diff --git a/packages/coding-agent/src/tools/fetch.ts b/packages/coding-agent/src/tools/fetch.ts
index 4cfed4d67..cbb6548e1 100644
--- a/packages/coding-agent/src/tools/fetch.ts
+++ b/packages/coding-agent/src/tools/fetch.ts
@@ -714,7 +714,7 @@ async function renderUrl(url: string, timeout: number, raw: boolean, signal?: Ab
 				}
 
 				const resized = await resizeImage(
-					{ type: "image", data: binary.buffer.toBase64(), mimeType: imageMimeType },
+					{ type: "image", data: Buffer.from(binary.buffer).toBase64(), mimeType: imageMimeType },
 					{ maxBytes: MAX_INLINE_IMAGE_OUTPUT_BYTES },
 				);
 				const isDecodedImage =
diff --git a/packages/coding-agent/src/utils/image-input.ts b/packages/coding-agent/src/utils/image-input.ts
index 8067e0ac6..e3742e6fc 100644
--- a/packages/coding-agent/src/utils/image-input.ts
+++ b/packages/coding-agent/src/utils/image-input.ts
@@ -231,7 +231,7 @@ export async function loadImageInput(options: LoadImageInputOptions): Promise<Lo
 		throw new ImageInputTooLargeError(inputBuffer.byteLength, maxBytes);
 	}
 
-	let outputData = new Uint8Array(inputBuffer).toBase64();
+	let outputData = Buffer.from(inputBuffer).toBase64();
 	let outputMimeType = mimeType;
 	let outputBytes = inputBuffer.byteLength;
 	let dimensionNote: string | undefined;
diff --git a/packages/coding-agent/src/utils/image-resize.ts b/packages/coding-agent/src/utils/image-resize.ts
index 123d0692a..9b562f3ff 100644
--- a/packages/coding-agent/src/utils/image-resize.ts
+++ b/packages/coding-agent/src/utils/image-resize.ts
@@ -136,7 +136,7 @@ export async function resizeImage(img: ImageContent, options?: ImageResizeOption
 				height: finalHeight,
 				wasResized: true,
 				get data() {
-					return best.buffer.toBase64();
+					return Buffer.from(best.buffer).toBase64();
 				},
 			};
 		}
@@ -155,7 +155,7 @@ export async function resizeImage(img: ImageContent, options?: ImageResizeOption
 					height: finalHeight,
 					wasResized: true,
 					get data() {
-						return best.buffer.toBase64();
+						return Buffer.from(best.buffer).toBase64();
 					},
 				};
 			}
@@ -183,7 +183,7 @@ export async function resizeImage(img: ImageContent, options?: ImageResizeOption
 						height: finalHeight,
 						wasResized: true,
 						get data() {
-							return best.buffer.toBase64();
+							return Buffer.from(best.buffer).toBase64();
 						},
 					};
 				}
@@ -200,7 +200,7 @@ export async function resizeImage(img: ImageContent, options?: ImageResizeOption
 			height: finalHeight,
 			wasResized: true,
 			get data() {
-				return best.buffer.toBase64();
+				return Buffer.from(best.buffer).toBase64();
 			},
 		};
 	} catch {