Recipients and groups

A recipient says which clients something goes to. fireClient takes one, and so does a set's audience.

Recipients

Recipient	Reaches
Lync.all	Every client.
player	One client.
{ alice, bob }	The listed clients.
group	The members of a group.
Lync.except(t)	Every client but t, where t is a player, a list or a group.

A recipient is resolved when the flush goes out, not when you name it. So Lync.except(group) follows the group's membership at every flush.

Joining

A client is reachable once it has called Lync.start() and its handshake has been accepted.

Sent to a client still joining	Result
A packet	Dropped.
A server request	Ends with "unanswered".
Set records	Sent once it joins, as the current state.

To message a client as soon as it can hear you, have it fire a packet after start and answer from that packet's listener.

Groups

A group is a set of players you maintain, such as a team or a lobby.

local Players = game:GetService("Players")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local Lync = require(ReplicatedStorage.Lync)

local red = Lync.group()

local function joined(player: Player)
    red:add(player)
end

Players.PlayerAdded:Connect(joined)
for _, player in Players:GetPlayers() do
    joined(player)
end

for _, member in red do
    print(member.Name)
end

Call	Does
add(player), remove(player)	Adding a member twice or removing a non-member does nothing.
has(player)	Whether the player is a member.
#group	The number of members.
for _, player in group	Each member, in no fixed order.
destroy()	Empties the group. Any later use throws.

Players who leave the game are removed from every group automatically.