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

# Split Testing

> A/B test agent variants on live traffic and compare per-variant outcomes.

Split testing routes an agent's live calls across **variants** —
weighted configurations that override specific fields (prompt, voice,
product, …) while inheriting everything else from the agent's deployed
config. Each call records which variant served it
(`agent_variant_id` / `agent_variant_label` on the
[Call object](/api-reference/calls#call-object)), and the stats
endpoint compares outcomes per variant.

The **control** variant (`is_control: true`) represents the agent's
deployed config unchanged. Enabling split testing auto-creates a
control if none exists.

## Endpoints

| Method   | Path                                          | Description                                        |
| -------- | --------------------------------------------- | -------------------------------------------------- |
| `GET`    | `/v1/agents/{agent_id}/variants`              | List variants                                      |
| `POST`   | `/v1/agents/{agent_id}/variants`              | Create a variant                                   |
| `PATCH`  | `/v1/agents/{agent_id}/variants/{variant_id}` | Update a variant                                   |
| `DELETE` | `/v1/agents/{agent_id}/variants/{variant_id}` | Delete a variant                                   |
| `POST`   | `/v1/agents/{agent_id}/split-testing`         | Enable / disable split testing (staged as a draft) |
| `GET`    | `/v1/agents/{agent_id}/variant-stats`         | Per-variant call stats                             |

## Variant object

```json theme={null}
{
  "id": 41,
  "label": "Warmer greeting",
  "weight": 50,
  "is_control": false,
  "prompt": "You are a warm, upbeat support agent…",
  "voice": null,
  "product": null,
  "background_track": null,
  "thinking_level": null,
  "acknowledgement_prompt_mode": null,
  "acknowledgement_prompt": null,
  "inbound_speak_order": null,
  "outbound_speak_order": null,
  "silence_interval_seconds": null,
  "silence_max_checkins": null,
  "created_at": "2026-04-20T18:24:10.113Z",
  "updated_at": "2026-04-20T18:24:10.113Z"
}
```

| Field                                                                                                                                                                                                                          | Type               | Description                                                                                                        |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------ | ------------------------------------------------------------------------------------------------------------------ |
| `id`                                                                                                                                                                                                                           | integer            | Variant id                                                                                                         |
| `label`                                                                                                                                                                                                                        | string             | ≤ 100 chars                                                                                                        |
| `weight`                                                                                                                                                                                                                       | integer            | 0–100, default 50. Traffic is distributed proportionally to weights                                                |
| `is_control`                                                                                                                                                                                                                   | boolean            | At most one control per agent                                                                                      |
| `prompt`, `voice`, `product`, `background_track`, `thinking_level`, `acknowledgement_prompt_mode`, `acknowledgement_prompt`, `inbound_speak_order`, `outbound_speak_order`, `silence_interval_seconds`, `silence_max_checkins` | field type \| null | **Overrides.** `null` = inherit the agent's deployed value; set a value to change just that field for this variant |

`POST` requires `label` (everything else optional) and returns `201`.
`PATCH` accepts any subset; `DELETE` returns `204`.

***

## Enable / disable split testing

<CodeGroup>
  ```bash cURL theme={null}
  curl -X POST https://api.thunderphone.com/v1/agents/12/split-testing \
    -H "Authorization: Bearer sk_live_YOUR_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{"enabled": true}'
  ```
</CodeGroup>

| Field     | Type    | Default | Description |
| --------- | ------- | ------- | ----------- |
| `enabled` | boolean | `true`  |             |

```json Response theme={null}
{
  "split_testing_enabled": false,
  "draft_split_testing_enabled": true
}
```

The toggle is staged as a **draft** on the agent — live traffic starts
(or stops) splitting only after you
[deploy](/api-reference/agents#deploy-the-draft). Enabling with no
control variant auto-creates one (`label: "Control"`, `weight: 100`).

***

## Variant stats

<CodeGroup>
  ```bash cURL theme={null}
  curl https://api.thunderphone.com/v1/agents/12/variant-stats \
    -H "Authorization: Bearer sk_live_YOUR_API_KEY"
  ```
</CodeGroup>

```json Response theme={null}
[
  {
    "variant_id": 40,
    "label": "Control",
    "is_control": true,
    "calls": 132,
    "success_rate": 84.1,
    "avg_duration_seconds": 163
  },
  {
    "variant_id": 41,
    "label": "Warmer greeting",
    "is_control": false,
    "calls": 129,
    "success_rate": 88.4,
    "avg_duration_seconds": 171
  }
]
```

| Field                  | Type            | Description                                                                                                          |
| ---------------------- | --------------- | -------------------------------------------------------------------------------------------------------------------- |
| `calls`                | integer         | Total calls served by the variant                                                                                    |
| `success_rate`         | number \| null  | % of graded, completed calls with `call_outcome="success"` (ungraded calls excluded); `null` when nothing graded yet |
| `avg_duration_seconds` | integer \| null | Mean duration of completed calls                                                                                     |

***

## Related

<CardGroup cols={2}>
  <Card title="Agents" icon="robot" href="/api-reference/agents">
    `split_testing_enabled` lives on the agent (draft/deploy).
  </Card>

  <Card title="Calls" icon="phone" href="/api-reference/calls">
    Filter call history by `agent_variant_id` fields on each call.
  </Card>
</CardGroup>