# Resolve variant groups for ids

`POST /discovery/v1/variants`

Resolve the variant group of each product id and return its siblings.

A follow-up to a search or collections result (like ``/facets``), so a token
authorized on either surface may call it. ``channel_id`` is a query parameter;
the ids, optional ``guid``, and optional ``return_fields`` travel in the JSON body.

Siblings and ``total`` cover only the members this channel can serve. Each
id's siblings are capped at 100; when a group is larger, the first 100 by
``@id`` are returned and ``total`` reflects the group's visible size, so
truncation is detectable.

``variants`` maps every requested id to its variant siblings (the id itself
excluded) and the group's total size.

## Request example

```bash
curl --request POST \
  --url 'https://api.eu1.luigisbox.ai/discovery/v1/variants?channel_id=<channel_id>' \
  --header 'x-lbx-visitor-id: <x-lbx-visitor-id>' \
  --header 'Authorization: Bearer <access_token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "guid": "example",
  "ids": [
    "example"
  ],
  "return_fields": [
    "example"
  ]
}'
```

## Query Parameters

| Name | Type | Required | Description | Constraints |
|---|---|---|---|---|
| `channel_id` | `string` | Yes | Channel identifier (serving destination). | >= 1 characters |

## Header Parameters

| Name | Type | Required | Description | Constraints |
|---|---|---|---|---|
| `x-lbx-visitor-id` | `string` | Yes | Stable per-browser visitor identifier, generated client-side and persisted (e.g. a UUID in localStorage or a first-party cookie). Send it whether or not personalization is on: it is what links a request to a visitor's history and to the analytics events reporting it. Keep it stable across page loads, sessions and token refreshes; never generate it server-side, or every visitor collapses into one. | >= 1 characters |

## Request Body

**Required.**

### application/json

Schema: `object`

#### Attributes

| Attribute | Type | Required | Description | Constraints |
|---|---|---|---|---|
| `guid` | `anyOf(string, null)` | No | Result-set identifier from a prior search or collections response; when given, variant groups are read from that result before falling back to the catalog. | — |
| `ids` | `Array<string>` | Yes | Catalog `@id` values to resolve, used verbatim. | >= 1 items; <= 200 items |
| `return_fields` | `Array<string>` | No | Object fields to return; empty for the default, or ['*'] for all fields. | <= 100 items |

#### Request body example

```json
{
  "guid": "example",
  "ids": [
    "example"
  ],
  "return_fields": [
    "example"
  ]
}
```

## Responses

| Status | Description | Content |
|---|---|---|
| `200` | Successful Response | application/json: object |
| `400` | Malformed request | application/json: object |
| `401` | Missing or invalid credentials | application/json: object |
| `403` | Authenticated but not permitted | application/json: object |
| `422` | Request validation failed | application/json: object |
| `429` | Rate limit exceeded | application/json: object |
| `502` | Upstream service failed | application/json: object |

### 200

Successful Response

#### application/json

Schema: `object`

##### Attributes

| Attribute | Type | Required | Description | Constraints |
|---|---|---|---|---|
| `variants` | `object` | No | Each requested id mapped to its variant siblings and the group's visible size. | — |
| `variants.*` | `object` | No | One requested id's variant siblings, with the group's visible size. | — |
| `variants.*.siblings` | `Array<object>` | No | The variant group's other members this channel can serve — the requested id itself excluded. Capped at 100; when the group is larger the first 100 by ``@id`` are returned and ``total`` reflects its visible size. | — |
| `variants.*.siblings[].@id` | `string` | Yes | Unique identity of the hit. | — |
| `variants.*.siblings[].@type` | `string` | Yes | Type of the hit (e.g. 'product'). | — |
| `variants.*.siblings[].*` | `any` | No | Additional property. | — |
| `variants.*.total` | `integer` | Yes | Member count of the group, counting only the members this channel can serve and including the requested id when it is one of them. An ungrouped or not-found id has empty ``siblings`` and ``total`` 0. Otherwise ``total`` minus the number of returned ``siblings`` is one for a requested id this channel can serve, zero for one it cannot, and more than one when the group is larger than the 100-member cap. | — |

##### Response example

```json
{
  "variants": {
    "additionalProperty": {
      "siblings": [
        {
          "@id": "example",
          "@type": "example"
        }
      ],
      "total": 1
    }
  }
}
```

