# wrapModel

URL: https://tailrace.dev/docs/reference/ai-sdk/wrap-model

> Wrap a LanguageModelV2 with Tailrace middleware - scan prompts, completions, and streams.



Wrap a language model so prompts and generated text pass through Tailrace policy at the **model** boundary.

## Import [#import]

```ts
import { wrapModel } from "@tailrace/ai-sdk";
```

## Signature [#signature]

```ts
function wrapModel(
  tailrace: Tailrace,
  model: LanguageModelV2,
  opts?: AiSdkWrapOptions,
): LanguageModelV2;
```

## Parameters [#parameters]

### `tailrace` [#tailrace]

A Tailrace instance from `createTailrace()`.

### `model` [#model]

Any AI SDK `LanguageModelV2` (for example from `@ai-sdk/openai`).

### `opts` [#opts]

Optional. See [AiSdkWrapOptions](/docs/reference/ai-sdk/options).

## Returns [#returns]

A new `LanguageModelV2` that delegates to the original model through Tailrace middleware. Pass it to `generateText`, `streamText`, or other AI SDK APIs.

## Middleware hooks [#middleware-hooks]

| Hook              | When                           | On `block`                                         |
| ----------------- | ------------------------------ | -------------------------------------------------- |
| `transformParams` | Before provider call           | Throws `PolicyViolationError`; provider not called |
| `wrapGenerate`    | After non-streaming completion | Throws `PolicyViolationError`                      |
| `wrapStream`      | On each stream chunk           | Depends on `streamBlockBehavior` (default: throw)  |

Scanned content: **text** parts in prompt messages. Non-text parts pass through in v0.1.

## Provider encoding [#provider-encoding]

The model boundary uses `encodeModelProvider(model)`:

* `openai` + `gpt-4o` → `openai/gpt-4o`
* Gateway id `openai/gpt-4o` → `openai/gpt-4o` (no double prefix)

Policy keys such as `openai/*` match this string.

## Example [#example]

```ts
import { createTailrace } from "@tailrace/core";
import { wrapModel } from "@tailrace/ai-sdk";
import { openai } from "@ai-sdk/openai";
import { generateText } from "ai";

const tailrace = createTailrace();
const model = wrapModel(tailrace, openai("gpt-4o"), {
  agent: "support",
  workflowId: "sess-1",
});

await generateText({ model, prompt: "Hello" });
```

## Throws [#throws]

* **`PolicyViolationError`**: policy resolved to `block` on input or non-streaming output, or on streaming output when `streamBlockBehavior` is `abort` or `buffer`.

## Related [#related]

* [wrapTools](/docs/reference/ai-sdk/wrap-tools)
* [streamBlockBehavior](/docs/reference/ai-sdk/options#streamblockbehavior)