oauth

The OAuth skill solves a critical problem developers face when configuring OAuth authentication providers for local development with portless domains. When using portless with the default `.localhost` TLD, major OAuth providers like Google and Apple reject redirect URIs because `.localhost` subdomains are not recognized in the Public Suffix List or are explicitly blocked by provider policies. This causes "redirect_uri_mismatch" and "invalid redirect" errors that prevent sign-in functionality from working locally.

The skill provides a straightforward solution: use portless with a valid TLD from the Public Suffix List (such as `.dev`, `.app`, or `.com`) instead of `.localhost`. By running `portless proxy start --tld dev`, developers can serve their applications on domains like `https://myapp.dev` that OAuth providers recognize and accept. The skill includes specific configuration guidance for each major provider, explaining their validation rules and showing exactly how to set up authorized redirect URIs.

This skill is essential for full-stack developers and teams building applications with social sign-in features. It addresses authentication setup for Google, Apple, Microsoft, Facebook, and GitHub OAuth providers. The guidance covers both individual developer workflows and team configurations, including recommendations for using subdomains of owned domains (like `myapp.local.yourcompany.dev`) to prevent DNS collisions and enable wildcard DNS records for team-wide consistency. The skill is particularly valuable when dealing with strict providers like Google and Apple that have rigid localhost policies.