Create chat room

POST/chat-rooms

Create a chat room. With two members (including yourself) it becomes a DIRECT room, otherwise a GROUP room. For DIRECT rooms an existing room is returned if one already exists. initialMessage is optional; passing it also creates the first message. A system message recording the creation is always added to a newly created room, whether or not initialMessage is given (not when an existing DIRECT room is returned).

Auth	Login required

Request body

memberIdsstring[]required

User IDs of the other members (required); at least one.

namestring

Room name (for GROUP rooms).

initialMessagestring

Message to post immediately.

Request
curl https://api.4s.link/chat-rooms \
  -X POST \
  -H "Authorization: Bearer 4s_at_..." \
  -H "Content-Type: application/json" \
  -d '{
  "memberIds": ["a1b2c3d4-..."],
  "initialMessage": "よろしくお願いします"
}'

Example response
{
  "id": "r1a2b3c4-...",
  "type": "GROUP",
  "name": "Project Team",
  "members": [
    {
      "id": "rm1a2b3-...",
      "status": "JOINED",
      "user": { "id": "a1b2c3d4-...", "slug": "taro", "firstName": "太郎", "lastName": "山田", "avatarUrl": "https://.../avatar.png" }
    }
  ],
  "lastMessage": { "id": "m1a2b3c4-...", "content": "よろしくお願いします", "createdAt": "2026-08-18T00:00:00.000Z" },
  "unreadCount": 0
}