backend

backend is a cursor rule for Cursor from meishanlaoyao/elysia-admin. It costs 0 tokens per session (2,036 once invoked), scanned A, original, MIT.

A set of rules for building backend modules with Elysia and Bun. It separates validation, business logic, HTTP routes, and optional background tasks into defined files.

In plain words
What is it for?
Use it when creating backend modules, routes, validation, cross-module data access, queues, or scheduled worker tasks.
Why use it?
It prevents business logic and database access from being mixed into the wrong layer, especially when modules need to use one another's data.

Cursor rule for Cursor

Written for Cursor: installed under .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/meishanlaoyao/elysia-admin/backend
Clone the repo
git clone --depth 1 https://github.com/meishanlaoyao/elysia-admin

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/meishanlaoyao/elysia-admin/backend.svg)](https://agentmods.dev/rules/meishanlaoyao/elysia-admin/backend)
Your own site
<a href="https://agentmods.dev/rules/meishanlaoyao/elysia-admin/backend"><img src="https://agentmods.dev/badge/rules/meishanlaoyao/elysia-admin/backend.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 2,036 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 5.1 $0.00000 $0.02036
Opus 5 $0.00000 $0.01018
Sonnet 5 $0.00000 $0.00407
Haiku 4.5 $0.00000 $0.00204

Measured 6d ago against content hash 6bf308b96faa, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, 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 6d ago.

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.

.cursor/rules/backend.mdc · 191 lines

How it starts

The opening of the file, as written. The whole thing — 191 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Backend Module Structure

Every module under server/src/modules/{group}-{name}/ should contain:

modules/{group}-{name}/
    dto.ts      ← Elysia validation + route DTO fragments; optional afterHandle hooks
    handle.ts   ← business logic only
    route.ts    ← HTTP mapping only
    task.ts     ← BullMQ / sandbox worker exports (optional; omit if no tasks)

No extra files. No renaming. Routes auto-register on startup.

task.ts: add only when registering queue/cron jobs in server/src/worker-sandbox/.

Cross-module handle (Cross-Table Data Access):

  • Each module may directly query only its own table schemas.
  • To access another module's table, call the owning module's exported PascalCase function from its handle.ts — do NOT import that module's @database/schema.
  • Route handlers = lower camelCase (create, findList); cross-module exports = PascalCase (GetUserBy, GetDeptInfoById).
  • If the helper is missing, add it in the owning module first, then import it from the consumer.
  • New business modules should stay self-contained; avoid mesh dependencies.

Layer Rules (Strict)

File Allowed Forbidden
dto.ts Elysia schema, response DTO, optional hooks complex orchestration, direct DB
handle.ts own-module schema + repository, QueryBuilder, shared, infrastructure; other modules' exported handle functions raw SQL, direct pg, new Elysia in handle, importing other modules' @database/schema for cross-table queries
route.ts bind dto+handle, return result business logic, DB access
task.ts export plain functions, call handle duplicate business logic, direct DB

Repository Functions (from @/core/database/repository)

InsertOne(schema, ctx)                          // insert, no return
InsertOneAndRes(schema, ctx)                    // insert, return record
InsertMany(schema, ctx, dataArray)              // bulk insert
FindOneByKey(schema, 'primaryKey', value)       // find by key
FindAll(schema, whereSQL, options?)             // find all (no pagination)
FindPage(schema, whereSQL, paginationOptions)   // paginated query
UpdateByKey(schema, 'primaryKey', ctx)          // update by key
UpdateByKeyAndRes(schema, 'primaryKey', ctx)    // update, return record
SoftDeleteByKeys(schema, 'primaryKey', ctx)     // soft delete (sets delFlag=true)
HardDelete(schema, whereSQL)                    // permanent delete
HardDeleteByKeys(schema, 'primaryKey', values) // permanent delete by keys
FindAllWithJoin(schema, builder, options?)      // find all with join
FindPageWithJoin(schema, builder, options)      // paginated with join

Read the full file on GitHub · 191 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. 6d ago First seen · 191 lines · 0 tokens per session scan A 6bf308b96faa

Subscribe to this mod's changes

backend is a cursor rule published in the GitHub repository meishanlaoyao/elysia-admin (49 stars, last pushed yesterday), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 2,036 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.