## Add or remove a reaction to a message

**post** `/v3/messages/{messageId}/reactions`

Add or remove emoji reactions to messages. Reactions let users express
their response to a message without sending a new message.

**Supported Reactions:**

- love ❤️
- like 👍
- dislike 👎
- laugh 😂
- emphasize ‼️
- question ❓
- custom - any emoji (use `custom_emoji` field to specify)
- sticker - an image peeled onto the message (use `url` or `attachment_id`)

**Stickers** are iMessage-only and cannot be removed — iMessage has no
unpeel operation, so `operation: "remove"` with `type: "sticker"` is
rejected. Position, size and rotation are optional via `placement`, and can
be changed afterwards with
`PATCH /v3/messages/{messageId}/reactions/{reactionId}`.

### Path Parameters

- `messageId: string`

### Body Parameters

- `operation: "add" or "remove"`

  Whether to add or remove the reaction

  - `"add"`

  - `"remove"`

- `type: ReactionType`

  Type of reaction. Standard iMessage tapbacks are love, like, dislike, laugh, emphasize, question.
  Custom emoji reactions have type "custom" with the actual emoji in the custom_emoji field.
  Sticker reactions have type "sticker" with sticker attachment details in the sticker field.

  - `"love"`

  - `"like"`

  - `"dislike"`

  - `"laugh"`

  - `"emphasize"`

  - `"question"`

  - `"custom"`

  - `"sticker"`

- `attachment_id: optional string`

  Reference to a sticker image pre-uploaded via `POST /v3/attachments`.
  Only valid when type is "sticker".

  Either `url` or `attachment_id` must be provided when type is
  "sticker", but not both.

- `custom_emoji: optional string`

  Custom emoji string. Required when type is "custom".

- `part_index: optional number`

  Optional index of the message part to react to.
  If not provided, reacts to the entire message (part 0).

- `placement: optional object { rotation, scale, x, y }`

  Optional position, size and rotation of a sticker on the target
  bubble. Only valid when type is "sticker".

  Every field is independent and optional — omit the object entirely,
  or any field within it, to keep the default (centred, default size,
  unrotated).

  - `rotation: optional number`

    Clockwise rotation in degrees.

  - `scale: optional number`

    Size relative to the default, where 1 matches the size a
    sticker gets natively.

    Values outside 0.5–1.5 are clamped rather than rejected. The
    upper bound keeps a sticker within the size range iMessage
    itself displays: its own limit is larger, but that allowance
    assumes the transparent padding Apple's stickers carry, which
    a full-bleed image does not have.

    Scale is linear, so 1.5 is a little over twice the area.

  - `x: optional number`

    Horizontal position on the target bubble, from -1 (far left) to
    1 (far right). 0 is centred.

  - `y: optional number`

    Vertical position on the target bubble, from -1 (top) to
    1 (bottom). 0 is centred.

- `url: optional string`

  Linq attachment URL of the sticker image — the `download_url`
  returned by `POST /v3/attachments`. Only valid when type is
  "sticker".

  Unlike a media part, this does **not** accept an arbitrary host:
  reactions have no download step, so the image must already be
  stored. To send a sticker from elsewhere, upload it with
  `POST /v3/attachments` first and pass `attachment_id`.

  Either `url` or `attachment_id` must be provided when type is
  "sticker", but not both.

### Returns

- `message: optional string`

- `status: optional string`

- `trace_id: optional string`

### Example

```http
curl https://api.linqapp.com/api/partner/v3/messages/$MESSAGE_ID/reactions \
    -H 'Content-Type: application/json' \
    -H "Authorization: Bearer $LINQ_API_V3_API_KEY" \
    -d '{
          "operation": "add",
          "type": "love",
          "attachment_id": "550e8400-e29b-41d4-a716-446655440000",
          "part_index": 1,
          "url": "https://cdn.linqapp.com/attachments/example/sticker.png"
        }'
```

#### Response

```json
{
  "message": "Reaction processed",
  "status": "accepted",
  "trace_id": "trace_id"
}
```