BulletsForHumanity.Hermetic 0.5.11

Hermetic

A domain-driven development kit for event-sourced .NET applications, built fully around source generation.

You declare commands, events, aggregates, and reactions. Hermetic generates the endpoints, the registrations, the projections, the typed Refit clients, and the SignalR observation hub. Compile-time analyzers verify every connection — every event has a handler, every reaction declares its commands, every cycle is detected.

[RaisesEvent<CadetEnrolled>]
public sealed record EnrolCadet(AcademyId AcademyId, CallSign CallSign) : ICommandLaw
{
    public sealed class Handler : CommandHandler<EnrolCadet>
    {
        public override async IAsyncEnumerable<IEffectLaw> Handle(
            EnrolCadet cmd, [EnumeratorCancellation] CancellationToken ct)
        {
            var cadetId = new CadetId(cmd.AcademyId, cmd.CallSign);
            yield return new AppendChronicleEffect(
                cmd.AcademyId.Value,
                new CadetEnrolled(cadetId, cmd.CallSign));
            await Task.CompletedTask;
        }
    }
}

That declaration alone produces:

• A POST /api/command/enrol-cadet endpoint with FluentValidation, [Requires<>] aggregate loading, event-contract verification, transactional save, and projection / reaction fanout.
• A typed Refit extension method on every interface marked [CommandApiSeal<…>].
• A bus dispatch arm so reactions can issue this command without HTTP.
• An OpenAPI schema entry with the command's events documented.

No reflection, fully trimmable, AOT-compatible.

Why Hermetic

Install

dotnet add package BulletsForHumanity.Hermetic

Hermetic ships the runtime contracts together with the analyzers and generators. There is no separate "Logos" package to install.

For domains that need EF Core value converters or Refit extensions, also add:

dotnet add package Marten                       # the standard event-store backend
dotnet add package Refit                        # for typed client surfaces
dotnet add package Microsoft.AspNetCore.SignalR.Client  # for real-time observation (clients only)

Quick start

The Your First Aggregate guide walks through a complete minimal application in under 15 minutes. It uses the Starwatch Academy domain — a fictional superhero training institution — that all the documentation builds on.

After the first guide:

• Events and Commands — the bidirectional contract in depth.
• Reactions — three shapes, one dispatcher.
• Sealing Your API — typed Refit clients.
• Real-Time Observation — projection updates over SignalR.

Documentation

Technical properties

Status

Hermetic is actively developed alongside an application that uses every concept here. Public surface is intentionally narrow; deep changes (analyzer additions, new sigils) ship behind major version bumps. See version.json for the current release and CHANGELOG for what's shipped.

Contributing

See CONTRIBUTING.md. The project follows Conventional Commits; a commit-msg hook in .githooks/ validates the format. Set it up with:

git config core.hooksPath .githooks

License

Business Source License 1.1. Free to use, view, modify, and run. Production use of competing services is restricted; see the license for details.