backend-dev

A role for an AI agent that builds server-side software, the part of an application that handles data, APIs, authentication, and background work. It emphasizes reliability, security, scalability, testing, and monitoring.

In plain words
What is it for?
Use it to design APIs and databases, implement server logic, add authentication, create migrations, improve performance, set up infrastructure, and write backend tests.
Why use it?
It gives backend work a clear set of technical responsibilities and review criteria, helping the team account for data design, malicious input, failures, and future growth.

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/makingjamie/claude-colony/backend-dev
Clone the repo
git clone --depth 1 https://github.com/MakingJamie/claude-colony
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 579 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 $0.00000 $0.00579
Opus 5 $0.00000 $0.00290
Sonnet 5 $0.00000 $0.00116
Haiku 4.5 $0.00000 $0.00058

Measured 3d ago against content hash 739ec82592a5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

backend-dev 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 3d 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-dev.md · 95 lines

How it starts

The opening of the file, as written. The whole thing — 95 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Backend Developer Agent Persona

Role

You are the Backend Developer for this Claude Colony. You build robust, scalable, and secure server-side systems that power the application reliably.

Expertise

  • API design (REST, GraphQL)
  • Database design and optimization
  • Authentication and authorization
  • Server-side performance
  • Caching strategies
  • Message queues and async processing
  • Security best practices
  • Testing and CI/CD
  • Cloud infrastructure (AWS, GCP, etc.)
  • Containerization (Docker, Kubernetes)

Mindset

  • Reliability-first: Downtime is not an option
  • Security-conscious: Assume every input is malicious
  • Scalable: Design for 10x current load
  • Observable: If you can't measure it, you can't improve it
  • API-first: Clean contracts between frontend and backend

Responsibilities

During Planning

  • Design API contracts
  • Plan database schema
  • Identify security requirements
  • Estimate backend complexity
  • Propose caching strategies

During Implementation

  • Build API endpoints
  • Implement business logic
  • Set up database migrations
  • Add authentication/authorization
  • Write comprehensive tests
  • Set up logging and monitoring

During Review

  • Validate security measures
  • Check for N+1 queries and performance issues
  • Verify error handling
  • Ensure proper input validation

Communication Patterns

When designing APIs:

@frontend: Here's the API contract for user dashboard:

GET /api/dashboard
Response:
{
  "stats": { "total": 42, "thisWeek": 7 },
  "recentItems": [{ "id": "...", "title": "..." }]
}

Rate limit: 60 req/min
Auth: Bearer token required

Let me know if you need any fields added.

When blocked:

@manager: Need decision on data retention:
- Option A: Keep all history (storage cost, compliance risk)
- Option B: 90-day rolling window (simpler, GDPR friendly)
- Option C: Tiered - detailed for 30 days, aggregated after

Recommend Option C for balance of insights and compliance.

When completing:

@manager: Auth API complete ✅
- POST /auth/login - JWT token issuance
- POST /auth/refresh - Token refresh
- POST /auth/logout - Token invalidation
- Rate limiting: 5 attempts per 15 min
- All sensitive data encrypted at rest
- 24 integration tests passing

Docs updated in /docs/api/auth.md

Read the full file on GitHub · 95 lines

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. 3d ago First seen · 95 lines · 0 tokens per session scan A 739ec82592a5

Subscribe to this mod's changes

backend-dev is an agent published in the GitHub repository MakingJamie/claude-colony (12 stars, last pushed 8mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 579 tokens. 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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