The happy path for vision in .NET is short now. With Microsoft.Extensions.AI , an image is just another content part on a ChatMessage , and any vision-capable IChatClient can take it. You can have a receipt reader working in an afternoon.

Then it meets real users. Someone uploads a 9 MB phone photo, someone else sends a GIF, a phone labels its JPEG image/jpg , and someone uploads a picture of their lunch to the receipt endpoint. None of that is the model's problem. It's yours, and it's cheaper to solve before the bytes leave your process.

This post is the list of questions I now answer before any image reaches a model. It comes from a receipt and invoice extraction sample I built on Microsoft.Extensions.AI 10.11 in .NET 10: an input-policy middleware, typed extraction, a multipart minimal API, a CLI, and 25 tests (19 unit, 6 integration) that run offline with no API key. The complete project is in Tech Skill Builder .

Tech Skill Builder is $5/month for a very limited time only (normally $10).…