Prompt Library

A curated collection of development rules and prompt templates for AI-assisted software development. Drop it into a project as a submodule and reference its rules and templates from your prompts to get consistent, opinionated output from AI coding assistants.

Quick Start

Add this library to your project as a git submodule:

git submodule add https://github.com/yourusername/prompt-library.git prompts
git submodule update --init --recursive

# Later, pull updates
git submodule update --remote prompts

Contents

Rules (rules/)

Opinionated standards an assistant should follow when writing code. Each rule is self-contained and includes context (where it applies), core principles, MoSCoW-prioritised rules, patterns and anti-patterns, a decision framework, and a TL;DR.

• kotlin.md — Functional Kotlin with Arrow (Option<A>, Either<E,A>, no nullable types)
• rust.md — Modern idiomatic Rust (2025 practices)
• domain-driven-design.md — DDD tactical and strategic patterns
• hexagonal-architecture.md — Ports & adapters
• simple-design.md — Beck/Fowler four rules of simple design (language-agnostic)
• kotest.md — Kotest + Testcontainers conventions
• mcp-best-practices.md — Designing and implementing MCP servers and clients

Templates (templates/)

Prompt scaffolds for common AI development tasks. Italicised paragraphs inside each template are instructions to the author — replace them with real content when filling the template in.

• 00-ralph_api_template.md — Feature spec for autonomous coding loops (behaviour, API contract, business rules, Gherkin examples, out-of-scope, acceptance criteria)
• 00-mcp-server_template.md — Prompt for building an MCP server feature/tool
• 00-feature_spec_template.md — Full feature specification (domain, schema, endpoints, access matrix, examples)
• 00-implementation_plan_template.md — Slice-by-slice plan derived from a spec
• 00-backend-prompt-template.md — Prompt for implementing a single backend slice
• 00-frontend-prompt-template.md — Prompt for implementing a single frontend slice
• 00-todo-template.md — Corrective-action TODO list generated from TODO comments
• 00-rules-template.md — Scaffold for adding a new rule to rules/

Usage

Reference rules in your prompts:

Consider the following rules when implementing this feature:
- prompts/rules/kotlin.md
- prompts/rules/hexagonal-architecture.md

Use a template as the scaffold for a feature spec or prompt:

Using prompts/templates/00-ralph_api_template.md, draft a spec for ...