Core

The core packages provide the contracts (Cephalon.Abstractions), the composition runtime (Cephalon.Engine), the decorator framework (Cephalon.Behaviors.*), and the default identifier strategy (Cephalon.Ids.Sfid). Every Cephalon app uses at least the first two.

Packages

Click any package name to jump to its source-doc (the canonical per-package detail synced from the engine repo).

Package	NuGet ID	Maturity	What it ships
Abstractions	Cephalon.Abstractions	M3	All public interfaces — IModule, IBehavior, IUserContext, ITenantContext, capability enums, manifest types. Zero runtime code.
Engine	Cephalon.Engine	M3	The composition runtime — module discovery, capability negotiation, runtime catalog, manifest emission.
Behaviors (base)	Cephalon.Behaviors	M3	The decorator base — IBehavior<TIn, TOut>, BehaviorPipelineBuilder, With* extension methods.
Behaviors.Http	Cephalon.Behaviors.Http	M3	HTTP-flavoured decorators — WithRequireScope, WithProblemDetails, WithIdempotency, WithRateLimit.
Behaviors.Messaging	Cephalon.Behaviors.Messaging	M3	Messaging-flavoured decorators — WithRetry, WithCircuitBreaker, WithOutbox, WithInbox.
Behaviors.Patterns	Cephalon.Behaviors.Patterns	M3	Composite patterns — WithSaga, WithProcessManager, WithBulkhead.
Behaviors.Sourcegen	Cephalon.Behaviors.Sourcegen	M2	Build-time source generator — emits typed registration glue for [Behavior]-tagged classes.
Ids.Sfid	Cephalon.Ids.Sfid	M3	Sfid value type + EF Core converter + IIdGenerator<Sfid>.

Install matrix

Scenario	Minimum packages
Anything Cephalon	Cephalon.Abstractions + Cephalon.Engine
Behaviors in a module	+ Cephalon.Behaviors (matching *.Http / *.Messaging flavour)
Source-generated behavior registration	+ Cephalon.Behaviors.Sourcegen
Sfid id strategy (default)	+ Cephalon.Ids.Sfid

Key types

Cephalon.Abstractions

public interface IModule
{
    ModuleDescriptor Describe();
}

public interface IBehavior<TIn, TOut>
{
    Task<TOut> HandleAsync(TIn input, CancellationToken ct);
}

public interface IUserContext
{
    string? UserId { get; }
    string? TenantId { get; }
    IReadOnlyList<string> Scopes { get; }
    bool IsAnonymous { get; }
}

public enum Capability
{
    Data, Eventing, Identity, Tenancy, Observability,
    Edge, Agentics, Retrieval, Audit, EventSourcing
}

Full surface: API Reference → Cephalon.Abstractions.

Cephalon.Engine

Entry points:

services.AddCephalonEngine();                          // bare engine
services.AddCephalonAspNetCore();                      // engine + ASP.NET Core host adapter
services.AddCephalonWorker();                          // engine + worker host adapter

builder.AddModulesFromAssemblies(typeof(Program).Assembly);
var app = builder.Services.Build(webBuilder);

Cephalon.Behaviors.*

// Decorator chain — applied right-to-left
builder.MapProfile<CreateOrderBehavior>(b => b
    .WithLogging()
    .WithRequireScope("orders:write")
    .WithOutbox()
    .WithRetry(maxAttempts: 3));

Configuration

Engine:* key	Owned by	Purpose
Engine:Id (required)	Cephalon.Engine	Unique identifier — emitted in every log, manifest, OTLP resource attribute.
Engine:Deployment	Cephalon.Engine	Topology + deployment id + region.
Engine:Composition	Cephalon.Engine	Model: "Modular" (currently only option).
Engine:FeatureOrganization	Cephalon.Engine	ModuleFirst
Engine:Data:IdStrategy	Cephalon.Ids.Sfid	"Sfid" (default), "Guid", "Long", "Custom"

Dependencies

Cephalon.Engine            depends on  Cephalon.Abstractions
Cephalon.Behaviors         depends on  Cephalon.Abstractions
Cephalon.Behaviors.Http    depends on  Cephalon.Behaviors
Cephalon.Behaviors.Sourcegen → analyzer (build-time only)
Cephalon.Ids.Sfid          depends on  Cephalon.Abstractions + Sfid.Net (external)

See also

• Technology → Core — narrative description.
• Guide → Concepts — what these primitives mean.
• Reference → API — namespace tree.