The feed hears new posts as they come

decePub opens PrivaPub's streaming API (one WebSocket for the persona, its
token given as the socket's protocol, never in a URL) and subscribes to the
stream of the feed in view: home, a list, local, federated, a hashtag or
notifications. New posts wait behind the "new" button as polled ones did;
a deletion or an edit applies at once. Polling stays for the feeds PrivaPub
does not stream and for any feed while the socket is down, which opens again
after a pause growing to a minute. The e2e test sees a post made elsewhere
in seconds and its deletion take the card away.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

Pages/Index.razor

@@ -7,8 +7,10 @@
 
 @* The feed page, the middle and right of three columns (NavMenu is the left): the feed with a tab per kind of feed,
    and the globe, which follows the posts in view (GlobePanel). Below lg the globe is a banner above the feed, closed by
-   default on phones. Pages of older posts load as the end comes near (wwwroot/js/feed.js); newer ones are polled every
-   45 seconds while the page is visible and shown on request, because PrivaPub has no streaming. *@
+   default on phones. Pages of older posts load as the end comes near (wwwroot/js/feed.js). Newer ones come through
+   PrivaPub's streaming API (StreamingService) for the feeds it streams, and are polled every 45 seconds while the page
+   is visible otherwise, or while the stream is down; either way they wait behind the "new" button. A deletion or an edit
+   the stream tells is applied at once. *@
 <div class="flex flex-col lg:grid lg:grid-cols-[minmax(0,1fr)_minmax(320px,42%)] gap-3 md:gap-4 w-full h-full">
 
 	<aside class="@(Filter.ShowGlobe ? "block" : "hidden") lg:block lg:order-last relative h-56 sm:h-64 lg:h-full flex-none min-h-0 rounded-xl neo-raised neo-xs overflow-hidden">
@@ -104,6 +106,7 @@
 	[Inject] TimelineService TimelineService { get; set; }
 	[Inject] GroupService GroupService { get; set; }
 	[Inject] ListService ListService { get; set; }
+	[Inject] StreamingService Streaming { get; set; }
 	[Inject] InstanceService InstanceService { get; set; }
 	[Inject] RequestStats RequestStats { get; set; }
 
@@ -133,6 +136,7 @@
 
 	protected override async Task OnInitializedAsync()
 	{
+		Streaming.Received += OnStream;
 		Filter = await LocalStorage.GetItemAsync<FeedFilter>(nameof(FeedFilter)) ?? new() { ShowGlobe = !CascadingState.Status.IsMobileMedia() };
 		if (Filter.TimelineType is TimelineType.Tag && Filter.Tag is not { Length: > 0 })
 			Filter.TimelineType = TimelineType.Home;
@@ -205,6 +209,8 @@
 
 		if (CascadingState.PersonaId != loadedPersonaId)
 		{
+			// a stream is the persona's: another one opens its own
+			await Streaming.Stop();
 			groups = await GroupService.List(CascadingState.PersonaId, cancellationToken);
 			lists = await ListService.All(cancellationToken);
 			loadedPersonaId = CascadingState.PersonaId;
@@ -238,6 +244,7 @@
 		maxId = page.MaxId;
 		minId = page.MinId;
 		lastPollAt = DateTime.UtcNow;
+		await Streaming.Follow(StreamOf(Filter), cancellationToken);
 		StateHasChanged();
 		await Locate(posts, cancellationToken);
 		if (feedModule is not null)
@@ -290,7 +297,7 @@
 		{
 			while (await pollTimer.WaitForNextTickAsync(cancellationToken))
 			{
-				if (IsLoading || CascadingState.IsOffline || minId is null || Filter.TimelineType is TimelineType.Nearby or TimelineType.Direct
+				if (IsLoading || CascadingState.IsOffline || minId is null || Streaming.IsOpen || Filter.TimelineType is TimelineType.Nearby or TimelineType.Direct
 					|| Filter.TimelineType is TimelineType.Groups && groups.FirstOrDefault(g => g.Id == Filter.GroupId)?.IsCommunity != true
 					|| !await feedModule.InvokeAsync<bool>("isVisible", cancellationToken))
 					continue;
@@ -322,6 +329,45 @@
 		}
 	}
 
+	/// <summary>The stream that tells this feed's new posts, or null for a feed PrivaPub does not stream.</summary>
+	static StreamSubscription StreamOf(FeedFilter filter) => filter.TimelineType switch
+	{
+		TimelineType.Home => new("user"),
+		TimelineType.Local => new("public:local"),
+		TimelineType.Federation => new("public:remote"),
+		TimelineType.Notifications => new("user:notification"),
+		TimelineType.Tag when filter.Tag is { Length: > 0 } tag => new("hashtag", Tag: tag),
+		TimelineType.Lists when filter.ListId is { Length: > 0 } list => new("list", List: list),
+		_ => null
+	};
+
+	/// <summary>What the stream tells: a new post or notification waits behind the "new" button; a deletion or an edit is
+	/// applied where the post is.</summary>
+	async Task OnStream(StreamMessage message)
+	{
+		switch (message.Event)
+		{
+			case "update" when message.Status is { } status && Filter.TimelineType is not TimelineType.Notifications:
+			case "notification" when message.Notification is not null && Filter.TimelineType is TimelineType.Notifications:
+				var post = message.Status is { } s ? FeedPost.Of(s) : FeedPost.Of(message.Notification);
+				if (posts.Concat(pending).Any(p => p.Key == post.Key))
+					return;
+				pending.Insert(0, post);
+				break;
+			case "delete" when message.DeletedId is { } id:
+				posts.RemoveAll(p => p.Key == id || p.Status?.Id == id);
+				pending.RemoveAll(p => p.Key == id || p.Status?.Id == id);
+				break;
+			case "status.update" when message.Status is { } edited:
+				foreach (var shown in posts.Concat(pending).Where(p => p.Status?.Id == edited.Id))
+					shown.Status = edited;
+				break;
+			default:
+				return;
+		}
+		await InvokeAsync(StateHasChanged);
+	}
+
 	async Task ShowPending()
 	{
 		var shown = pending;
@@ -400,6 +446,7 @@
 		yield return NerdRow.Of("max_id", maxId ?? (posts.Count > 0 ? Localizer["end"] : null));
 		yield return NerdRow.Of(Localizer["first page"], lastLoadTook is { } took ? NerdRow.Duration(took) : null);
 		yield return NerdRow.Of(Localizer["polled"], lastPollAt is { } polled ? NerdRow.Duration(DateTime.UtcNow - polled) + " " + Localizer["ago"] : null);
+		yield return NerdRow.Of(Localizer["stream"], Streaming.IsOpen ? Localizer["open"] : Localizer["closed, polling"]);
 		yield return NerdRow.Of(Localizer["poll every"], NerdRow.Duration(PollInterval));
 		yield return NerdRow.Of(Localizer["placed"], posts.Count > 0 ? $"{posts.Count(p => p.Location is not null)}/{posts.Count}" : null);
 		if (RequestStats.Latest(1).FirstOrDefault() is { } last)
@@ -412,6 +459,8 @@
 
 	public override async ValueTask DisposeAsync()
 	{
+		Streaming.Received -= OnStream;
+		await Streaming.Stop();
 		await pageCancellation.CancelAsync();
 		pageCancellation.Dispose();
 		loadCancellation?.Cancel();