GitHub Enterprise Server (GHES) support

[raghavpillai]

Summary

Better Hub currently only works with github.com. It would be great to support GitHub Enterprise Server (GHES) instances, since a lot of teams and orgs run private GHES deployments internally.

Problem

• All GitHub API calls, OAuth flows, and web URLs are hardcoded to github.com / api.github.com
• The socialProviders.github OAuth provider uses github.com endpoints exclusively
• Avatar URLs on GHES private-mode instances require web session cookies (API tokens don't work for the avatars subdomain)
• Links throughout the UI point to github.com with no way to override

Proposal

1. Centralized GitHub URL config — a single github-config.ts that reads from environment variables (GITHUB_WEB_URL, GITHUB_API_URL, GITHUB_GRAPHQL_URL, etc.) and falls back to github.com defaults. Every file that builds a GitHub URL imports from this config instead of hardcoding.

2. Generic OAuth — replace socialProviders.github with better-auth's genericOAuth plugin so the authorization and token endpoints can point at a GHES instance.

3. Avatar proxy for GHES private mode — a server-side route that authenticates with the GHES web UI, caches the session cookie, and proxies avatar images. A GhesImage component wraps next/image to transparently route GHES avatar URLs through the proxy.

4. UI link updates — swap all hardcoded https://github.com references in components to use the configurable base URL, so "Open in GitHub" links, breadcrumbs, and copy-link buttons all point at the correct host.

Configuration

The following env vars would control GHES mode (all optional, defaults to github.com):

NEXT_PUBLIC_GITHUB_WEB_URL=https://ghes.example.com
GITHUB_API_URL=https://ghes.example.com/api/v3
GITHUB_GRAPHQL_URL=https://ghes.example.com/api/graphql

# For private-mode avatar proxying
GHES_AVATAR_USERNAME=bot-account
GHES_AVATAR_PASSWORD=password

When none of these are set, behavior is identical to today.

Notes

• GHES uses /api/v3 and /api/graphql paths on the same host rather than separate api.github.com / github.com domains
• Private mode GHES instances serve avatars behind web session auth, not API token auth
• OAuth apps on GHES support the same OAuth2 flow, just with different endpoint URLs