fix(notifications): stabilize browser subscription identity

1 files changed, 20 insertions, 1 deletions

diff --git a/src/trigger/notifications.ts b/src/trigger/notifications.ts
index 5b2453c2..30a50a12 100644
--- a/src/trigger/notifications.ts
+++ b/src/trigger/notifications.ts
@@ -14,6 +14,15 @@ const isExpiredSubscriptionError = (error: unknown) => {
 	return statusCode === 404 || statusCode === 410;
 };
 
+const subscriptionEndpoint = (subscription: unknown) =>
+	typeof subscription === "object" &&
+	subscription !== null &&
+	"endpoint" in subscription &&
+	typeof subscription.endpoint === "string" &&
+	subscription.endpoint.length
+		? subscription.endpoint
+		: null;
+
 export const notificationsTask = schedules.task({
 	id: "notifications",
 	run: async (_payload, { ctx }) => {
@@ -56,6 +65,7 @@ export const notificationsTask = schedules.task({
 		};
 
 		const transientErrors: unknown[] = [];
+		const seenEndpoints = new Set<string>();
 
 		webpush.setVapidDetails(
 			(
@@ -81,7 +91,15 @@ export const notificationsTask = schedules.task({
 			).value,
 		);
 
-		for (const subscription of await getUserSubscriptions())
+		for (const subscription of await getUserSubscriptions()) {
+			const endpoint = subscriptionEndpoint(subscription.subscription);
+
+			if (endpoint) {
+				if (seenEndpoints.has(endpoint)) continue;
+
+				seenEndpoints.add(endpoint);
+			}
+
 			try {
 				await webpush.sendNotification(subscription.subscription, ".");
 			} catch (error) {
@@ -94,6 +112,7 @@ export const notificationsTask = schedules.task({
 
 				console.error(error);
 			}
+		}
 
 		if (transientErrors.length > 0)
 			throw new Error("Transient push delivery failures occurred", {