@aizigao/pi-fetch-pipeline

A tiny shared fetch middleware pipeline for Pi extensions.

Why

Multiple Pi extensions sometimes patch globalThis.fetch independently:

• proxy routing
• header rewriting
• cookie injection
• URL rewriting
• provider compatibility shims

If each extension patches fetch on its own, the last one loaded usually wins, or some requests bypass other extensions entirely.

@aizigao/pi-fetch-pipeline solves this by providing a shared global pipeline keyed by:

Symbol.for("aizigao.fetch.pipeline.v1")

Extensions can be installed independently and still compose safely.

Install

npm install @aizigao/pi-fetch-pipeline

Usage

import { registerFetchMiddleware } from "@aizigao/pi-fetch-pipeline";

registerFetchMiddleware({
  name: "headers-compat",
  priority: 10,
  middleware: async ({ input, init, next }) => {
    const headers = new Headers(init?.headers);
    headers.set("x-demo", "1");
    return next(input, { ...init, headers });
  },
});

Ordering

Middlewares are executed by ascending priority.

Suggested convention:

• 10: request/header compatibility rewrites
• 20: provider-specific host tweaks
• 50: proxy / transport routing

API

registerFetchMiddleware(registration)

Registers or replaces a named middleware and ensures the shared pipeline is installed.

ensureFetchPipeline()

Creates the shared pipeline state if missing and returns it.

installFetchPipeline()

Installs the patched globalThis.fetch if not already installed.

License

MIT