fix(pdf-server): detached-buffer on range re-request + stale e2e assertion (#561)

* fix(pdf-server): slice bytes before onDataRange to avoid detached buffer

PDF.js transfers the ArrayBuffer to its worker via postMessage, detaching
it in the main thread. When the same range is re-requested (common on
iOS/WKWebView under memory pressure during scroll/zoom/navigate), the
cached Uint8Array now wraps a detached buffer and onDataRange throws
'Buffer is already detached'.

Fix: pass result.bytes.slice() so the rangeCache entry stays valid.

* test(e2e): update pdf-annotations assertion for new display_pdf prompt text

The 91880a6 prompt rewrite changed the interact-enabled result text from
'Displaying PDF (viewUUID: ...)' to 'PDF opened. viewUUID: ...'. The e2e
test was still asserting the old string.

Author: ochafik

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);

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 }) => {