dotnet-nuget-proxy

.NET in the Claude Code Web Environment

This skill provides everything needed to get .NET working in a Claude Code web session, including SDK installation and NuGet proxy authentication.

When to Use This Skill

Use this skill whenever the user wants to:

• Install the .NET SDK in a Claude Code web session
• Run dotnet restore, dotnet build, dotnet run, or dotnet new
• Fix 401/407 proxy authentication errors from NuGet
• Create a new .NET project in the web environment
• Troubleshoot any .NET or NuGet connectivity issues

Automatic Setup via SessionStart Hook

For projects that use .NET regularly, a SessionStart hook can automatically install the SDK and configure the proxy when a Claude Code web session starts. This means dotnet restore just works from the first command.

To set this up in a project, add to .claude/settings.json:

{
  "hooks": {
    "SessionStart": [
      {
        "matcher": "startup",
        "hooks": [
          {
            "type": "command",
            "command": "bash \"$CLAUDE_PROJECT_DIR\"/.claude/plugins/dotnet-nuget-proxy-skill/hooks/session-start.sh"
          }
        ]
      }
    ]
  }
}

The path above assumes the plugin was cloned to .claude/plugins/dotnet-nuget-proxy-skill/. Adjust if installed elsewhere. Ensure the hook script is executable (chmod +x).

The hook checks CLAUDE_CODE_REMOTE internally and:

• Only runs in Claude Code web sessions (exits immediately on desktop)
• Installs .NET SDK from packages.microsoft.com if not present
• Compiles and installs the credential provider
• Starts the proxy daemon
• Persists the dotnet() shell function and _NUGET_UPSTREAM_PROXY via $CLAUDE_ENV_FILE

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Manual Decision Flow

Follow these steps in order when the user wants to use .NET (if no SessionStart hook is configured):

Step 1: Detect required .NET version from the project

IMPORTANT: Before installing any .NET SDK, check the project's .csproj or .sln files to determine the required version: