From fc814f50262627b2c32c2fcb593969c1d77509d5 Mon Sep 17 00:00:00 2001
From: Davide Scaini <davide.scaini@alumni.cern>
Date: Fri, 24 Apr 2026 23:16:50 +0200
Subject: [PATCH] =?UTF-8?q?fix:=20replace=20Buffer.from().toString('base64?=
 =?UTF-8?q?')=20with=20btoa=20helper=20=E2=80=94=20Buffer=20not=20availabl?=
 =?UTF-8?q?e=20in=20Expo=20RN?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 mobile/app/(tabs)/import.tsx | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/mobile/app/(tabs)/import.tsx b/mobile/app/(tabs)/import.tsx
index beb99dc..abf250b 100644
--- a/mobile/app/(tabs)/import.tsx
+++ b/mobile/app/(tabs)/import.tsx
@@ -228,10 +228,21 @@ async function fetchWheelBase64(instanceUrl: string): Promise<string> {
   const resp = await fetch(wheelUrl);
   if (!resp.ok) throw new Error(`Could not download Bincio engine (${resp.status}). Is the instance running?`);
   const buf = await resp.arrayBuffer();
-  _cachedWheelBase64 = Buffer.from(buf).toString('base64');
+  _cachedWheelBase64 = arrayBufferToBase64(buf);
   return _cachedWheelBase64;
 }
 
+function arrayBufferToBase64(buf: ArrayBuffer): string {
+  const bytes = new Uint8Array(buf);
+  let binary = '';
+  // Process in chunks to avoid spread-operator stack overflow on large arrays.
+  const CHUNK = 8192;
+  for (let i = 0; i < bytes.length; i += CHUNK) {
+    binary += String.fromCharCode(...(bytes.subarray(i, i + CHUNK) as unknown as number[]));
+  }
+  return btoa(binary);
+}
+
 // ── Styles ───────────────────────────────────────────────────────────────────
 
 const styles = StyleSheet.create({