hayate-fetch

Hayate ecosystem: Start here · Production golden app · Tested compatibility

Client-side WHATWG fetch for hayate: the same Request/Response types your server handles, pointed outward.

Status: alpha (0.x), typed. fetch(), the FetchBackend protocol, and the CPython and Cloudflare Workers backends are implemented and used by hayate-auth for OAuth token exchange. The design memo (Japanese, per project convention) lives in DESIGN.md; release history is in CHANGELOG.md.

Install

uv add hayate-fetch        # or: pip install hayate-fetch

For pooled asynchronous CPython requests, install the optional HTTPX backend:

uv add "hayate-fetch[httpx]"

Use

from hayate_fetch import fetch

response = await fetch(
    "https://api.example.com/books",
    method="POST",
    headers={"content-type": "application/json"},
    body='{"title":"Standards first"}',
)

if response.ok:
    book = await response.json()

Pass a prebuilt hayate Request when that is already the natural object:

from hayate import Request
from hayate_fetch import fetch

response = await fetch(Request("https://api.example.com/health"))

HTTP error statuses resolve to a Response; network failures raise OSError. Responses are buffered in the current public contract. Redirects follow by default, or pass default_backend(redirect="manual") to surface redirects consistently on CPython and Workers.

Backends

• CPython: UrllibBackend uses the standard library through asyncio.to_thread, so the package adds no HTTP dependency.
• Cloudflare Workers: WorkersBackend passes through to the platform's JavaScript fetch.
• HTTPX (optional, CPython): HttpxBackend adapts an application-owned httpx.AsyncClient, preserving its connection pool, timeout, TLS, proxy, and optional HTTP/2 configuration.
• Custom clients: implement the async FetchBackend.send(Request) -> Response protocol and pass it as backend=.

Keep one HTTPX client for the application lifetime rather than constructing it inside a hot request loop:

import httpx

from hayate_fetch import fetch
from hayate_fetch.httpx import HttpxBackend

async with httpx.AsyncClient() as client:
    response = await fetch(
        "https://api.example.com/books",
        backend=HttpxBackend(client),
    )

The default backend is selected from the runtime. Browser-only Fetch fields such as mode, credentials, and cache are intentionally outside the server-side subset.

License

MIT