Backend Architect

Backend Architect is an agent for Claude Code from 9thLevelSoftware/legion. It costs 34 tokens per session (1,984 once invoked), scanned A, original, no licence file.

A server-side system design specialist covering databases, APIs, cloud infrastructure, and services that run behind an application.

In plain words
What is it for?
Use it to design databases, APIs, cloud systems, and microservices—separate services that work together in one application.
Why use it?
It helps address backend structure, security, performance, and growth before they become maintenance problems.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md).

Good fit Use it to design databases, APIs, cloud systems, and microservices—separate services that work together in one application.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/9thlevelsoftware/legion/engineering-backend-architect
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.

Clone the repo
git clone --depth 1 https://github.com/9thLevelSoftware/legion

Made for: Claude Code.

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 Architect

README.md
[![agentmods](https://agentmods.dev/badge/agents/9thlevelsoftware/legion/engineering-backend-architect/github.svg)](https://agentmods.dev/agents/9thlevelsoftware/legion/engineering-backend-architect)
Your own site
<a href="https://agentmods.dev/agents/9thlevelsoftware/legion/engineering-backend-architect"><img src="https://agentmods.dev/badge/agents/9thlevelsoftware/legion/engineering-backend-architect/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for Backend Architect

Your own site · 80×15
<a href="https://agentmods.dev/agents/9thlevelsoftware/legion/engineering-backend-architect"><img src="https://agentmods.dev/badge/agents/9thlevelsoftware/legion/engineering-backend-architect.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 34 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,984 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 $0.00034 $0.01984
Opus 5.5 $0.00014 $0.00794
Sonnet 5.5 $0.00007 $0.00397
Haiku 4.5 $0.00003 $0.00198

Measured 1mo ago against content hash 026cbf373ec2, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

Backend Architect 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 1mo 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/engineering-backend-architect.md · 250 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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. 1mo ago First seen · 250 lines · 34 tokens per session scan A 026cbf373ec2

Subscribe to this mod's changes

Backend Architect is an agent published in the GitHub repository 9thLevelSoftware/legion (79 stars, last pushed 1mo ago), with no licence file. It adds 34 tokens to every session and 1,984 once invoked, about $0.0001 per session on Opus 5.5. 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.

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