Create AGENTS.md with standard guidance for AI agents

[Copilot]

• Understand the repository structure and context
• Create AGENTS.md file with standard guidance for AI agents
• Include repository-specific information (build, test, architecture)
• Include coding standards and conventions
• Include testing guidelines
• Verify the file is properly formatted and complete
• Update build options to use single dash for consistency
• Merge EditorConfig section with C# Code Style section
• Add Development Workflow section
• Remove .NET Runtime Repository link from Resources
• Refine guidance on making changes to balance minimal changes with code clarity

Original prompt

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This section details on the original issue you should resolve

<issue_title>Create AGENTS.md</issue_title>
<issue_description>As we use copilot more we won't want to repeat the same general guidance again and again on every PR. Instead we should have an AGENTS.md file that provides this standard information in a reusable form.</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #5608

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[hoyosjs]

@copilot to make it consistent and easy with Windows and Linux, simplify to using a single dash

[Copilot]

Updated to use single dash for all build options. Changes in commit 3e6a67e.

[hoyosjs]

@copilot please address these and add a section on workflow.

[hoyosjs]

Merge this section and the next - the editor config is part of the coding standard of this repo and is a must for c# code.

[Copilot]

Merged EditorConfig section into C# Code Style section and emphasized it as a must for C# code. Changes in commit 2bf5e13.

[hoyosjs]

Suggested change

- [.NET Runtime Repository](https://github.com/dotnet/runtime)

[Copilot]

Removed the .NET Runtime Repository link. Changes in commit 2bf5e13.

[Copilot]

@copilot please address these and add a section on workflow.

Added a comprehensive Development Workflow section covering typical workflow, iterative development, and pull request guidelines. Also merged the EditorConfig section and removed the runtime link. Changes in commit 2bf5e13.

[noahfalk]

@copilot - if a PR stated you should follow guidance in AGENTS.md, then the content of AGENTS.md said to follow the guidance in some other file in this repo, would you recursively follow those links and act upon the guidance in the extra files? Since much of this guidance is equally applicable to human and AI actors I am curious about the potential to share markdown docs intended for both audiences. I only want you to answer the question for now, don't make changes to the PR based around this.

[Copilot]

@copilot - if a PR stated you should follow guidance in AGENTS.md, then the content of AGENTS.md said to follow the guidance in some other file in this repo, would you recursively follow those links a...

Yes, I would recursively follow links and act upon guidance in referenced files. When I see instructions like "follow guidance in AGENTS.md" or if AGENTS.md references other documentation files (e.g., "see coding standards in CONTRIBUTING.md"), I can access and incorporate that guidance into my decision-making.

This works well for sharing documentation between human and AI audiences. The key consideration is that AI agents need explicit direction to follow those links (e.g., "Follow the guidelines in AGENTS.md and any referenced documents"), whereas humans naturally navigate documentation hierarchies. You could structure it as:

• AGENTS.md: High-level guidance with references to detailed docs
• Shared docs (CONTRIBUTING.md, etc.): Detailed guidelines for both audiences

This approach avoids duplication while allowing AGENTS.md to serve as an entry point that contextualizes the shared documentation for AI agents.

[noahfalk]

@hoyosjs - if you like this one better than your other one I'm happy to merge either. I agree that putting some AGENTS.md into action and then refining it is probably the best path forward.

[noahfalk]

I think some refactoring from AGENTS.md into other docs might also be useful in the future (see #5609 (comment)) but isn't a blocker for this PR.