Well this is the thing I'm confused about, having worked on some cloudfront stuff last month, documents like https://docs.aws.amazon.com/AmazonCloudFront/latest

Well this is the thing I'm confused about, having worked on some cloudfront stuff last month, documents like https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/header-caching.html https://docs.aws.amazon.com/AmazonCloudFront/latest/Develope... gave me the clear impression that every header cloudfront passes to the origin will be considered a cache key. In particular if you configure it to "forward all headers", which is what would surely be needed to pass this custom "X-Oversized-Header" onwards, it would effectively disable all caching. I'm clearly going to have to spend another day staring at the cloudfront documentation.