Paste a prompt into Claude or ChatGPT, describe your product module briefly, and get a .pbc.md behavior spec you can view, edit, and commit to your repo.
CLAUDE.md and AGENTS.md tell agents how to work in your repo. They don't tell agents what your product promises. That's a different artifact — the PBC layer.
A step-by-step guide to writing a .pbc.md file for your product's most critical module. Start with plain Markdown; add structured blocks agents can read.
Your repo has workflow instructions, session context, and feature specs. None of them answer what the product promises to do. That's the PBC layer.
A .pbc.md file opens in VS Code, renders on GitHub, reads like any Markdown doc. Drop it into pbc.stewie.sh and the same file becomes navigable UI.
After hitting the same product knowledge gap across multiple SaaS products, I built an open Markdown spec for capturing what your product promises to do.
A Product Behavior Contract (PBC) is a living, code-grounded spec that describes how your product actually behaves — not how you think it does.