diff --git a/examples/pdf-server/src/mcp-app.ts b/examples/pdf-server/src/mcp-app.ts
index c8281c03..6a59407c 100644
--- a/examples/pdf-server/src/mcp-app.ts
+++ b/examples/pdf-server/src/mcp-app.ts
@@ -3875,7 +3875,11 @@ async function loadPdfProgressively(urlToLoad: string): Promise<{
     requestDataRange(begin: number, end: number) {
       fetchRange(urlToLoad, begin, end)
         .then((result) => {
-          this.onDataRange(begin, result.bytes);
+          // PDF.js transfers the ArrayBuffer to its worker, detaching it.
+          // Pass a copy so the rangeCache entry stays valid for re-requests
+          // (iOS/WKWebView re-requests ranges under memory pressure and
+          // throws "Buffer is already detached" on the cached original).
+          this.onDataRange(begin, result.bytes.slice());
         })
         .catch((err: unknown) => {
           log.error(`Error fetching range ${begin}-${end}:`, err);
diff --git a/tests/e2e/pdf-annotations.spec.ts b/tests/e2e/pdf-annotations.spec.ts
index 8008f559..9d4ab958 100644
--- a/tests/e2e/pdf-annotations.spec.ts
+++ b/tests/e2e/pdf-annotations.spec.ts
@@ -50,7 +50,7 @@ async function extractViewUUID(page: Page): Promise<string> {
   const resultText = (await resultContent.textContent()) ?? "";
 
   // Extract viewUUID from the JSON result
-  // The text content includes: "Displaying PDF (viewUUID: <uuid>): ..."
+  // The text content includes: "PDF opened. viewUUID: <uuid>"
   const match = resultText.match(/viewUUID["\s:]+([a-f0-9-]{36})/);
   if (!match) {
     throw new Error(
@@ -107,7 +107,7 @@ test.describe("PDF Server - Annotations", () => {
     // (interact action list lives in the tool description, not the runtime result).
     expect(resultText).toContain("viewUUID");
     expect(resultText).toContain("interactEnabled");
-    expect(resultText).toContain("Displaying PDF");
+    expect(resultText).toContain("PDF opened");
   });
 
   test("interact tool is available in tool dropdown", async ({ page }) => {