> ## 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.

# Impact Analysis

> Find everything that depends on a service before you change it.

Changing a core service without knowing its dependents turns a contained refactor into a cascade of broken builds. This guide shows you how to map the full blast radius of any service change before touching a single line of code.

## Before you begin

* Your repository is connected and indexed in Potpie ([how to connect a repo](/tutorials/connect-your-repo))
* You know the name of the service or interface you want to change

## Run the analysis

<Steps>
  <Step title="Open Ask on your codebase">
    Go to [Potpie](https://app.potpie.ai) → **Ask** and select your repository.
  </Step>

  <Step title="Ask about dependencies">
    Describe the service you want to change and ask what depends on it:

    ```
        What depends on PaymentService and what breaks if I change its interface?
    ```

    Ask traverses the [knowledge graph](/concepts/knowledge-graph) outward from the target service, mapping every dependent function, class, and module across the repository.
  </Step>

  <Step title="Review the dependency map">
    Ask returns:

    * Every class, function, and module that calls or imports `PaymentService`
    * Each call site with its exact file path and line number
    * Transitive dependencies that would be affected by an interface change
  </Step>
</Steps>

## Results

Once you have the dependency map, you have two paths:

**Proceed manually** by updating each call site yourself using the file paths and line numbers, knowing nothing is missed.

**Hand off to Build** by pasting the dependency list into a [Build](/build-flow/build-a-feature) conversation. Build uses the same map to generate a spec and a diff across every affected file simultaneously.

## Try it on your codebase

→ [Explore your codebase with Ask](/tutorials/explore-your-codebase)