Why a Markdown File Beats a Message Bus

You have five AI coding agents. They need to know what to work on, what's already taken, and what's done. How do you coordinate them? The popular answer is a message bus. Agents publish and subscribe. They negotiate tasks, share context, broadcast status. It's the architecture you'd find in CrewAI, AutoGen, or any framework with "multi-agent" in the tagline. I tried that approach. Then I replaced it with a directory of markdown files — kanban-driven task dispatch for AI agents, using the filesystem instead of a broker. It's been six months, and I haven't looked back. The O(n²) problem with message buses When agents coordinate through messages, every agent potentially talks to every other agent. Agent A finishes a task and broadcasts "task 27 done." Agents B, C, D, and E all receive it. Agent B claims the next task and broadcasts "I'm taking task 28." Now everyone else needs to hear that, update their state, and avoid claiming the same task. With 5 agents, that's manageable. With 10, it