diff --git a/apple/macos-helper/Sources/AgentDeviceMacOSHelper/SnapshotTraversal.swift b/apple/macos-helper/Sources/AgentDeviceMacOSHelper/SnapshotTraversal.swift
index 1121eaa7f3..0149e017db 100644
--- a/apple/macos-helper/Sources/AgentDeviceMacOSHelper/SnapshotTraversal.swift
+++ b/apple/macos-helper/Sources/AgentDeviceMacOSHelper/SnapshotTraversal.swift
@@ -795,12 +795,18 @@ func rectAttribute(_ element: AXUIElement) -> RectResponse? {
     return nil
   }
 
-  return RectResponse(
-    x: Double(position.x),
-    y: Double(position.y),
-    width: Double(size.width),
-    height: Double(size.height)
-  )
+  return finiteRectResponse(position: position, size: size)
+}
+
+/// JSONEncoder throws on inf/NaN, which fails the whole snapshot. SwiftUI reports lazy
+/// containers scrolled out of view as an AXOpaqueProviderGroup at (inf, inf, 0, 0).
+func finiteRectResponse(position: CGPoint, size: CGSize) -> RectResponse? {
+  let x = Double(position.x)
+  let y = Double(position.y)
+  let width = Double(size.width)
+  let height = Double(size.height)
+  guard x.isFinite, y.isFinite, width.isFinite, height.isFinite else { return nil }
+  return RectResponse(x: x, y: y, width: width, height: height)
 }
 
 private func accessibilityAxValue(_ value: CFTypeRef?) -> AXValue? {
diff --git a/apple/macos-helper/Tests/AgentDeviceMacOSHelperTests/RectResponseTests.swift b/apple/macos-helper/Tests/AgentDeviceMacOSHelperTests/RectResponseTests.swift
new file mode 100644
index 0000000000..d93d9d05fc
--- /dev/null
+++ b/apple/macos-helper/Tests/AgentDeviceMacOSHelperTests/RectResponseTests.swift
@@ -0,0 +1,21 @@
+import XCTest
+
+@testable import AgentDeviceMacOSHelper
+
+final class RectResponseTests: XCTestCase {
+  func testFiniteRectKeepsItsValues() throws {
+    let rect = try XCTUnwrap(
+      finiteRectResponse(position: CGPoint(x: 1, y: 2), size: CGSize(width: 3, height: 4)))
+    XCTAssertEqual([rect.x, rect.y, rect.width, rect.height], [1, 2, 3, 4])
+  }
+
+  func testNonFiniteComponentYieldsNoRect() {
+    let nonFinite: [CGFloat] = [.infinity, -.infinity, .nan]
+    for value in nonFinite {
+      XCTAssertNil(finiteRectResponse(position: CGPoint(x: value, y: 0), size: .zero))
+      XCTAssertNil(finiteRectResponse(position: CGPoint(x: 0, y: value), size: .zero))
+      XCTAssertNil(finiteRectResponse(position: .zero, size: CGSize(width: value, height: 0)))
+      XCTAssertNil(finiteRectResponse(position: .zero, size: CGSize(width: 0, height: value)))
+    }
+  }
+}