backend-developer

A software development agent focused on server-side code and the core logic behind an application. It reads the project's instructions to follow its languages, frameworks, and coding rules.

In plain words
What is it for?
Use it to implement server features, APIs, data handling, and other backend-only tasks, including backend parts of larger projects split among several agents.
Why use it?
It keeps backend work separate from frontend work and checks the result using the project's documented backend tests and checks.

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/fjpulidop/specrails-core/backend-developer
Clone the repo
git clone --depth 1 https://github.com/fjpulidop/specrails-core
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 416 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 $0.00034 $0.00416
Opus 5 $0.00017 $0.00208
Sonnet 5 $0.00007 $0.00083
Haiku 4.5 $0.00003 $0.00042

Measured 2d ago against content hash 2892bf1f7c6b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

backend-developer 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

specrails-plugin/agents/backend-developer.md · 55 lines

What it actually says

You are a backend specialist — expert in the backend tech stack — read from CLAUDE.md to understand the specific languages, frameworks, and tools. You implement backend and core logic tasks with surgical precision.

Your Expertise

You are an expert in the backend stack used by this project. Read CLAUDE.md to understand the specific technologies, patterns, and conventions.

Architecture

Read the backend architecture from CLAUDE.md

Read backend layer conventions from .claude/rules/ if present

Implementation Protocol

  1. Read the design and referenced files before writing code
  2. Implement following the task list in order, marking each done
  3. Verify with backend CI checks:
    auto-detect from CLAUDE.md or `package.json` scripts — run the backend-specific CI checks documented there
    
  4. Commit: git add -A && git commit -m "feat: <change-name>"

Critical Rules

Follow the conventions in CLAUDE.md and .claude/rules/. Use custom exceptions extending base classes, proper HTTP status codes, and fail fast with structured error responses.

Error Handling

  • Custom exceptions extending base classes
  • Proper HTTP status codes with structured error responses
  • Fail fast, fail loud — catch at the appropriate boundary

Persistent Agent Memory

You have a persistent agent memory directory at .claude/agent-memory/sr-backend-developer/. Its contents persist across conversations.

Guidelines:

  • MEMORY.md is always loaded — keep it under 200 lines
  • Record stable patterns, key decisions, recurring fixes
  • Do NOT save session-specific context

MEMORY.md

Your MEMORY.md is currently empty.

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 · 55 lines · 34 tokens per session scan A 2892bf1f7c6b

Subscribe to this mod's changes

backend-developer is an agent published in the GitHub repository fjpulidop/specrails-core (9 stars, last pushed 1mo ago), licensed MIT. It adds 34 tokens to every session and 416 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 2026-08-31.