AGENTS.md rules / skills for Codex, Cursor, Claude Code, distilled from classic software engineering books about refactoring, architecture, DDD and code quality.
About · Rules / Skills · Books List · Usage · Books Compatibility
MIT licensed universal project rules for coding agents.
This repository contains ready-to-use rule sets inspired by well-known books on software design, architecture, refactoring, legacy code, reliability, and data-intensive systems.
For editor-specific setup in Codex, Claude Code, and Cursor, see USAGE.md. It covers always-on vs on-demand usage, skills, scoped rules, MCP or RAG patterns, and the preferred setup for each editor.
Each rule set is released in three tool-agnostic Markdown versions:
mini: the recommended version for most real task usenano: the compact fallback for very tight context budgetsfull: the canonical complete source and reference version
For constructive criticism from Reddit, see CRITICISM.md.
For release history, see CHANGELOG.md.
Metrics:
lines: physical line count fromwc -lrules: Markdown list items counted with the deterministic release conventionsize: raw bytes fromwc -c
| Rule Set | Full file | Full lines | Full rules | Full size | Mini file | Mini lines | Mini rules | Mini size | Nano file | Nano lines | Nano rules | Nano size |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A Philosophy of Software Design | full | 370 | 177 | 13561 B | mini | 46 | 28 | 5774 B | nano | 35 | 17 | 2258 B |
| Clean Architecture | full | 515 | 289 | 17782 B | mini | 49 | 31 | 5486 B | nano | 36 | 18 | 2254 B |
| Clean Code | full | 297 | 220 | 13851 B | mini | 47 | 29 | 3804 B | nano | 32 | 14 | 1235 B |
| Code Complete | full | 354 | 180 | 12407 B | mini | 56 | 38 | 6717 B | nano | 41 | 23 | 2544 B |
| Designing Data-Intensive Applications | full | 393 | 205 | 16084 B | mini | 55 | 37 | 6949 B | nano | 34 | 16 | 2575 B |
| Domain-Driven Design | full | 979 | 523 | 42424 B | mini | 48 | 30 | 5683 B | nano | 39 | 21 | 2266 B |
| Domain-Driven Design Distilled | full | 317 | 158 | 11351 B | mini | 56 | 38 | 6438 B | nano | 41 | 23 | 2535 B |
| Implementing Domain-Driven Design | full | 337 | 177 | 12848 B | mini | 57 | 39 | 7333 B | nano | 37 | 19 | 2723 B |
| Patterns of Enterprise Application Architecture | full | 404 | 196 | 15501 B | mini | 54 | 36 | 8099 B | nano | 35 | 17 | 2823 B |
| Refactoring | full | 433 | 242 | 17866 B | mini | 49 | 31 | 5167 B | nano | 37 | 19 | 1986 B |
| Release It! | full | 382 | 204 | 13542 B | mini | 48 | 30 | 6372 B | nano | 38 | 20 | 2205 B |
| The Pragmatic Programmer | full | 359 | 179 | 13398 B | mini | 65 | 47 | 7165 B | nano | 44 | 26 | 2263 B |
| Working Effectively with Legacy Code | full | 371 | 193 | 13817 B | mini | 50 | 32 | 5707 B | nano | 35 | 17 | 1792 B |
| Refactoring.Guru | full | 765 | 478 | 62561 B | mini | 64 | 46 | 6287 B | nano | 41 | 23 | 2593 B |
Author: John Ousterhout
The book focuses on fighting complexity through deep modules, simple interfaces, information hiding, and design choices that reduce cognitive load. This rule set is especially useful for API design, module design, and refactoring shallow abstractions.
Author: Robert C. Martin
The book describes designing systems around stable boundaries, the dependency rule, and the separation of business policies from details such as frameworks, databases, and UI. This rule set helps keep code resistant to technology churn.
Author: Robert C. Martin
The book focuses on readability, naming, small functions, responsibilities, tests, and simplicity. This rule set is a strong default for everyday coding and code review.
