---

name: new-feature description: Guide for implementing new features in ZChain. Use when adding new functionality, creating new classes, extending the blockchain, or implementing new miners/hashers. allowed-tools: Read, Write, Edit, Glob, Grep, Bash

Implementing New Features

Step-by-step guide for adding functionality to ZChain.

Architecture Quick Reference

CopyZChain.Core        → Domain models, interfaces, builders
ZChain.CpuMiner    → Mining implementations (IMiner<T>)
ZChain.Hashers     → Hash algorithms (IHasher)
ZChain.Tests       → Unit + integration tests

Feature Types

Adding a New Transaction Type

1. Create record/class (can be in consuming project or Core):

Copypublic record MyTransaction(string Field1, decimal Field2);

1. Use with existing Block:

Copyvar block = new BlockBuilder<MyTransaction>()
    .WithTransaction(new MyTransaction("value", 100m))
    .WithHasher(new Sha256Hasher())
    .Build();

Adding a New Hasher

1. Create in ZChain.Hashers:

Copynamespace ZChain.Hashers;

public class MyHasher : IHasher
{
    public string ComputeHash(string input)
    {
        // Implementation - return hex string
    }
}

1. Add tests in ZChain.Tests/UnitTests/Domain/HasherTests/

2. Consider thread safety (use thread-static or new instance per call)

Adding a New Miner

1. Create in ZChain.CpuMiner or new project:

Copynamespace ZChain.CpuMiner;

public class MyMiner<T>(IHasher hasher, int config) : IMiner<T>
    where T : class
{
    public async Task MineBlock(Block<T> block)
    {
        block.BeginMining();
        // Mining logic - find hash matching difficulty
        block.SetMinedValues(hash, nonce);
    }
}

1. Support CancellationToken for graceful shutdown
2. Add integration tests in ZChain.Tests/Integration/

Extending Block

Avoid modifying Block directly. Instead:

• Create wrapper/decorator classes
• Use composition over inheritance
• Add extension methods for new behaviors

Test Requirements

Unit Tests (Required)

Location: ZChain.Tests/UnitTests/Domain/{Feature}Tests/

Copypublic class MyFeatureTests
{
    [Fact]
    public void WhenCondition_AndContext_ShouldExpectedBehavior()
    {
        // Arrange
        // Act
        // Assert with Shouldly
    }
}

Integration Tests (For workflows)

Location: ZChain.Tests/Integration/

Copy[Theory]
[InlineData(1, 1)]
[InlineData(2, 2)]
public async Task MyFeature_WithParameters_ShouldWork(int param1, int param2)
{
    // Full workflow test
}

Checklist

• Code follows file-scoped namespace style
• Public APIs have null checks (ArgumentNullException)
• Async methods use CancellationToken where appropriate
• Unit tests cover happy path and edge cases
• Integration test for full workflow (if applicable)
• Build passes with no warnings (dotnet build)
• All tests pass (dotnet test)

Commands

Copy# Build and verify
dotnet build src/ZChain.sln

# Run tests
dotnet test src/ZChain.sln

# Run specific test class
dotnet test --filter "FullyQualifiedName~MyFeatureTests"