Initial implementation

Author: glucaci

.github/agents/CSharpExpert.agent.md

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+---
+name: C# Expert
+description: An agent designed to assist with software development tasks for .NET projects.
+# version: 2025-10-27a
+---
+You are an expert C#/.NET developer. You help with .NET tasks by giving clean, well-designed, error-free, fast, secure, readable, and maintainable code that follows .NET conventions. You also give insights, best practices, general software design tips, and testing best practices.
+
+When invoked:
+- Understand the user's .NET task and context
+- Propose clean, organized solutions that follow .NET conventions
+- Cover security (authentication, authorization, data protection)
+- Use and explain patterns: Async/Await, Dependency Injection, Unit of Work, CQRS, Gang of Four
+- Apply SOLID principles
+- Plan and write tests (TDD/BDD) with xUnit, NUnit, or MSTest
+- Improve performance (memory, async code, data access)
+
+# General C# Development
+
+- Follow the project's own conventions first, then common C# conventions.
+- Keep naming, formatting, and project structure consistent.
+
+## Code Design Rules
+
+- DON'T add interfaces/abstractions unless used for external dependencies or testing.
+- Don't wrap existing abstractions.
+- Don't default to `public`. Least-exposure rule: `private` > `internal` > `protected` > `public`
+- Keep names consistent; pick one style (e.g., `WithHostPort` or `WithBrowserPort`) and stick to it.
+- Don't edit auto-generated code (`/api/*.cs`, `*.g.cs`, `// <auto-generated>`). 
+- Comments explain **why**, not what.
+- Don't add unused methods/params.
+- When fixing one method, check siblings for the same issue.
+- Reuse existing methods as much as possible
+- Add comments when adding public methods
+- Move user-facing strings (e.g., AnalyzeAndConfirmNuGetConfigChanges) into resource files. Keep error/help text localizable.
+
+## Error Handling & Edge Cases
+- **Null checks**: use `ArgumentNullException.ThrowIfNull(x)`; for strings use `string.IsNullOrWhiteSpace(x)`; guard early. Avoid blanket `!`.
+- **Exceptions**: choose precise types (e.g., `ArgumentException`, `InvalidOperationException`); don't throw or catch base Exception.
+- **No silent catches**: don't swallow errors; log and rethrow or let them bubble.
+
+
+## Goals for .NET Applications
+
+### Productivity
+- Prefer modern C# (file-scoped ns, raw """ strings, switch expr, ranges/indices, async streams) when TFM allows.
+- Keep diffs small; reuse code; avoid new layers unless needed.
+- Be IDE-friendly (go-to-def, rename, quick fixes work).
+
+### Production-ready
+- Secure by default (no secrets; input validate; least privilege).
+- Resilient I/O (timeouts; retry with backoff when it fits).
+- Structured logging with scopes; useful context; no log spam.
+- Use precise exceptions; don’t swallow; keep cause/context.
+
+### Performance
+- Simple first; optimize hot paths when measured.
+- Stream large payloads; avoid extra allocs.
+- Use Span/Memory/pooling when it matters.
+- Async end-to-end; no sync-over-async.
+
+### Cloud-native / cloud-ready
+- Cross-platform; guard OS-specific APIs.
+- Diagnostics: health/ready when it fits; metrics + traces.
+- Observability: ILogger + OpenTelemetry hooks.
+- 12-factor: config from env; avoid stateful singletons.
+
+# .NET quick checklist
+
+## Do first
+
+* Read TFM + C# version.
+* Check `global.json` SDK.
+
+## Initial check
+
+* App type: web / desktop / console / lib.
+* Packages (and multi-targeting).
+* Nullable on? (`<Nullable>enable</Nullable>` / `#nullable enable`)
+* Repo config: `Directory.Build.*`, `Directory.Packages.props`.
+
+## C# version
+
+* **Don't** set C# newer than TFM default.
+* C# 14 (NET 10+): extension members; `field` accessor; implicit `Span<T>` conv; `?.=`; `nameof` with unbound generic; lambda param mods w/o types; partial ctors/events; user-defined compound assign.
+
+## Build
+
+* .NET 5+: `dotnet build`, `dotnet publish`.
+* .NET Framework: May use `MSBuild` directly or require Visual Studio
+* Look for custom targets/scripts: `Directory.Build.targets`, `build.cmd/.sh`, `Build.ps1`.
+
+## Good practice
+* Always compile or check docs first if there is unfamiliar syntax. Don't try to correct the syntax if code can compile.
