R9 Web Push, then the honest version: VAPID key, push subscriptions, encrypted pushes, 4.5.0 advertised

The server's VAPID key (PushKeys, made on first need, in Mongo) is the instance API's vapid.public_key and every app's
vapid_key. /api/v1/push/subscription (POST, GET, PUT, DELETE) keeps one subscription per access token, so per persona;
every notification kept (never a filtered one) is queued as a SendPush job for the subscriptions whose alert and policy
admit it, and sent through the `push` client (the safe handler, https only) encrypted as RFC 8291 aes128gcm or the
aesgcm draft with an ES256 VAPID JWT. 404/410 delete the subscription, 429/5xx/timeouts retry, other answers drop the
push. Subscriptions end with their tokens (revocation, sessions ended, suspension, deletion, a restore); backups hold
neither keys nor subscriptions. The walk of every Mastodon 4.3-4.5 client route (docs/MASTODON-API.md) added
conversations/:id/unread, domain_blocks/preview, v2 notifications clear and PUT policy, /oauth/userinfo and stubs, so both
instance APIs now say 4.5.0 (compatible; PrivaPub <release>). The pasture gets a push sink (pushsink.test) and
scenarios/push.sh in batch A.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WpVCoDeM1qUTRp4fXQdfof

PrivaPub/Domain/Social/Notifications.cs

@@ -7,6 +7,25 @@ namespace PrivaPub.Domain.Social
 {
 	public static class Notifications
 	{
+		// told of every notification once it is kept for the persona's lists and streams: never one the notification policy
+		// filtered or dropped, nor one its blocks and mutes hid. Web Push hangs here (R9, WebPushDispatcher, set while the
+		// host runs; the command line sets nothing). Whatever it does never fails the notification.
+		public static Func<Notification, CancellationToken, Task> Told { get; set; }
+
+		static async Task Tell(Notification notification, CancellationToken token)
+		{
+			if (Told is not { } told)
+				return;
+			try
+			{
+				await told(notification, token);
+			}
+			catch (Exception)
+			{
+				//the hook logs its own failures
+			}
+		}
+
 		public static async Task Add(string avatarId, NotificationType type, string fromAccountId, string fromActorUri, string postId,
 			CancellationToken token, string emoji = default, string emojiUrl = default, string text = default)
 		{
@@ -42,6 +61,7 @@ namespace PrivaPub.Domain.Social
 				var told = new Timelines.Streams.Event("notification", notification.ID);
 				Timelines.Streams.ToPersona(avatarId, new Timelines.Streams.Key(Timelines.Streams.User), told);
 				Timelines.Streams.ToPersona(avatarId, new Timelines.Streams.Key(Timelines.Streams.UserNotification), told);
+				await Tell(notification, token);
 			}
 			catch (MongoWriteException ex) when (ex.WriteError?.Category == ServerErrorCategory.DuplicateKey)
 			{
@@ -73,6 +93,7 @@ namespace PrivaPub.Domain.Social
 			var told = new Timelines.Streams.Event("notification", notification.ID);
 			Timelines.Streams.ToPersona(avatarId, new Timelines.Streams.Key(Timelines.Streams.User), told);
 			Timelines.Streams.ToPersona(avatarId, new Timelines.Streams.Key(Timelines.Streams.UserNotification), told);
+			await Tell(notification, CancellationToken.None);
 		}
 	}
 }