EF Core Lightweight mode: HTTP endpoint that injects the DbContext and cascades only via tuple return is still sent before commit (RequiresOutbox gate)

[jeremydmiller]

Follow-up to #3291 (fixed by #3298) and #3353 (fixed by #3357). Filed for completeness while auditing that area — the remaining uncovered shape in the same defect family.

Summary

The GH-3291 branch in EFCorePersistenceFrameProvider.ApplyTransactionSupport(chain, container) — the two-argument overload reached from AutoApplyTransactions — gates the Lightweight-mode outbox enlistment on chain.RequiresOutbox():

else if (isHttpChain(chain)
         && !isMultiTenanted(container, dbContextType)
         && chain.RequiresOutbox()          // <-- this gate
         && chain.ShouldFlushOutgoingMessages()
         && hasDatabaseBackedMessagePersistence(container))

HttpChain.RequiresOutbox() only reflects an injected IMessageBus/MessageContext service dependency (HttpChain.cs, ServiceDependencies(...).Contains(typeof(IMessageBus))). An endpoint that injects the DbContext (so CanApply is true and AutoApplyTransactions claims the chain through this overload) but cascades only via its return tuple never satisfies it:

[WolverinePost("/ef/lightweight/dbcontext-cascade")]
public static (IResult, ItemStored) Post(CreateItemCommand command, ItemsDbContext db)
{
    var item = new Item { Id = Guid.NewGuid(), Name = command.Name };
    db.Items.Add(item);
    return (Results.Ok(), new ItemStored(item.Id));
}

Verified

Probed on main + #3357 (EF-Core-only host, TransactionMiddlewareMode.Lightweight, AutoApplyTransactions, durable local queues, PostgreSQL message store), instrumenting the generated chain:

enlist=False cascade=True save=True standaloneFlush=True requiresOutbox=False

No EnlistInOutboxAsync; EnqueueCascadingAsync runs before SaveChangesAsync, and with MessageContext.Transaction null the send-now branch of MessageBus.PersistOrSendAsync dispatches the cascade before the commit — the same runtime symptom as #3291/#3353, reached through the third and last endpoint shape:

Endpoint shape	Claimed by	Status
injects IMessageBus, publishes explicitly	two-arg overload	fixed by #3298
storage action only, no DbContext injection	entityType overload	fixed by #3357
injects DbContext, cascades via tuple	two-arg overload	this issue

Suggested fix

Since #3357 the branch already requires database-backed message persistence (hasDatabaseBackedMessagePersistence, mirroring EfCoreEnvelopeTransaction's constructor precondition), so the RequiresOutbox() gate could simply be dropped — enlisting an endpoint that never cascades is a no-op flush at commit time, which is exactly the trade #3357 made for the storage-action overload. Alternatively, teach HttpChain.RequiresOutbox() to also return true when the chain has cascading return values (note RequiresOutbox() is only consumed by the EF Core frame provider plus a diagnostics usage source, so the blast radius is small either way).

Either way this should come with test automation mirroring Bug_3353_lightweight_storage_action_cascade (the Wolverine.Http.Tests.EfCoreOnly pinned-ApplicationAssembly pattern): assert EnlistInOutboxAsync present, no pre-commit dispatch, enlist → SaveChangesAsync → CommitAsync ordering.

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