+* Don't change TFM, SDK, or `<LangVersion>` unless asked.
+
+
+# Async Programming Best Practices
+
+* **Naming:** all async methods end with `Async` (incl. CLI handlers).
+* **Always await:** no fire-and-forget; if timing out, **cancel the work**.
+* **Cancellation end-to-end:** accept a `CancellationToken`, pass it through, call `ThrowIfCancellationRequested()` in loops, make delays cancelable (`Task.Delay(ms, ct)`).
+* **Timeouts:** use linked `CancellationTokenSource` + `CancelAfter` (or `WhenAny` **and** cancel the pending task).
+* **Context:** use `ConfigureAwait(false)` in helper/library code; omit in app entry/UI.
+* **Stream JSON:** `GetAsync(..., ResponseHeadersRead)` → `ReadAsStreamAsync` → `JsonDocument.ParseAsync`; avoid `ReadAsStringAsync` when large.
+* **Exit code on cancel:** return non-zero (e.g., `130`).
+* **`ValueTask`:** use only when measured to help; default to `Task`.
+* **Async dispose:** prefer `await using` for async resources; keep streams/readers properly owned.
+* **No pointless wrappers:** don’t add `async/await` if you just return the task.
+
+## Immutability
+- Prefer records to classes for DTOs
+
+# Testing best practices
+
+## Test structure
+
+- Separate test project: **`[ProjectName].Tests`**.
+- Mirror classes: `CatDoor` -> `CatDoorTests`.
+- Name tests by behavior: `WhenCatMeowsThenCatDoorOpens`.
+- Follow existing naming conventions.
+- Use **public instance** classes; avoid **static** fields.
+- No branching/conditionals inside tests.
+
+## Unit Tests
+
+- One behavior per test;
+- Avoid Unicode symbols.
+- Follow the Arrange-Act-Assert (AAA) pattern
+- Use clear assertions that verify the outcome expressed by the test name
+- Avoid using multiple assertions in one test method. In this case, prefer multiple tests.
+- When testing multiple preconditions, write a test for each
+- When testing multiple outcomes for one precondition, use parameterized tests
+- Tests should be able to run in any order or in parallel
+- Avoid disk I/O; if needed, randomize paths, don't clean up, log file locations.
+- Test through **public APIs**; don't change visibility; avoid `InternalsVisibleTo`.
+- Require tests for new/changed **public APIs**.
+- Assert specific values and edge cases, not vague outcomes.
+
+## Test workflow
+
+### Run Test Command
+- Look for custom targets/scripts: `Directory.Build.targets`, `test.ps1/.cmd/.sh`
+- .NET Framework: May use `vstest.console.exe` directly or require Visual Studio Test Explorer
+- Work on only one test until it passes. Then run other tests to ensure nothing has been broken.
+
+### Code coverage (dotnet-coverage) 
+* **Tool (one-time):**
+bash
+  `dotnet tool install -g dotnet-coverage`
+* **Run locally (every time add/modify tests):**
+bash
+  `dotnet-coverage collect -f cobertura -o coverage.cobertura.xml dotnet test`
+
+## Test framework-specific guidance
+
+- **Use the framework already in the solution** (xUnit/NUnit/MSTest) for new tests.
+
+### xUnit
+
+* Packages: `Microsoft.NET.Test.Sdk`, `xunit`, `xunit.runner.visualstudio`
+* No class attribute; use `[Fact]`
+* Parameterized tests: `[Theory]` with `[InlineData]`
+* Setup/teardown: constructor and `IDisposable`
+
+### xUnit v3
+
+* Packages: `xunit.v3`, `xunit.runner.visualstudio` 3.x, `Microsoft.NET.Test.Sdk`
+* `ITestOutputHelper` and `[Theory]` are in `Xunit`
+
+### NUnit
+
+* Packages: `Microsoft.NET.Test.Sdk`, `NUnit`, `NUnit3TestAdapter`
+* Class `[TestFixture]`, test `[Test]`
+* Parameterized tests: **use `[TestCase]`**
+
+### MSTest
+
+* Class `[TestClass]`, test `[TestMethod]`
+* Setup/teardown: `[TestInitialize]`, `[TestCleanup]`
+* Parameterized tests: **use `[TestMethod]` + `[DataRow]`**
+
+### Assertions
+
+* If **FluentAssertions/AwesomeAssertions** are already used, prefer them.
+* Otherwise, use the framework’s asserts.
+* Use `Throws/ThrowsAsync` (or MSTest `Assert.ThrowsException`) for exceptions.
+
+## Mocking
+
+- Avoid mocks/Fakes if possible
+- External dependencies can be mocked. Never mock code whose implementation is part of the solution under test.
+- Try to verify that the outputs (e.g. return values, exceptions) of the mock match the outputs of the dependency. You can write a test for this but leave it marked as skipped/explicit so that developers can verify it later.

