Outbox InMemory Transport Dispatch

ID: dispatch.outbox.inmemory
Name: Outbox InMemory transport dispatch
Maturity: GA
Summary: Publish leased outbox envelopes through in-process channels for tests and local pipelines without external brokers.

What It Does

AddInMemoryTransport() registers InMemoryTransportModule at the root. UseInMemoryDispatch on OutboxModuleBuilder registers shared transport outbox dispatch as a feature bridge. This simulates broker publication for integration tests and sample multi-module hosts running in one process.

Packages

Package	Role
`LiteBus.Outbox.Dispatch.InMemory`	Registration glue
`LiteBus.Outbox.Dispatch`	Shared dispatcher
`LiteBus.Transport.InMemory`	Channel-based transport

Requires

dispatch.transport-core
transport.inmemory
durable-core.outbox

Invariants

Default hook failure policy: CompleteDespiteHookFailure.
Same at-least-once processor semantics as broker outbox dispatch.
Destination name must align with consumer/InMemory ingress configuration in tests.

Non-Goals

Not a production message bus.
Does not provide cross-process delivery.

Public Surface

services.AddLiteBus(litebus =>
{
    litebus.AddInMemoryTransport();

    litebus.AddOutbox(outbox =>
    {
        outbox.EnableOutboxProcessor();
        outbox.UseInMemoryDispatch(options =>
        {
            options.DefaultDestination = "orders.events";
        });
    });
});

API	Role
`OutboxModuleBuilder.UseInMemoryDispatch(Action<TransportOutboxDispatcherOptions>? configure = null)`	Registers outbox transport dispatcher that requires the root in-memory transport
`TransportOutboxDispatchModule.DefaultHookFailurePolicy`	Defaults to `CompleteDespiteHookFailure`
`TransportOutboxDispatcher.DispatchAsync(OutboxEnvelope, CancellationToken)`	Shared outbox publish flow over in-process channel transport

Observability

Signal	Detail
`send {destination}`	In-memory publisher span per simulated broker send
`litebus.outbox.processor.published` / `failed`	Terminal store outcomes
`litebus.outbox.processor.persist_skipped`	Relevant when testing at-least-once republication scenarios

InMemoryOutboxAtLeastOnceIntegrationTests documents crash-between-publish-and-persist behavior at the processor layer.

Deep Docs

Test Coverage

Covered

Test method	Project
`OutboxDispatchExtensions_ShouldRegisterTransportDispatcher`	`LiteBus.Durable.IntegrationTests` (`Registration/`)
`ProcessPendingAsync_ShouldPublishEnvelopeToInMemoryDestination`	`LiteBus.Durable.IntegrationTests` (`Dispatch/Outbox/InMemory/`)
`ProcessPendingAsync_WhenTopicMissing_ShouldUseContractNameAsRoute`	`LiteBus.Durable.IntegrationTests` (`Dispatch/Outbox/InMemory/`)
`ProcessPendingAsync_WhenPersistSkippedAfterPublish_ShouldRepublishOnRetry`	`LiteBus.Durable.IntegrationTests` (`Dispatch/Outbox/InMemory/`)

Untested

Hook failure path with CompleteDespiteHookFailure.
Tenant routing strategy and route resolver overrides.
Cross-process outbox to inbox topology (adapter is in-process only).

Out-of-Scope

Production message bus role
Cross-process delivery