={onStatusChange} />);
+
+    expect(screen.getByRole("status")).toBeInTheDocument();
+    expect(screen.getByText("Loading score PDF...")).toBeInTheDocument();
+    expect(onStatusChange).toHaveBeenLastCalledWith("LOADING");
+    expect(loadScorePdf).toHaveBeenCalledWith(SAMPLE_BYTES);
+
+    await act(async () => {
+      deferred.resolve(doc);
+    });
+
+    expect(await screen.findByText("Page 1 of 3")).toBeInTheDocument();
+    expect(onStatusChange).toHaveBeenLastCalledWith("READY");
+    await waitFor(() => {
+      expect(page.render).toHaveBeenCalled();
+    });
+    expect(page.getViewport).toHaveBeenCalledWith({ scale: 1 });
+    expect(screen.getByRole("button", { name: "Previous page" })).toBeDisabled();
+    expect(screen.getByRole("button", { name: "Next page" })).toBeEnabled();
+  });
+
+  it("shows the file name when provided", async () => {
+    const { doc } = createFakeDocument(1);
+    mockLoadTaskOnce(Promise.resolve(doc));
+
+    render(<ScoreViewer data={SAMPLE_BYTES} fileName="setlist-opener.pdf" />);
+
+    expect(await screen.findByText("setlist-opener.pdf")).toBeInTheDocument();
+  });
+
+  it("transitions to FAILED with the error message and recovers on retry", async () => {
+    mockLoadTaskOnce(Promise.reject(new Error("broken bytes")));
+    const { doc } = createFakeDocument(2);
+    mockLoadTaskOnce(Promise.resolve(doc));
+    const onStatusChange = vi.fn();
+
+    render(<ScoreViewer data={SAMPLE_BYTES} onStatusChange={onStatusChange} />);
+
+    expect(await screen.findByRole("alert")).toBeInTheDocument();
+    expect(screen.getByText("Could not display the score")).toBeInTheDocument();
+    expect(screen.getByText("broken bytes")).toBeInTheDocument();
+    expect(onStatusChange).toHaveBeenLastCalledWith("FAILED");
+
+    fireEvent.click(screen.getByRole("button", { name: "Retry" }));
+
+    expect(await screen.findByText("Page 1 of 2")).toBeInTheDocument();
+    expect(onStatusChange).toHaveBeenLastCalledWith("READY");
+    expect(loadScorePdf).toHaveBeenCalledTimes(2);
+  });
+
+  it("stringifies non-Error load failures", async () => {
+    mockLoadTaskOnce(Promise.reject("password protected"));
+
+    render(<ScoreViewer data={SAMPLE_BYTES} />);
+
+    expect(await screen.findByRole("alert")).toBeInTheDocument();
+    expect(screen.getByText("password protected")).toBeInTheDocument();
+  });
+
+  it("navigates pages and clamps at both bounds", async () => {
+    const { doc } = createFakeDocument(3);
+    mockLoadTaskOnce(Promise.resolve(doc));
+
+    render(<ScoreViewer data={SAMPLE_BYTES} />);
+
+    expect(await screen.findByText("Page 1 of 3")).toBeInTheDocument();
+    const previousButton = screen.getByRole("button", { name: "Previous page" });
+    const nextButton = screen.getByRole("button", { name: "Next page" });
+    expect(previousButton).toBeDisabled();
+
+    fireEvent.click(nextButton);
+    expect(screen.getByText("Page 2 of 3")).toBeInTheDocument();
+
+    fireEvent.click(nextButton);
+    expect(screen.getByText("Page 3 of 3")).toBeInTheDocument();
+    expect(nextButton).toBeDisabled();
+
+    await waitFor(() => {
+      expect(doc.getPage).toHaveBeenCalledWith(3);
+    });
+
+    fireEvent.click(previousButton);
+    expect(screen.getByText("Page 2 of 3")).toBeInTheDocument();
