Monorepo Structure

Onboarding guide for new developers joining Pragmatic.Design.

---

1. Repository Layout

Pragmatic.Design/
├── Pragmatic.Abstractions/        # Shared interfaces (Layer 0) — zero deps
├── Pragmatic.Result/              # Result<T,E> monad (Layer 0)
├── Pragmatic.Ensure/              # Guard clauses (Layer 0)
├── Pragmatic.Validation/          # Fluent validation (Layer 1)
├── Pragmatic.Mapping/             # Object mapping (Layer 1)
├── Pragmatic.Specification/       # Specification pattern (Layer 1)
├── Pragmatic.Internationalization/# i18n, translations (Layer 1)
├── Pragmatic.Temporal/            # Date/time, business days (Layer 1)
├── Pragmatic.Caching/             # Cache abstraction (Layer 1)
├── Pragmatic.Resilience/          # Retry, circuit breaker (Layer 1)
├── Pragmatic.Configuration/       # Config providers (Layer 1)
├── Pragmatic.Logging/             # Structured logging (Layer 1)
├── Pragmatic.Patch/               # JSON Patch support (Layer 1)
├── Pragmatic.Actions/             # Mutations, queries, side effects (Layer 2)
├── Pragmatic.Endpoints/           # HTTP endpoint generation (Layer 2)
├── Pragmatic.Persistence/         # Entity persistence + EF Core (Layer 2)
├── Pragmatic.Events/              # Domain events (Layer 2)
├── Pragmatic.Composition/         # DI + host bootstrap (Layer 2)
├── Pragmatic.Identity/            # User identity, auth (Cross-cutting)
├── Pragmatic.Authorization/       # Permissions, policies (Cross-cutting)
├── Pragmatic.Messaging/           # Message bus, transports (Layer 2)
├── Pragmatic.Jobs/                # Background jobs (Layer 2)
├── Pragmatic.MultiTenancy/        # Tenant resolution (Cross-cutting)
├── Pragmatic.Storage/             # File/blob storage (Layer 2)
├── Pragmatic.Discovery/           # Service discovery (Layer 2)
├── Pragmatic.FeatureFlags/        # Feature toggles (Layer 1)
├── Pragmatic.SourceGenerator/     # Unified Roslyn source generator
├── Pragmatic.Integration.Tests/   # Cross-module integration tests
│
├── shared/                        # Code shared across generators and tests
│   ├── SourceGen/                 # CSharpTemplate, helpers (linked into SG projects)
│   ├── SourceGen.Tests/           # Shared SG test project
│   └── Testing/                   # Shared test utilities (linked into test projects)
│
├── examples/
│   └── showcase/                  # Full E2E demo app (Booking, Billing, Catalog, Accounts)
│       ├── src/                   # Boundary modules + host projects
│       └── tests/                 # Integration + unit tests against real DB
│
├── docs/                          # Design docs, sprints, architecture, how-to guides
│   ├── ROADMAP.md                 # Single source of truth for module status
│   ├── architecture/              # Cross-cutting architecture decisions
│   ├── sprints/                   # Sprint-scoped design docs
│   ├── completed/                 # Archived completed designs
│   ├── future/                    # Planned but not started
│   └── howto/                     # Practical guides (you are here)
│
├── docker/                        # Docker init scripts (e.g., init-databases.sql)
│
├── Directory.Build.props          # Shared MSBuild properties (all projects)
├── Directory.Build.targets        # Shared MSBuild targets (packaging, verify)
├── Directory.Packages.props       # Central Package Management (all NuGet versions)
├── Pragmatic.Design.slnx         # Root solution (XML-based .slnx format)
├── global.json                    # .NET SDK version pin
├── .editorconfig                  # Code style + naming conventions
├── README.md                      # Repo overview
├── CONTRIBUTING.md                # Contribution guidelines
├── LICENSE                        # MIT
└── SECURITY.md                    # Security policy

Layer dependency direction

Layer 0 (Foundation)     Layer 1 (Capabilities)     Layer 2 (Integration)
├── Abstractions         ├── Validation             ├── Actions
├── Result               ├── Mapping                ├── Endpoints
├── Ensure               ├── Specification          ├── Persistence + EFCore
├── DependencyInjection  ├── I18n                   ├── Events + EFCore
└── Identifiers          ├── Caching                ├── Composition + Host
                         ├── Resilience             ├── Authorization
                         ├── Configuration          ├── Messaging
                         └── Temporal               └── Jobs

Higher layers may depend on lower layers. Same-layer dependencies are allowed when explicitly designed. Never depend upward.

---

2. Module Anatomy

Every module follows the same structure:

Pragmatic.{Module}/
├── Pragmatic.{Module}.slnx        # Per-module solution (open just this module in IDE)
├── README.md                       # Quick start, API overview
├── SPECIFICATION.md                # Formal spec (where applicable)
├── src/
│   ├── Pragmatic.{Module}/         # Runtime library (net10.0)
│   ├── Pragmatic.{Module}.EFCore/  # EF Core integration (optional)
│   ├── Pragmatic.{Module}.AspNetCore/ # ASP.NET integration (optional)
│   └── Pragmatic.{Module}.SourceGenerator/ # Standalone SG (rare — most use unified SG)
├── tests/
│   └── Pragmatic.{Module}.Tests/
│       ├── Unit/                   # Pure unit tests
│       ├── Generator/              # SG snapshot tests
│       │   └── Snapshots/          # *.verified.cs files
│       └── Integration/            # Cross-module or DB tests
├── samples/
│   └── Pragmatic.{Module}.Samples/ # Runnable code examples
├── benchmarks/                     # BenchmarkDotNet projects (optional)
│   └── Pragmatic.{Module}.Benchmarks/
└── docs/                           # Module-specific documentation

Key rules

• One file = one class/struct/record. No exceptions.
• Namespace = folder path. A class at Pragmatic.Actions/src/Pragmatic.Actions/Mutation/Mutation.cs must be in namespace Pragmatic.Actions.Mutation. Exception: files under shared/ that use // ReSharper disable once CheckNamespace.
• Max 300-400 lines per file. If larger, split into partial class files or refactor responsibilities.
• File-scoped namespaces (namespace Foo;) enforced by .editorconfig.

Naming conventions (enforced by .editorconfig)

Element	Convention	Example
Class, struct, enum, method, property	PascalCase	CreateReservationMutation
Interface	IPascalCase	IMessageBus
Private field	_camelCase	_repository
Parameter, local	camelCase	userId
Type parameter	TPascalCase	TEntity
Constant	PascalCase	MaxRetryCount
Attribute	{Name}Attribute, always generic	[MapFrom<User>] not [MapFrom(typeof(User))]
Error type	{What}Error	NotFoundError

---

3. Build System

SDK version

Pinned in global.json:

{
  "sdk": {
    "version": "10.0.201",
    "rollForward": "latestPatch"
  }
}

All runtime libraries target net10.0. Source generators target netstandard2.0 (Roslyn requirement).

Directory.Build.props

This file is automatically imported by every project in the repo. It configures:

Section	What it does
Versioning	0.1.0-alpha across all packages
Build settings	LangVersion=latest, nullable enabled, TreatWarningsAsErrors=true
Project type detection	Auto-detects project type by name suffix: *.Tests, *.SourceGenerator, *.Analyzers, *.Benchmarks, *.Samples
Generator projects	Sets netstandard2.0, auto-includes shared/SourceGen/*.cs as linked files
Test projects	Sets net10.0, adds xunit + FluentAssertions + NSubstitute + Verify.Xunit + coverlet, auto-includes shared/Testing/ and shared/SourceGen/Testing/
Runtime libraries	Sets net10.0, enables packaging, AOT compatibility analyzers
Generator-Runtime dual-target	Opt-in IsGeneratorRuntime=true for libraries that need both netstandard2.0 and net10.0

You almost never need to repeat these settings in individual .csproj files.

Directory.Build.targets

Handles:

• Generator packaging: packs SG DLL into analyzers/dotnet/cs NuGet folder.
• Combined packages: when a generator has a sibling runtime library (e.g., Pragmatic.Mapping + Pragmatic.Mapping.SourceGenerator), both get packed into a single NuGet.
• Verify snapshot nesting: *.verified.cs files appear nested under their test file in Solution Explorer.
• Analyzer warnings: CA1822, CA1826, CA2007 are promoted to errors.

Central Package Management

All NuGet versions are declared once in Directory.Packages.props. Individual .csproj files reference packages without a Version attribute:

<!-- In .csproj -->
<PackageReference Include="FluentAssertions" />

<!-- Version resolved from Directory.Packages.props -->
<PackageVersion Include="FluentAssertions" Version="6.12.1" />

To update a package version, change it in Directory.Packages.props only.

Solution format (.slnx)

This repo uses the new XML-based .slnx format, not the legacy .sln. The root solution Pragmatic.Design.slnx organizes all projects into logical folders:

/Pragmatic.Result/          # Foundation modules
/Pragmatic.Validation/      # Capability modules
/Pragmatic.Actions/         # Integration modules
/Tests/                     # All test projects (flat)
/Examples/Showcase/         # Showcase app projects
/Integration Tests/         # E2E test projects
/docs/                      # Solution doc items

Each module also has its own .slnx (e.g., Pragmatic.Actions/Pragmatic.Actions.slnx) so you can open just one module in your IDE without loading the entire monorepo.

---

4. Source Generator Architecture

Unified SG

Almost all code generation lives in a single assembly: Pragmatic.SourceGenerator/src/Pragmatic.SourceGenerator/. This is the main IIncrementalGenerator entry point (PragmaticSourceGenerator.cs).

Pragmatic.SourceGenerator/src/Pragmatic.SourceGenerator/
├── PragmaticSourceGenerator.cs     # Entry point
├── Core/
│   ├── DetectedFeatures.cs         # Flags for which modules are referenced
│   ├── FeatureDetector.cs          # Scans referenced assemblies
│   └── ServiceTypeDetector.cs      # Identifies interfaces, abstracts, services
├── Features/
│   ├── Actions/                    # Mutation invokers, DI registration
│   ├── Caching/                    # Cache key generation
│   ├── Composition/                # Host bootstrap, startup steps
│   ├── Configuration/              # Config binding
│   ├── Endpoints/                  # HTTP endpoint generation
│   ├── FastEnum/                   # Enum extensions
│   ├── I18n/                       # Translation registries
│   ├── Identity/                   # Permission constants
│   ├── Jobs/                       # Job scheduling
│   ├── Mapping/                    # MapFrom/MapTo
│   ├── Messaging/                  # Handler registration, topology
│   ├── Patch/                      # Patch application
│   ├── Persistence/                # Entity config, repos, queries (6 sub-features)
│   ├── Result/                     # Result extensions
│   └── Validation/                 # Validator registration
├── Compositions/                   # Cross-feature enrichers
└── Diagnostics/                    # Diagnostic descriptors (PRAG0001-PRAG1899)

How it works: when a project references Pragmatic.Actions, FeatureDetector sees the Actions DLL in the compilation and sets HasActions = true in DetectedFeatures. The Actions feature then runs its Transform/Template pipeline to generate code. Remove the NuGet reference, and the feature disappears — no manual wiring needed.

Standalone generators (exceptions)

A few modules have their own SG assembly because they are designed to work independently:

• Pragmatic.Result.SourceGenerator
• Pragmatic.Internationalization.SourceGenerator (Country/Currency/Language)
• Pragmatic.Logging.SourceGenerator

Shared SG code

shared/SourceGen/ contains utility code automatically linked into every generator project:

• CSharpTemplate — the base class for all code generation templates
• NamingHelper — suffix deduplication, name normalization
• SymbolExtensions — Roslyn symbol helpers
• GeneratorHelpers — common patterns for IIncrementalGenerator
• AttributeNames — FQN constants for all Pragmatic attributes
• VirtualFolderHints — consistent hint name generation

Every feature follows the Transform/Model/Template pattern:

1. Transform — extracts data from Roslyn symbols into an immutable record model
2. Model — plain immutable data, no Roslyn types (enables caching)
3. Template — extends CSharpTemplate, renders the model into C# source

---

5. Adding New Code

Where to put a new entity

Entities go in a boundary module under the showcase (or your app). Place the entity class at the root of its sub-boundary folder:

Showcase.Booking/
├── Reservations/
│   ├── Reservation.cs            # Entity at folder root
│   ├── Mutations/
│   │   ├── CreateReservationMutation.cs
│   │   └── UpdateReservationMutation.cs
│   ├── Queries/
│   │   └── GetReservationQuery.cs
│   ├── Dtos/
│   │   └── ReservationDto.cs
│   └── Validators/
│       └── CreateReservationValidator.cs

The entity class is annotated with Pragmatic attributes ([Entity], [BelongsTo<Booking>], etc.) and the SG handles the rest (repository, entity config, create method, setters).

Where to put a new action (mutation/query/side effect)

• Mutations (write operations): {SubBoundary}/Mutations/{Name}Mutation.cs
• Queries (read operations): {SubBoundary}/Queries/{Name}Query.cs
• Actions (side effects): {SubBoundary}/Actions/{Name}Action.cs

The SG generates invokers, DI registration, and endpoint wiring automatically from these classes.

Where to put a new endpoint

Custom endpoints go in {SubBoundary}/Endpoints/. Most endpoints are auto-generated from mutations and queries via the [Endpoint] attribute, so you only need explicit endpoint files for non-standard routes.

