feat(security): complete capability messaging workflows

Tiku.Api/Controllers/HealthController.cs

@@ -45,6 +45,16 @@ public sealed class HealthController(
         var outboxPending = database
             ? await dbContext.Set<OutboxMessage>().CountAsync(cancellationToken)
             : -1;
+        var outboxOldestSentTime = database
+            ? await dbContext.Set<OutboxMessage>()
+                .Select(message => (DateTime?)message.SentTime)
+                .MinAsync(cancellationToken)
+            : null;
+        var outboxOldestAgeSeconds = outboxOldestSentTime is null
+            ? 0
+            : Math.Max(0, (DateTimeOffset.UtcNow - new DateTimeOffset(outboxOldestSentTime.Value)).TotalSeconds);
+        var outboxAlert = outboxPending >= messagingOptions.OutboxBacklogAlertCount ||
+                          outboxOldestAgeSeconds >= messagingOptions.OutboxOldestMessageAlertSeconds;
         var ready = database && redis && rabbitMq;
         var response = new
         {
@@ -52,7 +62,14 @@ public sealed class HealthController(
             database,
             redis = new { configured = redisSecurityStore.IsConfigured, ready = redis },
             rabbitMq = new { configured = messagingOptions.IsConfigured, ready = rabbitMq },
-            outbox = new { pending = outboxPending },
+            outbox = new
+            {
+                pending = outboxPending,
+                oldestAgeSeconds = Math.Round(outboxOldestAgeSeconds, 1),
+                alert = outboxAlert,
+                backlogAlertCount = messagingOptions.OutboxBacklogAlertCount,
+                oldestMessageAlertSeconds = messagingOptions.OutboxOldestMessageAlertSeconds
+            },
             checkedAt = DateTimeOffset.UtcNow
         };
         return ready ? Ok(response) : StatusCode(StatusCodes.Status503ServiceUnavailable, response);