Four years into running a codebase with half a million lines of Python and TypeScript, my PR review process looked like this: a senior engineer skims the diff, leaves three style comments and a "LGTM," merges. Real bugs ship anyway. The ones that make it through are always the boring kind — edge cases in error handling, cache invalidation timing, stuff nobody thinks to check.

So I put an AI agent on it. Not a GitHub copilot suggestion. An autonomous agent that runs on every commit, reads the full diff, maintains a persistent review history, and posts comments without human prompting.

The agent is called nebula-eng-reviewer and it runs on Nebula.…