Announcements

Store review takes days; an announcement takes seconds: one Firestore document renders as a banner in every open surface (the kit calls these broadcasts). This is remote data, which CWS sanctions; remote code never is.

Publish a broadcast

Firebase console → Firestore → broadcasts collection → create a doc with any ID. The ID doubles as the dismissal key: reuse an ID and users who dismissed it won’t see it again.

field	type	required	notes
message	string	yes	banner text; keep it to one line
level	string	no	info (default) · warning · promo; styling only
link	string	no	https only; renders as “Learn more”
activeFrom	number	no	epoch ms; hidden before this
activeUntil	number	no	epoch ms; hidden after this
minVersion	string	no	only shown on extension versions ≥ this (e.g. "1.2.0")

Delete the doc (or set activeUntil in the past) to retract it.

Typical uses: incident notice (warning), launch or discount (promo with an activeUntil), feature announcements. For “update available” nudges, announce broadly and gate the feature in code; minVersion targets newer versions, not older ranges.

How it flows

The background holds an onSnapshot listener on the collection (public read-only, enforced by Firestore rules) and mirrors it into storage.local.broadcasts; <BroadcastBanner> in the popup, sidepanel, and options page shows the first active one. Dismissals are per-message and local (storage.local.broadcastDismissals). Offline, the last mirrored list keeps serving. The extension never writes to the collection; the rules say write: if false for all clients.

Show “what’s new” after an update

The changelog notice after an extension update rides the same banner pipeline with no Firestore involved: runtime.onInstalled (reason "update") writes a local broadcast to storage.local.updateNotice with the ID update-<version> and a link to site.config.ts → urls.changelog.

<BroadcastBanner> renders it after any server broadcast. Dismissal uses the shared per-ID store, so it’s always dismissible (a CWS policy point) and shows once per version; the stored ID doubles as the “seen version” record. The pure logic lives in apps/extension/utils/update-notice.ts.