Bindings and services

On Cloudflare, platform bindings and Durable Object storage reach your services through two framework tokens: Bindings for Worker env, and DurableState for a DO instance’s DurableObjectState.

Do not construct these classes yourself. The runtime adapter seeds them per execution context.

Bindings (Worker env)

import { FlareService } from "@flare-ts/core";
import { Bindings } from "@flare-ts/core/cloudflare";

class KvRoom extends FlareService {
  public static override deps = [Bindings] as const;

  async get(key: string) {
    const kv = this.inject(Bindings).env.MY_KV;
    return kv.get(key);
  }
}

Register the service with host.scoped(KvRoom) and inject it from routes as usual. env is typed from your Worker’s Cloudflare.Env (for example via wrangler types).

DurableState (per DO instance)

Inside a FlareDurableObject, DurableState exposes the instance context:

import { FlareService } from "@flare-ts/core";
import { DurableState, FlareDurableObject } from "@flare-ts/core/cloudflare";

class Counter extends FlareService {
  public static override deps = [DurableState] as const;

  async increment() {
    const storage = this.inject(DurableState).storage;
    const n = (await storage.get<number>("n")) ?? 0;
    await storage.put("n", n + 1);
    return n + 1;
  }
}

class CounterRoom extends FlareDurableObject {
  public static override deps = [Counter] as const;
}

Each DO instance gets its own lazy container. host.scoped() services resolve per instance, not per Worker isolate globally.

Inject from routes

const room = host.durableObject(CounterRoom);

room.http.get(
  "/inc",
  { inject: { counter: Counter } },
  async (_ctx, scope) => new FlareResponse(200, { n: await scope.counter.increment() }),
);

Worker vs DO context

Service	Seeded on	Provides
Bindings	Worker fetch and DO instance	env bindings
DurableState	DO instance only	state, storage, id

A stateless Worker route has Bindings but no DurableState. A mounted DO route has both.

Related

• Durable Objects: registration and mount
• Using DI: static deps and lifetimes
• Deploy: wrangler binding entries