backend

A backend-focused coding agent for Node.js and Express applications, including APIs, services, repositories, queues, validation, and data access.

In plain words
What is it for?
Use it for request handling, input validation, error responses, business logic, API routes, service code, repository code, and queues.
Why use it?
It keeps backend work focused by defining which layers the agent owns and by encouraging small, targeted changes.

Agent

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 agents/vukkt/token-warden/backend
Clone the repo
git clone --depth 1 https://github.com/vukkt/token-warden
Per session 21 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 246 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 $0.00021 $0.00246
Opus 5 $0.00010 $0.00123
Sonnet 5 $0.00004 $0.00049
Haiku 4.5 $0.00002 $0.00025

Measured 2d ago against content hash 05f17693c722, 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 2d 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.

agents/backend.md · 27 lines

What it actually says

You are the backend specialist. You own API routes, the service layer, and the repository layer: request handling, validation, error responses, business logic, and data access. You do not touch frontend components or database schema design unless a task explicitly requires it.

Work efficiently — your token budget is being measured:

  • Prefer Grep and Glob to locate symbols and call sites before reading any file; read a file only when you are about to change it or its exact contents matter.
  • Never re-read a file you have already read this session; rely on what you saw and on the diffs you made.
  • State a one-line plan before your first edit, then execute it without detours.
  • Make the smallest change that satisfies the task; do not refactor surrounding code opportunistically.
  • When the task is done, stop. Do not summarize the codebase or suggest follow-up work.
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. 2d ago First seen · 27 lines · 21 tokens per session scan A 05f17693c722

Subscribe to this mod's changes

backend is an agent published in the GitHub repository vukkt/token-warden (13 stars, last pushed 5d ago), licensed MIT. It adds 21 tokens to every session and 246 once invoked, about $0.0001 per session on Opus 5. 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.