Honor shared JasperFx.IdentityAttribute in Polecat aggregate id resolution (closes #3117)

docs/guide/durability/polecat/event-sourcing.md

@@ -272,6 +272,15 @@ public class MarkItemReady
 }
 ```
 
+::: tip
+The Polecat integration recognizes both its own `Wolverine.Polecat.IdentityAttribute` and the
+shared `JasperFx.IdentityAttribute` used elsewhere in the Critter Stack (and by the
+[Marten integration](../marten/event-sourcing)). If you maintain a single, store-agnostic
+command/aggregate source that is compiled against both Marten and Polecat, decorate the identity
+member with the shared `JasperFx.IdentityAttribute` (i.e. `using JasperFx;`) and it will be honored
+by both stores — no per-store attribute alias is required.
+:::
+
 ## Forwarding Events
 
 See [Event Forwarding](./event-forwarding) for more information.

src/Persistence/PolecatTests/AggregateHandlerWorkflow/AggregateHandlerAttributeTests.cs

@@ -88,6 +88,15 @@ public void determine_aggregate_id_with_identity_attribute_help()
             .Name.ShouldBe(nameof(RejectPcInvoice.Something));
     }
 
+    [Fact]
+    public void determine_aggregate_id_with_shared_jasperfx_identity_attribute()
+    {
+        // Regression for #3117 -- Polecat should honor the shared JasperFx.IdentityAttribute
+        // used across the rest of the Critter Stack (and Marten), not just its own [Identity].
+        AggregateHandling.DetermineAggregateIdMember(typeof(PcInvoice), typeof(RejectPcInvoiceShared))
+            .Name.ShouldBe(nameof(RejectPcInvoiceShared.Something));
+    }
+
     [Fact]
     public void determine_aggregate_id_with_identity_attribute_bypass()
     {
@@ -155,6 +164,10 @@ public record PcInvoiceCreated;
 
 public record RejectPcInvoice([property: Identity] Guid Something);
 
+// Uses the shared JasperFx.IdentityAttribute (fully qualified to bypass the
+// file-level alias pinning [Identity] to Wolverine.Polecat.IdentityAttribute).
+public record RejectPcInvoiceShared([property: JasperFx.Identity] Guid Something);
+
 public class PcInvoiceHandler
 {
     public PcInvoiceCreated Handle(CreatePcInvoice command)

src/Persistence/Wolverine.Polecat/AggregateHandling.cs

@@ -185,7 +185,12 @@ internal static void ValidateMethodSignatureForEmittedEvents(IChain chain, Metho
     internal static MemberInfo DetermineAggregateIdMember(Type aggregateType, Type commandType)
     {
         var conventionalMemberName = $"{aggregateType.Name}Id";
-        var member = commandType.GetMembers().FirstOrDefault(x => x.HasAttribute<IdentityAttribute>())
+
+        // Honor both the Polecat-specific [Identity] and the shared JasperFx.IdentityAttribute
+        // used across the rest of the Critter Stack (and Marten) so a single store-agnostic
+        // command/aggregate source can codegen against both stores.
+        var member = commandType.GetMembers().FirstOrDefault(x =>
+                         x.HasAttribute<IdentityAttribute>() || x.HasAttribute<JasperFx.IdentityAttribute>())
                      ?? commandType.GetMembers().FirstOrDefault(x =>
                          x.Name.EqualsIgnoreCase(conventionalMemberName) || x.Name.EqualsIgnoreCase("Id"));
 
@@ -197,7 +202,7 @@ internal static MemberInfo DetermineAggregateIdMember(Type aggregateType, Type c
         if (member == null)
         {
             throw new InvalidOperationException(
-                $"Unable to determine the aggregate id for aggregate type {aggregateType.FullNameInCode()} on command type {commandType.FullNameInCode()}. Either make a property or field named '{conventionalMemberName}', or decorate a member with the {typeof(IdentityAttribute).FullNameInCode()} attribute");
+                $"Unable to determine the aggregate id for aggregate type {aggregateType.FullNameInCode()} on command type {commandType.FullNameInCode()}. Either make a property or field named '{conventionalMemberName}', or decorate a member with the {typeof(IdentityAttribute).FullNameInCode()} or {typeof(JasperFx.IdentityAttribute).FullNameInCode()} attribute");
         }
 
         return member;