diff --git a/apps/web/src/pages/ReaderPageVerticalRestore.test.ts b/apps/web/src/pages/ReaderPageVerticalRestore.test.ts
index d533831..859fc13 100644
--- a/apps/web/src/pages/ReaderPageVerticalRestore.test.ts
+++ b/apps/web/src/pages/ReaderPageVerticalRestore.test.ts
@@ -1,19 +1,128 @@
-import { readFileSync } from "node:fs";
-import { describe, expect, it } from "vitest";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+type ReaderPageElement = {
+  dataset: { readerPage: string };
+  getBoundingClientRect: () => { top: number; bottom: number };
+  scrollIntoView: ReturnType<typeof vi.fn>;
+};
+
+const runtime = vi.hoisted(() => ({
+  stateIndex: 0,
+  refIndex: 0,
+  states: [] as unknown[],
+  frame: null as { closest: ReturnType<typeof vi.fn>; querySelector: ReturnType<typeof vi.fn> } | null,
+  previousMode: "vertical",
+  effects: [] as Array<() => void | (() => void)>,
+  pageElements: [] as ReaderPageElement[]
+}));
+
+vi.mock("react", async () => {
+  const actual = await vi.importActual<typeof import("react")>("react");
+  return {
+    ...actual,
+    useCallback: (callback: unknown) => callback,
+    useEffect: (effect: () => void | (() => void)) => {
+      runtime.effects.push(effect);
+    },
+    useRef: (initial: unknown) => {
+      if (runtime.refIndex === 0) {
+        runtime.refIndex += 1;
+        return { current: runtime.frame };
+      }
+      runtime.refIndex += 1;
+      return { current: initial };
+    },
+    useState: (initial: unknown) => {
+      const index = runtime.stateIndex;
+      runtime.stateIndex += 1;
+      return [runtime.states[index] ?? initial, vi.fn()];
+    }
+  };
+});
+
+vi.mock("../api/client", () => ({
+  api: {
+    cbzPages: vi.fn().mockResolvedValue({
+      bookId: 39,
+      pageCount: 80,
+      pages: Array.from({ length: 80 }, (_, index) => ({ page: index + 1, name: `page-${index + 1}.jpg` }))
+    }),
+    cbzPageUrl: (bookId: number, page: number) => `/books/${bookId}/pages/${page}`
+  }
+}));
+
+import { CbzReader } from "../reader/CbzReader";
+
+function pageElement(page: number, top: number, height = 1000): ReaderPageElement {
+  return {
+    dataset: { readerPage: String(page) },
+    getBoundingClientRect: () => ({ top, bottom: top + height }),
+    scrollIntoView: vi.fn()
+  };
+}
+
+function runEffects() {
+  for (const effect of runtime.effects) effect();
+}
 
 describe("ReaderPage vertical restore", () => {
-  it("resets the reader page when opening another book so an invalid progression starts at the top", () => {
-    const source = readFileSync(new URL("./ReaderPage.tsx", import.meta.url), "utf8");
-    const bookResetEffect = source.slice(source.indexOf("useEffect(() => {\n    setReaderControls"), source.indexOf("  useEffect(() => {\n    if (book?.format", source.indexOf("useEffect(() => {\n    setReaderControls")));
-
-    expect(bookResetEffect).toContain("setPage(1)");
+  beforeEach(() => {
+    runtime.stateIndex = 0;
+    runtime.refIndex = 0;
+    runtime.effects = [];
+    runtime.pageElements = Array.from({ length: 80 }, (_, index) => pageElement(index + 1, index * 1000));
+    runtime.frame = {
+      closest: vi.fn(() => ({
+        getBoundingClientRect: () => ({ top: 0, bottom: 900 }),
+        addEventListener: vi.fn(),
+        removeEventListener: vi.fn(),
+        querySelectorAll: vi.fn(() => runtime.pageElements)
+      })),
+      querySelector: vi.fn((selector: string) => {
+        const match = selector.match(/\[data-reader-page="(\d+)"\]/);
+        return match ? runtime.pageElements[Number(match[1]) - 1] : null;
+      })
+    };
+    runtime.states = [
+      {
+        bookId: 39,
+        pageCount: 80,
+        pages: Array.from({ length: 80 }, (_, index) => ({ page: index + 1, name: `page-${index + 1}.jpg` }))
+      },
+      undefined,
+      undefined,
+      0,
+      0,
+      { width: 900, height: 900 },
+      null,
+      {}
+    ];
+    vi.stubGlobal("requestAnimationFrame", (callback: FrameRequestCallback) => {
+      callback(0);
+      return 1;
+    });
+    vi.stubGlobal("cancelAnimationFrame", vi.fn());
+    vi.stubGlobal(
+      "ResizeObserver",
+      vi.fn(() => ({
+        observe: vi.fn(),
+        disconnect: vi.fn()
+      }))
+    );
   });
 
