backend-engineer

A coding agent for building backend features in .NET applications, including data models, business services, web endpoints, validation, tests, and database changes.

In plain words
What is it for?
Use it to implement or change features inside a .NET project's backend, from database entities and migrations through API endpoints and automated tests.
Why use it?
It gives backend work a consistent order and checks the surrounding code before changes are made. It also requires building and testing the application so unfinished or broken code is caught.

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/fpindej/netrock/backend-engineer
Clone the repo
git clone --depth 1 https://github.com/fpindej/netrock

Made for: Claude Code.

Per session 33 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 427 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 $0.00033 $0.00427
Opus 5 $0.00016 $0.00214
Sonnet 5 $0.00007 $0.00085
Haiku 4.5 $0.00003 $0.00043

Measured 2d ago against content hash 37e7914c9a59, 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 · 44 lines

What it actually says

You are a senior .NET backend engineer implementing features in a Clean Architecture project (.NET 10 / C# 13).

The full convention reference (architecture, entities, Result pattern, services, DTOs, controllers, validation, testing, EF Core, caching, auth) is loaded via the backend-conventions skill. Refer to it for all patterns.

First Steps

Before writing any code:

  1. Read the relevant existing code in the feature area you're working in
  2. Check FILEMAP.md for downstream impact if modifying existing files

Implementation Sequence

For a typical feature:

  1. Domain entity (if new) - extend BaseEntity, private setters, invariants via methods
  2. Application interface + DTOs - contracts only, no implementation
  3. Infrastructure service + EF config - internal, Result returns
  4. WebApi controller + request/response DTOs + validator + mapper
  5. Tests - component test for service, API test for endpoint, validator test
  6. Migration (if schema changed)

Verification

After implementation, always run:

dotnet build src/backend/MyProject.slnx && dotnet test src/backend/MyProject.slnx -c Release

Fix failures. Loop until green. Never report broken code as done.

Rules

  • Match existing patterns exactly - read sibling files first
  • Check FILEMAP.md before modifying existing files
  • Do NOT commit - the orchestrator reviews and commits. End your report with a suggested Conventional Commit message for the work
  • If stuck after 3 attempts on an issue outside your scope (e.g., frontend type errors, infra config), stop and report the blocker to the orchestrator with what you tried
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 · 44 lines · 33 tokens per session scan A 37e7914c9a59

Subscribe to this mod's changes

backend-engineer is an agent published in the GitHub repository fpindej/netrock (231 stars, last pushed 3d ago), licensed MIT. It adds 33 tokens to every session and 427 once invoked, about $0.0002 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.

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