Isolate MAX chat commands from outbox sends

server/QMax.Api/Services/MaxOutboxService.cs

@@ -16,9 +16,12 @@ public sealed class MaxOutboxService(
     IHubContext<QMaxHub> hubContext,
     ILogger<MaxOutboxService> logger)
 {
+    private static readonly TimeSpan InitialChatActionRetryDelay = TimeSpan.FromMinutes(10);
+    private static readonly TimeSpan MaxChatActionRetryDelay = TimeSpan.FromHours(6);
+
     public async Task<int> ProcessOnceAsync(CancellationToken cancellationToken)
     {
-        var processed = await ProcessPendingChatActionsAsync(cancellationToken);
+        var processed = 0;
 
         var candidates = await db.Messages
             .Include(message => message.Chat)
@@ -47,18 +50,20 @@ public sealed class MaxOutboxService(
             }
         }
 
-        return processed;
+        return processed + await ProcessPendingChatActionsAsync(cancellationToken);
     }
 
     private async Task<int> ProcessPendingChatActionsAsync(CancellationToken cancellationToken)
     {
+        var now = DateTimeOffset.UtcNow;
         var pending = await db.Chats
             .Where(chat => chat.PendingMaxAction != null)
             .ToListAsync(cancellationToken);
         pending = pending
+            .Where(chat => IsChatActionDue(chat, now))
             .OrderBy(chat => chat.PendingMaxActionRequestedAt ?? chat.UpdatedAt)
             .ThenBy(chat => chat.Id)
-            .Take(10)
+            .Take(1)
             .ToList();
 
         var processed = 0;
@@ -74,6 +79,30 @@ public sealed class MaxOutboxService(
         return processed;
     }
 
+    private static bool IsChatActionDue(Chat chat, DateTimeOffset now)
+    {
+        if (chat.PendingMaxActionLastAttemptAt is null)
+        {
+            return true;
+        }
+
+        return now - chat.PendingMaxActionLastAttemptAt.Value >= GetChatActionRetryDelay(chat.PendingMaxActionAttempts);
+    }
+
+    private static TimeSpan GetChatActionRetryDelay(int attempts)
+    {
+        if (attempts <= 1)
+        {
+            return InitialChatActionRetryDelay;
+        }
+
+        var multiplier = Math.Pow(2, Math.Min(attempts - 1, 5));
+        var retryDelay = TimeSpan.FromTicks((long)(InitialChatActionRetryDelay.Ticks * multiplier));
+        return retryDelay <= MaxChatActionRetryDelay
+            ? retryDelay
+            : MaxChatActionRetryDelay;
+    }
+
     private async Task<bool> ProcessChatActionAsync(Chat chat, CancellationToken cancellationToken)
     {
         var pendingAction = chat.PendingMaxAction;
@@ -110,6 +139,8 @@ public sealed class MaxOutboxService(
         {
             chat.PendingMaxAction = null;
             chat.PendingMaxActionRequestedAt = null;
+            chat.PendingMaxActionLastAttemptAt = null;
+            chat.PendingMaxActionAttempts = 0;
             chat.PendingMaxActionError = null;
         }
         else