> ## Documentation Index
> Fetch the complete documentation index at: https://replyke-feat-push-rich-payload-fields.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Add Entity to List

> Add an entity to a list

Adds an entity to the specified list for the authenticated user. Prevents duplicate additions.

## Path Parameters

<ParamField path="listId" type="string" required>
  ID of the target list
</ParamField>

## Body Parameters

<ParamField body="entityId" type="string" required>
  ID of the entity to add to the list
</ParamField>

## Response

<ResponseField name="id" type="string">
  Unique list identifier
</ResponseField>

<ResponseField name="projectId" type="string">
  Project identifier
</ResponseField>

<ResponseField name="userId" type="string">
  ID of the user who owns the list
</ResponseField>

<ResponseField name="name" type="string">
  Name of the list
</ResponseField>

<ResponseField name="entityIds" type="array">
  Updated array of entity IDs saved in this list (includes the newly added entity)
</ResponseField>

<ResponseField name="createdAt" type="string">
  Creation timestamp in ISO 8601 format
</ResponseField>

<ResponseField name="updatedAt" type="string">
  Last update timestamp in ISO 8601 format
</ResponseField>

## Error Responses

<AccordionGroup>
  <Accordion title="Missing listId or entityId - 400 Bad Request">
    ```json theme={null}
    {
      "error": "Missing listId",
      "code": "list/missing-data"
    }
    ```
  </Accordion>

  <Accordion title="List Not Found - 404 Not Found">
    ```json theme={null}
    {
      "error": "List not found",
      "code": "list/not-found"
    }
    ```
  </Accordion>

  <Accordion title="Entity Already Exists - 409 Conflict">
    ```json theme={null}
    {
      "error": "Entity already exists in the list",
      "code": "list/entity-exists"
    }
    ```
  </Accordion>

  <Accordion title="Server Error - 500 Internal Server Error">
    ```json theme={null}
    {
      "error": "Internal server error.",
      "code": "list/server-error",
      "details": "<Error message>"
    }
    ```
  </Accordion>
</AccordionGroup>

***

## Notes

* Entity will not be added again if it already exists in the list.
* The response includes the updated and populated list object.