Per-Mediation DI Scopes

ID: runtime.dispatch-scopes
Name: Per-mediation DI scopes
Maturity: GA
Summary: Creates isolated service-provider scopes per mediation call through IMessageDispatchScopeFactory.

What It Does

The Microsoft DI and Autofac adapters each register one container-specific IMessageDispatchScopeFactory. MessageModule requires that contract and does not inspect a container or silently fall back to the root provider. MessageMediator creates one dispatch scope per call and retains it through async completion. Manual hosts may explicitly register RootMessageDispatchScopeFactory when root-provider resolution is intentional.

Public Surface

API	Role
`IMessageDispatchScopeFactory.CreateScope()`	Creates one dispatch scope
`IMessageDispatchScope.ServiceProvider`	Service provider for handler resolution
Microsoft DI dispatch-scope factory	Opens an `IServiceScope` per dispatch
Autofac dispatch-scope factory	Opens an `ILifetimeScope` per dispatch
`RootMessageDispatchScopeFactory`	Explicit root-provider opt-in

Packages

LiteBus.Runtime.Abstractions for contracts
LiteBus.Runtime for explicit root-provider implementation
LiteBus.Runtime.Extensions.Microsoft.DependencyInjection or LiteBus.Runtime.Extensions.Autofac for container implementations
LiteBus.Messaging for the consumer

Requires

runtime.message-module
runtime.message-mediator

Invariants

One dispatch scope per mediation operation.
Scoped provider is disposed on scope dispose.
Missing scope-factory composition fails before the container is used.
Explicit root dispatch does not dispose the root container.

Non-Goals

Cross-message shared scopes.

Observability

No dedicated scope metric.

Test Coverage

Covered Use Cases

`MediationScopeRetentionTests.Mediate_delayed_task_retains_dispatch_scope_until_task_completes`

Test kind: Unit
Expected outcome: scope retained until delayed task completion

`MediationScopeRetentionTests.Mediate_stream_result_retains_dispatch_scope_until_enumeration_completes`

Test kind: Unit
Expected outcome: scope retained for full stream enumeration

Untested Use Cases

Use case	Priority	Notes
Manual-host root opt-in across a complete mediator pipeline	Medium	The explicit factory is unit-covered; host-specific composition remains application-owned

Out-of-Scope Use Cases

Nested scope orchestration in core runtime.

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