+    await waitFor(() => {
+      expect(doc.getPage).toHaveBeenCalledWith(2);
+    });
+  });
+
+  it("zooms in and out with clamping and returns to fit-width", async () => {
+    const { doc, page } = createFakeDocument(1);
+    mockLoadTaskOnce(Promise.resolve(doc));
+
+    render(<ScoreViewer data={SAMPLE_BYTES} />);
+
+    expect(await screen.findByText("Page 1 of 1")).toBeInTheDocument();
+    const zoomInButton = screen.getByRole("button", { name: "Zoom in" });
+    const zoomOutButton = screen.getByRole("button", { name: "Zoom out" });
+    const fitWidthButton = screen.getByRole("button", { name: "Fit width" });
+    expect(fitWidthButton).toHaveAttribute("aria-pressed", "true");
+
+    fireEvent.click(zoomInButton);
+    expect(fitWidthButton).toHaveAttribute("aria-pressed", "false");
+    await waitFor(() => {
+      expect(page.getViewport).toHaveBeenCalledWith({ scale: 1.25 });
+    });
+
+    for (let clicks = 0; clicks < 8; clicks += 1) {
+      fireEvent.click(zoomInButton);
+    }
+    await waitFor(() => {
+      expect(page.getViewport).toHaveBeenCalledWith({ scale: 4 });
+    });
+
+    for (let clicks = 0; clicks < 12; clicks += 1) {
+      fireEvent.click(zoomOutButton);
+    }
+    await waitFor(() => {
+      expect(page.getViewport).toHaveBeenCalledWith({ scale: 0.5 });
+    });
+
+    fireEvent.click(fitWidthButton);
+    expect(fitWidthButton).toHaveAttribute("aria-pressed", "true");
+  });
+
+  it("re-renders at fit-width scale when the container resizes", async () => {
+    let resizeCallback: ResizeObserverCallback | null = null;
+    class FakeResizeObserver {
+      constructor(callback: ResizeObserverCallback) {
+        resizeCallback = callback;
+      }
+      observe() {}
+      unobserve() {}
+      disconnect() {}
+    }
+    vi.stubGlobal("ResizeObserver", FakeResizeObserver);
+
+    const { doc, page } = createFakeDocument(1);
+    mockLoadTaskOnce(Promise.resolve(doc));
+
+    render(<ScoreViewer data={SAMPLE_BYTES} />);
+
+    expect(await screen.findByText("Page 1 of 1")).toBeInTheDocument();
+
+    act(() => {
+      resizeCallback?.(
+        [{ contentRect: { width: 300 } } as ResizeObserverEntry],
+        {} as ResizeObserver
+      );
+    });
+
+    await waitFor(() => {
+      expect(page.getViewport).toHaveBeenCalledWith({ scale: 0.5 });
+    });
+  });
+
+  it("keeps the READY layout when a page render is cancelled mid-flight", async () => {
+    const renderFailure = Promise.reject(new Error("Rendering cancelled"));
+    renderFailure.catch(() => undefined);
+    const page = createFakePage(renderFailure);
+    const { doc } = createFakeDocument(1, page);
+    mockLoadTaskOnce(Promise.resolve(doc));
+
+    render(<ScoreViewer data={SAMPLE_BYTES} />);
+
+    expect(await screen.findByText("Page 1 of 1")).toBeInTheDocument();
+    await waitFor(() => {
+      expect(page.render).toHaveBeenCalled();
+    });
+    expect(screen.getByText("Page 1 of 1")).toBeInTheDocument();
+  });
+
+  it("keeps the READY layout when fetching a page fails after load", async () => {
+    const doc = {
+      numPages: 1,
+      getPage: vi.fn(() => Promise.reject(new Error("destroyed")))
+    } as unknown as PDFDocumentProxy;
+    mockLoadTaskOnce(Promise.resolve(doc));
+
+    render(<ScoreViewer data={SAMPLE_BYTES} />);
