Hey folks! We're excited to share a preview of a new API coming in #Fedify 1.6 that should make structuring larger federated apps much cleaner: FederationBuilder.

As your Fedify applications grow, you might encounter circular dependency issues when registering dispatchers and listeners across multiple files. The new FederationBuilder pattern helps solve this by separating the configuration phase from instantiation.

Instead of this:

// federation.ts
import { createFederation } from "@fedify/fedify";

export const federation = createFederation<AppContext>({
  kv: new DbKvStore(), 
  queue: new RedisMessageQueue(),
  // Other options...
});

// Now we need to import this federation instance in other files
// to register dispatchers and listeners...

You can now do this:

// builder.ts
import { createFederationBuilder } from "@fedify/fedify";

export const builder = createFederationBuilder<AppContext>();

// other files can import and configure this builder...

// actors.ts
import { builder } from "./builder.ts";
import { Person } from "@fedify/fedify";

builder.setActorDispatcher("/users/{handle}", async (ctx, handle) => {
  // Actor implementation
});

// inbox.ts
import { builder } from "./builder.ts";
import { Follow } from "@fedify/fedify";

builder.setInboxListeners("/users/{handle}/inbox", "/inbox")
  .on(Follow, async (ctx, follow) => {
    // Follow handling
  });

// main.ts — Only create the Federation instance at startup
import { builder } from "./builder.ts";

// Build the Federation object with actual dependencies
export const federation = await builder.build({
  kv: new DbKvStore(),
  queue: new RedisMessageQueue(),
  // Other options...
});

This pattern helps avoid circular dependencies and makes your code more modular. Each part of your app can configure the builder without needing the actual Federation instance.

The full documentation will be available when 1.6 is released, but we wanted to share this early with our community. Looking forward to your feedback when it lands!

Want to try it right now? You can install the development version from JSR or npm:

# Deno
deno add jsr:@fedify/fedify@1.6.0-dev.777+1206cb01

# Node.js
npm add @fedify/fedify@1.6.0-dev.777

# Bun
bun add @fedify/fedify@1.6.0-dev.777

#ActivityPub #fedidev