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

# Test Canvas

> Send a test message through a compiled E.V.I. canvas in sandbox mode.

```http theme={null}
POST /api/v1/evi/canvases/{id}/test
Authorization: Bearer theo_sk_...
Content-Type: application/json

{
  "message": "Check stock for SKU-1234",
  "history": [
    { "role": "user", "content": "Hello" },
    { "role": "assistant", "content": "Hi! How can I help?" }
  ]
}
```

Compiles the canvas (or uses cached compilation) and sends a test message through the sandbox. Tool calls are simulated with mock data — no real external requests are made.

## Parameters

* `message` (string, required) — The test message (max 4000 chars).
* `history` (array, optional) — Up to 10 previous messages for multi-turn testing. Each has `role` ("user" or "assistant") and `content`.

## Response

```json theme={null}
{
  "response": "SKU-1234 currently has 47 units in stock...",
  "cost_cents": 5
}
```

## Sandbox Constraints

* No real external HTTP requests
* Tool calls return simulated mock data
* Responses are concise for testing
* Credits are debited at the standard rate

Returns `422` if the canvas fails compilation.