Runtime context

Three files now run your repo's relationship with AI. Agents stopped guessing, because three Markdown files started telling them what they need. AGENTS.md says how to build and test the project. SKILL.md packs up capabilities the agent carries from project to project. DESIGN.md hands over your visual system so nothing drifts off-brand. Three files, plain Markdown, and the repo explains itself.

One thing people botch: these are not protocols. MCP is how an agent talks to a system. These files are what it needs to know about your project. Different job.

Why Markdown and not some clever format? Agents read it better than anything else, because it is most of what they trained on. And one file in one spot kills the scatter, no more rules spread across .cursorrules, CLAUDE.md, and whatever ships next week. That scatter is vendor lock-in.

This is the top of the stack, where the other three pillars get delivered. Tokens gave the values. Machine-readable systems gave the meaning. Spec-driven development gave the intent. Runtime context is how all of it reaches the agent at the moment it acts. Skip it and the agent scavenges for build commands, hallucinates one, and breaks your pipeline.

The fix is one rule everyone can follow: make AGENTS.md the single source of truth and point every tool-specific file at it instead of duplicating context everywhere.

None of this is finished, and that is worth saying plainly. The file names are converging, but they are young, and the harder problem past host-to-agent context, getting agents to coordinate with each other, is still unsettled. The bet is not that the format is done. It is that writing intent down in a file the agent can read beats hoping it guesses.

You do not make an agent reliable by making it smarter. You make it reliable by writing down what it needs in a file it can actually read. Three files, maintained once, used everywhere.