# Fastapi Backend

> FastAPI backend patterns for AI Doctor Assistant Use when this capability is needed.

- Skill: `tomevault-io/fastapi-backend` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/fastapi-backend`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/fastapi-backend/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/fastapi-backend

---


# FastAPI Backend Development Skill

## Tech Stack
- FastAPI with async/await patterns
- Pydantic v2 for validation
- SQLAlchemy 2.0 with async sessions
- aiosqlite for SQLite async support
- uv for dependency management (NOT pip)
- ruff for formatting and linting
- pytest-asyncio for testing

## Key Patterns

### Pydantic v2
```python
# Correct (v2)
obj = MyModel.model_validate(data)
json_str = obj.model_dump_json()

# Wrong (v1 - don't use)
# obj = MyModel.parse_obj(data)
```

### Async Database Sessions
```python
from src.database import get_session
from fastapi import Depends
from sqlalchemy.ext.asyncio import AsyncSession

@app.get("/items")
async def get_items(session: AsyncSession = Depends(get_session)):
    result = await session.execute(select(Item))
    return result.scalars().all()
```

### Error Handling
```python
from fastapi import HTTPException

if not item:
    raise HTTPException(status_code=404, detail="Item not found")
```

## File Structure
```
src/
├── __init__.py
├── main.py              # FastAPI app entry
├── config.py            # Settings from env vars
├── models/              # Pydantic models
├── services/            # Business logic
├── agents/              # Claude Agent SDK agents
│   ├── briefing_agent.py
│   ├── tools.py         # @tool definitions
│   └── hooks.py         # Langfuse hooks
├── routers/             # API routes
└── database.py          # SQLAlchemy setup
```

## Running Commands
```bash
# Start server
uv run uvicorn src.main:app --reload

# Run tests
uv run pytest

# Format code
uv run ruff format .

# Lint code
uv run ruff check . --fix
```

## Code Style
- Use `from __future__ import annotations` for forward refs
- Type hints on ALL function signatures
- Use `async def` for I/O-bound operations
- Organize routers by domain (patients, briefings)

---
> Source: [ramanshrivastava/build-ai-agents](https://github.com/ramanshrivastava/build-ai-agents) — distributed by [TomeVault](https://tomevault.io).
<!-- tomevault:4.0:skill_md:2026-06-16 -->