+
+    expect(await screen.findByText("Page 1 of 1")).toBeInTheDocument();
+    await waitFor(() => {
+      expect(doc.getPage).toHaveBeenCalled();
+    });
+    expect(screen.getByText("Page 1 of 1")).toBeInTheDocument();
+  });
+
+  it("destroys the loading task on unmount and ignores late results", async () => {
+    const deferred = createDeferred<PDFDocumentProxy>();
+    const { destroy } = mockLoadTaskOnce(deferred.promise, () =>
+      Promise.reject(new Error("already destroyed"))
+    );
+    const onStatusChange = vi.fn();
+
+    const { unmount } = render(
+      <ScoreViewer data={SAMPLE_BYTES} onStatusChange={onStatusChange} />
+    );
+    unmount();
+
+    expect(destroy).toHaveBeenCalledTimes(1);
+
+    const { doc } = createFakeDocument(1);
+    await act(async () => {
+      deferred.resolve(doc);
+    });
+    expect(onStatusChange).not.toHaveBeenCalledWith("READY");
+  });
+
+  it("ignores a late failure after unmount", async () => {
+    const deferred = createDeferred<PDFDocumentProxy>();
+    mockLoadTaskOnce(deferred.promise);
+    const onStatusChange = vi.fn();
+
+    const { unmount } = render(
+      <ScoreViewer data={SAMPLE_BYTES} onStatusChange={onStatusChange} />
+    );
+    unmount();
+
+    await act(async () => {
+      deferred.reject(new Error("too late"));
+    });
+    expect(onStatusChange).not.toHaveBeenCalledWith("FAILED");
+  });
+});
diff --git a/apps/desktop/src/features/score/ScoreViewer.tsx b/apps/desktop/src/features/score/ScoreViewer.tsx
new file mode 100644
index 00000000..82692469
--- /dev/null
+++ b/apps/desktop/src/features/score/ScoreViewer.tsx
@@ -0,0 +1,317 @@
+import { useEffect, useMemo, useRef, useState } from "react";
+import type { PDFDocumentProxy, RenderTask } from "pdfjs-dist";
+import {
+  AlertCircle,
+  ChevronLeft,
+  ChevronRight,
+  FileMusic,
+  Loader2,
+  MoveHorizontal,
+  RotateCw,
+  ZoomIn,
+  ZoomOut,
+} from "lucide-react";
+import { createTranslator, detectPreferredLocale } from "../../i18n";
+import { Button } from "@/components/ui/button";
+import { Card, CardContent } from "@/components/ui/card";
+import { loadScorePdf } from "./pdfjs";
+
+/** Viewer lifecycle states following the clearfolio LOADING/FAILED/READY contract. */
+export type ScoreViewerStatus = "LOADING" | "FAILED" | "READY";
+
+/** Props accepted by the score PDF viewer. */
+export interface ScoreViewerProps {
+  /**
+   * Validated score PDF bytes to display, or `null` when no score is
+   * attached. Following the validated-resource-only rule the viewer never
+   * loads arbitrary URLs; callers (PR3 wires Tauri `read_score_pdf`) must
+   * hand it bytes they already validated.
+   */
+  data: Uint8Array | null;
+  /** Optional display name of the attached score file. */
+  fileName?: string;
+  /** Optional observer notified on every LOADING/FAILED/READY transition. */
+  onStatusChange?: (status: ScoreViewerStatus) => void;
+}
+
+const ZOOM_STEP = 1.25;
+const MIN_ZOOM = 0.5;
+const MAX_ZOOM = 4;
+
+/**
+ * Render a score PDF from validated in-memory bytes with pdf.js.
+ *
+ * Implements the clearfolio viewer state machine (LOADING spinner, FAILED
+ * error with retry, READY canvas) plus rehearsal-friendly page navigation
+ * and zoom in/out/fit-width controls.
