@datafn/extfn

@datafn/extfn is the DataFn integration layer for extfn.

It keeps DataFn authority in the extension background context and gives popup, options, sidepanel, and content code a proxy client surface that stays aligned with the public @datafn/client API.

What this package owns

• background authority setup
• background request routing for DataFn RPC methods
• cross-context proxy client creation
• subscription fanout and cleanup for extension contexts

It does not move DataFn semantics into extfn core.

Public surface

The package exports:

• createDatafnExtfnAuthority(...)
• createDatafnExtfnProxyClient(...)
• createBrowserDatafnExtfnBridge(...)
• datafnExtfn(...)
• createDatafnExtfnRoutes(...)

Options

DatafnExtfnOptions is based on the current public DatafnClientConfig shape.

Supported keys:

• schema
• clientId
• namespace
• sync
• storage
• plugins
• searchProvider
• requestTimeoutMs

Not supported:

• authContext

If you need auth/session behavior, keep that in consumer code or another package-owned layer and pass DataFn the resulting configuration or storage behavior explicitly.

Background authority

Create the authority in background code only.

import { createDatafnExtfnAuthority } from "@datafn/extfn";
import { demoNamespace, demoSchema } from "./demoSchema.js";

const authority = createDatafnExtfnAuthority(
  {
    schema: demoSchema,
    clientId: "authority:demo",
    namespace: demoNamespace,
  },
  {
    address: {
      context: "background",
    },
  },
);

authority.attachBrowserRuntimeBridge();

The authority:

• rejects non-background startup
• reuses @datafn/client storage adapters
• owns subscription lifecycle
• speaks extfn-compatible request/response/event envelopes to extension contexts

Popup, options, sidepanel, and content clients

Create a proxy client in any non-background context.

import { createDatafnExtfnProxyClient } from "@datafn/extfn";

const client = createDatafnExtfnProxyClient({
  schema: demoSchema,
  clientId: "popup:demo",
  namespace: demoNamespace,
});

const notes = await client.query({
  resource: "note",
  version: 1,
  select: ["id", "title"],
});

You can also pass explicit runtime options:

const client = createDatafnExtfnProxyClient(
  {
    schema: demoSchema,
    clientId: "content:demo",
    namespace: demoNamespace,
  },
  {
    address: {
      context: "content",
      contentScriptId: "highlights",
      tabId: 12,
    },
  },
);

Using the plugin helper

datafnExtfn(...) returns a runtime plugin plus convenience accessors.

Use it when your package wants to bundle:

• a stable plugin id
• background route registration
• a reusable proxy-client factory

Keep in mind that background authority startup is still package-owned logic.

Example in this repo

See:

• extfn/examples/svelte-datafn-demo/extfn.config.ts
• extfn/examples/svelte-datafn-demo/src/background/index.ts
• extfn/examples/svelte-datafn-demo/src/demoClient.ts

Validation from repo root

npm run test -- --filter=@datafn/extfn
npm run build -- --filter=svelte-datafn-demo
npm exec extfn scan -- --config extfn/examples/svelte-datafn-demo/extfn.config.ts