Migrates ASP.NET Web API content negotiation and formatters to ASP.NET Core equivalents. Converts MediaTypeFormatter subclasses to InputFormatter/OutputFormatter, replaces IContentNegotiator with OutputFormatterSelector, and updates formatter registration from HttpConfiguration.Formatters to MvcOptions.
Install
npx skills add microsoft/upgrade-agent-plugins --skill migrating-mvc-content-negotiationnpx skills add microsoft/upgrade-agent-plugins --skill migrating-mvc-content-negotiation -a claude-code -gnpx skills add microsoft/upgrade-agent-plugins --skill migrating-mvc-content-negotiation -a codex -ggemini skills install https://github.com/microsoft/upgrade-agent-plugins.git --path plugins/upgrade-agent/upgrade/dotnet/skills/lazy/web/mvc/migrating-mvc-content-negotiationgh skill install microsoft/upgrade-agent-plugins migrating-mvc-content-negotiationgit clone --depth 1 https://github.com/microsoft/upgrade-agent-plugins /tmp/microsoft__upgrade-agent-plugins
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/microsoft__upgrade-agent-plugins/plugins/upgrade-agent/upgrade/dotnet/skills/lazy/web/mvc/migrating-mvc-content-negotiation ~/.claude/skills/migrating-mvc-content-negotiation # Claude Code
cp -R /tmp/microsoft__upgrade-agent-plugins/plugins/upgrade-agent/upgrade/dotnet/skills/lazy/web/mvc/migrating-mvc-content-negotiation ~/.agents/skills/migrating-mvc-content-negotiation # Codex, Cursor, Gemini CLI, Copilot, OpenCode