+ */
+export function ScoreViewer({ data, fileName, onStatusChange }: ScoreViewerProps) {
+  const t = useMemo(() => createTranslator(detectPreferredLocale()), []);
+  const [status, setStatus] = useState<ScoreViewerStatus>("LOADING");
+  const [errorMessage, setErrorMessage] = useState<string | null>(null);
+  const [pdfDocument, setPdfDocument] = useState<PDFDocumentProxy | null>(null);
+  const [pageNumber, setPageNumber] = useState(1);
+  const [pageCount, setPageCount] = useState(0);
+  const [zoom, setZoom] = useState(1);
+  const [fitWidth, setFitWidth] = useState(true);
+  const [containerWidth, setContainerWidth] = useState(0);
+  const [retryToken, setRetryToken] = useState(0);
+  const canvasRef = useRef<HTMLCanvasElement | null>(null);
+  const containerRef = useRef<HTMLDivElement | null>(null);
+
+  useEffect(() => {
+    if (data !== null) {
+      onStatusChange?.(status);
+    }
+  }, [data, status, onStatusChange]);
+
+  useEffect(() => {
+    if (data === null) {
+      return;
+    }
+
+    let cancelled = false;
+    setStatus("LOADING");
+    setErrorMessage(null);
+    setPdfDocument(null);
+
+    const loadingTask = loadScorePdf(data);
+    loadingTask.promise
+      .then((loadedDocument) => {
+        if (cancelled) {
+          return;
+        }
+        setPdfDocument(loadedDocument);
+        setPageCount(loadedDocument.numPages);
+        setPageNumber(1);
+        setStatus("READY");
+      })
+      .catch((error: unknown) => {
+        if (cancelled) {
+          return;
+        }
+        setErrorMessage(error instanceof Error ? error.message : String(error));
+        setStatus("FAILED");
+      });
+
+    return () => {
+      cancelled = true;
+      void loadingTask.destroy().catch(() => undefined);
+    };
+  }, [data, retryToken]);
+
+  useEffect(() => {
+    const container = containerRef.current;
+    if (status !== "READY" || !container || typeof ResizeObserver === "undefined") {
+      return;
+    }
+
+    const observer = new ResizeObserver((entries) => {
+      for (const entry of entries) {
+        setContainerWidth(entry.contentRect.width);
+      }
+    });
+    observer.observe(container);
+    return () => observer.disconnect();
+  }, [status]);
+
+  useEffect(() => {
+    const canvas = canvasRef.current;
+    if (status !== "READY" || !pdfDocument || !canvas) {
+      return;
+    }
+
+    let cancelled = false;
+    let renderTask: RenderTask | null = null;
+
+    pdfDocument
+      .getPage(pageNumber)
+      .then((page) => {
+        if (cancelled) {
+          return;
+        }
+        const baseViewport = page.getViewport({ scale: 1 });
+        const scale =
+          fitWidth && containerWidth > 0 ? containerWidth / baseViewport.width : zoom;
+        const viewport = page.getViewport({ scale });
+        canvas.width = Math.floor(viewport.width);
+        canvas.height = Math.floor(viewport.height);
+        renderTask = page.render({ canvas, viewport });
+        renderTask.promise.catch(() => {
+          // Cancelled renders (rapid page/zoom changes) are expected.
+        });
+      })
+      .catch(() => {
+        // The document was destroyed mid-flight; the load effect owns errors.
+      });
+
+    return () => {
+      cancelled = true;
+      renderTask?.cancel();
+    };
+  }, [status, pdfDocument, pageNumber, zoom, fitWidth, containerWidth]);
+
+  /** Move to the previous page, clamped at the first page. */
+  const goToPreviousPage = () => {
+    setPageNumber((current) => Math.max(1, current - 1));
+  };
+
+  /** Move to the next page, clamped at the last page. */
+  const goToNextPage = () => {
+    setPageNumber((current) => Math.min(pageCount, current + 1));
+  };
+
+  /** Switch to manual zoom and enlarge, clamped at the maximum scale. */
+  const zoomIn = () => {
+    setFitWidth(false);
+    setZoom((current) => Math.min(MAX_ZOOM, current * ZOOM_STEP));
+  };
+
+  /** Switch to manual zoom and shrink, clamped at the minimum scale. */
+  const zoomOut = () => {
+    setFitWidth(false);
+    setZoom((current) => Math.max(MIN_ZOOM, current / ZOOM_STEP));
+  };
+
+  /** Re-enable fit-width so the page tracks the container size. */
+  const fitToWidth = () => {
+    setFitWidth(true);
+  };
+
+  /** Re-run the load state machine with the same validated bytes. */
+  const retry = () => {
+    setRetryToken((current) => current + 1);
+  };
+
+  if (data === null) {
+    return (
+      <Card className="border-2 border-dashed border-cyan-300/20 bg-slate-950/50 backdrop-blur-xl">
+        <CardContent className="flex flex-col items-center justify-center py-16 text-center">
+          <div className="mb-4 rounded-full border border-cyan-300/30 bg-cyan-300/10 p-4 text-cyan-200">
+            <FileMusic className="size-8" aria-hidden="true" />
+          </div>
+          <p className="max-w-sm text-slate-400">{t("scoreViewerEmpty")}</p>
+        </CardContent>
