> ## Documentation Index
> Fetch the complete documentation index at: https://redop.useagents.site/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Resource Definition

> Reference for resource definitions, resource contents, and template URI behavior in Redop.

## Shape

```ts theme={null}
app.resource("users://{id}/profile", {
  name: "User profile",
  description: "Read a user's profile",
  mimeType: "application/json",
  subscribe: true,
  afterResponse: async ({ uri, result, error }) => {},
  handler: async ({ uri, params, request }) => ({
    type: "text",
    text: JSON.stringify({ uri, id: params.id, transport: request.transport }),
  }),
});
```

## Fields

| Field           | Required | Purpose                                                                                                                           |
| --------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------- |
| `name`          | Yes      | Human-readable resource name.                                                                                                     |
| `description`   | No       | Description shown to clients.                                                                                                     |
| `mimeType`      | No       | Resource MIME type.                                                                                                               |
| `subscribe`     | No       | Opt in to `resources/subscribe`.                                                                                                  |
| `icons`         | No       | Optional icons for supporting clients.                                                                                            |
| `before`        | No       | Resource-local hook that runs before middleware and the handler.                                                                  |
| `after`         | No       | Resource-local hook that runs after a successful result and may replace it.                                                       |
| `afterResponse` | No       | Resource-local hook that runs after the response is written. Receives either `result` or `error` and cannot replace the response. |
| `middleware`    | No       | Middleware scoped to this resource only.                                                                                          |
| `handler`       | Yes      | Returns `ResourceContents`.                                                                                                       |

## `ResourceContents`

* `{ type: "text", text, mimeType? }`
* `{ type: "blob", blob, mimeType? }`

## Template URIs

If the resource URI contains `{name}` placeholders, Redop matches the concrete URI and passes the extracted values in `params`.

When you register the resource with a literal template URI, Redop also infers the `params` type from those placeholders. This means `app.resource("users://{id}/profile", ...)` gives you `params.id: string` in the handler, hooks, and resource middleware. Static resources do not get template params, so `params` is `undefined` there.

Redop also validates resource registration inputs early:

* the resource URI must be non-empty, trimmed, and free of whitespace
* the resource URI must include a valid scheme such as `file:`, `app:`, or `users:`
* URI templates must have balanced `{}` expressions
* duplicate resource URIs are rejected
* the resource `name` must be non-empty and trimmed

## Notes

* Use `afterResponse` for non-critical post-response work such as logging, metrics, or audit events.
* Use `after` instead when the logic must still be able to replace the successful resource result.