Add GitHub Copilot instructions and agent configurations by rmarinho · Pull Request #285 · dotnet/android-tools

rmarinho · 2026-02-24T15:03:40Z

Summary

Adds GitHub Copilot instructions, agent configuration, and modernizes the README.

Changes

.github/copilot-instructions.md (new)

Project-specific guidelines for AI-assisted development:

Multi-targeting: netstandard2.0 (required for .NET Framework / Visual Studio hosts) + net9.0
C# language: LangVersion=latest, file-scoped namespaces
JSON: Use System.Text.Json with source generators
Nullable: Enabled with INTERNAL_NULLABLE_ATTRIBUTES polyfill for netstandard2.0
Formatting: Tabs, .editorconfig rules, XML doc comments for public APIs
Testing: NUnit framework, AAA pattern, existing naming conventions
Logging: Action<TraceLevel, string> delegates

.github/CSharpExpert.agent.md (new)

Expert C#/.NET agent for this Android SDK tooling library:

Multi-targeting awareness (netstandard2.0 + $(DotNetTargetFramework))
Async best practices with ConfigureAwait(false)
NUnit testing guidance with existing naming patterns
Code design rules (SOLID, least-exposure)

README.md (updated)

Updated description with current API surface (SdkManager, runners, JdkInstaller, etc.)
Fixed .NET version requirement (6 to 9)
Added multi-targeting section explaining netstandard2.0 requirement
Removed outdated references (Xamarin feed, mailing list, Mono coding guidelines)
Updated repo link (xamarin/xamarin-android to dotnet/android)

Xamarin.Android.Tools.AndroidSdk.csproj

Changed LangVersion from 9.0 to latest

Testing

No behavioral code changes - documentation and build configuration only. Build verified locally.

Copilot

Pull request overview

This PR adds GitHub Copilot configuration files to provide AI assistance with repository-specific conventions and patterns. The files aim to guide Copilot on C# 9.0 language constraints, project structure, testing practices, and development patterns for the Xamarin.Android.Tools library.

Changes:

Adds .github/copilot-instructions.md with C# development guidelines
Adds .github/CSharpExpert.agent.md with C#/.NET expert agent configuration
Adds .github/principal-software-engineer.agent.md with principal-level engineering guidance

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 12 comments.

File	Description
`.github/copilot-instructions.md`	Project-specific C# guidelines including language version, nullable types, project structure, and API patterns
`.github/CSharpExpert.agent.md`	C#/.NET expert agent configuration with async patterns, testing, and code design rules
`.github/principal-software-engineer.agent.md`	Principal-level engineering guidance on design patterns, technical leadership, and debt management

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- Remove applyTo header (should apply to all files, not just *.cs) - Update C# version guidance to respect LangVersion from .csproj - Clarify Arcade SDK status (legacy pinned version, not fully onboarded) - Remove ASP.NET-specific guidance (caching, pagination, auth testing) - Clean up testing section (remove API endpoint references) - Fix performance section to be library-appropriate Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

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jonathanpeppers · 2026-02-24T17:21:26Z

@@ -1,26 +1,26 @@
-<?xml version="1.0" encoding="utf-8"?>


I would undo any changes to this file. Seems unrelated random changes.

If you want to change to net10.0 that should be a new PR.

- Revert Directory.Build.props and azure-pipelines.yaml (net10 is separate PR) - Change LangVersion from 9.0 to latest in csproj - Remove C# 9.0 features section (no longer relevant with latest) - Remove Naming Conventions section (editorconfig handles it) - Always use file-scoped namespaces - Use System.Text.Json with source generators - Add nullable extension guidance for netstandard2.0 - Fix CSharpExpert.agent.md: NUnit not xUnit, dynamic TFM reference - Remove applyTo header, Arcade SDK references - Clean up ASP.NET-specific guidance Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Revert Directory.Build.props and azure-pipelines.yaml (net10 is separate PR) - Change LangVersion from 9.0 to latest in csproj - Remove C# 9.0 features section (no longer relevant with latest) - Remove Naming Conventions section (editorconfig handles it) - Always use file-scoped namespaces - Use System.Text.Json with source generators - Add nullable extension guidance for netstandard2.0 - Fix CSharpExpert.agent.md: NUnit not xUnit, dynamic TFM reference - Remove applyTo header, Arcade SDK references - Clean up ASP.NET-specific guidance Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Update README: modernize for current project state - Update description with current APIs (SdkManager, runners, etc.) - Fix build badge URL to dnceng-public - Update repo link to dotnet/android - Fix .NET version requirement (6 -> 9) - Add multi-targeting section explaining netstandard2.0 requirement - Remove outdated Xamarin feed, mailing list, Mono coding guidelines - Simplify test command Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Update to .NET 10 - Directory.Build.props: DotNetTargetFrameworkVersion 9.0 -> 10.0 - azure-pipelines.yaml: DotNetCoreVersion 9.0.x -> 10.0.x - README.md and copilot-instructions.md: reference net10.0 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Revert "Update to .NET 10" This reverts commit 979699c.