+      </Card>
+    );
+  }
+
+  if (status === "LOADING") {
+    return (
+      <Card
+        className="border-cyan-300/20 bg-slate-950/75 backdrop-blur-xl"
+        role="status"
+        aria-live="polite"
+        aria-busy="true"
+      >
+        <CardContent className="flex flex-col items-center justify-center py-16 text-center">
+          <Loader2 className="mb-4 size-10 animate-spin text-cyan-300" aria-hidden="true" />
+          <p className="animate-pulse text-slate-400">{t("scoreViewerLoading")}</p>
+        </CardContent>
+      </Card>
+    );
+  }
+
+  if (status === "FAILED") {
+    return (
+      <Card
+        className="border-rose-300/30 bg-rose-950/40 backdrop-blur-xl"
+        role="alert"
+        aria-live="assertive"
+      >
+        <CardContent className="flex flex-col items-center justify-center py-14 text-center">
+          <div className="mb-4 rounded-full border border-rose-300/30 bg-rose-300/10 p-4 text-rose-200">
+            <AlertCircle className="size-8" aria-hidden="true" />
+          </div>
+          <h3 className="mb-2 text-lg font-black text-rose-100">{t("scoreViewerFailedTitle")}</h3>
+          {errorMessage && (
+            <p className="mb-4 rounded-md bg-rose-300/10 px-4 py-2 text-sm font-medium text-rose-100">
+              {errorMessage}
+            </p>
+          )}
+          <Button variant="outline" className="h-12 min-w-32 text-base" onClick={retry}>
+            <RotateCw aria-hidden="true" />
+            {t("scoreViewerRetry")}
+          </Button>
+        </CardContent>
+      </Card>
+    );
+  }
+
+  const pageIndicator = t("scoreViewerPageIndicator")
+    .replace("{current}", String(pageNumber))
+    .replace("{total}", String(pageCount));
+
+  return (
+    <Card className="border-cyan-300/20 bg-slate-950/75 backdrop-blur-xl">
+      <CardContent className="flex flex-col gap-4">
+        <div className="flex flex-wrap items-center justify-between gap-3">
+          {fileName && (
+            <div className="flex min-w-0 items-center text-sm font-semibold text-slate-200">
+              <FileMusic className="mr-2 size-4 shrink-0 text-cyan-300" aria-hidden="true" />
+              <span className="truncate">{fileName}</span>
+            </div>
+          )}
+          <div className="flex flex-wrap items-center gap-2">
+            <Button
+              variant="outline"
+              size="icon-lg"
+              className="size-12"
+              aria-label={t("scoreViewerZoomOut")}
+              onClick={zoomOut}
+            >
+              <ZoomOut aria-hidden="true" />
+            </Button>
+            <Button
+              variant="outline"
+              size="icon-lg"
+              className="size-12"
+              aria-label={t("scoreViewerZoomIn")}
+              onClick={zoomIn}
+            >
+              <ZoomIn aria-hidden="true" />
+            </Button>
+            <Button
+              variant={fitWidth ? "secondary" : "outline"}
+              className="h-12 px-4 text-base"
+              aria-label={t("scoreViewerFitWidth")}
+              aria-pressed={fitWidth}
+              onClick={fitToWidth}
+            >
+              <MoveHorizontal aria-hidden="true" />
+              {t("scoreViewerFitWidth")}
+            </Button>
+          </div>
+        </div>
+        <div ref={containerRef} className="overflow-auto rounded-lg border border-white/10 bg-slate-900/60">
+          <canvas ref={canvasRef} className="mx-auto block max-w-none" />
+        </div>
+        <div className="flex items-center justify-center gap-4">
+          <Button
+            variant="outline"
+            size="icon-lg"
+            className="size-14"
+            aria-label={t("scoreViewerPrevPage")}
+            disabled={pageNumber <= 1}
+            onClick={goToPreviousPage}
+          >
+            <ChevronLeft className="size-6" aria-hidden="true" />
+          </Button>
+          <span className="min-w-28 text-center text-sm font-semibold text-slate-200">
+            {pageIndicator}
+          </span>
+          <Button
+            variant="outline"
+            size="icon-lg"
+            className="size-14"
+            aria-label={t("scoreViewerNextPage")}
+            disabled={pageNumber >= pageCount}
+            onClick={goToNextPage}
+          >
+            <ChevronRight className="size-6" aria-hidden="true" />
+          </Button>
+        </div>
+      </CardContent>
+    </Card>
+  );
+}
diff --git a/apps/desktop/src/features/score/pdfjs.ts b/apps/desktop/src/features/score/pdfjs.ts
new file mode 100644
index 00000000..b62526c8
--- /dev/null
+++ b/apps/desktop/src/features/score/pdfjs.ts
@@ -0,0 +1,29 @@
+import { getDocument, GlobalWorkerOptions, type PDFDocumentLoadingTask } from "pdfjs-dist";
+import scorePdfWorkerUrl from "pdfjs-dist/build/pdf.worker.min.mjs?url";
+
+/**
+ * Point pdf.js at the locally bundled worker asset.
