Every AI app I've shipped recently rewrote the same plumbing. The OAuth dance for Slack. Encrypted storage for an API key. Refresh-token logic that finally fails on the 3rd call after an hour. Wiring up an MCP client to a server behind a bearer token someone pasted into a Notion page.
In April 2026, Google Labs released a spec called DESIGN.md. It's a design system specification readable by AI agents, packaged with a CLI validator: npx @google/design.md lint. With DESIGN.md in the picture, we now have three different file types for instructing AI agents. AGENTS.md has been spreading as an industry standard since 2025 (jointly developed by OpenAI, Google, Sourcegraph, Cursor, an