Copilot

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 7 comments.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-02-24T18:19:57Z

+## Project-Specific Context
+
+This is the **Xamarin.Android.Tools** library - tools for interacting with the Android SDK:
+- Multi-targets: `netstandard2.0` and `$(DotNetTargetFramework)` (currently `net9.0`)


Typo: "netstandard2.0" is misspelled as "\netstandard2.0" (with backslashes instead of backticks). This should be netstandard2.0 for proper markdown formatting.

Copilot · 2026-02-24T18:19:57Z

+
+- Apply code-formatting style defined in `.editorconfig`
+- Use **tabs** for indentation in C# files (as per `.editorconfig`)
+- Always use **file-scoped namespaces** (`namespace Xamarin.Android.Tools;`)


The instruction to "Always use file-scoped namespaces" conflicts with the existing codebase convention. All C# files in the repository use traditional block-scoped namespaces (namespace X { }), not file-scoped namespaces (namespace X;). The instructions should be updated to use block-scoped namespaces to match the existing convention found throughout the codebase.

Copilot · 2026-02-24T18:19:58Z

+This is the **Xamarin.Android.Tools** library - tools for interacting with the Android SDK:
+- Multi-targets: `netstandard2.0` and `$(DotNetTargetFramework)` (currently `net9.0`)
+- **`netstandard2.0` is required** — this package is consumed by .NET Framework hosts (e.g., Visual Studio on Windows). All public API and core logic **must** compile against netstandard2.0. Use `#if NET5_0_OR_GREATER` guards for newer runtime features (e.g., `ArrayPool`, `Process.Kill(true)`)
+- C# Language Version: `LangVersion=latest` — use the latest C# features available for each target framework


The statement "LangVersion=latest — use the latest C# features available for each target framework" may be misleading. While the csproj now uses LangVersion=latest, this doesn't mean developers should freely use all latest C# features. The project multi-targets netstandard2.0, which has limitations on what C# features can be used (e.g., file-scoped namespaces require C# 10+, which isn't fully supported in netstandard2.0 scenarios). Consider clarifying that "latest" refers to the latest language features compatible with each target framework's constraints.

- Fix LangVersion guidance: clarify netstandard2.0 constraints - Change file-scoped to block-scoped namespaces (matches existing codebase) - Remove System.Text.Json guidance (not used in project) - Fix nullable string handling: use null-coalescing operator instead of non-existent OrEmpty() extension Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Add documentation to guide GitHub Copilot when working with this codebase: - .github/copilot-instructions.md: Project-specific coding guidelines - netstandard2.0 compatibility requirements - Block-scoped namespace convention (matches existing codebase) - Nullable reference types patterns - NUnit testing framework usage - Build and test commands - .github/CSharpExpert.agent.md: C# expert agent for code assistance - Code design rules and workflow guidance - Async best practices - Testing guidance with NUnit - README.md: Updated project description and build requirements Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jonathanpeppers · 2026-02-24T18:46:47Z

Closing in favor of:

If there is still something useful here, maybe we can put in a new PR -- or rebase/reopen.

These files were part of a separate copilot instructions PR (#285/#287). Main now has its own copilot-instructions.md. Removing: - CSharpExpert.agent.md (not in main) - principal-software-engineer.agent.md (not in main) - copilot-instructions.md changes (reverted to main) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings February 24, 2026 15:03

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rmarinho force-pushed the feature/add-copilot-instructions branch from 20076ed to 8872d18 Compare February 24, 2026 16:23

rmarinho added a commit that referenced this pull request Feb 24, 2026

Merge feature/add-copilot-instructions with PR #285 fixes

0d6f6d9

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

rmarinho requested review from Copilot and jonathanpeppers February 24, 2026 17:13

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rmarinho force-pushed the feature/add-copilot-instructions branch from 5e40e04 to 6a4142b Compare February 24, 2026 17:40

rmarinho requested a review from Copilot February 24, 2026 17:43

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rmarinho requested a review from Copilot February 24, 2026 18:14

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rmarinho force-pushed the feature/add-copilot-instructions branch from 1130086 to bd335eb Compare February 24, 2026 18:43

jonathanpeppers closed this Feb 24, 2026

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Summary

Changes

.github/copilot-instructions.md (new)

.github/CSharpExpert.agent.md (new)

README.md (updated)

Xamarin.Android.Tools.AndroidSdk.csproj

Testing

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jonathanpeppers commented Feb 24, 2026

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rmarinho commented Feb 24, 2026 •

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