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

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* 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 91880a6d 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.
This commit is contained in:
Olivier Chafik 2026-03-23 20:17:25 +00:00 • committed by GitHub
commit e8a4ea5f89
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1 changed files with 7 additions and 3 deletions
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6
examples/pdf-server/src/mcp-app.ts
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@ -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);