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.
npx agentmods add skills/martian56/claude-engineer/backend-developmentnpx skills add martian56/claude-engineer --skill backend-developmentgit clone --depth 1 https://github.com/martian56/claude-engineerWrote 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.
[](https://agentmods.dev/skills/martian56/claude-engineer/backend-development)<a href="https://agentmods.dev/skills/martian56/claude-engineer/backend-development"><img src="https://agentmods.dev/badge/skills/martian56/claude-engineer/backend-development.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00063 | $0.00615 |
| Opus 5 | $0.00032 | $0.00308 |
| Sonnet 5 | $0.00013 | $0.00123 |
| Haiku 4.5 | $0.00006 | $0.00061 |
Grade A, and why
backend-development 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 4d 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.
How it starts
The opening of the file, as written. The whole thing — 36 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Backend Development
Announce at start: "I'm using claude-engineer:backend-development to build the FastAPI backend."
The stack (defaults)
Python 3.12+ · FastAPI · SQLAlchemy 2.0 async (asyncpg) · Alembic · Pydantic v2 +
pydantic-settings · uv (deps/venv) · ruff (lint+format) · mypy (types) · pytest (tests).
Domain-modular layout: src/<domain>/{router,schemas,models,service,dependencies}.py.
The standard kit (scaffold these by default)
- Auth & security - OAuth2 password flow, JWT access + refresh, password hashing (argon2/bcrypt), rate limiting, CORS, security headers.
- Async jobs & scheduling - a task queue + scheduled jobs over Redis (see the reference for the recommended library and why).
- Caching & object storage - Redis cache patterns + an S3/MinIO storage abstraction.
- Observability - structured logging, Sentry, OpenTelemetry traces,
/health+/readyendpoints.
Non-negotiables
- Async all the way - async engine + session-per-request dependency; no sync DB calls in request paths.
- Migrations are real - every schema change ships an Alembic migration (async-compatible); never auto-create in prod paths.
- Typed & validated - Pydantic v2 request/response models; mypy clean (hard gate).
- Tested - pytest + pytest-asyncio + httpx AsyncClient against a real test DB; meet the coverage threshold.
- Config via pydantic-settings - no secrets in code; env-driven; documented required vars.
- Services in Docker, app native - connect to Postgres/Redis/MinIO/Mailpit on localhost (
claude-engineer:docker-dev-environment); run uvicorn natively.
Full detail: read references/fastapi-stack.md (exact project structure, SQLAlchemy 2.0 patterns, async Alembic setup, the job-queue recommendation, auth, observability, the blessed-packages list, pyproject.toml) on demand.
Red flags - STOP
- A sync DB driver or blocking I/O in an async endpoint.
- A model change without a matching Alembic migration.
- Secrets/config literals in source instead of pydantic-settings + env.
- Shipping an endpoint with no test.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 4d ago First seen · 36 lines · 63 tokens per session scan A 1edc2592f0ed
backend-development is a skill published in the GitHub repository martian56/claude-engineer (2 stars, last pushed 2mo ago), licensed MIT. It adds 63 tokens to every session and 615 once invoked, about $0.0003 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.
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