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

# Auth Middleware

> Update authentication middleware consistently across every protected route.

Updating authentication middleware with unmapped route dependencies leaves some routes on the old implementation. In a large API, manually auditing every route for middleware usage is error-prone.

**Build** maps every route that depends on the middleware through the [knowledge graph](/concepts/knowledge-graph), generates the updated implementation, and surfaces every affected file as a **diff** before applying anything.

**Request:**

```
Update the authentication middleware to support OAuth
```

**Build traces:**

* Every route that applies the current middleware
* Every file that imports or configures it
* Any tests that cover the existing behavior

**Code generation includes:**

* Updated middleware implementation with OAuth support
* Adjustments to every dependent route where the interface changes
* Modified test coverage reflecting the new behavior

The complete change set appears as a **diff** before PR creation. [Create the PR](/build-flow/build-a-feature#what-it-produces) directly from the **diff** view.

Try it yourself on your codebase → [Build a Feature](/tutorials/make-code-changes)