backend-developer

backend-developer is a skill for Claude Code from sawrus/agent-guides. It costs 23 tokens per session (468 once invoked), scanned A, original, MIT.

A Python backend development guide focused on FastAPI, SQLAlchemy, Pydantic, Alembic, and pytest. It covers asynchronous input and database operations, typed code, validation, migrations, and application structure.

In plain words
What is it for?
Building APIs, defining database models and migrations, validating data, organizing business logic, and writing Python backend tests.
Why use it?
It provides consistent practices for building and checking Python server code instead of leaving architecture and error handling to guesswork.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit Building APIs, defining database models and migrations, validating data, organizing business logic, and writing Python backend tests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sawrus/agent-guides/backend-developer
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.

Any agent
npx skills add sawrus/agent-guides --skill backend-developer
Clone the repo
git clone --depth 1 https://github.com/sawrus/agent-guides

Made for: Claude Code.

Wrote 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.

agentmods badge for backend-developer

README.md
[![agentmods](https://agentmods.dev/badge/skills/sawrus/agent-guides/backend-developer/github.svg)](https://agentmods.dev/skills/sawrus/agent-guides/backend-developer)
Your own site
<a href="https://agentmods.dev/skills/sawrus/agent-guides/backend-developer"><img src="https://agentmods.dev/badge/skills/sawrus/agent-guides/backend-developer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for backend-developer

Your own site · 80×15
<a href="https://agentmods.dev/skills/sawrus/agent-guides/backend-developer"><img src="https://agentmods.dev/badge/skills/sawrus/agent-guides/backend-developer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 468 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00023 $0.00468
Opus 5 $0.00012 $0.00234
Sonnet 5 $0.00005 $0.00094
Haiku 4.5 $0.00002 $0.00047

Measured 7d ago against content hash d3106a3b008a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, 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 7d 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.

areas/software/full-stack/skills/backend-developer/SKILL.md · 59 lines

What it actually says

Backend Developer Skill

Expertise: Python 3.12+, FastAPI, SQLAlchemy (Async), Pydantic V2, Pytest.

🧠 Mindset

  • Type Safety: Uses strict type hints. mypy must pass.
  • Async First: All I/O operations must be async.
  • Explicit/Implicit: Prefer explicit dependency injection over global state.
  • Error Handling: Catch specific exceptions, never bare except Exception:.

🛠️ Toolkit

Category Library Usage
Web Framework fastapi Routing, Dependency Injection, Validation
ORM sqlalchemy Async ORM, Models
Migrations alembic Database schema versions
Validation pydantic Data transfer objects, settings
Testing pytest Unit and Integration tests

📋 Implementation Checklist

  1. Models & Migrations:

    • Define SQLAlchemy models.
    • Generate migration: alembic revision --autogenerate -m "desc".
    • Verify architecture rules: Models do not import from API.
  2. Repositories:

    • CRUD operations.
    • Return Pydantic models or ORM objects (depending on project pattern).
  3. Services:

    • Business logic.
    • Transaction management (async with session.begin():).
  4. API:

    • Status codes (201 for creation, 204 for no content).
    • Proper HTTP verbs.
  5. Tests:

    • Fixtures for DB session.
    • client.post(...) for API tests.
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. 7d ago First seen · 59 lines · 23 tokens per session scan A d3106a3b008a

Subscribe to this mod's changes

backend-developer is a skill published in the GitHub repository sawrus/agent-guides (17 stars, last pushed 10d ago), licensed MIT. It adds 23 tokens to every session and 468 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 2026-09-03.

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