# Fit checks

> Use task_type fit with primary and secondary object ids to test whether one object can fit with another object or container.

Source: https://fourechelon.com/docs/fit-checks · Machine-readable: https://fourechelon.com/openapi.json · Index: https://fourechelon.com/llms.txt

## task

fit

## question

Can this object fit with, or inside, that one — and by how much clearance?

## required

| Field | Type | Description |
| --- | --- | --- |
| input.object_id | string | The object being placed or checked. |
| input.secondary_id | string | The container, mating part, or envelope. |
| input.cad_scene | object | Structured geometry containing both ids. point_cloud_scene also works. |

## returns

| Field | Type | Description |
| --- | --- | --- |
| fit_result.fits | Boolean verdict for the pair. |
| fit_result.clearance | Measured gap, in the units of the scene. |
| fit_result.blocking | Which faces or entities cause a failure. |

## notes

Clearance is reported as a number, not an adjective. If you need a pass/fail gate, threshold the measurement yourself so the tolerance lives in your code and is auditable.

## Example

```bash
curl https://fourechelon.com/api/v1/responses \
  -H "Authorization: Bearer $FOUR_ECHELON_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "rowe-1.0",
    "input": {
      "task_type": "fit",
      "object_id": "bracket",
      "secondary_id": "housing",
      "cad_scene": { "schema": "four-cad.cad_scene.v1", "solids": [] }
    }
  }'
```