What is python-backend CLAUDE.md?

Project guidance for a Python web backend built with FastAPI, SQLAlchemy, Pydantic, and Alembic. It defines how the code is organised and where different kinds of logic belong.

Use it when adding or changing API endpoints, services, database repositories, data schemas, models, or application startup code.

It removes guesswork about the project structure and helps keep request handling, business rules, database access, and data definitions separate.

How jmcmeen/python-backend configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to jmcmeen/python-backend. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/jmcmeen/python-backend/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/jmcmeen/python-backend

Made for: Claude Code.

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README.md

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Per session 1,197 This file is loaded in full into every session.

When invoked 1,197 The same file — it is already loaded in full.

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.

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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 5.1	$0.01197	$0.01197
Opus 5.5	$0.00479	$0.00479
Sonnet 5.5	$0.00239	$0.00239
Haiku 4.5	$0.00120	$0.00120

Measured 2mo ago against content hash a868ac06df62, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

python-backend CLAUDE.md 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 2mo 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.md · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

Project Overview

This is a Python backend template using a layered architecture with FastAPI, SQLAlchemy, Pydantic, and Alembic.

Architecture Rules

Endpoints are thin wrappers. app/api/ handlers must only validate input (via schemas), call a service, and return a response. No business logic in route handlers.
Business logic lives in services. app/services/ contains all domain logic. Services must be framework-independent and testable in isolation -- no FastAPI or SQLAlchemy imports.
Repositories abstract data access. app/repositories/ wraps all ORM/database calls behind clean method signatures. Never use raw ORM queries outside of repositories.
Schemas are not models. app/schemas/ (Pydantic) defines API contracts. app/models/ (SQLAlchemy) defines database tables. They evolve independently.
Utils stay small. If a utility in app/utils/ grows complex, promote it to a service.
main.py is wiring only. Mount routers, set up middleware, run startup hooks. Nothing else.

Directory Conventions

API versioning: app/api/v1/, app/api/v2/, etc.
One file per domain entity in models, schemas, services, and repositories (e.g., user.py, user_service.py, user_repo.py).
Tests mirror the source structure: tests/unit/ for services/utils, tests/integration/ for API and DB tests.
Database migrations go in migrations/ (Alembic).

Tech Stack

FastAPI + Uvicorn
SQLAlchemy (ORM) + Alembic (migrations)
Pydantic (validation and settings via BaseSettings)
pytest + httpx + pytest-asyncio (testing)

Commands

Use uv and the Makefile. Don't suggest pip or invoke pytest directly.

make dev-setup           # first-time onboarding (install + pre-commit + .env)
make dev                 # uvicorn --reload
make test                # pytest + coverage (80% floor)
make test-unit           # services/utils only
make test-integration    # API/DB only
make lint                # ruff check + format check
make fmt                 # ruff format + safe fixes
make typecheck           # mypy --strict against app/
make migrate             # alembic upgrade head
make migration m="..."   # generate an autogenerated revision
make up                  # docker compose up -d --build
make down                # docker compose down (preserves volumes)
make nuke                # docker compose down -v --rmi all --remove-orphans

Read the full file on GitHub · 79 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.

2mo ago First seen · 79 lines · 1,197 tokens per session scan A a868ac06df62

Subscribe to this mod's changes

python-backend CLAUDE.md is an instructions file published in the GitHub repository jmcmeen/python-backend (8 stars, last pushed 5mo ago), licensed CC0-1.0. It adds 1,197 tokens to every session, about $0.0048 per session on Opus 5.5. 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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python-backend: Instructions file for Claude Code