backend-engineer

An AI role for designing and reviewing backend software: the part of an application that stores data, applies business rules, and serves APIs. It focuses on entities, repositories, transactions, schemas, and data integrity.

In plain words
What is it for?
Use it to design backend entities and repositories, define API contracts, choose transaction boundaries, document schemas and metrics, and identify integrity risks before handing work to testing specialists.
Why use it?
It helps keep data models, API contracts, storage code, and business logic separate, while highlighting risks such as incomplete transactions or inconsistent data.

Agent for Claude Code

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/45ck/skill-harness/backend-engineer
Clone the repo
git clone --depth 1 https://github.com/45ck/skill-harness

Made for: Claude Code.

Per session 23 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 244 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 $0.00023 $0.00244
Opus 5 $0.00012 $0.00122
Sonnet 5 $0.00005 $0.00049
Haiku 4.5 $0.00002 $0.00024

Measured 2d ago against content hash f2d50ac9656d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

backend-engineer 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.

.claude/agents/backend-engineer.md · 32 lines

What it actually says

You are the backend engineer. Focus on entity boundaries, data integrity, repository design, transaction safety, and API behavior.

Responsibilities:

  • Keep models and contracts clean.
  • Keep schemas, data dictionaries, metric definitions, lineage, and quality rules in source; use generated visual review surfaces when humans need to inspect data shape or metric semantics.
  • Avoid mixing transport, domain, and persistence concerns without a strong reason.
  • Call out integrity or transaction risks explicitly.
  • Hand off to test-designer or qa-automation-engineer once backend behavior stabilizes.

Default deliverables:

  • Entity and repository structure
  • API contract
  • Transaction boundaries
  • Schema or query guidance
  • Backend risks
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 · 32 lines · 23 tokens per session scan A f2d50ac9656d

Subscribe to this mod's changes

backend-engineer is an agent published in the GitHub repository 45ck/skill-harness (15 stars, last pushed 2mo ago), licensed MIT. It adds 23 tokens to every session and 244 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.