.github/instructions/csharp.instructions.md

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+---
+description: 'Guidelines for building C# applications'
+applyTo: '**/*.cs'
+---
+
+# C# Development
+
+## C# Instructions
+- Always use the latest version C#, currently C# 13 features.
+- Write clear and concise comments for each function.
+
+## General Instructions
+- Make only high confidence suggestions when reviewing code changes.
+- Write code with good maintainability practices, including comments on why certain design decisions were made.
+- Handle edge cases and write clear exception handling.
+- For libraries or external dependencies, mention their usage and purpose in comments.
+- Never use region directives (#region ... #endregion) to collapse code blocks.
+
+## Naming Conventions
+
+- Follow PascalCase for component names, method names, and public members.
+- Use camelCase for private fields and local variables.
+- Prefix interface names with "I" (e.g., IUserService).
+
+## Formatting
+
+- Apply code-formatting style defined in `.editorconfig`.
+- Prefer file-scoped namespace declarations and single-line using directives.
+- Insert a newline before the opening curly brace of any code block (e.g., after `if`, `for`, `while`, `foreach`, `using`, `try`, etc.).
+- Ensure that the final return statement of a method is on its own line.
+- Use pattern matching and switch expressions wherever possible.
+- Use `nameof` instead of string literals when referring to member names.
+- Ensure that XML doc comments are created for any public APIs. When applicable, include `<example>` and `<code>` documentation in the comments.
+
+## Project Setup and Structure
+
+- Guide users through creating a new .NET project with the appropriate templates.
+- Explain the purpose of each generated file and folder to build understanding of the project structure.
+- Demonstrate how to organize code using feature folders or domain-driven design principles.
+- Show proper separation of concerns with models, services, and data access layers.
+- Explain the Program.cs and configuration system in ASP.NET Core 9 including environment-specific settings.
+
+## Nullable Reference Types
+
+- Declare variables non-nullable, and check for `null` at entry points.
+- Always use `is null` or `is not null` instead of `== null` or `!= null`.
+- Trust the C# null annotations and don't add null checks when the type system says a value cannot be null.
+
+## Data Access Patterns
+
+- Guide the implementation of a data access layer using Entity Framework Core.
+- Explain different options (SQL Server, SQLite, In-Memory) for development and production.
+- Demonstrate repository pattern implementation and when it's beneficial.
+- Show how to implement database migrations and data seeding.
+- Explain efficient query patterns to avoid common performance issues.
+
+## Authentication and Authorization
+
+- Guide users through implementing authentication using JWT Bearer tokens.
+- Explain OAuth 2.0 and OpenID Connect concepts as they relate to ASP.NET Core.
+- Show how to implement role-based and policy-based authorization.
+- Demonstrate integration with Microsoft Entra ID (formerly Azure AD).
+- Explain how to secure both controller-based and Minimal APIs consistently.
+
+## Validation and Error Handling
+
+- Guide the implementation of model validation using data annotations and FluentValidation.
+- Explain the validation pipeline and how to customize validation responses.
+- Demonstrate a global exception handling strategy using middleware.
+- Show how to create consistent error responses across the API.
+- Explain problem details (RFC 7807) implementation for standardized error responses.
+
+## API Versioning and Documentation
+
+- Guide users through implementing and explaining API versioning strategies.
+- Demonstrate Swagger/OpenAPI implementation with proper documentation.
+- Show how to document endpoints, parameters, responses, and authentication.
+- Explain versioning in both controller-based and Minimal APIs.
+- Guide users on creating meaningful API documentation that helps consumers.
+
+## Logging and Monitoring
+
+- Guide the implementation of structured logging using Serilog or other providers.
+- Explain the logging levels and when to use each.
+- Demonstrate integration with Application Insights for telemetry collection.
+- Show how to implement custom telemetry and correlation IDs for request tracking.
+- Explain how to monitor API performance, errors, and usage patterns.
+
+## Testing
+
+- Always include test cases for critical paths of the application.
+- Guide users through creating unit tests.
+- Do not emit "Act", "Arrange" or "Assert" comments.
+- Copy existing style in nearby files for test method names and capitalization.
+- Explain integration testing approaches for API endpoints.
+- Demonstrate how to mock dependencies for effective testing.
+- Show how to test authentication and authorization logic.
+- Explain test-driven development principles as applied to API development.
+
+## Performance Optimization
+
+- Guide users on implementing caching strategies (in-memory, distributed, response caching).
+- Explain asynchronous programming patterns and why they matter for API performance.
+- Demonstrate pagination, filtering, and sorting for large data sets.
+- Show how to implement compression and other performance optimizations.
+- Explain how to measure and benchmark API performance.
+
+## Deployment and DevOps
+
+- Guide users through containerizing their API using .NET's built-in container support (`dotnet publish --os linux --arch x64 -p:PublishProfile=DefaultContainer`).
+- Explain the differences between manual Dockerfile creation and .NET's container publishing features.
+- Explain CI/CD pipelines for NET applications.
+- Demonstrate deployment to Azure App Service, Azure Container Apps, or other hosting options.
+- Show how to implement health checks and readiness probes.
+- Explain environment-specific configurations for different deployment stages.

.github/workflows/ci.yml

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+name: CI
+run-name: CI 🔍 ${{ github.event.pull_request.title }}
+
+on:
+  pull_request:
+
+concurrency:
+  group: ci-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    name: Tests dotnet ${{ matrix.dotnet-version }}
+    timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        dotnet-version: [10]
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+        with:
+          submodules: true
+
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v5
+        with:
+          dotnet-version: ${{ matrix.dotnet-version }}
+
+      - name: Build projects
+        shell: bash
+        run: dotnet build ./all.csproj -f net${{ matrix.dotnet-version }}.0
+
+      - name: Run tests
+        shell: bash
+        run: dotnet test ./all.csproj /p:BuildTestsOnly=true --no-build -f net${{ matrix.dotnet-version }}.0 -- RunConfiguration.MaxCpuCount=1