The Agent Harness: Turning AI Slop Into Shipping Software

Thesis: You can use AI coding agents on real production codebases and get predictable, high-quality results if you treat the agent like a junior engineer who needs guardrails, not a magic wand. Audience: Mid-level and senior software engineers curious about AI-assisted development but skeptical of the hype. Series Arc The story follows a real Laravel + React codebase over ~3 months and ~258 commits from a legacy monolith with no tests to a well-structured application with automated quality gates, a React SPA migration in progress, and an AI agent that reliably ships production code with minimal supervision. Stage 1: The Foundation — Tests First, Everything Else Second Post 1: "Before You Let an Agent Touch Your Code, Write the Tests" Why tests are the prerequisite for AI-assisted development, not an afterthought. How wrapping a legacy codebase in characterization tests creates the safety net that makes everything else possible. Covers the move from SQLite to MySQL in tests, the UserFac