Project bible
Harness
A description of how the project is built and why: system boundaries, agreements, principles and values: what matters more when choosing and what is never allowed. The agent reads it before working, so you do not repeat yourself in every task. Concrete do and do-not instructions are derived from it into rules. The bible lives in CLAUDE.md for Claude Code or AGENTS.md for Codex and Cursor, or in separate files they point to.
Rules and the project bible
| Rules | Project bible | |
|---|---|---|
| Answers | how to act here | how the project is built and why |
| Form | short do and do-not instructions | a connected description and principles |
| When the agent reads it | always or when it touches matching files | before work, as a whole |
| Example | "run tests with npm test" | "payments are a separate system we do not edit" |
| Where it comes from | derived from the bible and agent mistakes | written by people who know the project |
Source: Claude Code best practices
Where it appears · 2
- Will AI agents take your job · Harness
- AGENTS.md and CLAUDE.md, specs, rules and skills · Specs and context