feat: Add keyed service support for decorator registration (Phase 2 of #3)

[ncipollina]

Summary

This PR completes Phase 2 of issue #3 by adding full support for keyed service registrations with decorators. Users can now register services with keys and DecoWeaver will automatically apply decorators while preserving the keyed service semantics.

Closes #3

New Features

Keyed Service Registration Support

• ✅ Keyed parameterless registration: AddKeyedScoped<TService, TImplementation>(serviceKey)
• ✅ Keyed factory delegate (two-parameter): AddKeyedScoped<TService, TImplementation>(serviceKey, factory)
• ✅ Keyed factory delegate (single-parameter): AddKeyedScoped<TService>(serviceKey, factory)
• ✅ All lifetimes supported: AddKeyedScoped, AddKeyedTransient, AddKeyedSingleton
• ✅ Multiple keys per service: Register the same service type with different keys independently
• ✅ All key types supported: string, int, enum, custom objects

Nested Key Strategy

To prevent circular resolution while preserving the user's original key:

• User's original key is preserved for resolution via GetRequiredKeyedService(userKey)
• Internally, DecoWeaver creates a nested key: "{userKey}|{ServiceAQN}|{ImplAQN}"
• Each key gets an independent decorator chain - no sharing between keys

Example Usage

// Basic keyed service with decorator
[DecoratedBy<LoggingRepository<>>]
public class SqlRepository<T> : IRepository<T> { }

// Register with string key
services.AddKeyedScoped<IRepository<User>, SqlRepository<User>>("sql");

// Register same service type with different keys
services.AddKeyedScoped<IRepository<User>, CosmosRepository<User>>("cosmos");

// Resolve using original key
var sqlRepo = serviceProvider.GetRequiredKeyedService<IRepository<User>>("sql");
var cosmosRepo = serviceProvider.GetRequiredKeyedService<IRepository<User>>("cosmos");

// Keyed with factory delegate
services.AddKeyedScoped<IRepository<User>, SqlRepository<User>>(
    "sql",
    (sp, key) => new SqlRepository<User>("Server=sql01")
);

Implementation Changes

Core Generator Changes

1. Extended RegistrationKind enum with three keyed service variants:

   • KeyedParameterless
   • KeyedFactoryTwoTypeParams
   • KeyedFactorySingleTypeParam

2. Updated ClosedGenericRegistration model:

   • Added ServiceKeyParameterName field to capture the key parameter name

3. Enhanced ClosedGenericRegistrationProvider:

   • Detects keyed service signatures (2 or 3 parameters)
   • Validates object? type for service key parameter
   • Detects Func<IServiceProvider, object?, T> for keyed factory delegates

4. Updated InterceptorEmitter:

   • Added 3 new interceptor emission methods for keyed variants
   • Generates nested key using DecoratorKeys.ForKeyed() helper
   • Preserves user's original key for decorated factory registration

Test Coverage

Added 7 comprehensive test cases (039-045):

• ✅ 039: KeyedService_SingleDecorator - Basic keyed service with single decorator
• ✅ 040: KeyedService_MultipleKeys - Same service type with different keys
• ✅ 041: KeyedService_MultipleDecorators - Decorator stacking with keyed services
• ✅ 042: KeyedService_IntegerKey - Non-string key type
• ✅ 043: KeyedService_FactoryDelegate - Keyed service with factory delegate
• ✅ 044: KeyedService_NoDecorators - Pass-through without decorators
• ✅ 045: KeyedService_Transient - Different lifetime variation

All existing tests pass with updated snapshots.

Sample Project

Updated sample project with working examples:

• Example 5: Keyed service with string key "primary"
• Example 6: Multiple keyed services with keys "cache" and "database"

Documentation

Comprehensive documentation updates:

• ✅ changelog.md: Added 1.0.3-beta release notes
• ✅ usage/class-level-decorators.md: Added 170+ line keyed services section with examples
• ✅ README.md: Updated Key Features section to include keyed services
• ✅ CLAUDE.md: Added keyed service patterns to supported registrations and dedicated section
• ✅ releasenotes.props: Added 1.0.3-beta condition and release notes
• ✅ Directory.Build.props: Updated version to 1.0.3-beta

Technical Details

Nested Key Format

// User provides: "sql"
// Generated internal key: "sql|System.IRepository`1[[User]]|MyApp.SqlRepository`1[[User]]"
var nestedKey = DecoratorKeys.ForKeyed(serviceKey, typeof(IRepository<User>), typeof(SqlRepository<User>));

Generated Interceptor Pattern

[InterceptsLocation(...)]
internal static IServiceCollection AddKeyedScoped_0<TService, TImplementation>(
    this IServiceCollection services,
    object? serviceKey)
    where TService : class
    where TImplementation : class, TService
{
    // Create nested key to prevent circular resolution
    var nestedKey = DecoratorKeys.ForKeyed(serviceKey, typeof(TService), typeof(TImplementation));
    
    // Register undecorated implementation with nested key
    services.AddKeyedScoped<TService, TImplementation>(nestedKey);
    
    // Register decorated factory with user's original key
    services.AddKeyedScoped<TService>(serviceKey, (sp, key) =>
    {
        var current = sp.GetRequiredKeyedService<TService>(nestedKey);
        current = DecoratorFactory.Create(sp, typeof(TService), typeof(CachingDecorator<>), current);
        current = DecoratorFactory.Create(sp, typeof(TService), typeof(LoggingDecorator<>), current);
        return current;
    });
    
    return services;
}

Breaking Changes

None. This is a purely additive feature that does not affect any existing functionality.

Test Plan

• ✅ All existing tests pass (45 tests total)
• ✅ 7 new test cases covering keyed service scenarios
• ✅ Solution builds successfully in Release mode
• ✅ Sample project runs and demonstrates keyed services working correctly
• ✅ All snapshots updated and verified

Related Issues

Closes #3 (Phase 2: Keyed service support)

🤖 Generated with Claude Code

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[ncipollina]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".