Retrieves all messages for a specific application. Returns both messages sent to the candidate (outbound) and responses from the candidate (inbound). Messages are ordered by sent date, newest first.

Authentication: Requires valid x-api-key header.

Response Example:

{
  "data": [
    {
      "external_id": "uuid123456",
      "message_id": "msg001",
      "message_body": "Thank you for applying! We'd like to schedule an interview.",
      "message_direction": "to_candidate",
      "message_type": "text",
      "sent_at": "Thu, 23 Oct 2025 13:12:47 GMT",
      "status": "SENT",
      "subject": null
    },
    {
      "external_id": "response789012",
      "message_id": "msg002",
      "message_body": "I am available for an interview next week.",
      "message_direction": "from_candidate",
      "message_type": "text",
      "sent_at": "Thu, 23 Oct 2025 13:12:47 GMT",
      "status": "DELIVERED",
      "subject": null
    },
    {
      "external_id": "response789015",
      "message_id": "msg005",
      "message_body": "Hey your interview is scheduled for next week.",
      "message_direction": "to_candidate",
      "message_type": "email",
      "sent_at": "Thu, 23 Oct 2025 13:12:47 GMT",
      "status": "DELIVERED",
      "subject": "Interview Scheduled"
    },
  ]
}