### 400

Malformed request

#### application/json

Schema: `object`

##### Attributes

| Attribute | Type | Required | Description | Constraints |
|---|---|---|---|---|
| `exception_details` | `object` | No | Machine-readable error context; empty object when there is nothing to add. | — |
| `exception_details.validation_errors` | `anyOf(Array<object>, null)` | No | Every field-level problem found in the request, when validation is what failed. Absent when the rejection is not about a specific value. | — |
| `exception_details.validation_errors[].loc` | `Array<anyOf(string, integer)>` | Yes | Path to the offending value from the request root, e.g. `["body", "filters", 0, "operator"]`. | — |
| `exception_details.validation_errors[].msg` | `string` | Yes | What is wrong with the value at `loc`. | — |
| `exception_details.validation_errors[].type` | `string` | Yes | Stable machine code for the problem, e.g. `missing` or `string_too_short`. | — |
| `exception_details.*` | `any` | No | Additional property. | — |
| `reason` | `string` | Yes | Human-readable, actionable error message. | — |
| `request_id` | `anyOf(string, null)` | No | Request correlation ID (matches the X-Request-Id response header). | — |

##### Response example

```json
{
  "exception_details": {
    "validation_errors": [
      {
        "loc": [
          "example"
        ],
        "msg": "example",
        "type": "example"
      }
    ]
  },
  "reason": "example",
  "request_id": "example"
}
```

### 401

Missing or invalid credentials

#### application/json

Schema: `object`

##### Attributes

| Attribute | Type | Required | Description | Constraints |
|---|---|---|---|---|
| `exception_details` | `object` | No | Machine-readable error context; empty object when there is nothing to add. | — |
| `exception_details.validation_errors` | `anyOf(Array<object>, null)` | No | Every field-level problem found in the request, when validation is what failed. Absent when the rejection is not about a specific value. | — |
| `exception_details.validation_errors[].loc` | `Array<anyOf(string, integer)>` | Yes | Path to the offending value from the request root, e.g. `["body", "filters", 0, "operator"]`. | — |
| `exception_details.validation_errors[].msg` | `string` | Yes | What is wrong with the value at `loc`. | — |
| `exception_details.validation_errors[].type` | `string` | Yes | Stable machine code for the problem, e.g. `missing` or `string_too_short`. | — |
| `exception_details.*` | `any` | No | Additional property. | — |
| `reason` | `string` | Yes | Human-readable, actionable error message. | — |
| `request_id` | `anyOf(string, null)` | No | Request correlation ID (matches the X-Request-Id response header). | — |

##### Response example

```json
{
  "exception_details": {
    "validation_errors": [
      {
        "loc": [
          "example"
        ],
        "msg": "example",
        "type": "example"
      }
    ]
  },
  "reason": "example",
  "request_id": "example"
}
```

### 403

Authenticated but not permitted

#### application/json

Schema: `object`

##### Attributes

| Attribute | Type | Required | Description | Constraints |
|---|---|---|---|---|
| `exception_details` | `object` | No | Machine-readable error context; empty object when there is nothing to add. | — |
| `exception_details.validation_errors` | `anyOf(Array<object>, null)` | No | Every field-level problem found in the request, when validation is what failed. Absent when the rejection is not about a specific value. | — |
| `exception_details.validation_errors[].loc` | `Array<anyOf(string, integer)>` | Yes | Path to the offending value from the request root, e.g. `["body", "filters", 0, "operator"]`. | — |
| `exception_details.validation_errors[].msg` | `string` | Yes | What is wrong with the value at `loc`. | — |
| `exception_details.validation_errors[].type` | `string` | Yes | Stable machine code for the problem, e.g. `missing` or `string_too_short`. | — |
| `exception_details.*` | `any` | No | Additional property. | — |
| `reason` | `string` | Yes | Human-readable, actionable error message. | — |
| `request_id` | `anyOf(string, null)` | No | Request correlation ID (matches the X-Request-Id response header). | — |

##### Response example

```json
{
  "exception_details": {
    "validation_errors": [
      {
        "loc": [
          "example"
        ],
        "msg": "example",
        "type": "example"
      }
    ]
  },
  "reason": "example",
  "request_id": "example"
}
```

