From c3f4250442efd2d44feb37aca1a65cc0195d16be Mon Sep 17 00:00:00 2001
From: Vincent Koc <vincentkoc@ieee.org>
Date: Fri, 6 Mar 2026 00:57:57 -0500
Subject: [PATCH] Gateway: guard base64 image size accounting

---
 src/gateway/openai-http.ts | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/gateway/openai-http.ts b/src/gateway/openai-http.ts
index 1f37dfb1fae..8e255d92764 100644
--- a/src/gateway/openai-http.ts
+++ b/src/gateway/openai-http.ts
@@ -300,7 +300,11 @@ async function resolveImagesForRequest(
   for (const url of urls) {
     const source = parseImageUrlToSource(url);
     if (source.type === "base64") {
-      totalBytes += estimateBase64DecodedBytes(source.data);
+      const base64Data = source.data;
+      if (typeof base64Data !== "string") {
+        throw new Error("image_url data URI is missing payload data");
+      }
+      totalBytes += estimateBase64DecodedBytes(base64Data);
       if (totalBytes > limits.maxTotalImageBytes) {
         throw new Error(
           `Total image payload too large (${totalBytes}; limit ${limits.maxTotalImageBytes})`,