From f5272b84025990932dd47d0748c9a0b96ff8f9c4 Mon Sep 17 00:00:00 2001
From: Ian Paschal <git@ianpaschal.com>
Date: Wed, 26 Aug 2026 07:55:11 +0200
Subject: [PATCH] CC-124: `<PdfViewer/>` State Not Reset on File Change

---
 src/components/PdfViewer/PdfViewer.hooks.ts | 10 ++++++++++
 src/components/PdfViewer/PdfViewer.tsx      |  2 +-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/components/PdfViewer/PdfViewer.hooks.ts b/src/components/PdfViewer/PdfViewer.hooks.ts
index 4a88811..327f956 100644
--- a/src/components/PdfViewer/PdfViewer.hooks.ts
+++ b/src/components/PdfViewer/PdfViewer.hooks.ts
@@ -31,6 +31,7 @@ export const DEFAULT_CONFIG: PdfViewerConfig = {
 };
 
 export const usePdfViewer = (
+  file: string | File | ArrayBuffer | null,
   customConfig?: Partial<PdfViewerConfig>,
 ): UsePdfViewerReturn => {
   const config = {
@@ -39,6 +40,7 @@ export const usePdfViewer = (
   };
   const containerRef = useRef<HTMLDivElement>(null);
   const ref = useRef<HTMLDivElement>(null);
+  const [prevFile, setPrevFile] = useState(file);
   const [numPages, setNumPages] = useState<number | null>(null);
   const [pageNumber, setPageNumber] = useState(config.initialPage);
   const [scale, setScale] = useState(config.initialScale ?? 1);
@@ -46,6 +48,14 @@ export const usePdfViewer = (
   const isScrollingTo = useRef(false);
   const scrollTimeoutRef = useRef<ReturnType<typeof setTimeout>>();
 
+  if (file !== prevFile) {
+    setPrevFile(file);
+    setNumPages(null);
+    setPageNumber(config.initialPage);
+    setScale(config.initialScale ?? 1);
+    pdfPageWidthRef.current = null;
+  }
+
   useEffect(() => () => clearTimeout(scrollTimeoutRef.current), []);
 
   const scrollToPage = useCallback((page: number) => {
diff --git a/src/components/PdfViewer/PdfViewer.tsx b/src/components/PdfViewer/PdfViewer.tsx
index ef2f740..0dca5f9 100644
--- a/src/components/PdfViewer/PdfViewer.tsx
+++ b/src/components/PdfViewer/PdfViewer.tsx
@@ -39,7 +39,7 @@ export const PdfViewer = ({
   if (workerSrc && pdfjs.GlobalWorkerOptions.workerSrc !== workerSrc) {
     pdfjs.GlobalWorkerOptions.workerSrc = workerSrc;
   }
-  const viewer = usePdfViewer(restConfig);
+  const viewer = usePdfViewer(file, restConfig);
   return (
     <div ref={viewer.containerRef} className={clsx(styles.pdfViewer, className)}>
       {(loading || viewer.state.numPages === null) && (