backend

backend is a cursor rule for Cursor from gracefullight/docusaurus-plugins. It costs 15 tokens per session (476 once invoked), scanned A, a copy of backend, MIT.

A set of rules for building backend APIs with separate routing, business logic, data access, and model layers.

In plain words
What is it for?
Use it to structure API services, validate requests, implement authentication, access databases safely, manage configuration, and support real or local fallback integrations.
Why use it?
It keeps server code easier to test and maintain while requiring input validation, safe database queries, controlled transactions, and protected authentication.

Cursor rule for Cursor

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/gracefullight/docusaurus-plugins/backend
Clone the repo
git clone --depth 1 https://github.com/gracefullight/docusaurus-plugins

Made for: Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for backend

README.md
[![agentmods](https://agentmods.dev/badge/rules/gracefullight/docusaurus-plugins/backend.svg)](https://agentmods.dev/rules/gracefullight/docusaurus-plugins/backend)
Your own site
<a href="https://agentmods.dev/rules/gracefullight/docusaurus-plugins/backend"><img src="https://agentmods.dev/badge/rules/gracefullight/docusaurus-plugins/backend.svg" alt="Measured on agentmods" height="20"></a>
Per session 15 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 476 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 89% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00015 $0.00476
Opus 5 $0.00008 $0.00238
Sonnet 5 $0.00003 $0.00095
Haiku 4.5 $0.00002 $0.00048

Measured today against content hash 30f41c5cc068, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

backend scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

89% identical to backend — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.cursor/rules/backend.mdc · 39 lines

How it starts

The opening of the file, as written. The whole thing — 39 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Backend Coding Standards

Core Rules

  1. Clean architecture: router -> service -> repository -> models
  2. No business logic in route handlers
  3. All inputs validated with your stack's validation library
  4. Parameterized queries only (never string interpolation)
  5. JWT + bcrypt for auth; rate limit auth endpoints
  6. Async where supported; type annotations on all signatures
  7. Custom exceptions via centralized error module (not raw HTTP exceptions)
  8. Explicit ORM loading strategy: do not rely on default relation loading when query shape matters
  9. Explicit transaction boundaries: group one business operation into one request/service-scoped unit of work
  10. Safe ORM lifecycle: do not share mutable ORM session/entity manager across concurrent work unless ORM explicitly supports it
  11. Config from environment, with graceful fallback: DB URLs, API keys, secrets from env vars or secret managers, never hardcode. When integrating a third-party API (OpenAI, Anthropic, Stripe, etc.), write BOTH paths: (a) real call when process.env.<KEY> is present, (b) deterministic local fallback when absent. Mark the deferred branch with // TODO(oma-deferred): integrate <vendor> when key is provisioned. Shipping only the fallback (no env-conditional branch) leaves the spec unmet; shipping only the real call without fallback breaks demos when the key is missing.
  12. Stateless services: no in-memory session or user state between requests — use external stores
  13. Backing services as resources: DB, queue, cache are swappable resources connected via config

Architecture

Router (HTTP) → Service (Business Logic) → Repository (Data Access) → Models

Principles

  • DRY: Business logic in Service, data access in Repository
  • Single Responsibility: Classes and functions should have one responsibility
  • Dependency Inversion: Use your framework's DI mechanism
  • KISS: Keep it simple and clear

Read the full file on GitHub · 39 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. today First seen · 39 lines · 15 tokens per session scan A 30f41c5cc068

Subscribe to this mod's changes

backend is a cursor rule published in the GitHub repository gracefullight/docusaurus-plugins (22 stars, last pushed 2mo ago), licensed MIT. It adds 15 tokens to every session and 476 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to backend, differing in 2 lines, and is treated as a copy.