In-Memory Inbox Ingress

ID: ingress.inmemory
Name: In-memory inbox ingress
Maturity: GA
Summary: Consumes in-process channel deliveries and accepts them into the inbox through shared transport ingress (testing and single-process dev).

Purpose and Scope

UseInMemoryIngress registers InMemoryInboxIngressModule. The module maps in-memory transport destinations into TransportInboxIngressOptions, registers the shared handler and consumer, and runs the same accept path as broker ingress without Docker.

This is the reference matrix for cross-broker ingress behavior (idempotency, headers, requeue on/off) that broker Docker suites intentionally omit or only partially cover.

Public Surface

bus.AddInMemoryTransport();
bus.AddInbox(inbox => inbox.UseInMemoryIngress(ingress =>
{
    ingress.UseOptions(new InMemoryInboxIngressOptions
    {
        Destination = "commands.inbox",
        RequeueOnFailure = true,
        Safety = new TransportInboxIngressSafetyOptions
        {
            MaxInFlightMessages = 4
        }
    });
}));

Builder API	Role
`InboxModuleBuilder.UseInMemoryIngress(Action<InMemoryInboxIngressModuleBuilder>)`	Registration extension
`InMemoryInboxIngressModuleBuilder.UseOptions(InMemoryInboxIngressOptions)`	Destination channel settings
`InMemoryInboxIngressModuleBuilder.DisableIngressConsumer()`	Handler without consumer loop
`InMemoryInboxIngressModule`	Child module

InMemory Options and Parity vs AMQP

Capability	InMemory ingress	AMQP ingress
Destination required	`Destination` required	`QueueName` required
Root transport required	`AddInMemoryTransport()`	`AddAmqpTransport(...)`
Native receive control	none	`PrefetchCount`
`RequeueOnFailure` toggle	yes (default true)	yes (default true)
Shared `Safety` settings	yes	yes
Declare destination knobs	no	yes

Packages

LiteBus.Inbox.Ingress.InMemory
LiteBus.Transport.InMemory (explicit root transport)

Requires

ingress.registration
Shared ingress capabilities
transport.inmemory
Inbox storage and contracts

Invariants

Process-local only; not cross-process.
Same ack and requeue policy as broker ingress via TransportInboxIngressConsumer.
Identity and idempotency defaults remain broker-scoped through shared mapper options.

Non-Goals

Production multi-node intake.
Broker-specific semantics (TTL, DLQ, federation).

Observability

Shared ingress metrics and logs apply unchanged:

Signal	Meaning
`ingress.ack_failed_after_accept`	Ack failed after inbox accept
EventId 3002	Loop restart after transport failure
EventId 3003	Batch timer flush failure
EventId 3004	Ack failed after accept

Identity, Idempotency, and Trusted Headers

InMemory ingress uses the same mapping defaults as broker adapters:

Setting	Default	Result
`RequireStableIdentity`	true	Missing message id fails closed
`Safety.TrustApplicationHeaders`	false	App idempotency and tenant headers are ignored
Broker-scoped idempotency key	`ingress:{destination}:{brokerMessageId}`	Duplicate redelivery maps to same dedup key

Test Coverage

Covered

Test method	Project
`UseInMemoryIngress_ShouldAcceptProcessAndDispatchCommand`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`PublishThroughInMemoryTransport_ShouldAcceptProcessAndDispatchCommand`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`DuplicateMessageId_ShouldCreateSingleInboxRow`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`UnknownContract_ShouldDiscardWithoutStoreWrite`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`InvalidJson_ShouldDiscardWithoutStoreWrite`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`StoreFull_ShouldNotIncreasePendingRowsBeyondCapacity`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`RequeueEnabled_WithTransientStoreFailure_ShouldEventuallyAccept`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`RequeueDisabled_WithPoisonMessage_ShouldDiscardWithoutStoreWrite`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`MissingContractName_ShouldDiscardWithoutStoreWrite`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`MissingContractVersion_ShouldDiscardWithoutStoreWrite`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`WrongContractVersion_ShouldDiscardWithoutStoreWrite`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`InvalidMessageId_ShouldDiscardWithoutStoreWrite`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`WrongClrShape_ShouldDiscardWithoutStoreWrite`	`LiteBus.Durable.IntegrationTests` (`Ingress/InMemory/`)
`InboxIngressExtensions_ShouldRegisterIngressServices`	`LiteBus.Durable.IntegrationTests` (`Registration/`)

Untested

DisableIngressConsumer with in-memory ingress (covered for AMQP in PostgreSQL registration tests only).
Cross-process in-memory delivery (by design process-local).
Batch-accept path through InMemory ingress builder surface (shared consumer supports it but builder does not expose knobs).

Out-of-Scope

Durability across process restarts (storage axis provides envelope durability after accept).
Production multi-node intake.
Simulating broker-specific edge cases (TTL, DLQ, federation).