Every time I submit a Pull Request (PR) to an open-source project, I watch the CI pipeline kick off. More and more often, an AI assistant like CodeRabbit, Copilot, or Claude pops up a few minutes later to review my changes, categorize bugs, or suggest updates.
It got me wondering: How hard is it to build one of these from scratch?
As it turns out, you don't need a heavy, expensive third-party platform. You can build a fully customized, line-by-line AI code reviewer directly inside GitHub Actions using a short Python script and the Gemini API.
Here is exactly how it works, what the code looks like, and a breakdown of how each piece functions.
What We Are Building
