GitHub Radius feature spec

[zachcasper]

This pull request adds a comprehensive feature specification document for the GitHub Radius prototype. The document outlines the integration of Radius with GitHub repositories and Copilot, and details user journeys, technical workflows, and UI mockups for deploying applications from GitHub to AWS and Azure. The specification serves as a foundational reference for the development and future expansion of the GitHub Radius feature.

Feature Specification and User Journeys:

• Added 2026-03-github-radius-feature-spec.md, a detailed specification document describing the GitHub Radius prototype, its integration points (GitHub Actions, Copilot, GUI), and supported cloud providers (AWS, Azure).
• Documented primary user journeys, including deploying open-source applications to AWS/Azure, defining multiple environments, and visualizing code changes and their impact.
• Included step-by-step technical workflows for deploying to AWS, covering authentication, environment setup, resource definition, and deployment monitoring, complete with UI mockups and example commands.
• Outlined future out-of-scope journeys for Google Cloud support, Copilot-driven app creation, and migration to self-hosted Radius.
• Described the Radius platform constitution, resource modeling, and recipe parameter configuration processes, establishing the groundwork for standardization and extensibility.# Description

Contributor checklist

Please verify that the PR meets the following requirements, where applicable:

• An overview of proposed schema changes is included in a linked GitHub issue.
  • Yes
  • Not applicable
• A design document PR is created in the design-notes repository, if new APIs are being introduced.
  • Yes
  • Not applicable
• The design document has been reviewed and approved by Radius maintainers/approvers.
  • Yes
  • Not applicable
• A PR for the samples repository is created, if existing samples are affected by the changes in this PR.
  • Yes
  • Not applicable
• A PR for the documentation repository is created, if the changes in this PR affect the documentation or any user facing updates are made.
  • Yes
  • Not applicable
• A PR for the recipes repository is created, if existing recipes are affected by the changes in this PR.
  • Yes
  • Not applicable

[Copilot]

Pull request overview

Adds a design-note feature specification for the “GitHub Radius” prototype, describing GitHub-native Radius + Copilot integration and end-to-end user journeys (with UI mockups) for deploying a GitHub repo to AWS/Azure.

Changes:

• Add a comprehensive spec document covering user journeys and technical workflow for AWS environment setup and deployment.
• Add/update a UI mockup image referenced by the spec.

Reviewed changes

Copilot reviewed 1 out of 17 changed files in this pull request and generated 7 comments.

File	Description
eng/design-notes/github/2026-03-github-radius-feature-spec.md	New feature spec with user journeys, AWS OIDC/IAM workflow, and deployment UX walkthrough (with mockups + example commands/policies).
eng/design-notes/github/2026-03-github-radius-feature-spec/image13.png	Adds a mockup image used by the deployment step in the spec.