Author: Steve McConnell
The book covers a broad range of software construction practices: routine design, variables, classes, control flow, defensive programming, coding standards, and testing. This rule set helps agents make disciplined implementation decisions.
Author: Martin Kleppmann
The book covers reliability, scalability, consistency, replication, partitioning, transactions, data streams, and schema evolution. This rule set is intended for systems where data ownership, event flows, and consistency semantics matter.
Author: Eric Evans
The book introduces domain modeling, ubiquitous language, bounded contexts, tactical patterns, and strategic design. This rule set helps agents think in terms of the business model rather than tables, controllers, or DTOs.
Author: Vaughn Vernon
The book is a short, practical introduction to DDD. It focuses on subdomains, bounded contexts, context mapping, and basic tactical patterns. This rule set is a good fit when you want the benefits of DDD without excessive ceremony.
Author: Vaughn Vernon
The book shows how to apply DDD in real systems: aggregates, domain events, contexts, integrations, and application architecture. This rule set is more implementation-focused than domain-driven-design-distilled.
Author: Martin Fowler
The book catalogues enterprise application patterns: layers, service layer, transaction script, domain model, data mapper, repository, unit of work, identity map, DTO, and integration patterns. This rule set helps choose an appropriate pattern instead of mixing responsibilities accidentally.
Author: Martin Fowler
The book describes safe ways to improve code structure without changing observable behavior. This rule set emphasizes small steps, tests, code smell detection, and keeping refactoring separate from feature changes.
Source: Refactoring.Guru
The site provides a practical refactoring process, code smell catalog, and catalog of refactoring techniques. This rule set is useful when an agent needs to diagnose smells, choose a safe treatment, preserve behavior, and stop before cleanup turns into uncontrolled redesign.
Author: Michael T. Nygard
The book focuses on systems that survive production reality: failures, overload, timeouts, retries, circuit breakers, bulkheads, backpressure, observability, and deployment behavior. This rule set is useful for services, APIs, queues, integrations, and critical production paths.
Authors: Andrew Hunt, David Thomas
The book describes a pragmatic approach to software development: responsibility, DRY at the knowledge level, orthogonality, automation, fast feedback, prototyping, and adaptability. This rule set works well as a general engineering layer.
Author: Michael Feathers
The book explains how to safely change difficult, poorly tested code: characterization tests, seams, dependency breaking, sprout method, wrap method, and incremental risk reduction. This rule set is best for legacy work where the first goal is regaining control.
For choosing rule sets, skills, and delivery patterns, see USAGE.md. For combining multiple books, see COMPATIBILITY.md. For the book extraction workflow, see ADDING_THE_BOOK.md.
These rules are inspired by the books listed above. They are not official materials from the authors or publishers, and they are not a substitute for reading the books.
The files in this repository are practical engineering instructions written for AI coding tools. They intentionally avoid reproducing book text. Use them as lightweight working agreements, not as summaries or study notes.
AI coding agent rules are project-level instructions that guide tools like Codex, Cursor, Claude Code, and GitHub Copilot when generating, reviewing, or refactoring code.
AI coding agent skills are task-specific instruction packs that agents load only when a workflow needs them, such as refactoring, reviewing, legacy-code changes, reliability work, or domain modeling.
AGENTS.md is a Markdown file used to give coding agents project-specific instructions, workflows, constraints, and coding standards.
Yes. You can copy selected rule sets into CLAUDE.md as project memory or turn a focused mini rule set into a Claude Code skill.
Yes. You can adapt the rule sets into Cursor project rules or keep them as AGENTS.md-style instructions.
Yes. The rules and skills are plain Markdown and can be adapted into GitHub Copilot custom instructions, prompt files, or reusable task-specific guidance.
AI coding agent rules, Agent skills, AGENTS.md examples, Claude Code rules, Cursor rules, Codex rules, GitHub Copilot custom instructions, CLAUDE.md, software engineering rules for AI coding assistants, Clean Code rules for AI, Refactoring rules for AI agents, Domain-Driven Design rules, Clean Architecture rules.
The code and rules in this repository are released under the MIT License.
See LICENSE for details.