GitHub Copilot modernization for .NET

Scans .NET solution files, project dependencies, and package references to build a dependency graph that informs upgrade sequencing. The agent analyzes project-level metadata (csproj files, package.json equivalents, NuGet references) to determine which projects must be upgraded in what order to maintain build integrity and resolve transitive dependency conflicts. This enables dependency-aware upgrade planning rather than naive sequential upgrades.

Applies AI-driven code transformations to modernize C# syntax and APIs for target .NET versions (8, 9, 10). The agent generates and applies code changes (e.g., nullable reference types, record types, top-level statements, LINQ improvements) and observes user manual edits to learn patterns, then applies learned transformations to similar code patterns elsewhere in the solution. This combines template-based transformations with reinforcement from user corrections.

Automatically discovers and executes unit tests in the .NET project after code transformations are applied, using the native test runner (likely xUnit, NUnit, or MSTest based on project configuration). Test results are parsed to validate that transformations did not introduce regressions. Failed tests block further transformations or prompt user intervention, creating a safety gate for automated upgrades.

Automatically creates Git commits during the upgrade process, grouping related code transformations semantically (e.g., 'Upgrade NuGet packages', 'Modernize C# syntax', 'Update API calls'). Each commit is atomic and reversible, allowing developers to review and cherry-pick changes or revert specific upgrade steps. Commits are created within the repository context, respecting the current branch and Git state.

Exposes upgrade capabilities through a custom 'Modernize' agent in the Copilot Chat interface, allowing developers to interact with the upgrade process conversationally. Developers can ask natural language questions (e.g., 'Upgrade my solution to .NET 9'), and the agent orchestrates the full upgrade workflow: analysis, planning, transformation, testing, and commit creation. The agent maintains context across multiple chat turns, enabling iterative refinement of upgrade decisions.

Allows developers to specify the target .NET version (8, 9, or 10) and optionally enable automatic remediation of security vulnerabilities in dependencies during the upgrade. When security remediation is enabled, the agent identifies vulnerable NuGet packages and upgrades them to patched versions as part of the upgrade process. This decouples version upgrades from security updates, giving developers control over the scope of changes.

Analyzes .NET code and project structure within the local VS Code environment without retaining code snippets, custom tasks, or analysis results beyond the immediate session. Code is processed by the Copilot backend but explicitly not stored, logged, or used for model training. This design prioritizes privacy for enterprises handling proprietary code while still leveraging cloud-based AI capabilities for analysis.