wrapModel

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

Signature

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

Parameters

`tailrace`

A Tailrace instance from createTailrace().

`model`

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

`opts`

Optional. See AiSdkWrapOptions.

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

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

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

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

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

wrapModel

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