REVERSE ENGINEERING CURSOR'S LLM CLIENT

Summary from the TLDR InfoSec newsletter

In this post, the authors used TensorZero, an open-source framework for optimizing LLM applications with downstream feedback signals, to observe the API calls and tokens sent between Cursor and the LLM providers. They first ran into errors connecting to TensorZero running locally because Cursor first sends a request to Cursor's servers for additional processing, so the authors needed to set up a reverse proxy to expose a public endpoint that would forward requests back to the local machine. They then had to solve for CORS issues. Eventually, they managed to wire Cursor up properly and included sample system prompts and interactions between a user session and what Cursor generates.