-  it("does not restore an unknown vertical scroll anchor to the middle of the book", () => {
-    const source = readFileSync(new URL("./ReaderPage.tsx", import.meta.url), "utf8");
-    const changeZoomBlock = source.slice(source.indexOf("const changeZoom = useCallback"), source.indexOf("  const zoomControls", source.indexOf("const changeZoom = useCallback")));
+  it("anchors the current CBZ/CBR page when the reader opens directly in vertical mode", () => {
+    CbzReader({
+      bookId: 39,
+      page: 40,
+      zoom: 100,
+      mode: "vertical",
+      onPageCommit: vi.fn(),
+      onControlsChange: vi.fn()
+    });
 
-    expect(changeZoomBlock).toContain("scrollRatioY");
-    expect(changeZoomBlock).not.toMatch(/scrollRatioY[\s\S]*:\s*0\.5/);
+    runEffects();
+
+    expect(runtime.pageElements[39].scrollIntoView).toHaveBeenCalledWith({ block: "start" });
   });
 });
diff --git a/apps/web/src/reader/CbzReader.tsx b/apps/web/src/reader/CbzReader.tsx
index c1c33a7..dcb639e 100644
--- a/apps/web/src/reader/CbzReader.tsx
+++ b/apps/web/src/reader/CbzReader.tsx
@@ -23,7 +23,8 @@ export function CbzReader({
   onControlsChange: (controls: ReaderControls) => void;
 }) {
   const frameRef = useRef<HTMLDivElement>(null);
-  const previousModeRef = useRef<ReaderMode>(mode);
+  const previousModeRef = useRef<ReaderMode | null>(null);
+  const pendingVerticalAnchorRef = useRef(false);
   const [pages, setPages] = useState<CbzPagesDto | null>(null);
   const [documentError, setDocumentError] = useState<string>();
   const [pageError, setPageError] = useState<string>();
@@ -124,15 +125,23 @@ export function CbzReader({
   useEffect(() => {
     if (mode !== "vertical") {
       previousModeRef.current = mode;
+      pendingVerticalAnchorRef.current = false;
       return;
     }
-    if (previousModeRef.current !== "vertical") {
+    if (previousModeRef.current !== "vertical") pendingVerticalAnchorRef.current = true;
+    if (pendingVerticalAnchorRef.current) {
+      const target = frameRef.current?.querySelector<HTMLElement>(`[data-reader-page="${currentPage}"]`);
+      if (!target) {
+        previousModeRef.current = mode;
+        return;
+      }
+      pendingVerticalAnchorRef.current = false;
       requestAnimationFrame(() => {
-        frameRef.current?.querySelector<HTMLElement>(`[data-reader-page="${currentPage}"]`)?.scrollIntoView({ block: "start" });
+        target.scrollIntoView({ block: "start" });
       });
     }
     previousModeRef.current = mode;
-  }, [currentPage, mode]);
+  }, [currentPage, mode, pages]);
 
   useEffect(() => {
     if (mode !== "vertical" || !pages) return;
diff --git a/apps/web/src/reader/PdfReader.tsx b/apps/web/src/reader/PdfReader.tsx
index ec62213..07bea01 100644
--- a/apps/web/src/reader/PdfReader.tsx
+++ b/apps/web/src/reader/PdfReader.tsx
@@ -149,7 +149,8 @@ function PdfPageCanvas({
 export function PdfReader({ url, page, backHref, zoom, mode, onPageCommit, onControlsChange }: PdfReaderProps) {
   const frameRef = useRef<HTMLDivElement>(null);
   const canvasRef = useRef<HTMLCanvasElement>(null);
-  const previousModeRef = useRef<ReaderMode>(mode);
+  const previousModeRef = useRef<ReaderMode | null>(null);
+  const pendingVerticalAnchorRef = useRef(false);
   const [documentProxy, setDocumentProxy] = useState<pdfjs.PDFDocumentProxy | null>(null);
   const [pages, setPages] = useState(1);
   const [documentError, setDocumentError] = useState<PdfFailure>();
@@ -190,15 +191,23 @@ export function PdfReader({ url, page, backHref, zoom, mode, onPageCommit, onCon
   useEffect(() => {
     if (mode !== "vertical") {
       previousModeRef.current = mode;
+      pendingVerticalAnchorRef.current = false;
       return;
     }
-    if (previousModeRef.current !== "vertical") {
+    if (previousModeRef.current !== "vertical") pendingVerticalAnchorRef.current = true;
+    if (pendingVerticalAnchorRef.current) {
+      const target = frameRef.current?.querySelector<HTMLElement>(`[data-reader-page="${currentPage}"]`);
+      if (!target) {
+        previousModeRef.current = mode;
+        return;
+      }
+      pendingVerticalAnchorRef.current = false;
       requestAnimationFrame(() => {
-        frameRef.current?.querySelector<HTMLElement>(`[data-reader-page="${currentPage}"]`)?.scrollIntoView({ block: "start" });
+        target.scrollIntoView({ block: "start" });
       });
     }
     previousModeRef.current = mode;
-  }, [currentPage, mode]);
+  }, [currentPage, documentProxy, mode]);
 
   useEffect(() => {
     if (mode !== "vertical") return;