fastapi

A guide to building web APIs with FastAPI, a Python framework for serving application endpoints. It covers request models, dependencies, streaming responses, and serving frontend files.

In plain words
What is it for?
Use it when adding routes, Pydantic data models, server-sent event streams, injected clients, or a frontend served by a FastAPI application.
Why use it?
It helps keep FastAPI code consistent with the project’s conventions and current patterns.

Skill for Claude CodeCodex

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 skills/secondlifes/code-intel/fastapi
Any agent
npx skills add SecondLifes/code-intel --skill fastapi
Clone the repo
git clone --depth 1 https://github.com/SecondLifes/code-intel

Made for: Claude Code, Codex.

Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,500 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 95% copy Near-identical to another mod 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 $0.00057 $0.02500
Opus 5 $0.00028 $0.01250
Sonnet 5 $0.00011 $0.00500
Haiku 4.5 $0.00006 $0.00250

Measured yesterday against content hash 78fd5dc9b000, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fastapi 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 yesterday.

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.

Origin

This is a copy

95% identical to fastapi — 9 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/fastapi/SKILL.md · 331 lines

How it starts

The opening of the file, as written. The whole thing — 331 lines — stays where its author put it; the contents beside it link to each section on GitHub.

FastAPI

Official FastAPI skill to write code with best practices, keeping up to date with new versions and features.

Usage

You say What happens
"Add a new endpoint for X" / "add a route to search_routes.py" Consult this skill for the current Depends/response-model/streaming patterns before writing the route — keep it thin, delegate logic to src/services/*_svc.py per this repo's own convention.
"Add SSE/streaming to an endpoint" Read references/streaming.md for the EventSourceResponse/yield pattern — matches /api/ask/stream and /api/research/stream's existing style.
"Add a dependency-injected client (Qdrant/Ollama)" Read references/dependencies.md for Annotated[..., Depends(...)] — this repo's DIP convention for route handlers.
Ambiguous/no specific FastAPI question Skim Quick Reference first; it links to the relevant references/*.md file by topic.

Quick Reference

Read the full file on GitHub · 331 lines

Files

What ships with it

6 files 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.

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. yesterday First seen · 331 lines · 57 tokens per session scan A 78fd5dc9b000

Subscribe to this mod's changes

fastapi is a skill published in the GitHub repository SecondLifes/code-intel (2 stars, last pushed 21d ago), licensed Apache-2.0. It adds 57 tokens to every session and 2,500 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to fastapi, differing in 9 lines, and is treated as a copy.

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