> ## Documentation Index
> Fetch the complete documentation index at: https://eo.utopy.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# eoc

> Effect-aware oRPC contract builder.

`eoc` is an Effect-aware wrapper around oRPC's `oc` contract builder.

Use it when contract definitions should accept `ORPCTaggedError` classes directly in `.errors(...)`.

```ts title="import.ts" theme={null}
import { eoc } from "effect-orpc";
```

## Define a contract leaf

```ts title="contract.ts" theme={null}
const contract = {
  users: {
    get: eoc
      .errors({ UserNotFoundError })
      .input(z.object({ id: z.string() }))
      .output(z.object({ id: z.string(), name: z.string() })),
  },
};
```

## Router-level options

```ts title="contract-router.ts" theme={null}
const contract = eoc
  .prefix("/api")
  .tag("Users")
  .router({
    users: {
      list: eoc.route({ method: "GET", path: "/users" }).output(z.array(User)),
    },
  });
```

## See also

* [Contract-first APIs](/effect-v4/capabilities/contract-first)
* [`implementEffect`](/effect-v4/reference/implement-effect)