### 422

Request validation failed

#### application/json

Schema: `object`

##### Attributes

| Attribute | Type | Required | Description | Constraints |
|---|---|---|---|---|
| `exception_details` | `object` | No | Machine-readable error context; empty object when there is nothing to add. | — |
| `exception_details.validation_errors` | `anyOf(Array<object>, null)` | No | Every field-level problem found in the request, when validation is what failed. Absent when the rejection is not about a specific value. | — |
| `exception_details.validation_errors[].loc` | `Array<anyOf(string, integer)>` | Yes | Path to the offending value from the request root, e.g. `["body", "filters", 0, "operator"]`. | — |
| `exception_details.validation_errors[].msg` | `string` | Yes | What is wrong with the value at `loc`. | — |
| `exception_details.validation_errors[].type` | `string` | Yes | Stable machine code for the problem, e.g. `missing` or `string_too_short`. | — |
| `exception_details.*` | `any` | No | Additional property. | — |
| `reason` | `string` | Yes | Human-readable, actionable error message. | — |
| `request_id` | `anyOf(string, null)` | No | Request correlation ID (matches the X-Request-Id response header). | — |

##### Response example

```json
{
  "exception_details": {
    "validation_errors": [
      {
        "loc": [
          "example"
        ],
        "msg": "example",
        "type": "example"
      }
    ]
  },
  "reason": "example",
  "request_id": "example"
}
```

### 429

Rate limit exceeded

#### application/json

Schema: `object`

##### Attributes

| Attribute | Type | Required | Description | Constraints |
|---|---|---|---|---|
| `exception_details` | `object` | No | Machine-readable error context; empty object when there is nothing to add. | — |
| `exception_details.validation_errors` | `anyOf(Array<object>, null)` | No | Every field-level problem found in the request, when validation is what failed. Absent when the rejection is not about a specific value. | — |
| `exception_details.validation_errors[].loc` | `Array<anyOf(string, integer)>` | Yes | Path to the offending value from the request root, e.g. `["body", "filters", 0, "operator"]`. | — |
| `exception_details.validation_errors[].msg` | `string` | Yes | What is wrong with the value at `loc`. | — |
| `exception_details.validation_errors[].type` | `string` | Yes | Stable machine code for the problem, e.g. `missing` or `string_too_short`. | — |
| `exception_details.*` | `any` | No | Additional property. | — |
| `reason` | `string` | Yes | Human-readable, actionable error message. | — |
| `request_id` | `anyOf(string, null)` | No | Request correlation ID (matches the X-Request-Id response header). | — |

##### Response example

```json
{
  "exception_details": {
    "validation_errors": [
      {
        "loc": [
          "example"
        ],
        "msg": "example",
        "type": "example"
      }
    ]
  },
  "reason": "example",
  "request_id": "example"
}
```

### 502

Upstream service failed

#### application/json

Schema: `object`

##### Attributes

| Attribute | Type | Required | Description | Constraints |
|---|---|---|---|---|
| `exception_details` | `object` | No | Machine-readable error context; empty object when there is nothing to add. | — |
| `exception_details.validation_errors` | `anyOf(Array<object>, null)` | No | Every field-level problem found in the request, when validation is what failed. Absent when the rejection is not about a specific value. | — |
| `exception_details.validation_errors[].loc` | `Array<anyOf(string, integer)>` | Yes | Path to the offending value from the request root, e.g. `["body", "filters", 0, "operator"]`. | — |
| `exception_details.validation_errors[].msg` | `string` | Yes | What is wrong with the value at `loc`. | — |
| `exception_details.validation_errors[].type` | `string` | Yes | Stable machine code for the problem, e.g. `missing` or `string_too_short`. | — |
| `exception_details.*` | `any` | No | Additional property. | — |
| `reason` | `string` | Yes | Human-readable, actionable error message. | — |
| `request_id` | `anyOf(string, null)` | No | Request correlation ID (matches the X-Request-Id response header). | — |

##### Response example

```json
{
  "exception_details": {
    "validation_errors": [
      {
        "loc": [
          "example"
        ],
        "msg": "example",
        "type": "example"
      }
    ]
  },
  "reason": "example",
  "request_id": "example"
}
```