A post named by its page is found as by its id

Pixelfed names one of our posts by the address of its page
(/@name/<post id>, the post's url) in its Like, Announce and their Undo,
so its likes were dropped as unknown objects. Before an activity is
handled, such a reference to a post of ours, as its object or the object
of the activity it undoes, is replaced by the post's id. Found by the
pasture's new Pixelfed peer.

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

PrivaPub/Federation/Inbox/InboxProcessor.cs

@@ -26,10 +26,12 @@ namespace PrivaPub.Federation.Inbox
 		readonly IReadOnlyDictionary<string, IActivityHandler> _handlers;
 		readonly ILogger<InboxProcessor> _logger;
 		readonly IInteractionLedger _ledger;
+		readonly ILocalActorService _localActors;
 
 		public InboxProcessor(IRemoteActorService remoteActors, IEnumerable<IActivityHandler> handlers, ILogger<InboxProcessor> logger,
-			IInteractionLedger ledger = default)
+			IInteractionLedger ledger = default, ILocalActorService localActors = default)
 		{
+			_localActors = localActors;
 			_remoteActors = remoteActors;
 			_handlers = handlers.ToDictionary(h => h.Type, StringComparer.Ordinal);
 			_logger = logger;
@@ -65,6 +67,7 @@ namespace PrivaPub.Federation.Inbox
 			Arrival.Current = arrival;
 			try
 			{
+				await LocalReferences.Canonicalise(activity, _localActors?.BaseAddress, token);
 				await handler.Handle(activity, actor, token);
 			}
 			catch (Exception ex) when (ex is not OperationCanceledException)