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

# Debug Chat API

> Create and exchange messages in debug chat sessions to test agent variants outside of production traffic.

The Debug Chat API lets you exercise an agent variant programmatically — create a session against a specific variant and send user turns into it to see the agent's replies, without touching production traffic. Use it for interactive testing, regression checks, and CI-style suites against a branch before you publish.

## What you can do

* Create a debug chat session targeting a specific agent variant.
* Send a user turn into an existing session and read back the agent response.

## Regional base URLs

| Region | Base URL                     |
| ------ | ---------------------------- |
| US     | `https://api.us.poly.ai`     |
| EU     | `https://api.eu.poly.ai`     |
| UK     | `https://api.uk.poly.ai`     |
| Studio | `https://api.studio.poly.ai` |

## Identifiers

Agent Studio labels and API parameters use different names for the same things. When you read an ID from Agent Studio, map it to the API parameter using this table:

| Agent Studio label    | API parameter | Example            |
| --------------------- | ------------- | ------------------ |
| Project ID / Agent ID | `agentId`     | `PROJECT-58RP822I` |

<Note>**Agent ID is the same value as Project ID.** "Agent" is the current product name; "Project" is the legacy term still surfaced in some Agent Studio screens and URLs. Use the value you see in Agent Studio as the `agentId` path parameter — no transformation needed.</Note>

## Authentication

The Debug Chat API uses API key authentication with the `X-API-KEY` header. API keys are scoped to account, project, and region. Issue keys from the API keys section of Agent Studio, or request one from your PolyAI representative.

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
curl --request POST \
  --url "https://api.us.poly.ai/v1/agents/{agentId}/debug-chat" \
  --header "X-API-KEY: $POLYAI_API_KEY"
```

<Warning>
  **The Agent Studio instance and API region must match.** A key generated from `studio.poly.ai` only works against `api.studio.poly.ai`. To call `api.us.poly.ai`, you must generate the key from `studio.us.poly.ai` (and likewise for `eu` and `uk`). A mismatch returns `401 Unauthorized`.

  | Agent Studio URL            | API base URL                 |
  | --------------------------- | ---------------------------- |
  | `https://studio.poly.ai`    | `https://api.studio.poly.ai` |
  | `https://studio.us.poly.ai` | `https://api.us.poly.ai`     |
  | `https://studio.eu.poly.ai` | `https://api.eu.poly.ai`     |
  | `https://studio.uk.poly.ai` | `https://api.uk.poly.ai`     |
</Warning>