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

# x-tfy-routing-config Header Removal — v0.133

> The x-tfy-routing-config request header is retired from AI Gateway in v0.133. Migrate routing logic to Virtual Models.

<Warning>
  **Applicable to:** Users whose applications send the `x-tfy-routing-config` header directly in request headers, or rely on prompt/agent flows that inject this header automatically.
</Warning>

## What Is Changing

We are retiring support for the `x-tfy-routing-config` request header in AI Gateway. This header is **not supported on and after v0.133**.

## Why This Change

Routing logic should be configured declaratively via [Virtual Models](/docs/ai-gateway/virtual-model) rather than passed as request headers.

## What You Need to Do

1. Move routing logic (targets, weights/priorities, retries, fallbacks) into a **Virtual Model**.
2. Update clients to call the Virtual Model name/path instead of sending `x-tfy-routing-config`.
3. Validate behavior in staging before upgrading to `v0.133`.

## Migration Guidance

Refer to the [Virtual Models documentation](/docs/ai-gateway/virtual-model) for detailed setup instructions.

***

If you need help migrating, reach out and we'll be happy to assist.