fix(files): lower xlsx preview row cap to 1k and type workbookRef properly

waleedlatif1 · claude · waleedlatif1 · commit a284499de309 · 2026-04-04T20:58:34.000-07:00
Reduces XLSX_MAX_ROWS from 10,000 to 1,000 to prevent browser sluggishness
on large spreadsheets. Types workbookRef with the proper xlsx.WorkBook
interface instead of unknown, removing the unsafe cast.

Co-Authored-By: Claude Opus 4.6 &lt;noreply@anthropic.com&gt;
diff --git a/apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/file-viewer.tsx b/apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/file-viewer.tsx
@@ -935,7 +935,7 @@ h1, h2, h3, h4, h5, h6 { margin: 16px 0 8px; }
 </style></head><body>${html}</body></html>`
 }
 
-const XLSX_MAX_ROWS = 10_000
+const XLSX_MAX_ROWS = 1_000
 
 interface XlsxSheet {
   name: string
@@ -961,7 +961,7 @@ const XlsxPreview = memo(function XlsxPreview({
   const [activeSheet, setActiveSheet] = useState(0)
   const [currentSheet, setCurrentSheet] = useState<XlsxSheet | null>(null)
   const [renderError, setRenderError] = useState<string | null>(null)
-  const workbookRef = useRef<unknown>(null)
+  const workbookRef = useRef<import('xlsx').WorkBook | null>(null)
 
   useEffect(() => {
     if (!fileData) return
@@ -1002,7 +1002,7 @@ const XlsxPreview = memo(function XlsxPreview({
     async function parseSheet() {
       try {
         const XLSX = await import('xlsx')
-        const workbook = workbookRef.current as ReturnType<typeof XLSX.read>
+        const workbook = workbookRef.current!
         const name = sheetNames[activeSheet]
         const sheet = workbook.Sheets[name]
         const allRows = XLSX.utils.sheet_to_json<string[]>(sheet, { header: 1 })
