References

Configuration

Key	Values	Default
`driver`	`null`, `ws`, `redis`, `pusher`	`null`
`path`	WebSocket endpoint path	`/app/ws`
`redis`	`{ url }` — required by the `redis` driver	—
`pusher`	Pusher credentials — required by the `pusher` driver	—

The null driver discards everything broadcast to it. That is the right default for tests and for a development machine with no broker running, and it is why a missing configuration shows up as silence rather than as an error.

The BroadcastEvent interface

Any object implementing this can be handed to Broadcast.send():

Member	Required	Defaults to
`broadcastOn()`	Yes	—
`broadcastAs()`	No	The class's constructor name
`broadcastWith()`	No	`{}`

Because broadcastAs() falls back to the constructor name, renaming an event class silently renames the event clients listen for. Implement it explicitly on anything a browser subscribes to and the wire name stops depending on a refactor.

Commands

@zerotal/broadcasting ships two channel commands:

Command	What it does
`bun zt channel:list`	List registered broadcast channel authorization rules
`bun zt make:channel OrderChannel`	Add a channel authorization rule to `routes/channels.ts`

Broadcast facade

Method	Signature	Description
`Broadcast.send(event, opts?)`	`(event: BroadcastEvent, opts?: { exceptSocketId?: string }) => void`	Broadcast an event to every channel from its `broadcastOn()`.
`Broadcast.to(channel, name, data?, opts?)`	`(channel: string, eventName: string, data?: unknown, opts?) => void`	Push a raw event to one channel without an event class.
`Broadcast.on(channel)`	`(channel: string) => AnonymousBroadcast`	Begin an anonymous public broadcast (fluent `.as().with().send()`).
`Broadcast.private(channel)`	`(channel: string) => AnonymousBroadcast`	Anonymous broadcast on a private channel.
`Broadcast.presence(channel)`	`(channel: string) => AnonymousBroadcast`	Anonymous broadcast on a presence channel.
`Broadcast.channel(pattern, callback)`	`(pattern: string, callback: ChannelCallback) => void`	Register a channel authorization rule (call in `routes/channels.ts`).
`Broadcast.channels()`	`() => { pattern: string; paramNames: string[] }[]`	List registered channel patterns.
`Broadcast.getMembers(channel)`	`(channel: string) => PresenceMember[]`	Members of a presence channel (real driver only).
`Broadcast.fake()`	`() => BroadcastFake`	Swap in an in-memory recorder for tests.
`Broadcast.resetFake()`	`() => void`	Restore container-backed resolution.

getMembers() reads state the driver holds, so it returns an empty list under the null driver and under fake(). Assert presence membership against a real driver, or assert on the broadcasts themselves instead.

Errors

Error	Thrown when
`BroadcastProviderNotRegisteredError`	The `Broadcast` facade is used before `BroadcastProvider` is registered.
`MissingChannelParameterError`	A `[param]` placeholder is interpolated without its value.

Both extend BroadcastError, which extends ZerotalError, so one catch on BroadcastError covers the pair and a ZerotalError handler catches them alongside the rest of the framework's errors.

Broadcast notifications

Notifications can be delivered over a broadcast channel in real time — add 'broadcast' to a notification's channels() and implement toBroadcast(). See Notifications → Broadcasting.

Next steps

Broadcasting overview — the guide's front page and the rest of the sections.
Events — writing the events this facade sends.
Testing — the fake and its assertions.