Where to put tests

Test type	Location
Module unit test	Pragmatic.{Module}/tests/Pragmatic.{Module}.Tests/Unit/
SG snapshot test	Pragmatic.{Module}/tests/Pragmatic.{Module}.Tests/Generator/
Showcase unit test	examples/showcase/tests/Showcase.Tests/Unit/
Showcase integration test	examples/showcase/tests/Showcase.IntegrationTests/
Cross-module integration	Pragmatic.Integration.Tests/

Namespace conventions

Namespace must match folder path. For a class at:

Showcase.Booking/Reservations/Mutations/CreateReservationMutation.cs

The namespace is:

namespace Showcase.Booking.Reservations.Mutations;

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6. Testing Strategy

Unit tests

Every module has unit tests in tests/Pragmatic.{Module}.Tests/Unit/. Test framework stack:

• xunit — test runner
• FluentAssertions — assertion library
• NSubstitute — mocking

Test naming convention: {Method}_{Scenario}_{Expected}

// Examples:
// Validate_WithNullInput_ThrowsArgumentNull
// CreateReservation_WithValidData_ReturnsSuccess
// MapToDto_WithMissingProperty_SkipsProperty

Source generator snapshot tests

Every SG feature must have snapshot tests using Verify. The pattern:

1. Test class extends a module-specific base that wraps GeneratorTestHelper.
2. Feed C# source code to the generator.
3. Assert the generated output matches the *.verified.cs snapshot.

[Fact]
public Task MapFrom_SimpleClass_GeneratesMapping()
{
    var source = """
        [MapFrom(typeof(User))]
        public partial class UserDto { public string Name { get; set; } }
        """;
    var result = RunGenerator(source);
    return Verify(GetGeneratedSource(result, "UserDto.Mapping"));
}

Snapshots live in Generator/Snapshots/ and are version-scrubbed (every test project must have a ModuleInitializer.cs with the version scrubber regex).

Integration tests (Showcase)

End-to-end tests run against a real PostgreSQL database using Testcontainers:

examples/showcase/tests/Showcase.IntegrationTests/
├── Authorization/     # Permission enforcement tests
├── DomainActions/     # Mutation/query execution tests
├── Endpoints/         # HTTP endpoint tests
├── EntityPersistence/ # CRUD + soft delete + audit tests
├── Queries/           # Query filter + pagination tests
└── Infrastructure/    # Fixture, base classes

Every new feature should have at least one integration test in the Showcase.

Test counts

The repo currently has ~4,400 tests across all modules. Key numbers: SG 210, Persistence 295, EFCore 585, Actions 273, Result 455, Validation 353, Showcase 200, Integration 153.

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7. Common Commands

Build

# Build entire monorepo
dotnet build Pragmatic.Design.slnx

# Build a single module
dotnet build Pragmatic.Actions/src/Pragmatic.Actions/Pragmatic.Actions.csproj

# Build with warnings as errors (CI mode)
dotnet build Pragmatic.Design.slnx --warnaserror

Test

# Run all tests
dotnet test Pragmatic.Design.slnx

# Run a single module's tests
dotnet test Pragmatic.Actions/tests/Pragmatic.Actions.Tests/

# Run showcase integration tests (requires Docker for PostgreSQL)
dotnet test examples/showcase/tests/Showcase.IntegrationTests/

# Run a specific test by name
dotnet test Pragmatic.Actions/tests/Pragmatic.Actions.Tests/ --filter "CreateMutation_WithValidInput_GeneratesInvoker"

# Run SG tests only
dotnet test Pragmatic.SourceGenerator/tests/Pragmatic.SourceGenerator.Tests/

Working with the Showcase

# Start infrastructure (PostgreSQL, RabbitMQ)
docker compose -f examples/showcase/docker-compose.yml up -d

# Run the showcase host
dotnet run --project examples/showcase/src/Showcase.Host/

# Run integration tests
dotnet test examples/showcase/tests/Showcase.IntegrationTests/

Package restore

dotnet restore Pragmatic.Design.slnx

Opening in IDE

You can open the full monorepo:

Pragmatic.Design.slnx

Or open just one module for faster IDE performance:

Pragmatic.Actions/Pragmatic.Actions.slnx

Or the showcase independently:

examples/showcase/Showcase.slnx

---

Quick Reference

Question	Answer
What .NET version?	10.0 (SDK 10.0.201, pinned in global.json)
What C# version?	latest (currently C# 14)
Solution format?	.slnx (XML-based, not legacy .sln)
Package versions?	Central in Directory.Packages.props
Where is the SG?	Pragmatic.SourceGenerator/src/Pragmatic.SourceGenerator/
Where is shared SG code?	shared/SourceGen/ (auto-linked into generator projects)
Where is the showcase?	examples/showcase/
Where is the roadmap?	docs/ROADMAP.md
Test framework?	xunit + FluentAssertions + NSubstitute + Verify
Mocking?	NSubstitute (not Moq)
Integration test DB?	PostgreSQL via Testcontainers
Git workflow?	Always rebase, never merge. Squash PRs.