Contract Registration

Header

• ID: analyzers.missing-contract-on-handled-type, analyzers.explicit-contract-registration
• Diagnostics: LB1007 (Warning), LB1017 (Warning)
• Maturity: GA
• Summary: Guards durable command and event contract discovery by checking attribute and configuration registration paths.

Rule Split

LB1007

Reports for handled durable command or event message types when all of the following are true:

• Type is used by a command or event handler.
• Type does not declare [MessageContract].
• Type is not explicitly registered by Contracts.Register<T>(), Register(typeof(T), ...), RegisterFromAssembly(...), or AddFromAssembly(...).

LB1017

Reports for attributed durable message types when all of the following are true:

• Type declares [MessageContract(...)].
• Type is durable (ICommand, ICommand<TResult>, or IEvent).
• Type is not explicitly registered by Register or assembly scanning (RegisterFromAssembly or AddFromAssembly).

Bad Example

using System.Threading;
using System.Threading.Tasks;
using LiteBus.Commands.Abstractions;

public sealed record ProcessPaymentCommand(int PaymentId) : ICommand;

public sealed class ProcessPaymentCommandHandler : ICommandHandler<ProcessPaymentCommand>
{
    public Task HandleAsync(ProcessPaymentCommand command, CancellationToken cancellationToken = default)
        => Task.CompletedTask;
}

Expected diagnostic:

• LB1007 because ProcessPaymentCommand has no attribute and no registration.

Good Example

using LiteBus.Commands.Abstractions;
using LiteBus.Messaging.Abstractions;

[MessageContract("payments.process-payment", 1)]
public sealed record ProcessPaymentCommand(int PaymentId) : ICommand;

public static class ModuleConfiguration
{
    public static void Configure(ContractsRegistry contracts)
    {
        contracts.Register<ProcessPaymentCommand>("payments.process-payment", 1);
    }
}

This avoids both warnings:

• LB1007 is satisfied by attribute and explicit registration.
• LB1017 is satisfied by explicit registration.

Suppression Guidance

• Prefer explicit registration over suppression because contract discovery predictability matters in durable paths.
• If registration happens in generated code or external composition, suppress at the narrowest scope and document where registration occurs.
• Do not suppress broadly in .editorconfig unless a whole project intentionally relies on runtime-only contract discovery.

Test Coverage

Source: tests/LiteBus.Analyzers.UnitTests/MissingMessageContractRegistrationAnalyzerTests.cs, tests/LiteBus.Analyzers.UnitTests/ExplicitMessageContractRegistrationAnalyzerTests.cs