+ *
+ * The worker URL is resolved by Vite from the pinned `pdfjs-dist` package at
+ * build time and emitted as a same-origin asset, so it satisfies the Tauri
+ * `script-src 'self'` Content Security Policy. No CDN or remote script is
+ * ever referenced.
+ */
+export function configureScorePdfWorker(): void {
+  if (GlobalWorkerOptions.workerSrc !== scorePdfWorkerUrl) {
+    GlobalWorkerOptions.workerSrc = scorePdfWorkerUrl;
+  }
+}
+
+/**
+ * Start parsing validated in-memory score PDF bytes with pdf.js.
+ *
+ * Only caller-provided bytes are accepted (validated-resource-only rule);
+ * this helper never fetches arbitrary URLs. The bytes are copied before they
+ * are handed to pdf.js because pdf.js transfers the underlying buffer to its
+ * worker, which would otherwise detach the caller's copy and break retries.
+ */
+export function loadScorePdf(data: Uint8Array): PDFDocumentLoadingTask {
+  configureScorePdfWorker();
+  return getDocument({ data: new Uint8Array(data) });
+}
diff --git a/apps/desktop/src/locales/en/common.json b/apps/desktop/src/locales/en/common.json
index 4e098662..0366dd0e 100644
--- a/apps/desktop/src/locales/en/common.json
+++ b/apps/desktop/src/locales/en/common.json
@@ -62,6 +62,16 @@
   "roleSwitcherTitle": "Role-specific View",
   "allRoles": "All Roles",
   "overlapWarning": "Clash warning",
+  "scoreViewerEmpty": "No score PDF attached. Attach a validated score PDF to view it here.",
+  "scoreViewerLoading": "Loading score PDF...",
+  "scoreViewerFailedTitle": "Could not display the score",
+  "scoreViewerRetry": "Retry",
+  "scoreViewerPrevPage": "Previous page",
+  "scoreViewerNextPage": "Next page",
+  "scoreViewerPageIndicator": "Page {current} of {total}",
+  "scoreViewerZoomIn": "Zoom in",
+  "scoreViewerZoomOut": "Zoom out",
+  "scoreViewerFitWidth": "Fit width",
   "youtubePlaceholder": "YouTube URL...",
   "importYoutube": "Import YouTube",
   "importingYoutube": "Importing...",
diff --git a/apps/desktop/src/locales/ko/common.json b/apps/desktop/src/locales/ko/common.json
index 2b59d5ee..a2725e62 100644
--- a/apps/desktop/src/locales/ko/common.json
+++ b/apps/desktop/src/locales/ko/common.json
@@ -62,6 +62,16 @@
   "roleSwitcherTitle": "악기/보컬 역할",
   "allRoles": "전체 보기",
   "overlapWarning": "충돌 주의",
+  "scoreViewerEmpty": "첨부된 악보 PDF가 없습니다. 검증된 악보 PDF를 첨부하면 여기에 표시됩니다.",
+  "scoreViewerLoading": "악보 PDF를 불러오는 중...",
+  "scoreViewerFailedTitle": "악보를 표시할 수 없습니다",
+  "scoreViewerRetry": "다시 시도",
+  "scoreViewerPrevPage": "이전 페이지",
+  "scoreViewerNextPage": "다음 페이지",
+  "scoreViewerPageIndicator": "{total}페이지 중 {current}페이지",
+  "scoreViewerZoomIn": "확대",
+  "scoreViewerZoomOut": "축소",
+  "scoreViewerFitWidth": "폭 맞춤",
   "youtubePlaceholder": "유튜브 URL...",
   "importYoutube": "유튜브 가져오기",
   "importingYoutube": "가져오는 중...",
diff --git a/apps/desktop/vite.config.ts b/apps/desktop/vite.config.ts
index 45902137..6cd70a20 100644
--- a/apps/desktop/vite.config.ts
+++ b/apps/desktop/vite.config.ts
@@ -19,7 +19,12 @@ export default defineConfig({
     setupFiles: ["./src/setupTests.ts"],
     coverage: {
       provider: "v8",
-      include: ["src/App.tsx", "src/lib/export.ts", "src/i18n/index.ts"],
+      include: [
+        "src/App.tsx",
+        "src/lib/export.ts",
+        "src/i18n/index.ts",
+        "src/features/score/ScoreViewer.tsx"
+      ],
       thresholds: {
         lines: 90,
         functions: 90,
diff --git a/package-lock.json b/package-lock.json
