GitHub Copilot trusted a client header for premium-request billing

Follow-up to my previous Copilot/mitmproxy post.

While looking at the traffic I noticed Copilot’s own LLM requests used X-initiator: agent and didn’t consume premium quota. That made me curious what would happen if I changed my own requests from user to agent.

Turns out the model still responded, but those requests didn’t decrement my premium quota or show up in the billing analytics.