Tabs and Identity

Every tab has a name

Each hook or provider instance gets a sourceName. It is attached to every message that tab sends, so other tabs can show who did something (“Deploy finished, from Tab Owl”). If you do not set one, a unique name is generated per tab.

useBroadcastChannel('app', { sourceName: 'settings-tab' });

Two rules:

• Keep it unique per tab. A tab ignores any message whose source equals its own sourceName. Two tabs sharing a name never receive each other’s messages.
• Do not build it inline with crypto.randomUUID() on every render: the name would change constantly and break the self-filter. Generate once (in state, a ref, or outside the component) or set a stable label.

Ping: who else is here?

ping() broadcasts a probe and collects answers from the other tabs currently on the channel:

const { ping, isPingInProgress } = useBroadcastChannel('app', { sourceName: 'Tab A' });

const sources = await ping(300); // e.g. ['Tab B', 'Tab C']

• Returns the source names of other tabs only (your own tab is excluded).
• Tabs that joined the channel after your ping, or that closed, simply do not answer. The result is a snapshot, not a live subscription: ping again to refresh.
• isPingInProgress is true while a ping is collecting answers, handy for a spinner.

Ping answers come from tabs with the same channel name and namespace. Internal PING/PONG messages never appear in messages and never trigger onMessage.

Late-joining tabs

Identity does not bring history. A tab that opens later sees only messages sent after it opened, whatever keepLatestMessage or getLatestMessage say. To bring a new tab up to date, let it ask and let an existing tab answer: see Late-joining tabs.