index 8a479475..f22ce9aa 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -32,6 +32,7 @@
         "class-variance-authority": "^0.7.1",
         "clsx": "^2.1.1",
         "lucide-react": "^1.20.0",
+        "pdfjs-dist": "6.1.200",
         "react": "^19.2.4",
         "react-dom": "^19.2.7",
         "tailwind-merge": "^3.6.0",
@@ -1018,6 +1019,256 @@
         "@jridgewell/sourcemap-codec": "^1.4.14"
       }
     },
+    "node_modules/@napi-rs/canvas": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas/-/canvas-1.0.2.tgz",
+      "integrity": "sha512-EYEqlMYaCbpZDz+IgDH5xp9MTd3ui4dmGqbQYryhMLnSRxrhHKq5KQWHHKxFUcEP4Hp8/BWgvqXocX4j7iSbOQ==",
+      "license": "MIT",
+      "optional": true,
+      "workspaces": [
+        "e2e/*"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      },
+      "optionalDependencies": {
+        "@napi-rs/canvas-android-arm64": "1.0.2",
+        "@napi-rs/canvas-darwin-arm64": "1.0.2",
+        "@napi-rs/canvas-darwin-x64": "1.0.2",
+        "@napi-rs/canvas-linux-arm-gnueabihf": "1.0.2",
+        "@napi-rs/canvas-linux-arm64-gnu": "1.0.2",
+        "@napi-rs/canvas-linux-arm64-musl": "1.0.2",
+        "@napi-rs/canvas-linux-riscv64-gnu": "1.0.2",
+        "@napi-rs/canvas-linux-x64-gnu": "1.0.2",
+        "@napi-rs/canvas-linux-x64-musl": "1.0.2",
+        "@napi-rs/canvas-win32-arm64-msvc": "1.0.2",
+        "@napi-rs/canvas-win32-x64-msvc": "1.0.2"
+      }
+    },
+    "node_modules/@napi-rs/canvas-android-arm64": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-android-arm64/-/canvas-android-arm64-1.0.2.tgz",
+      "integrity": "sha512-IMXKVQod0ol4vt3gmClUfXz4JAgHYESGPCUqmH3lQxBoL0K/2greJaQE1HVBVxWWFKfLc4OLZVdxg7kXVyXv+g==",
+      "cpu": [
+        "arm64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "android"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
+    "node_modules/@napi-rs/canvas-darwin-arm64": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-darwin-arm64/-/canvas-darwin-arm64-1.0.2.tgz",
+      "integrity": "sha512-Sc8tPi6cF+5lqOzCCKFALJHhDiRwyMzTPYm3bbhdXsOunU0lQO5f05ucyOzN2r55I23Hg5bsjH63uSCvWp3EgQ==",
+      "cpu": [
+        "arm64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
+    "node_modules/@napi-rs/canvas-darwin-x64": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-darwin-x64/-/canvas-darwin-x64-1.0.2.tgz",
+      "integrity": "sha512-niDXZ9LhKB1zLrUdYB64RHQFDGz9rr0eGx061qtJJU3U20EMMIx28ADF5fVYbhtOgkWQrBjFicfaye1yM0U62A==",
+      "cpu": [
+        "x64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
+    "node_modules/@napi-rs/canvas-linux-arm-gnueabihf": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-linux-arm-gnueabihf/-/canvas-linux-arm-gnueabihf-1.0.2.tgz",
+      "integrity": "sha512-sgatQL9JxGRH/Amzcvu0P3t8Am3duou74CisfuJ41Dwt8cWy723z/9KZ8LlgmxfypEwEZxSTNFJtU8d281lmhQ==",
+      "cpu": [
+        "arm"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
+    "node_modules/@napi-rs/canvas-linux-arm64-gnu": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-linux-arm64-gnu/-/canvas-linux-arm64-gnu-1.0.2.tgz",
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+      "cpu": [
+        "arm64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
+    "node_modules/@napi-rs/canvas-linux-arm64-musl": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-linux-arm64-musl/-/canvas-linux-arm64-musl-1.0.2.tgz",
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+      "cpu": [
+        "arm64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
