Like Groups API

Status	Implementation
✅ Shipped	src/feats/groups/

A like group is how users apply to attend an event. The group is formed by one user (the creator) plus optional friends. Once enough event authors approve the group, the group is approved and a private chat is created for the participants.

See also: Approval algorithm, Like-groups model.

All endpoints require Authorization: Bearer <supabase-access-token>.

Endpoints

Method	Path	Description
GET	/groups	List my groups (as creator or member)
GET	/groups/:id	Get a group
POST	/groups/:id/members	Add a friend to the group
DELETE	/groups/:id/members/:userId	Remove a member
GET	/groups/:id/approvals	List approvals for the group
POST	/groups/:id/approve	Approve the group (event author only)
POST	/groups/:id/reject	Reject the group (event author only)

Group creation happens via POST /events/:id/like.

Get group

GET /groups/:id
Authorization: Bearer <token>

{
  "id": "uuid",
  "eventId": "uuid",
  "creatorId": "uuid",
  "status": "pending",
  "memberIds": ["uuid", "uuid"],
  "createdAt": "2026-04-01T00:00:00Z"
}

Visibility: members of the group, the event creator, and event authors.

Manage members

POST /groups/:id/members
{ "userId": "friend-uuid" }

Rules:

• Caller must be the group creator.
• The user being added must be a friend of the group creator.
• The user must not already be in another pending group for the same event.
• Group is in pending (cannot mutate after approved / rejected).

Limit	Value
Members per group	10 (including creator)

DELETE /groups/:id/members/:userId

Removing members before approval recalculates the approval threshold; existing approvals still count. See Approval algorithm → edge cases.

Approvals

GET /groups/:id/approvals

{
  "data": [
    {
      "id": "uuid",
      "groupId": "uuid",
      "authorId": "uuid",
      "decision": "consent",
      "createdAt": "2026-04-01T00:00:00Z"
    }
  ]
}

The decision field is either consent (approve) or refuse (reject).

POST /groups/:id/approve
POST /groups/:id/reject

Authorization: caller must be a current author of the group's event. Each author can only vote once per group.

Approve — consensus algorithm

The threshold formula:

effectiveT = min(consentThreshold, eligible_organizers)

Where eligible_organizers = event authors who haven't refused yet.

Status transitions:

• approved: consents >= effectiveT
• rejected: eligible - refuses < effectiveT (threshold can no longer be reached)
• pending: otherwise

When approved:

1. Group status → approved.
2. A chat of type approved_group is created with all members + all authors as participants.
3. Response includes the new chatId.

{
  "id": "group-uuid",
  "status": "approved",
  "approved": true,
  "chatId": "new-chat-uuid"
}

Reject

When a single author refuses and the threshold becomes unreachable, status → rejected. No chat is created.

Errors

Status	Reason
400	Group not in pending state
403	Caller is not group creator / event author / member
404	Group not found
409	Member already in another pending group for this event

Constants

Constant	Value
MAX_MEMBERS	10 (including creator)
EXPIRATION_HOURS	24
DEFAULT_PAGE_SIZE	20
MAX_PAGE_SIZE	100

Implementation notes

Source: src/feats/groups/.

• The consensus algorithm uses min(consentThreshold, eligible_organizers); see Approval algorithm for the rationale.
• memberKey is a canonical sorted string of member IDs, ensuring unique pending group compositions per event via a partial unique index.
• Group lifecycle and chat creation are wrapped in a single Drizzle transaction so partial state cannot escape.
• Approval decisions are recorded in an append-only like_group_audit table.