+    "node_modules/@napi-rs/canvas-linux-riscv64-gnu": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-linux-riscv64-gnu/-/canvas-linux-riscv64-gnu-1.0.2.tgz",
+      "integrity": "sha512-fXRjnPihdnbO6qy1QQOgxAonb68A0TCEG7rj1x7v7rxNElsE8EVIKIEUTvyDtU+sthYSbX+8e7g3oZiLGnOmxw==",
+      "cpu": [
+        "riscv64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
+    "node_modules/@napi-rs/canvas-linux-x64-gnu": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-linux-x64-gnu/-/canvas-linux-x64-gnu-1.0.2.tgz",
+      "integrity": "sha512-nPR97DXhbWIAy7yazF3jc06kEPMqYMLmPzFOVNlwKPfIoSChnI+x7dc0hTLaihz3jxrjL6j4BbA7earxfx4X3g==",
+      "cpu": [
+        "x64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
+    "node_modules/@napi-rs/canvas-linux-x64-musl": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-linux-x64-musl/-/canvas-linux-x64-musl-1.0.2.tgz",
+      "integrity": "sha512-l7zZY5+jL5qnBZtDz7CoBtY6p7EkHu422g/0zWwrOrzIwWyWxZFRfZZORY1UG7YApymPLx+UbOkN206xXn/c1Q==",
+      "cpu": [
+        "x64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
+    "node_modules/@napi-rs/canvas-win32-arm64-msvc": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-win32-arm64-msvc/-/canvas-win32-arm64-msvc-1.0.2.tgz",
+      "integrity": "sha512-yE0koHCFF4PIbMc2o2SEALhnipz7WBISh5glLvQiomtIoCcW0np3H4Lw93ceJAfJttTTeIIWFbwH84F7EVzjMQ==",
+      "cpu": [
+        "arm64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "win32"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
+    "node_modules/@napi-rs/canvas-win32-x64-msvc": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/@napi-rs/canvas-win32-x64-msvc/-/canvas-win32-x64-msvc-1.0.2.tgz",
+      "integrity": "sha512-okU8/t2foV6C31n0GtvEMbfD5rOFc70+/6xUNME9Guld29sgSOIGUEDScAWFlcP3k5TYQRl9TNkwJEEjh15w8A==",
+      "cpu": [
+        "x64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "win32"
+      ],
+      "engines": {
+        "node": ">= 10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Brooooooklyn"
+      }
+    },
     "node_modules/@napi-rs/wasm-runtime": {
       "version": "1.1.4",
       "resolved": "https://registry.npmjs.org/@napi-rs/wasm-runtime/-/wasm-runtime-1.1.4.tgz",
@@ -1140,9 +1391,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1160,9 +1408,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1180,9 +1425,6 @@
         "ppc64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1200,9 +1442,6 @@
         "s390x"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1220,9 +1459,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1240,9 +1476,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1482,9 +1715,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1502,9 +1732,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1522,9 +1749,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1542,9 +1766,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3850,6 +4071,18 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/pdfjs-dist": {
+      "version": "6.1.200",
+      "resolved": "https://registry.npmjs.org/pdfjs-dist/-/pdfjs-dist-6.1.200.tgz",
+      "integrity": "sha512-o8MolyzirkkLrcdsae/HEOiIcXWI7DS5zGpvqW8xTC2YUsW30rltFw2bDGvw/fskUdEMrQm2br68jzDS5BH2vw==",
+      "license": "Apache-2.0",
+      "engines": {
+        "node": ">=22.13.0 || >=24"
+      },
+      "optionalDependencies": {
+        "@napi-rs/canvas": "^1.0.0"
+      }
+    },
     "node_modules/picocolors": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",